214 results on '"Simo, Gustave"'
Search Results
2. SOX2 dosage sustains tumor-promoting inflammation to drive disease aggressiveness by modulating the FOSL2/IL6 axis
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Njouendou, Abdel Jelil, Szarvas, Tibor, Tiofack, Arnol Auvaker Zebaze, Kenfack, Rovaldo Nguims, Tonouo, Pamela Derliche, Ananga, Sidonie Noa, Bell, Esther H. M. Dina, Simo, Gustave, Hoheisel, Jörg D., Siveke, Jens T., and Lueong, Smiths S.
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- 2023
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3. Assessment of the capacity of Whatman filter papers as support to store stools for the molecular diagnostic testing of soil-transmitted helminthiasis
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Nguemnang Kamdem, Cyrille, Soubgwi Fogue, Pythagore, Zebaze Tiofack, Auvaker Arnol, Mezajou Mewamba, Estelle, Tekeu Mengoue, Loic Edmond, Womeni, Macaire Hilaire, and Simo, Gustave
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- 2023
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4. Diversity of trypanosome species in small ruminants, dogs and pigs from three sleeping sickness foci of the south of Chad
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Vourchakbe, Joël, Tiofack Zebaze, Arnol Auvaker, Kante Tagueu, Sartrien, Demba Kodindo, Israël, Barka Padja, Abdoul, and Simo, Gustave
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- 2023
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5. Trypanosome infections in animals from tsetse infected areas of Cameroon and their sensitivity and resistance molecular profiles for diminazene aceturate and isometamidium chloride
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Mewamba, Estelle Mezajou, Magang, Eugenie Melaine Kemta, Tiofack, Arnol Auvaker Zebaze, Woguia, Gilles-fils, Bouaka, Calmes Ursain Tsakeng, Kamga, Rolin Mitterran Ndeffo, Farikou, Oumarou, Fogue, Pythagore Sobgwi, Tume, Christopher, Ravel, Sophie, and Simo, Gustave
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- 2023
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6. Molecular characterization of early breast cancer onset to understand disease phenotypes in African patients
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Tonouo, Pamela Derliche, Dina Bell, Esther, Tiofack Zebaze, Arnol Auvaker, Ndounga, Eliane, Noa Ananga, Sidonie, Atenguena, Etienne, Simo, Gustave, Njouendou, Abdel Jelil, and Lueong, Smiths S.
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- 2023
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7. Fine mapping of Ascaris lumbricoides, Trichuris trichiura and hookworm infections in sub-districts of Makenene in Centre Region of Cameroun
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Kamdem, Cyrille Nguemnang, Tiofack, Auvaker Arnol Zebaze, Mewamba, Estelle Mezajou, Tchounkeu, Esthelline Yangea, Tatang, Joël Rostand Atiokeng, Mengoue, Edmond Loic Tekeu, Mbagnia, Carole Mureille Tchami, Fogue, Pythagore Soubgwi, Womeni, Hilaire Macaire, and Simo, Gustave
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- 2022
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8. G6PD distribution in sub-Saharan Africa and potential risks of using chloroquine/hydroxychloroquine based treatments for COVID-19
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da Rocha, Jorge E. B., Othman, Houcemeddine, Tiemessen, Caroline T., Botha, Gerrit, Ramsay, Michèle, Masimirembwa, Collen, Adebamowo, Clement, Choudhury, Ananyo, Brandenburg, Jean-Tristan, Matshaba, Mogomotsi, Simo, Gustave, Gamo, Francisco-Javier, and Hazelhurst, Scott
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- 2021
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9. The internal transcribed spacer 1 sequence polymorphism brings updates to tsetse species distribution in the northern Cameroon: Importance in planning efficient vector control.
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Feudjio Soffack, Steve, Melachio Tanekou, Tito Tresor, Farikou, Oumarou, Kame Ngasse, Ginette Irma, Tchami Mbagnia, Mureille Carole, Wondji, Murielle, Wondji, Charles S., Abd‐Alla, Adly M. M., Geiger, Anne, Simo, Gustave, and Njiokou, Flobert
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TSETSE-flies ,SPECIES distribution ,VECTOR control ,AFRICAN trypanosomiasis ,AFRICAN animals ,SYMPATRIC speciation - Abstract
Vector control remains one of the best strategies to prevent the transmission of trypanosome infections in humans and livestock and, thus, a good way to achieve the elimination of human African trypanosomiasis and animal African trypanosomiasis. A key prerequisite for the success of any vector control strategy is the accurate identification and correct mapping of tsetse species. In this work, we updated the tsetse fly species identification and distribution in many geographical areas in Cameroon. Tsetse flies were captured from six localities in Cameroon, and their species were morphologically identified. Thereafter, DNA was extracted from legs of each tsetse fly and the length polymorphism of internal transcribed spacer‐1 (ITS1) region of each fly was investigated using PCR. ITS1 DNA fragments of each tsetse species were sequenced. The sequences obtained were analysed and compared to those available in GenBank. This enabled to confirm/infirm results of the morphologic identification and then, to establish the phylogenetic relationships between tsetse species. Morphologic features allowed to clearly distinguish all the tsetse species captured in the South Region of Cameroon, that is, Glossina palpalis palpalis, G. pallicera, G. caliginea and G. nigrofusca. In the northern area, G. morsitans submorsitans could also be distinguished from G. palpalis palpalis, G. tachinoides and G. fuscipes, but these three later could not be distinguished with routine morphological characters. The ITS1 length polymorphism was high among most of the studied species and allowed to identify the following similar species with a single PCR, that is, G. palpalis palpalis with 241 or 242 bp and G. tachinoides with 221 or 222 bp, G. fuscipes with 236 or 237 bp. We also updated the old distribution of tsetse species in the areas assessed, highlighting the presence of G. palpalis palpalis instead of G. fuscipes in Mbakaou, or in sympatry with G. morsitans submorsitans in Dodeo (northern Cameroon). This study confirms the presence of G. palpalis palpalis in the Adamawa Region of Cameroon. It highlights the limits of using morphological criteria to differentiate some tsetse species. Molecular tools based on the polymorphism of ITS1 of tsetse flies can differentiate tsetse species through a simple PCR before downstream analyses or vector control planning. [ABSTRACT FROM AUTHOR]
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- 2024
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10. Molecular identification of diminazene aceturate resistant trypanosomes in tsetse flies from Yoko in the Centre region of Cameroon and its epidemiological implications
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Simo, Gustave, Magang, Eugenie Melaine Kemta, Mewamba, Estelle Mezajou, Farikou, Oumarou, Kamga, Rolin Mitterran Ndeffo, Tume, Christopher, Solano, Philippe, and Ravel, Sophie
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- 2020
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11. Molecular identification of diminazene aceturate-resistant strains of Trypanosoma congolense in naturally infected domestic animals of Yoko in the centre region of Cameroon
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Mewamba, Estelle Mezajou, Farikou, Oumarou, Kamga, Rolin Mitterran Ndefo, Magang, Melaine Eugenie Kemta, Tume, Christopher, Tiofack, Arnol Auvaker Zébazé, Ravel, Sophie, and Simo, Gustave
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- 2020
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12. Diversity of tsetse flies and trypanosome species circulating in the area of Lake Iro in southeastern Chad
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Signaboubo, Djoukzoumka, Payne, Vincent Khan, Moussa, Ibrahim Mahamat Alhadj, Hassane, Hassane Mahamat, Berger, Petra, Kelm, Soerge, and Simo, Gustave
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- 2021
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13. Molecular identification of different trypanosome species in tsetse flies caught in the wildlife reserve of Santchou in the western region of Cameroon
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Kamdem, Cyrille Nguemnang, Tiofack, Arnol Auvaker Zebaze, Mewamba, Estelle Mezajou, Ofon, Elvis Amih, Gomseu, Emmanuel Boris Djoumessi, and Simo, Gustave
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- 2020
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14. A countrywide molecular survey leads to a seminal identification of the invasive cattle tick Rhipicephalus (Boophilus) microplus in Cameroon, a decade after it was reported in Cote d’Ivoire
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Silatsa, Barberine A., Kuiate, Jules-Roger, Njiokou, Flobert, Simo, Gustave, Feussom, Jean-Marc K., Tunrayo, Alabi, Amzati, Gaston S., Bett, Bernard, Bishop, Richard, Githaka, Naftaly, Opiyo, Stephen O., Djikeng, Appolinaire, and Pelle, Roger
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- 2019
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15. Characterization of CYP2B6 and CYP2A6 Pharmacogenetic Variation in Sub‐Saharan African Populations.
