33 results on '"Limam L"'
Search Results
2. Extracting User Interests from Search Query Logs: A Clustering Approach.
- Author
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Limam, L., Coquil, D., Kosch, H., and Brunie, L.
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- 2010
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3. MoidEx: Location-based mTourism system on mobile devices.
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Doller, M., Kockerandl, G., Jans, S., and Limam, L.
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- 2009
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4. Live-ticker supported sports video annotation
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Mayer, T. R., Coquil, D., Mario Döller, Limam, L., Stegmaier, F., and Kosch, H.
5. Multi-application Personalization: Data Propagation Evaluation on a Real-life Search Query Log
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Viviani, Marco, Bennani, Nadia, Egyed-Zsigmond, Elod, Limam, Lyes, COQUIL, David, Distribution, Recherche d'Information et Mobilité (DRIM), Laboratoire d'InfoRmatique en Image et Systèmes d'information (LIRIS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-École Centrale de Lyon (ECL), Université de Lyon-Université Lumière - Lyon 2 (UL2)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Université Lumière - Lyon 2 (UL2), Viviani, M, Limam, L, Bennani, N, Egyed Zsigmond, E, and Coquil, D
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User information ,Environmental Engineering ,User profile ,Web search query ,Group method of data handling ,Computer science ,User modeling ,02 engineering and technology ,computer.software_genre ,Computer Graphics and Computer-Aided Design ,Personalization ,Data modeling ,Computer Networks and Communication ,020204 information systems ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,[INFO]Computer Science [cs] ,Data mining ,Cluster analysis ,computer - Abstract
In the field of multi-application personalization, several techniques have been proposed to support user modeling. None of them have sufficiently investigated the opportunity for a multi-application profile to evolve over time in order to avoid data inconsistency and the subsequent loss of income for website users and companies. In this paper, we propose a model addressing this issue and we focus in particular on user profile data propagation management. Data propagation is a way to reduce the amount of inconsistent user profile information over several applications, even in the case of temporary coalitions of applications as happens in Digital Ecosystems. To evaluate our model, we first extract user profiles using logs of the large real-life AOL search engine. Then, we simulate data propagation along semantically related user information. © 2012 IEEE
- Published
- 2012
6. Pseudotumoral pelviperitoneal tuberculosis mimicking ovarian cancer: A case report.
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Mejda Z, Rihab L, Raoua B, Ahlem B, Arwa G, Sofiene G, Imen J, Nabil BC, Ahmed Z, Mohamed Hichem L, and Leila S
- Abstract
Tuberculosis is a rare but treatable infectious disease that continues to pose a significant health issue in regions with high prevalence. Its abdominopelvic localization can mimic advanced ovarian cancer, leading to diagnostic challenges. This report describes the case of a 33-year-old woman who was admitted to the gastroenterology unit with ascites, peritoneal thickening, and an ovarian mass on imaging. The diagnosis of abdominopelvic and peritoneal tuberculosis was confirmed after laparoscopy. The patient underwent antitubercular chemotherapy and showed clinical improvement., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2024.)
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- 2024
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7. Prevalence of Fasciola hepatica infection in slaughtered sheep from Northwest Tunisia and its risk factors: Association with gastrointestinal helminths infection and anaemia.