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Twesigomwe, David, Drögemöller, Britt I., Wright, Galen E. B., Adebamowo, Clement, Agongo, Godfred, Boua, Palwendé R., Matshaba, Mogomotsi, Paximadis, Maria, Ramsay, Michèle, Simo, Gustave, Simuunza, Martin C., Tiemessen, Caroline T., Lombard, Zané, and Hazelhurst, Scott
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SUB-Saharan Africans ,PHARMACOGENOMICS ,HAPLOTYPES ,GENETIC variation ,ETHNOLINGUISTIC groups ,AFRICAN diaspora - Abstract
Genetic variation in CYP2B6 and CYP2A6 is known to impact interindividual response to antiretrovirals, nicotine, and bupropion, among other drugs. However, the full catalogue of clinically relevant pharmacogenetic variants in these genes is yet to be established, especially across African populations. This study therefore aimed to characterize the star allele (haplotype) distribution in CYP2B6 and CYP2A6 across diverse and understudied sub‐Saharan African (SSA) populations. We called star alleles from 961 high‐depth full genomes using StellarPGx, Aldy, and PyPGx. In addition, we performed CYP2B6 and CYP2A6 star allele frequency comparisons between SSA and other global biogeographical groups represented in the new 1000 Genomes Project high‐coverage dataset (n = 2,000). This study presents frequency information for star alleles in CYP2B6 (e.g., *6 and *18; frequency of 21–47% and 2–19%, respectively) and CYP2A6 (e.g., *4, *9, and *17; frequency of 0–6%, 3–10%, and 6–20%, respectively), and predicted phenotypes (for CYP2B6), across various African populations. In addition, 50 potentially novel African‐ancestry star alleles were computationally predicted by StellarPGx in CYP2B6 and CYP2A6 combined. For each of these genes, over 4% of the study participants had predicted novel star alleles. Three novel star alleles in CYP2A6 (*54, *55, and *56) and CYP2B6 apiece, and several suballeles were further validated via targeted Single‐Molecule Real‐Time resequencing. Our findings are important for informing the design of comprehensive pharmacogenetic testing platforms, and are highly relevant for personalized medicine strategies, especially relating to antiretroviral medication and smoking cessation treatment in Africa and the African diaspora. More broadly, this study highlights the importance of sampling diverse African ethnolinguistic groups for accurate characterization of the pharmacogene variation landscape across the continent. [ABSTRACT FROM AUTHOR]
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- 2024
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16. Molecular characterization of lower vaginal swabs for Human papilloma virus in association with Chlamydia trachomatis infection in Cameroonian Women
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Fogue, Pythagore, Djeudong, Geraldo, Bouting, George, Aglago, Elom, Simo, Gustave, and Lueong, Smiths
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- 2018
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17. Do Cryptic Reservoirs Threaten Gambiense-Sleeping Sickness Elimination?
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Büscher, Philippe, Bart, Jean-Mathieu, Boelaert, Marleen, Bucheton, Bruno, Cecchi, Giuliano, Chitnis, Nakul, Courtin, David, Figueiredo, Luisa M., Franco, José-Ramon, Grébaut, Pascal, Hasker, Epco, Ilboudo, Hamidou, Jamonneau, Vincent, Koffi, Mathurin, Lejon, Veerle, MacLeod, Annette, Masumu, Justin, Matovu, Enock, Mattioli, Raffaele, Noyes, Harry, Picado, Albert, Rock, Kat S., Rotureau, Brice, Simo, Gustave, Thévenon, Sophie, Trindade, Sandra, Truc, Philippe, and Van Reet, Nick
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- 2018
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18. Trypanosome infections in naturally infected horses and donkeys of three active sleeping sickness foci in the south of Chad
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Vourchakbé, Joël, Tiofack, Arnol Auvaker Z., Mbida, Mpoame, and Simo, Gustave
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- 2020
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19. A comprehensive survey of the prevalence and spatial distribution of ticks infesting cattle in different agro-ecological zones of Cameroon
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Silatsa, Barberine A., Simo, Gustave, Githaka, Naftaly, Mwaura, Stephen, Kamga, Rolin M., Oumarou, Farikou, Keambou, Christian, Bishop, Richard P., Djikeng, Appolinaire, Kuiate, Jules-Roger, Njiokou, Flobert, and Pelle, Roger
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- 2019
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20. Association between highly active antiretroviral therapy (HAART) and hypertension in persons living with HIV/AIDS at the Bamenda regional hospital, Cameroon
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Pepanze Jill, Mbunka Muhamed Awolu, Simo Gustave, Tayong Gladys, and Samuel Nambile Cumber
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hypertension ,haart ,haart-naïve ,association ,plwhiv ,Medicine - Abstract
INTRODUCTION: The introduction of highly active antiretroviral therapy (HAART) in the treatment of HIV infection has provided different good results: like long-term viral suppression, the decrease of opportunistic infections, and repair of the immune system. METHODS: we carried out a hospital-based cross-sectional analytic study involving 315 participants 228 were on HAART (group 1) and 87 were HAART-naive (group 2) at the HIV treatment centre of the Bamenda regional hospital with our study population being all people living with HIV (PLWHIV) in the North West region of Cameroon. The sampling was performed from the 15th of March to the 30th of June 2017. The questionnaire was administered face to face with participants and their vital signs taken. Blood pressure was measured using an automated electronic blood pressure monitor and hypertension (HTN) was considered as systolic blood pressure (BP) e" 140 mmHg and/or diastolic BP e" 90mmHg. RESULTS: the prevalence of hypertension in the HAART group was 36.44% (n=82, CI: 30.15%-43.10%) compared to that of the HAART-naive group which was 13.33% (n=12, CI: 7.08%-22.13%, P=0.01). HAART was associated with HTN after controlling for gender, family history of hypertension, body mass index (BMI), smoking and alcohol consumption. The odds ratio of the HAART-treated versus the HAART-naive was 3.86 (95% CI: 1.98-7.50). we also found an association between TDF/3TC/EFV (OR=2.83), AZT/3TC/NVP (OR=2.82), AZT/3TC+EFV (OR=3.48) and TDF/3TC+NVP (OR=2.36) and HTN whereas those on AZT+3TC+ATV/r (OR=0.84) and TDF+3TC+ATV/r (OR=0.45) were not associated to hypertension. CONCLUSION: our result suggests that blood pressure should be periodically measured and treated when necessary in PLWHIV on HAART.
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- 2019
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21. Prevalence of blood and skin trypanosomes in domestic and wild fauna from two sleeping sickness foci in Southern Cameroon.
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Magang, Eugenie Melaine Kemta, Kamga, Rolin Mitterran Ndefo, Telleria, Jenny, Tichit, Magali, Crouzols, Aline, Kaboré, Jacques, Hardy, David, Bouaka, Calmes Ursain Tsakeng, Jamonneau, Vincent, Rotureau, Brice, Kuete, Victor, Bart, Jean-Mathieu, and Simo, Gustave
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TRYPANOSOMA ,AFRICAN trypanosomiasis ,TRYPANOSOMA brucei ,NEGLECTED diseases ,DOMESTIC animals ,SKIN infections - Abstract
Although studies on African Trypanosomiases revealed a variety of trypanosome species in the blood of various animal taxa, animal reservoirs of Trypanosoma brucei gambiense and anatomical niches such as skin have been overlooked in most epidemiological settings. This study aims to update epidemiological data on trypanosome infections in animals from human African trypanosomiasis (HAT) foci of Cameroon. Blood and skin snips were collected from 291 domestic and wild animals. DNA was extracted from blood and skin snips and molecular approaches were used to identify different trypanosomes species. Immunohistochemical analyses were used to confirm trypanosome infections in skin snips. PCR revealed 137 animals (47.1%) with at least one trypanosome species in the blood and/or in the skin. Of these 137 animals, 90 (65.7%) and 32 (23.4%) had trypanosome infections respectively in the blood and skin. Fifteen (10.9%) animals had trypanosome infections in both blood and skin snip. Animals from the Campo HAT focus (55.0%) were significantly (X
2 = 17.6; P< 0.0001) more infected than those (29.7%) from Bipindi. Trypanosomes of the subgenus Trypanozoon were present in 27.8% of animals while T. vivax, T. congolense forest type and savannah type were detected in 16.5%, 10.3% and 1.4% of animals respectively. Trypanosoma b. gambiense infections were detected in the blood of 7.6% (22/291) of animals. No T. b. gambiense infection was detected in skin. This study highlights the presence of several trypanosome species in the blood and skin of various wild and domestic animals. Skin appeared as an anatomical reservoir for trypanosomes in animals. Despite methodological limitations, pigs, sheep, goats and wild animals were confirmed as potential reservoirs of T. b. gambiense. These animal reservoirs must be considered for the designing of control strategies that will lead to sustainable elimination of HAT. Author summary: Human African Trypanosomiasis (HAT) is a neglected tropical disease affecting some sub-Saharan Africa countries. Although HAT elimination can be considered as achieved in some foci, the interruption of its transmission by 2030 remains a challenge. Animal reservoir and skin-dwelling trypanosomes have emerged as factors that can compromise sustainable elimination of HAT. It is in this light that T. b. gambiense infections and different trypanosome species were identified in blood and skin of domestic and wild animals from two HAT foci of the forest region of Cameroon. For this study, blood and skin snip samples were collected from domestic and wild animals. Molecular tools were used to identify different trypanosome species. Several trypanosome species including trypanosomes of the subgenus Trypanozoon, T. vivax and T. congolense were detected in the blood and skin of several animal taxa. Immuno-histochemical tools confirmed trypanosome infections in the skin. Pigs, sheep, goats and wild animals were confirmed as potential animal reservoirs of T. b. gambiense. Results of this study highlighted the necessity of considering animal reservoirs as well as skin-dwelling trypanosomes in the designing of new control strategies that will lead to the interruption of HAT transmission by 2030. [ABSTRACT FROM AUTHOR]- Published
- 2023
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22. Detection of Wolbachia and different trypanosome species in Glossina palpalis palpalis populations from three sleeping sickness foci of southern Cameroon
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Kanté, Sartrien Tagueu, Melachio, Trésor, Ofon, Elvis, Njiokou, Flobert, and Simo, Gustave
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- 2018
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23. Prevalence of symbionts and trypanosome infections in tsetse flies of two villages of the “Faro and Déo” division of the Adamawa region of Cameroon
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Kame-Ngasse, Ginette Irma, Njiokou, Flobert, Melachio-Tanekou, Tito Trésor, Farikou, Oumarou, Simo, Gustave, and Geiger, Anne
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- 2018
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24. Micro RNA expression profiles in peripheral blood cells of rats that were experimentally infected with Trypanosoma congolense and different Trypanosoma brucei subspecies
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Simo, Gustave, Lueong, Smiths, Grebaut, Pascal, Guny, Gerard, and Hoheisel, Jörg D.
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- 2015
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25. Molecular identification of Trypanosoma brucei gambiense in naturally infected pigs, dogs and small ruminants confirms domestic animals as potential reservoirs for sleeping sickness in Chad
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Vourchakbé Joël, Tiofack Zebaze Arnol Auvaker, Kante Tagueu Sartrien, Mpoame Mbida, and Simo Gustave
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animal reservoir ,trypanosoma brucei gambiense ,sleeping sickness ,domestic animals ,Infectious and parasitic diseases ,RC109-216 - Abstract
Human African trypanosomiasis (HAT) has been targeted for zero transmission to humans by 2030. Animal reservoirs of gambiense-HAT could jeopardize these elimination goals. This study was undertaken to identify potential host reservoirs for Trypanosoma brucei gambiense by detecting its natural infections in domestic animals of Chadian HAT foci. Blood samples were collected from 267 goats, 181 sheep, 154 dogs, and 67 pigs. Rapid diagnostic test (RDT) and capillary tube centrifugation (CTC) were performed to search for trypanosomes. DNA was extracted from the buffy coat, and trypanosomes of the subgenus Trypanozoon as well as T. b. gambiense were identified by PCR. Of 669 blood samples, 19.4% were positive by RDT and 9.0% by CTC. PCR revealed 150 animals (22.4%) with trypanosomes belonging to Trypanozoon, including 18 (12%) T. b. gambiense. This trypanosome was found in all investigated animal species and all HAT foci. Between animal species or villages, no significant differences were observed in the number of animals harboring T. b. gambiense DNA. Pigs, dogs, sheep and goats appeared to be potential reservoir hosts for T. b. gambiense in Chad. The identification of T. b. gambiense in all animal species of all HAT foci suggests that these animals should be considered when designing new control strategies for sustainable elimination of HAT. Investigations aiming to decrypt their specific role in each epidemiological setting are important to achieve zero transmission of HAT.
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- 2020
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26. Molecular identification of Wolbachia and Sodalis glossinidius in the midgut of Glossina fuscipes quanzensis from the Democratic Republic of Congo
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Simo Gustave, Kanté Sartrien Tagueu, Madinga Joule, Kame Ginette, Farikou Oumarou, Ilombe Gillon, Geiger Anne, Lutumba Pascal, and Njiokou Flobert
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Glossina fuscipes quanzensis ,Wolbachia ,Sodalis glossinidius ,Democratic Republic of Congo ,PCR ,Infectious and parasitic diseases ,RC109-216 - Abstract
During the last 30 years, investigations on the microbiome of different tsetse species have generated substantial data on the bacterial flora of these cyclical vectors of African trypanosomes, with the overarching goal of improving the control of trypanosomiases. It is in this context that the presence of Wolbachia and Sodalis glossinidius was studied in wild populations of Glossina fuscipes quanzensis from the Democratic Republic of Congo. Tsetse flies were captured with pyramidal traps. Of the 700 Glossina f. quanzensis captured, 360 were dissected and their midguts collected and analyzed. Sodalis glossinidius and Wolbachia were identified by PCR. The Wolbachia-positive samples were genetically characterized with five molecular markers. PCR revealed 84.78% and 15.55% midguts infected by Wolbachia and S. glossinidius, respectively. The infection rates varied according to capture sites. Of the five molecular markers used to characterize Wolbachia, only the fructose bis-phosphate aldolase gene was amplified for about 60% of midguts previously found with Wolbachia infections. The sequencing results confirmed the presence of Wolbachia and revealed the presence of S. glossinidius in the midgut of Glossina f. quanzensis. A low level of midguts were naturally co-infected by both bacteria. The data generated in this study open a framework for investigations aimed at understanding the contribution of these symbiotic microorganisms to the vectorial competence of Glossina fuscipes quanzensis.
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- 2019
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27. Trypanosome Infections and Anemia in Cattle Returning from Transhumance in Tsetse-Infested Areas of Cameroon.
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Farikou, Oumarou, Simo, Gustave, Njiokou, Flobert, Kamé Ngassé, Ginette Irma, Achiri Fru, Martin, and Geiger, Anne
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TRANSHUMANCE ,CATTLE ,MIXED infections ,ANEMIA ,TRYPANOSOMIASIS ,ANIMAL herds - Abstract
The objective of this work was to assess the anemic status and the use of an immunological test and PCR-based methods to determine the infection rates of trypanosomes species. Transhumance aims to provide cattle with greener pastures and greater water resources than in the Djerem region during the dry season. Two criteria were used to assess the health status of the animals, the prevalence of trypanosomiasis and the level of anemia. In addition, we have evaluated the effectiveness, in trypanosomiasis detection, of the Very Diag Kit (CEVA Santé animale), a Rapid diagnosis test (RDT) based on immunological identification of T. congolense s.l. and T. vivax, responsible for AAT. Four trypanosome species (Trypanosoma congolense savannah type (Tcs), T. congolense forest type (Tcf), T. brucei s.l. (Tbr) and T. vivax (Tvx)) were identified in cattle sampled in four villages. The overall infection rate determined by PCR (68.6%) was much higher than those generally reported in cattle from the Adamawa region (35 to 50%). Infections (including mixed infections) by Tc s.l. (Tcs + Tcf) were predominant (45.7%). The infection rates were also determined using the Very Diag Kit allowing us to identify Tc s.l. and Tvx in the field in less than 20 min. This method provided, for the global infection, a higher rate (76.5%) than that determined by PCR (68.6%), although it is supposed to be less sensitive than PCR. Tc s.l. infection rate (37.8%) was similar to that (38.8%) determined by PCR (Tcs + Tcf single infections). In contrast, the prevalence of Tvx single infections measured by RDT (18%) was nearly two-fold higher than that (9.4%) measured by PCR. Thus, further comparative analyses seem to be needed in order to more accurately assess the sensitivity and specificity of the Very Diag test under our conditions of use on blood samples. The mean PCVs in trypanosome-infected as well as in uninfected cattle were below 25%, the threshold below which an animal is considered anemic. Our study shows that cattle return from transhumance in poor health. It raises questions about its real benefit, especially since the herds are themselves likely to become vectors of trypanosomiasis and possibly of other diseases. At least, effective measures have to be undertaken to treat all cattle coming back from transhumance. [ABSTRACT FROM AUTHOR]
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- 2023
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28. Characterization of CYP2D6 Pharmacogenetic Variation in Sub‐Saharan African Populations.