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Hammami I, Amdouni Y, Romdhane R, Sassi L, Farhat N, Rekik M, and Gharbi M
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- Animals, Sheep, Prevalence, Tunisia epidemiology, Risk Factors, Sheep, Domestic, Female, Male, Gastrointestinal Diseases veterinary, Gastrointestinal Diseases epidemiology, Gastrointestinal Diseases parasitology, Abattoirs, Helminthiasis, Animal epidemiology, Helminthiasis, Animal parasitology, Intestinal Diseases, Parasitic veterinary, Intestinal Diseases, Parasitic epidemiology, Intestinal Diseases, Parasitic parasitology, Fascioliasis veterinary, Fascioliasis epidemiology, Fascioliasis parasitology, Sheep Diseases epidemiology, Sheep Diseases parasitology, Fasciola hepatica isolation & purification, Anemia veterinary, Anemia epidemiology, Anemia parasitology, Anemia etiology
- Abstract
We investigated herein the prevalence of Fasciola hepatica infection in sheep at Sejnane slaughterhouse, governorate of Bizerte, Northwest of Tunisia, using three different diagnostic techniques (liver dissection, bile examination, and coprology). Faeces, liver, gall bladder as well as blood samples were collected from 603 slaughtered sheep in two seasons: winter and summer. Faecal egg counts of F. hepatica were estimated using sedimentation technique. Livers were examined for the presence of flukes, and bile collected from gall bladder was examined by sedimentation technique for the presence of F. hepatica eggs. Faecal egg counts of gastrointestinal helminths were estimated using flotation followed by the McMaster technique. Blood samples were used to estimate blood cell count (RBC) (×10
6 /mL), haemoglobin (Hb) (g/dL), and haematocrit (Ht) (%) levels. A total of 1714 F. hepatica flukes were collected from 68 infected livers, the number of flukes per sheep ranged between naught and 195. Bile examination (16.78% ± 1.83; 51/310) showed the higher infection prevalence, followed by liver dissection (11.28% ± 1.17; 68/603) and coprology (9.12% ± 1.08; 55/603) (p = 0.015). Infection prevalences were significantly higher in young sheep aged of less than 1 year (8.13% ± 1.22; 49/498), in cross-bred sheep (10.61% ± 1.39%; 64/478), and in summer (7.13% ± 1.82; 43/293) (p < 0.05). There was no significant difference in infection prevalence by gastrointestinal helminths in F. hepatica-infected and F. hepatica-non-infected animals (p > 0.05). The overall prevalence of F. hepatica-infected anaemic sheep was higher (22.73% ± 4.47; 20/88) than F. hepatica-non-infected anaemic sheep (p < 0.05). Fasciola hepatica infection is frequent in sheep from Sejnane representing hence an important constraint for the development of the sheep industry in this region. Therefore, it is necessary to establish and implement a specific control programme to reduce fasciolosis infection risks including animal owners' education., (© 2024 The Author(s). Veterinary Medicine and Science published by John Wiley & Sons Ltd.)- Published
- 2024
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8. Diagnostic performance of real-time quantitative PCR in tear samples in various subtypes of herpes simplex keratitis.
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Hoarau G, Haigh O, Vauloup-Fellous C, Boucher R, Rouquette A, Faure P, Limam L, Labetoulle M, and Rousseau A
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- Humans, Retrospective Studies, Real-Time Polymerase Chain Reaction, Tears, Keratitis, Herpetic diagnosis, Herpesvirus 1, Human genetics, Lacerations
- Abstract
Diagnosis of herpes simplex keratitis (HSK) is mostly based on clinical findings, yet biological confirmation supports management of challenging cases. This study evaluated the place of real-time quantitative PCR (RT-qPCR) on tear samplings in the management of HSK. Clinical records of patients who underwent tear sampling tested by RT-qPCR for herpes simplex virus type 1 for an acute episode of corneal inflammation or defect between January 2013 and December 2021 were retrospectively reviewed, and results were compared to clinical diagnosis (i.e., HSK or not) based on biomicroscopic findings and medical history. Of 465 tested tear samples from 364 patients, a clinical diagnosis of active (ongoing) HSK was recorded in 240 cases, among which 76 were RT-qPCR positive (global sensitivity of 31.6%, specificity of 99.5%). Sensitivity of RT-qPCR was higher in epithelial (97.4%) and stromal keratitis with ulceration (48.7%), compared to other types of HSK (23.5% in keratouveitis, 13.6% in endotheliitis, 11.1% in postherpetic neurotrophic keratopathy, and 8.1% in stromal keratitis without ulceration). The highest viral loads were detected from epithelial and stromal keratitis with ulceration, while in HSK with no epithelial involvement, the viral load detected was 196-fold lower, on average. The proportion of clinically characterized HSK patients with negative tear samples was higher in patients receiving antiviral treatment ( P < 0.0001). RT-qPCR, performed on tear samples, can help in confirming diagnosis in case of presumed HSK, including clinical forms with no obvious epithelial involvement. The sensitivity of tear sampling is much higher whenever epithelial keratitis is present., Competing Interests: The authors declare no conflict of interest.