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Twesigomwe, David, Drögemöller, Britt I., Wright, Galen E.B., Adebamowo, Clement, Agongo, Godfred, Boua, Palwendé R., Matshaba, Mogomotsi, Paximadis, Maria, Ramsay, Michèle, Simo, Gustave, Simuunza, Martin C., Tiemessen, Caroline T., Lombard, Zané, and Hazelhurst, Scott
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SUB-Saharan Africans ,CYTOCHROME P-450 CYP2D6 ,CYTOCHROME P-450 ,WHOLE genome sequencing ,ETHNOLINGUISTIC groups ,PHARMACOGENOMICS - Abstract
Cytochrome P450 2D6 (CYP2D6) is a key enzyme in drug response owing to its involvement in the metabolism of ~ 25% of clinically prescribed medications. The encoding CYP2D6 gene is highly polymorphic, and many pharmacogenetics studies have been performed worldwide to investigate the distribution of CYP2D6 star alleles (haplotypes); however, African populations have been relatively understudied to date. In this study, the distributions of CYP2D6 star alleles and predicted drug metabolizer phenotypes—derived from activity scores—were examined across multiple sub‐Saharan African populations based on bioinformatics analysis of 961 high‐depth whole genome sequences. This was followed by characterization of novel star alleles and suballeles in a subset of the participants via targeted high‐fidelity Single‐Molecule Real‐Time resequencing (Pacific Biosciences). This study revealed varying frequencies of known CYP2D6 alleles and predicted phenotypes across different African ethnolinguistic groups. Twenty‐seven novel CYP2D6 star alleles were predicted computationally and two of them were further validated. This study highlights the importance of studying variation in key pharmacogenes such as CYP2D6 in the African context to better understand population‐specific allele frequencies. This will aid in the development of better genotyping panels and star allele detection approaches with a view toward supporting effective implementation of precision medicine strategies in Africa and across the African diaspora. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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29. Genetic characterization of Trypanosoma brucei circulating in domestic animals of the Fontem sleeping sickness of Cameroon
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Simo, Gustave, Njitchouang, Guy Roger, Njiokou, Flobert, Cuny, Gerard, and Asonganyi, Tazoacha
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- 2012
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30. Prevalence of Sodalis glossinidius and different trypanosome species in Glossina palpalis palpalis caught in the Fontem sleeping sickness focus of the southern Cameroon
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Kanté Tagueu Sartrien, Farikou Oumarou, Njiokou Flobert, and Simo Gustave
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Glossina palpalis palpalis ,Symbiont ,Sodalis glossinidius ,Trypanosoma Sp ,PCR ,Infectious and parasitic diseases ,RC109-216 - Abstract
Tsetse flies are the cyclical vector of human and animal African trypanosomiasis. To improve vector control in order to achieve the elimination of human African trypanosomiasis (HAT) and boost the control of animal diseases, investigations have been undertaken on the tripartite association between tsetse, trypanosome, and symbionts. It is in this light that Sodalis glossinidius and different trypanosomes were identified in Glossina palpalis palpalis caught in Fontem in southern Cameroon. For this study, DNA was extracted from whole flies, and S. glossinidius and different trypanosome species were identified by polymerase chain reaction (PCR). Statistical analyses were performed to compare the trypanosome and S. glossinidius infection rates and to look for an association between these microorganisms. Of the 274 G. p. palpalis caught, 3.3% (9/274) were teneral. About 35% (96/274) of these flies harbored S. glossinidius. Of the 265 non-teneral flies, 37.7% were infected by trypanosomes. The infection rates of Trypanosoma congolense “forest type” and Trypanosoma vivax were 26.04% and 18.11%, respectively. About 6.41% of tsetse harbored mixed infections of T. congolense and T. vivax. Of the 69 tsetse with T. congolense infections, 33.33% (23/69) harbored S. glossinidius while 71.86% (69/96) of flies harboring S. glossinidius were not infected by trypanosomes. No association was observed between S. glossinidius and trypanosome infections. Some wild tsetse harbor S. glossinidius and trypanosomes, while others have no infection or are infected by only one of these microorganisms. We conclude that the presence of S. glossinidius does not favor trypanosome infections in G. p. palpalis of the Fontem focus.
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- 2018
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31. Transcriptomics and proteomics in human African trypanosomiasis: Current status and perspectives
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Geiger, Anne, Simo, Gustave, Grébaut, Pascal, Peltier, Jean-Benoît, Cuny, Gérard, and Holzmuller, Philippe
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- 2011
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32. Prevalence of pathogenic trypanosome species in naturally infected cattle of three sleeping sickness foci of the south of Chad.
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Vourchakbé, Joël, Tiofack, Arnol Auvaker Zebaze, Kante, Sartrien Tagueu, Barka, Padja Abdoul, and Simo, Gustave
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TRYPANOSOMA brucei ,CATTLE ,AFRICAN animals ,MIXED infections ,HUMAN DNA - Abstract
Although a diversity of trypanosome species have been detected in various animal taxa from human African trypanosomosis (HAT) foci, cattle trypanosomosis has not been addressed in HAT foci of west and central African countries including Chad. This study aimed to determine the prevalence of pathogenic trypanosome species in cattle from three HAT foci of the south of Chad. Blood samples were collected from 1466 randomly selected cattle from HAT foci of Mandoul, Maro, and Moïssala in the south of Chad. For each animal, the sex, age and body condition were recorded. Rapid diagnostic test (RDT) was used to search Trypanosoma brucei gambiense antibodies while the capillary tube centrifugation (CTC) test and PCR-based methods enabled to detect and identify trypanosome species. From the 1466 cattle, 45 (3.1%) were positive to RDT. The prevalence of trypanosome infections revealed by CTC and PCR-based method were respectively 2.7% and 11.1%. Trypanosomes of the subgenus Trypanozoon were dominant (6.5%) followed by T. congolense savannah (2.9%), T. congolense forest (2.5%) and T. vivax (0.8%). No animal was found with DNA of human infective trypanosome (T. b. gambiense). The overall prevalence of trypanosome infections was significantly higher in animal from the Maro HAT focus (13.8%) than those from Mandoul (11.1%) and Moïssala HAT foci (8.0%). This prevalence was also significantly higher in animal having poor body condition (77.5%) than those with medium (11.2%) and good (0.5%) body condition. The overall prevalence of single and mixed infections were respectively 9.4% and 1.6%. This study revealed natural infections of several pathogenic trypanosome species in cattle from different HAT foci of Chad. It showed similar transmission patterns of these trypanosome species and highlighted the need of developing control strategies for animal African trypanosomosis (AAT) with the overarching goal of improving animal health and the economy of smallholder farmers. [ABSTRACT FROM AUTHOR]
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- 2022
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33. Fine-scale mapping of Schistosoma mansoni infections and infection intensities in sub-districts of Makenene in the Centre region of Cameroon.
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Mewamba, Estelle Mezajou, Tiofack, Arnol Auvaker Zebaze, Kamdem, Cyrille Nguemnang, Tchounkeu, Esthelline Yangea, Tatang, Rostand Joël Atiokeng, Mengoue, Loic Edmond Tekeu, Mbagnia, Mureille Carole Tchami, Njiokou, Flobert, Casacuberta-Partal, Miriam, Womeni, Hilaire Macaire, and Simo, Gustave
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SCHISTOSOMA mansoni ,BODY surface mapping ,GLOBAL Positioning System ,SCHOOL children - Abstract
Background: Schistosomiasis control relies mainly on mass drug administration of Praziquantel (PZQ) to school aged children (SAC). Although precision mapping has recently guided decision making, the sub-districts and the epidemiological differences existing between bio-ecological settings in which infected children come from were not taken into consideration. This study was designed to fill this gap by using POC-CCA and KK to comparatively determine the prevalence and infection intensities of Schistosoma mansoni (S. mansoni) and to perform fine-scale mapping of S. mansoni infections and its infection intensities with the overarching goal of identifying sub-districts presenting high transmission risk where control operations must be boosted to achieve schistosomiasis elimination. Methodology: During a cross- sectional study conducted in Makenene, 1773 stool and 2253 urine samples were collected from SAC of ten primary schools. S. mansoni infections were identified using the point of care circulating cathodic antigen (POC-CCA) and Kato-Katz (KK) test respectively on urine and stool samples. Geographical coordinates of houses of infected SAC were recorded using a global position system device. Schistosome infections and infection intensities were map using QGIS software. Results: The prevalence of S. mansoni inferred from POC-CCA and KK were 51.3% and 7.3% respectively. Most infected SAC and those bearing heavy infections intensities were clustered in sub-districts of Baloua, Mock-sud and Carrière. Houses with heavily-infected SAC were close to risky biotopes. Conclusion: This study confirms the low sensitivity of KK test compared to POC-CCA to accurately identify children with schistosome infection and bearing different schistosome burden. Fine-scale mapping of schistosome infections and infection intensities enabled to identify high transmission sub-districts where control measures must be boosted to reach schistosomiasis elimination. Author summary: Although some disparities in terms of prevalence and infection intensities have been acknowledged within and between schistosomiasis endemic areas, the current control measures did not take into consideration the disparities within endemic areas. To improve the control of schistosomiasis, a fine-scale mapping of schistosome infections and their intensities were undertaken using KK in comparison to POC-CCA to identify sub-districts with potential high transmission risk and where control operations must be boosted to achieve elimination. After the identification of schistosome infections by the point of care circulating cathodic antigen (POC-CCA) and Kato-Katz (KK) test, the geographical coordinates of each infected child's house were recorded using a global position system device (GPS). QGIS software was used to create a map showing schistosome infections and their infection intensities. Our results showed that the majority of infected children and those bearing heavy infection intensities were clustering mostly in Baloua, Carrière and Mock-Sud sub-districts of Makenene while children with light and moderate infection intensity were widely distributed and far away from risky biotopes. The fine-scale mapping of schistosome infections and their infection intensities enable to identify hotspot transmission sites where control strategy must be boosted to achieve the elimination of intestinal schistosomiasis in Makenene. [ABSTRACT FROM AUTHOR]
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- 2022
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34. Genetic structure of Trypanosoma congolense 'forest type' circulating in domestic animals and tsetse flies in the South-West region of Cameroon
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Fogue Pythagore Soubgwi, Njiokou Flobert, and Simo Gustave
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Trypanosoma congolense “forest type” ,microsatellite markers ,tsetse fly ,domestic animals ,population genetics ,Infectious and parasitic diseases ,RC109-216 - Abstract
Despite the economic impact of trypanosome infections, few investigations have been undertaken on the population genetics and transmission dynamics of animal trypanosomes. In this study, microsatellite markers were used to investigate the population genetics of Trypanosoma congolense “forest type”, with the ultimate goal of understanding its transmission dynamics between tsetse flies and domestic animals. Blood samples were collected from pigs, sheep, goats and dogs in five villages in Fontem, South-West region of Cameroon. In these villages, tsetse were captured, dissected and their mid-guts collected. DNA was extracted from blood and tsetse mid-guts and specific primers were used to identify T. congolense “forest type”. All positive samples were genetically characterized with seven microsatellite markers. Genetic analyses were performed on samples showing single infections of T. congolense “forest type”. Of the 299 blood samples, 137 (46%) were infected by T. congolense “forest type”. About 3% (54/1596) of tsetse fly mid-guts were infected by T. congolense “forest type”. Of 182 samples with T. congolense “forest type”, 52 were excluded from the genetic analysis. The genetic analysis on the 130 remaining samples revealed polymorphism within and between subpopulations of the target trypanosome. The dendrogram of genetic similarities was subdivided into two clusters and three sub-clusters, indicating one major and several minor genotypes of T. congolense “forest type” in tsetse and domestic animals. The low FSTvalues suggest low genetic differentiation and no sub-structuration within subpopulations. The same T. congolense genotypes appear to circulate in tsetse and domestic animals.
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- 2017
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35. Field assessment in Cameroon of a reader of POC-CCA lateral flow strips for the quantification of Schistosoma mansoni circulating cathodic antigen in urine.
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Mewamba, Estelle Mezajou, Tiofack, Arnol Auvaker Zebaze, Kamdem, Cyrille Nguemnang, Ngassam, Romuald Isaka Kamwa, Mbagnia, Mureille Carole Tchami, Nyangiri, Oscar, Noyes, Harry, Womeni, Hilaire Marcaire, Njiokou, Flobert, and Simo, Gustave
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SCHISTOSOMA mansoni ,URINE ,SCHOOL children ,POINT-of-care testing ,INFECTION ,ANTIGENS - Abstract
Background: Determining Schistosoma mansoni infection rate and intensity is challenging due to the low sensitivity of the Kato-Katz (KK) test that underestimates the true disease prevalence. Circulating cathodic antigen (CCA) excreted in urine is constantly produced by adult worms and has been used as the basis of a simple, non-invasive point of care test (POC-CCA) for Schistosoma mansoni infections. Although the abundance of CCA in urine is proportional to worm burden, the POC-CCA test is marketed as a qualitative test, making it difficult to investigate the wide range of infection intensities. This study was designed to compare the prevalence and intensity of S. mansoni by KK and POC-CCA and quantify, on fresh and frozen (<-20°C) urine samples, CCA using the visual scores and the ESEquant LR3 reader. Methodology: Stool and urine samples were collected from 759 school-aged children. The prevalence and intensity of S. mansoni were determined using KK and POC-CCA. The degree of the positivity of POC-CCA was estimated by quantifying CCA on fresh and frozen urine samples using visual scores and strip reader. The prevalence, the infection intensity as well the relative amounts of CCA were compared. Results: The S. mansoni infection rates inferred from POC-CCA and KK were 40.7% and 9.4% respectively. Good correlations were observed between infection intensities recorded by; i) the reader and visual scoring system on fresh (Rho = 0.89) and frozen samples (Rho = 0.97), ii) the reader on fresh urine samples and KK (epg) (Rho = 0.44). Nevertheless, 238 POC-CCA positive children were negative for KK, and sixteen of them had high levels of CCA. The correlation between results from the reader on fresh and frozen samples was good (Rho = 0.85). On frozen samples, CCA was not detected in 55 samples that were positive in fresh urine samples. Conclusion: This study confirmed the low sensitivity of KK and the high capacity of POC-CCA to provide reliable data on the prevalence and intensity of S. mansoni infections. The lateral flow reader enabled accurate quantification of CCA under field conditions on fresh and frozen urine samples with less time and effort than KK. Author summary: Diagnosis of schistosomiasis has relied on the Kato-Katz technique which remains challenging due to its low sensitivity. To overcome this limitation, the Point-of-care-Circulating Cathodic Antigen (POC-CCA) test has been developed to detect CCA produced by adult living worm. However, this test is sold for qualitative use only because it is difficult to estimate the intensity of the positive band by eye. This study was designed with the aim of comparing the prevalence and intensity of S. mansoni infections by KK and POC-CCA and quantifying under field conditions on fresh and frozen (<-20°C) urine samples, CCA using the visual scores and the ESEquant LR3 reader. We conducted the KK and POC-CCA tests on stool and urine samples collected from SAC (5 to 4 years) in Makenene, Cameroon. Our results showed discrepancies between results from KK and POC-CCA test. The numerical values generated by the reader made it possible to avoid subjective visual interpretation of POC-CCA results. This study also identified children with high levels of CCA in their urine but without schistosome eggs in their stools. The good correlation observed between results obtained on fresh and frozen urine samples confirmed that POC-CCA test can be used on samples stored for one year at -20° C. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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36. Identification of different trypanosome species in the mid-guts of tsetse flies of the Malanga (Kimpese) sleeping sickness focus of the Democratic Republic of Congo
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Simo Gustave, Silatsa Barberine, Flobert Njiokou, Lutumba Pascal, Mansinsa Philemon, Madinga Joule, Manzambi Emile, De Deken Reginald, and Asonganyi Tazoacha
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Sleeping sickness ,Animal African trypanosomiasis ,Trypanosomes ,Blood meals ,Tsetse flies ,Mid-guts ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background The Malanga sleeping sickness focus of the Democratic Republic of Congo has shown an epidemic evolution of disease during the last century. However, following case detection and treatment, the prevalence of the disease decreased considerably. No active survey has been undertaken in this focus for a couple of years. To understand the current epidemiological status of sleeping sickness as well as the animal African trypanosomiasis in the Malanga focus, we undertook the identification of tsetse blood meals as well as different trypanosome species in flies trapped in this focus. Methods Pyramidal traps were use to trap tsetse flies. All flies caught were identified and live flies were dissected and their mid-guts collected. Fly mid-gut was used for the molecular identification of the blood meal source, as well as for the presence of different trypanosome species. Results About 949 Glossina palpalis palpalis were trapped; 296 (31.2%) of which were dissected, 60 (20.3%) blood meals collected and 57 (19.3%) trypanosome infections identified. The infection rates were 13.4%, 5.1%, 3.5% and 0.4% for Trypanosoma congolense savannah type, Trypanosoma brucei s.l., Trypanosoma congolense forest type and Trypanosoma vivax, respectively. Three mixed infections including Trypanosoma brucei s.l. and Trypanosoma congolense savannah type, and one mixed infection of Trypanosoma vivax and Trypanosoma congolense savannah type were identified. Eleven Trypanosoma brucei gambiense infections were identified; indicating an active circulation of this trypanosome subspecies. Of all the identified blood meals, about 58.3% were identified as being taken on pigs, while 33.3% and 8.3% were from man and other mammals, respectively. Conclusion The presence of Trypanosoma brucei in tsetse mid-guts associated with human blood meals is indicative of an active transmission of this parasite between tsetse and man. The considerable number of pig blood meals combined with the circulation of Trypanosoma brucei gambiense in this focus suggests a transmission cycle involving humans and domestic animals and could hamper eradication strategies. The various species of trypanosomes identified in the Malanga sleeping sickness focus indicates the coexistence of animal and human African Trypanosomiasis. The development of new strategies integrating control measures for human and animal trypanosomiasis may enable the reduction of the control costs in this locality.