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- 2023
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9. First morphometric and molecular characterization of Fasciola spp. in Northwest Tunisia.
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Hammami I, Ciuca L, Maurelli MP, Romdhane R, Sassi L, Rjeibi MR, Farhat N, Simo AK, Rinaldi L, Rekik M, and Gharbi M
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- Sheep genetics, Animals, Cattle, Phylogeny, Tunisia epidemiology, DNA, Helminth genetics, Fasciola genetics, Fascioliasis epidemiology, Fascioliasis veterinary, Fasciola hepatica genetics, Cattle Diseases epidemiology
- Abstract
The aim of this study was to characterize the Tunisian Fasciola spp. flukes by morphometric and molecular analyses. Flukes were collected from livers of sheep slaughtered in Sejnane slaughterhouses (Bizerte gouvernorate, Northwest Tunisia) between January and March 2021.Five morphometric parameters were determined for all the liver flukes, as follows: (i) total body length (BL), (ii) distance between ventral sucker and the tail (VS-T), (iii) distance between oral sucker and ventral sucker (OS-VS), (iv) abdomen diameter (AD), (v) tail diameter (TD) and the body length to width ratio (BL/BW). Molecular identification of the fluke specimens was carried out by polymerase chain reaction, restriction fragment polymorphism (PCR-RFLP) of a 680 bp sequence of the internal transcribes spacer 1 (ITS1) gene and by amplification, sequencing, and phylogenetic analysis of a 500 bp sequence of the ITS2 gene. Morphometric measurements showed that the mean of the total body length of the adult flukes was 21.1 ± 2.7 mm with minimum and maximum lengths of 13 and 31 mm, respectively. The PCR-RFLP analysis revealed a single profile consisting of three bands of approximately 370, 100, and 60 bp. Fasciola sequences described in the present study (GenBank numbers: OQ457027 and OQ457028) showed 99.58-100% identity to Fasciola hepatica. In conclusion, the results of this study show that molecular and phylogenetic analyses confirm the presence of a single species of F. hepatica in the Sejnane region Northwest of Tunisia. However, further studies are needed to identify the occurrence of Fasciola species in other Tunisian regions., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
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- 2023
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10. Conservation agriculture has no significant impact on sheep digestive parasitism.
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ElHamdi S, Sassi L, Rekik M, Dhehibi M, Cheikh M'hamed H, and Gharbi M
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Conservation agriculture (CONS A) is a sustainable agriculture system based on crop rotation with no tillage. It has various environmental advantages compared to conventional agriculture (CONV A): decreased water evaporation, erosion, and CO
2 emissions. In this first study of its kind, we aim to evaluate the impact of this type of agriculture on sheep gastrointestinal parasites. Two lamb groups aged between 5 and 10 months were randomly included to graze separately on CONS A and CONV A pastures. Each group was composed of two batches of three lambs, and these were followed up for two rearing months. Liveweight, hematological parameter variation, and digestive parasites were studied. At the end of the study period, lambs were slaughtered the carcass yield was determined, and a helminthological autopsy was performed on the digestive tracts of the animals to estimate different parasitological indicators. There was no difference between lambs reared on CONS A and those reared on CONV A for all parasite indicators (infestation intensity, abundance, and prevalence). The same trend was also obtained for hematological parameters, liveweight evolution, and carcass yield. These results prove that there is no impact of CONS A on the sheep's digestive parasitism. Further studies are needed to support these findings on larger animal samples and to investigate the impact of conservation agriculture on other parasite species. Similar studies could also be conducted on ruminant species., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 ElHamdi, Sassi, Rekik, Dhehibi, Cheikh M'hamed and Gharbi.)- Published
- 2023
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11. [Virological diagnosis of anterior herpetic ocular disease on tear sample: A simple and non-invasive technique].