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- 2012
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37. Population genetics of Glossina palpalis palpalis from central African sleeping sickness foci
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Solano Philippe, Causse Sandrine, De Meeûs Thierry, Ravel Sophie, Simo Gustave, Melachio Trésor, Lutumba Pascal, Asonganyi Tazoacha, and Njiokou Flobert
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Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Glossina palpalis palpalis (Diptera: Glossinidae) is widespread in west Africa, and is the main vector of sleeping sickness in Cameroon as well as in the Bas Congo Province of the Democratic Republic of Congo. However, little is known on the structure of its populations. We investigated G. p. palpalis population genetic structure in five sleeping sickness foci (four in Cameroon, one in Democratic Republic of Congo) using eight microsatellite DNA markers. Results A strong isolation by distance explains most of the population structure observed in our sampling sites of Cameroon and DRC. The populations here are composed of panmictic subpopulations occupying fairly wide zones with a very strong isolation by distance. Effective population sizes are probably between 20 and 300 individuals and if we assume densities between 120 and 2000 individuals per km2, dispersal distance between reproducing adults and their parents extends between 60 and 300 meters. Conclusions This first investigation of population genetic structure of G. p. palpalis in Central Africa has evidenced random mating subpopulations over fairly large areas and is thus at variance with that found in West African populations of G. p. palpalis. This study brings new information on the isolation by distance at a macrogeographic scale which in turn brings useful information on how to organise regional tsetse control. Future investigations should be directed at temporal sampling to have more accurate measures of demographic parameters in order to help vector control decision.
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- 2011
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38. Human African Trypanosomiasis transmission, Kinshasa, Democratic Republic of Congo
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Simo, Gustave, Diabakana, Philemon Mansinsa, Mesu, Victor Kande Betu Ku, Manzambi, Emile Zola, Ollivier, Gaelle, Asonganyi, Tazoacha, Cuny, Gerard, and Grebaut, Pascal
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Trypanosomiasis -- Development and progression ,Trypanosomiasis -- Diagnosis ,Trypanosomiasis -- Research ,Disease transmission -- Research - Abstract
To investigate the epidemiology of human African trypanosomiasis (sleeping sickness) in Kinshasa, Democratic Republic of Congo, 2 entomologic surveys were conducted in 2005. Trypanosoma brucei gambiense and human-blood meals were [...]
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- 2006
39. The Genetics of Human Schistosomiasis Infection Intensity and Liver Disease: A Review.
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Mewamba, Estelle M., Nyangiri, Oscar A., Noyes, Harry A., Egesa, Moses, Matovu, Enock, and Simo, Gustave
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HUMAN genetics ,SCHISTOSOMIASIS ,FIBROSIS ,LIVER diseases ,PARASITE life cycles ,HEPATIC fibrosis ,VENOUS pressure ,PARASITOLOGY - Abstract
Schistosomiasis remains the fourth most prevalent parasitic disease affecting over 200 million people worldwide. Control efforts have focussed on the disruption of the life cycle targeting the parasite, vector and human host. Parasite burdens are highly skewed, and the majority of eggs are shed into the environment by a minority of the infected population. Most morbidity results from hepatic fibrosis leading to portal hypertension and is not well-correlated with worm burden. Genetics as well as environmental factors may play a role in these skewed distributions and understanding the genetic risk factors for intensity of infection and morbidity may help improve control measures. In this review, we focus on how genetic factors may influence parasite load, hepatic fibrosis and portal hypertension. We found 28 studies on the genetics of human infection and 20 studies on the genetics of pathology in humans. S. mansoni and S. haematobium infection intensity have been showed to be controlled by a major quantitative trait locus SM1 , on chromosome 5q31-q33 containing several genes involved in the T
h 2 immune response, and three other loci of smaller effect on chromosomes 1, 6, and 7. The most common pathology associated with schistosomiasis is hepatic and portal vein fibroses and the SM2 quantitative trait locus on chromosome six has been linked to intensity of fibrosis. Although there has been an emphasis on Th 2 cytokines in candidate gene studies, we found that four of the five QTL regions contain Th 17 pathway genes that have been included in schistosomiasis studies: IL17B and IL12B in SM1, IL17A and IL17F in 6p21-q2, IL6R in 1p21-q23 and IL22RA2 in SM2. The Th 17 pathway is known to be involved in response to schistosome infection and hepatic fibrosis but variants in this pathway have not been tested for any effect on the regulation of these phenotypes. These should be priorities for future studies. [ABSTRACT FROM AUTHOR]- Published
- 2021
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40. Detection of Brucella antibodies in domestic animals of southern Cameroon: Implications for the control of brucellosis.
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Kamga, Rolin M. N., Silatsa, Barberine A., Farikou, Oumarou, Kuiate, Jules‐Roger, and Simo, Gustave
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DOMESTIC animals ,BRUCELLA ,GOAT diseases ,SHEEP diseases ,ENZYME-linked immunosorbent assay ,IMMUNOGLOBULINS ,ZOONOSES ,SWINE - Abstract
Brucellosis is one of the world's most widespread bacterial zoonoses caused by Brucella. It leads to considerable economic losses as a result of low productivity of infected animals and the long debilitating illness in humans. Despite its impact on human and animal health, little attention has been paid on Brucella infections in domestic animals. It is in this light that the prevalence of Brucella antibodies was determined in domestic animals with the overarching goal of improving our knowledge on brucellosis in southern Cameroon. During cross‐sectional studies conducted from December 2016 to August 2018 in five sites of southern Cameroon, blood samples were collected in cattle, sheep, goat, pig and dog. Plasma was obtained from each blood sample and Brucella antibodies were detected using the Rose Bengal test and the enzyme‐linked immunosorbent assay (ELISA). From 1873 animals that were sampled, the overall prevalence of Brucella antibodies using Indirect enzyme‐linked immunosorbent assay (i‐ELISA) was 6.35% (118/1873): 9.12% (78/855) in cattle; 8.04% (30/373) in sheep; 6.06% (2/33) in dog, 1.87% (3/160) in pig and 1.1% (5/452) in goat. Between animal species (p‐value <.0001, x2 = 33.63) as well as sampling sites (p‐value =.0001, x2 = 18.97), significant differences were observed in the prevalence of Brucella antibodies. Yoko and Noun localities have shown the highest prevalence of 8.6% (30/348) and 7.2% (78/1070), respectively. This prevalence was significantly higher (p =.03, x2 = 1.25) in female than male cattle. Between adult (16.923%) and young cattle (7.8%), significant difference (p =.04, x2 = 6.42) was observed in the prevalence of Brucella antibodies. This study shows that the prevalence of Brucella antibodies varies between animal species and localities. It also shows several domestic animals of southern Cameroon that have been in contact with Brucella. It enabled to identify villages where investigations on the transmission dynamic must be focused for the final goal of developing control measures for this neglected zoonotic disease. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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41. Copy number variation in human genomes from three major ethno-linguistic groups in Africa.
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Nyangiri, Oscar A., Noyes, Harry, Mulindwa, Julius, Ilboudo, Hamidou, Kabore, Justin Windingoudi, Ahouty, Bernardin, Koffi, Mathurin, Asina, Olivier Fataki, Mumba, Dieudonne, Ofon, Elvis, Simo, Gustave, Kimuda, Magambo Phillip, Enyaru, John, Alibu, Vincent Pius, Kamoto, Kelita, Chisi, John, Simuunza, Martin, Camara, Mamadou, Sidibe, Issa, and MacLeod, Annette
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GENOMES ,DNA copy number variations ,AFRICANS ,DISEASE susceptibility ,HUMAN genome ,HAPLOTYPES - Abstract
Background: Copy number variation is an important class of genomic variation that has been reported in 75% of the human genome. However, it is underreported in African populations. Copy number variants (CNVs) could have important impacts on disease susceptibility and environmental adaptation. To describe CNVs and their possible impacts in Africans, we sequenced genomes of 232 individuals from three major African ethno-linguistic groups: (1) Niger Congo A from Guinea and Côte d'Ivoire, (2) Niger Congo B from Uganda and the Democratic Republic of Congo and (3) Nilo-Saharans from Uganda. We used GenomeSTRiP and cn.MOPS to identify copy number variant regions (CNVRs). Results: We detected 7608 CNVRs, of which 2172 were only deletions, 2384 were only insertions and 3052 had both. We detected 224 previously un-described CNVRs. The majority of novel CNVRs were present at low frequency and were not shared between populations. We tested for evidence of selection associated with CNVs and also for population structure. Signatures of selection identified previously, using SNPs from the same populations, were overrepresented in CNVRs. When CNVs were tagged with SNP haplotypes to identify SNPs that could predict the presence of CNVs, we identified haplotypes tagging 3096 CNVRs, 372 CNVRs had SNPs with evidence of selection (iHS > 3) and 222 CNVRs had both. This was more than expected (p < 0.0001) and included loci where CNVs have previously been associated with HIV, Rhesus D and preeclampsia. When integrated with 1000 Genomes CNV data, we replicated their observation of population stratification by continent but no clustering by populations within Africa, despite inclusion of Nilo-Saharans and Niger-Congo populations within our dataset. Conclusions: Novel CNVRs in the current study increase representation of African diversity in the database of genomic variants. Over-representation of CNVRs in SNP signatures of selection and an excess of SNPs that both tag CNVs and are subject to selection show that CNVs may be the actual targets of selection at some loci. However, unlike SNPs, CNVs alone do not resolve African ethno-linguistic groups. Tag haplotypes for CNVs identified may be useful in predicting African CNVs in future studies where only SNP data is available. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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42. First detection of Theileria parva in cattle from Cameroon in the absence of the main tick vector Rhipicephalus appendiculatus.