- Author
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Faure P, Limam L, de Saint-Sauveur G, Da Cunha E, Best AL, Bénichou J, Remongin PE, Vauloup-Fellous C, Eid L, Labetoulle M, and Rousseau A
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- DNA, Viral analysis, Humans, Retrospective Studies, Epithelium, Corneal chemistry, Herpes Simplex, Keratitis, Herpetic diagnosis
- Abstract
Introduction: Virological diagnosis of anterior ocular herpetic disease (AOHD) is essential for the management of these often-chronic pathologies that may require long-term therapy. PCR has become the gold standard, but the type of sampling (tears, corneal scraping, aqueous tap) has not been standardized. In this study, we studied the technique of tear sampling for the diagnosis of AOHD., Materials and Method: We retrospectively analyzed the medical files of patients with a positive tear sample (Schirmer strip) for herpes simplex 1 virus (HSV-1) in the Department of Ophthalmology of Paris-Saclay Bicêtre Hospital between January 2018 and December 2020. We studied the clinical and virological characteristics (viral loads) of these cases of proven AOHD., Results: Thirty-six samples (33 patients) were included: 12 epithelial keratitis, 9 stromal HSK with ulceration, 5 uveitis, 4 stromal HSK without ulceration, 3 blepharitis, 1 endothelial HSK, 1 neurotrophic keratitis, and 1 conjunctivitis. The mean viral load was 3.9×10
5 copies/mL. Viral load was higher in cases of corneal ulceration (5.2×105 ±9.4×105 versus 1.2×102 ±1.7×102 copies/mL, P<1×10-4 ). There was no significant difference between primary episodes and relapses., Conclusion: Tear sampling using Schirmer strips is a simple, non-invasive method that can be useful for the virological diagnosis of various clinical forms of AOHD., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)- Published
- 2022
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12. Performance of the QIAprep& Viral RNA UM Kit assay (Qiagen), an automatable method for RT-qPCR detection of SARS-CoV-2 without RNA extraction.
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Fenaux H, Limam L, Soutiere MP, Veillet F, Escuret V, and Roque-Afonso AM
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- COVID-19 Nucleic Acid Testing, Humans, RNA, Viral analysis, RNA, Viral genetics, Sensitivity and Specificity, COVID-19 diagnosis, SARS-CoV-2 genetics
- Abstract
We evaluated the performance of the QIAprep& Viral RNA UM Kit (Qiagen) for SARS-CoV-2 detection. It displayed specificity and sensitivity required for SARS-CoV-2 RNA detection from swab transport media without RNA extraction. This method identifies accurately patients at risk of transmission while saving time and cost of extraction., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)
- Published
- 2022
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13. Delays in the Surgical Pathway in Breast cancer Patients in Tunisia: A Descriptive Prospective Study.
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Meriam K, Manel L, Jihene S, Hédi K, Ali M, and Thouraya A
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Objectives: Describe the surgical pathway and identify the different waiting times to surgery of women with a breast cancer in the Gynecology Department of the University Hospital of Sousse in Tunisia., Methods: It is a descriptive prospective study based on an assessment of professional practices using the process approach method. The study focused on the surgical management of women with breast cancer followed and scheduled for surgical treatment.The data were collected using a data collection sheet, developed according to a literature review., Results: The sample consisted of 77 women. Ten waiting times have been calculated. Global time to first treatment (surgical treatment) was 78.5 days with an interquartile range (IIQ) of [55.5-113.25 days]. The information period was 10 days with an IIQ of 3-19 days. The global time of access to surgery was 43.5 days with an IIQ of 40-54.75., Conclusion: Delays in access to care appear to be a potential marker of inequalities in access to care and an indicator of the performance of the healthcare system and can influence patient prognosis. The reduction of these delays must be integrated into a continuous quality improvement approach., (© Indian Association of Surgical Oncology 2021.)