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Silatsa, Barberine A., Simo, Gustave, Githaka, Naftaly, Kamga, Rolin, Oumarou, Farikou, Keambou Tiambo, Christian, Machuka, Eunice, Domelevo, Jean‐Baka, Odongo, David, Bishop, Richard, Kuiate, Jules‐Roger, Njiokou, Flobert, Djikeng, Appolinaire, and Pelle, Roger
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THEILERIA , *THEILERIA parva , *RHIPICEPHALUS , *CATTLE , *CULICOIDES , *NUCLEIC acid probes , *BLOOD collection , *TICK-borne diseases - Abstract
A major risk factor for the spread of livestock diseases and their vectors is the uncontrolled transboundary movement of live animals for trade and grazing. Such movements constrain effective control of tick‐transmitted pathogens, including Theileria parva. Only limited studies have been undertaken to identify ticks and tick‐borne diseases (TTBDs) affecting cattle in central African countries, including Cameroon. We hereby report the collection of baseline data on the prevalence of T. parva in Cameroon through a countrywide cross‐sectional survey, conducted in 2016, involving collection of blood samples from cattle from 63 sites across the five agro‐ecological zones (AEZs) of the country. ELISA‐based surveillance of infected cattle was performed on 479 randomly selected samples and revealed specific antibodies to T. parva in 22.7% and T. mutans in 41.1% of cattle. Screening of 1,340 representative DNA samples for the presence of T. parva identified 25 (1.86%) positives using a p104 antigen gene‐based nested PCR assay. The positives were distributed across agro‐ecological zones I, II, III and V. None of the p104 positive cattle exhibited clinical symptoms of East Coast fever (ECF). Using reverse line blot (RLB), 58 (4.3%) and 1,139 (85%) of the samples reacted with the T. parva and T. mutans oligonucleotide probes, respectively. This represents the first report of T. parva from Cameroon. Surprisingly, no Rhipicephalus appendiculatus ticks, the main vector of T. parva, were identified in a parallel study involving comprehensive morphological and molecular survey of tick species present in the country. Only two of the 25 p104 positive cattle were PCR‐positive for the CD8+ T‐cell target schizont‐expressed antigen gene Tp1. Cloning and sequencing of Tp1 amplicons revealed sequence identity with the reference T. parva Muguga. This new finding raises serious concerns of a potential spread of ECF into the central African region. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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43. Association between IL1 gene polymorphism and human African trypanosomiasis in populations of sleeping sickness foci of southern Cameroon.
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Ofon, Elvis, Noyes, Harry, Ebo’o Eyanga, Vincent, Njiokou, Flobert, Koffi, Mathurin, Fogue, Pythagore, Hertz-Fowler, Christiane, MacLeod, Annette, Matovu, Enock, Simo, Gustave, and null, null
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AFRICAN trypanosomiasis ,DISEASES - Abstract
Background: Human African Trypanosomiasis (HAT) is a neglected tropical disease caused by infections due to Trypanosoma brucei subspecies. In addition to the well-established environmental and behavioural risks of becoming infected, there is evidence for a genetic component to the response to trypanosome infection. We undertook a candidate gene case-control study to investigate genetic associations further. Methodology: We genotyped one polymorphism in each of seven genes (IL1A, IL1RN, IL4RN, IL6, HP, HPR, and HLA-G) in 73 cases and 250 controls collected from 19 ethno-linguistic subgroups stratified into three major ethno-linguistic groups, 2 pooled ethno-linguistic groups and 11 ethno-linguistic subgroups from three Cameroonian HAT foci. The seven polymorphic loci tested consisted of three SNPs, three variable numbers of tandem repeat (VNTR) and one INDEL. Results: We found that the genotype (TT) and minor allele (T) of IL1A gene as well as the genotype 1A3A of IL1RN were associated with an increased risk of getting Trypanosoma brucei gambiense and develop HAT when all data were analysed together and also when stratified by the three major ethno-linguistic groups, 2 pooled ethno-linguistic subgroups and 11 ethno-linguistic subgroups. Conclusion: This study revealed that one SNP rs1800794 of IL1A and one VNTR rs2234663 of IL1RN were associated with the increased risk to be infected by Trypanosoma brucei gambiense and develop sleeping sickness in southern Cameroon. The minor allele T and the genotype TT of SNP rs1800794 in IL1A as well as the genotype 1A3A of IL1RN rs2234663 VNTR seem to increase the risk of getting Trypanosoma brucei gambiense infections and develop sleeping sickness in southern Cameroon. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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44. A polymorphism in the haptoglobin, haptoglobin related protein locus is associated with risk of human sleeping sickness within Cameroonian populations.
- Author
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null, null, Ofon, Elvis, Fogue, Pythagore, Simo, Gustave, MacLeod, Annette, Noyes, Harry, Hertz-Fowler, Christiane, Mulindwa, Julius, Ilboudo, Hamidou, Simuunza, Martin, Ebo'o, Vincent, Njiokou, Flobert, Koffi, Mathurin, and Bucheton, Bruno
- Subjects
AFRICAN trypanosomiasis ,HAPTOGLOBINS ,DISEASE susceptibility ,GENETIC polymorphisms ,CAMEROONIANS ,EPIDEMIOLOGY ,GENETICS ,MEDICAL care - Abstract
Background: Human African Trypanosomiasis (HAT) is a neglected disease targeted for elimination as a public health problem by 2020. Elimination requires a better understanding of the epidemiology and clinical evolution of HAT. In addition to the classical clinical evolution of HAT, asymptomatic carriers and spontaneous cure have been reported in West Africa. A genetic component to human susceptibility to HAT has been suggested to explain these newly observed responses to infection. In order to test for genetic associations with infection response, genetic polymorphism in 17 genes were tested (APOL1, IL1B, IL4, IL4R, IL6, IL8, IL12B, IL12RB1, IL10, TNFA, INFG, MIF, HLA-G, HLA-A, HP, HPR and CFH). Methodology: A case-control study was performed on 180 blood samples collected from 56 cases and 124 controls from Cameroon. DNA was extracted from blood samples. After quality control, 25 samples (24 controls and 1 case) were eliminated. The genotyping undertaken on 155 individuals including 55 cases and 100 controls were investigated at 96 loci (88 SNPs and 8 indels) located on 17 genes. Associations between these loci and HAT were estimated via a case-control association test. Results: Analyses of 64 SNPs and 4 indels out of 96 identified in the selected genes reveal that the minor allele (T) of rs8062041 in haptoglobin (HP) appeared to be protective against HAT (p = 0.0002395, OR 0.359 (CI
95 [0.204–0.6319])); indicating higher frequency in cases compared to controls. This minor allele with adjusted p value of 0.0163 is associated with a lower risk (protective effect) of developing sleeping sickness. Conclusion: The haptoglobin related protein HPR and HP are tightly linked and both are duplicated in some people and may lead to higher activity. This increased production could be responsible of the protection associated with rs8062041 even though this SNP is within HP. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
45. Candidate genes-based investigation of susceptibility to Human African Trypanosomiasis in Côte d’Ivoire.
- Author
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Ahouty, Bernardin, Koffi, Mathurin, Ilboudo, Hamidou, Simo, Gustave, Matovu, Enock, Mulindwa, Julius, Hertz-Fowler, Christiane, Bucheton, Bruno, Sidibé, Issa, Jamonneau, Vincent, MacLeod, Annette, Noyes, Harry, N’Guetta, Simon-Pierre, and null, null
- Subjects
AFRICAN trypanosomiasis ,DISEASE susceptibility ,SINGLE nucleotide polymorphisms ,PHENOTYPES ,BONFERRONI correction ,GENETIC polymorphisms ,GENETICS - Abstract
Human African Trypanosomiasis (HAT) or sleeping sickness is a Neglected Tropical Disease. Long regarded as an invariably fatal disease, there is increasing evidence that infection by T. b. gambiense can result in a wide range of clinical outcomes, including latent infections, which are long lasting infections with no parasites detectable by microscopy. The determinants of this clinical diversity are not well understood but could be due in part to parasite or host genetic diversity in multiple genes, or their interactions. A candidate gene association study was conducted in Côte d’Ivoire using a case-control design which included a total of 233 subjects (100 active HAT cases, 100 controls and 33 latent infections). All three possible pairwise comparisons between the three phenotypes were tested using 96 SNPs in16 candidate genes (IL1, IL4, IL4R, IL6, IL8, IL10, IL12, IL12R, TNFA, INFG, MIF, APOL1, HPR, CFH, HLA-A and HLA-G). Data from 77 SNPs passed quality control. There were suggestive associations at three loci in IL6 and TNFA in the comparison between active cases and controls, one SNP in each of APOL1, MIF and IL6 in the comparison between latent infections and active cases and seven SNP in IL4, HLA-G and TNFA between latent infections and controls. No associations remained significant after Bonferroni correction, but the Benjamini Hochberg false discovery rate test indicated that there were strong probabilities that at least some of the associations were genuine. The excess of associations with latent infections despite the small number of samples available suggests that these subjects form a distinct genetic cluster different from active HAT cases and controls, although no clustering by phenotype was observed by principle component analysis. This underlines the complexity of the interactions existing between host genetic polymorphisms and parasite diversity. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
46. Introducing the TrypanoGEN biobank: A valuable resource for the elimination of human African trypanosomiasis.
- Author
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Ilboudo, Hamidou, Noyes, Harry, Mulindwa, Julius, Kimuda, Magambo Phillip, Koffi, Mathurin, Kaboré, Justin Windingoudi, Ahouty, Bernadin, Ngoyi, Dieudonné Mumba, Fataki, Olivier, Simo, Gustave, Ofon, Elvis, Enyaru, John, Chisi, John, Kamoto, Kelita, Simuunza, Martin, Alibu, Vincent P., Lejon, Veerle, Jamonneau, Vincent, Macleod, Annette, and Camara, Mamadou
- Subjects
TREATMENT of African trypanosomiasis ,AFRICAN trypanosomiasis ,BIOBANKS ,PUBLIC health ,PREVENTION - Abstract
The article offers information on TrypanoGEN biobank used for the elimination of human African trypanosomiasis (HAT). Topics discussed include efforts of World Health Organization in the elimination of the disease as a public health problem; role of TrypanoGEN network in understanding and eliminating the genetic basis of human susceptibility to trypanosomiasis; and characteristics and requirements of the HAT biobank;.
- Published
- 2017
- Full Text
- View/download PDF
47. Relationship between hyperglycemia, antioxidant capacity and some enzymatic and non-enzymatic antioxidants in African patients with type 2 diabetes.
- Author
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Pieme, Constant Anatole, Tatangmo, Jérôme Antony, Simo, Gustave, Nya, Prosper Cabral Biapa, Moor, Vicky Jocelyne Ama, Moukette, Bruno Moukette, Nzufo, Francine Tankeu, Nono, Borgia Legrand Njinkio, and Sobngwi, Eugene
- Subjects
OXIDANT status ,HYPERGLYCEMIA ,AFRICANS ,TYPE 2 diabetes ,BIOMARKERS ,PATIENTS ,DISEASES - Abstract
Background and purpose: Studies demonstrate that free radicals are involved in the pathogenesis of diabetic complications. The aim of this study was to determine the implication of total antioxidant capacity (TAC) and some enzymatic and non-enzymatic antioxidants as suitable biomarkers of diabetic complications risk factors. Methods: A total of 90 patients (70 patients with or without diabetic complications +20 normal healthy) were examined by evaluating the level of lipid peroxidation, nitrogen monoxide (NO), fasting blood glucose, glycated haemoglobin (HbA1c), enzymatic and non-enzymatic antioxidants using standard spectrophotometric methods. Results: The fasting blood glucose and HbA1c levels were respectively 2.05 and 2.32 times higher in the group of patients with diabetes and complications (DPWC) compared to those of healthy persons. A statistically higher level of malondialdehyde (MDA), NO and TAC was observed in a group of patients with diabetes and complications compared to those without complications (DPNC). A significant positive correlation was found between catalase (CAT) and fasting blood glucose while a significant and negative correlation was noted between reduced glutathione (GSH) and fasting blood glucose. Also was noted a significant relationship between HbA1c and other markers of oxidative stress. Conclusions: The results suggest that the plasma levels of CAT, TAC and reduced glutathione could give information on the risk of developing complications of diabetes, considering that the modification of these biomarkers levels were associated with oxidative stress. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
48. Genetic structure of Trypanosoma congolense “forest type” circulating in domestic animals and tsetse flies in the South-West region of Cameroon.
- Author
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Soubgwi Fogue, Pythagore, Njiokou, Flobert, and Simo, Gustave
- Abstract
Copyright of Parasite (1252607X) is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2017
- Full Text
- View/download PDF
49. Xenomonitoring of sleeping sickness transmission in Campo (Cameroon).
- Author
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Grébaut, Pascal, Melachio, Trésor, Nyangmang, Simplice, Eyenga, Vincent Ebo'o, Njitchouang, Guy-Roger, Ofon, Elvis, Njiokou, Flobert, and Simo, Gustave
- Subjects
AFRICAN trypanosomiasis ,SPATIAL distribution (Quantum optics) ,GLOSSINA palpalis ,ENDEMIC diseases ,VECTOR control - Abstract
Background: The sleeping sickness focus of Campo in South Cameroon is still active, at a low endemic level, for more than a century, despite a regular medical surveillance. The present study focuses on the spatial distribution of xenomonitoring information obtained from an entomological survey performed in the dry season 2012. It appears that humans constitute a third of the blood meals and that the flies' densities were coherent with those classically observed in the different biotopes. Paradoxically, the epicenter of the focus is the place where the risk indicators are the lowest ones. Methods: Particular attention was paid to the entomological device so that it covered the main part of human activities in the study area. One hundred and sixty-two pyramidal traps were used to catch tsetse flies twice a day that were identified, counted, dissected. Molecular analysis using classical and specific molecular markers was conducted to determine the importance of trypanosome infections and the nature of the feeding hosts. This information was used to calculate a Transmission Risk Index and to define a gradient of risk that was projected into a Geographical Information System. Results: Conventional entomological indicators such as species identification of tsetse flies or the Apparent Density per Trap per day, show that Glossina palpalis palpalis is the main species in the campo area which is classically distributed into the different biotopes of the study area. Molecular analysis reveals that humans constitute a third of the blood feeding hosts and that 20 % of the dissected flies were infected with trypanosomes, principally with Nannomonas. Nevertheless, one fly was carrying Trypanosoma brucei gambiense, the pathogen agent of sleeping sickness, showing that the reservoir is still active in the epicenter of the focus. Paradoxically, the Transmission Risk Index is not important in the epicenter, demonstrating that endemic events are not only depending on the man/vector contact. Conclusion: Xenomonitoring provides a valuable guide/tool to determine places at higher risk for vector/human contact and to identify trypanosomes species circulating in the focus. This information from xenomonitoring demonstrates that decision makers should include a veterinary device in a control strategy. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
50. Challenges facing the elimination of sleeping sickness in west and central Africa: sustainable control of animal trypanosomiasis as an indispensable approach to achieve the goal.
- Author
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Simo, Gustave and Rayaisse, Jean Baptiste
- Subjects
- *
AFRICAN trypanosomiasis , *DISEASE eradication , *TRYPANOSOMIASIS in animals , *PREVENTION - Abstract
African trypanosomiases are infectious diseases caused by trypanosomes. African animal trypanosomiasis (AAT) remains an important threat for livestock production in some affected areas whereas human African trypanosomiasis (HAT) is targeted for elimination in 2020. In West and Central Africa, it has been shown that the parasites causing these diseases can coexist in the same tsetse fly or the same animal. In such complex settings, the control of these diseases must be put in the general context of trypanosomiasis control or "one health" concept where the coordination of control operations will be beneficial for both diseases. In this context, implementing control activities on AAT will help to sustain HAT control. It will also have a positive impact on animal health and economic development of the regions. The training of inhabitants on how to implement and sustain vector control tools will enable a long-term sustainability of control operations that will lead to the elimination of HAT and AAT. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
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