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- 2022
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14. Genome variation in tick infestation and cryptic divergence in Tunisian indigenous sheep.
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Ahbara AM, Khbou MK, Rhomdhane R, Sassi L, Gharbi M, Haile A, Rekik M, Rischkowsky B, and Mwacharo JM
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- Animals, Cattle, Genome, Genotype, Mosquito Vectors, Polymorphism, Single Nucleotide, Sheep genetics, Tick Infestations genetics, Tick Infestations veterinary
- Abstract
Background: Ticks are obligate haematophagous ectoparasites considered second to mosquitos as vectors and reservoirs of multiple pathogens of global concern. Individual variation in tick infestation has been reported in indigenous sheep, but its genetic control remains unknown., Results: Here, we report 397 genome-wide signatures of selection overlapping 991 genes from the analysis, using ROH, LR-GWAS, XP-EHH, and F
ST , of 600 K SNP genotype data from 165 Tunisian sheep showing high and low levels of tick infestations and piroplasm infections. We consider 45 signatures that are detected by consensus results of at least two methods as high-confidence selection regions. These spanned 104 genes which included immune system function genes, solute carriers and chemokine receptor. One region spanned STX5, that has been associated with tick resistance in cattle, implicating it as a prime candidate in sheep. We also observed RAB6B and TF in a high confidence candidate region that has been associated with growth traits suggesting natural selection is enhancing growth and developmental stability under tick challenge. The analysis also revealed fine-scale genome structure indicative of cryptic divergence in Tunisian sheep., Conclusions: Our findings provide a genomic reference that can enhance the understanding of the genetic architecture of tick resistance and cryptic divergence in indigenous African sheep., (© 2022. The Author(s).)- Published
- 2022
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15. Presence of antibodies to Crimean Congo haemorrhagic fever virus in sheep in Tunisia, North Africa.
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Khamassi Khbou M, Romdhane R, Bouaicha Zaafouri F, Bouajila M, Sassi L, Appelberg SK, Schulz A, Mirazimi A, Groschup MH, Rekik M, Benzarti M, and Gharbi M
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- Animals, Sheep, Tunisia epidemiology, Hemorrhagic Fever Virus, Crimean-Congo, Hemorrhagic Fever, Crimean diagnosis, Hemorrhagic Fever, Crimean epidemiology, Hemorrhagic Fever, Crimean veterinary, Ixodidae, Sheep Diseases epidemiology, Ticks
- Abstract
Crimean-Congo haemorrhagic fever (CCHF) is an emerging tick-borne disease causing severe and fatal haemorrhagic syndrome in humans. Hyalomma spp. ticks are the primary vectors and sheep are important CCHF virus (CCHFV)-amplifying hosts. In this study, blood samples and ticks collected in October 2019 from 270 sheep from 15 farms across Tunisia constituted the main research material. Moreover, the sera of the same animals taken at different periods between 2018 and 2019 were also used to obtain comparative results. To investigate the presence of anti-CCHFV antibodies in sheep, all sera were tested using ELISA. Reactive sera were further characterised by a virus neutralisation test (VNT). Overall, one out of the 270 tested sheep was both ELISA- and strongly VNT-positive to CCHFV. Another two sheep were borderline ELISA-positive but did not exhibit neutralising antibodies. Ninety-one ticks were collected from all sampled sheep, of which 34 (37.4%) belonged to Hyalomma spp. This is the first report of anti-CCHFV antibodies in sheep from Tunisia. Both the results of this study and the recent CCHFV detection in ticks collected from camels in southern Tunisia indicate that further studies are needed to determine the competent tick vector in the country and to characterise the epidemiological cycle of CCHFV., (© 2021 The Authors. Veterinary Medicine and Science published by John Wiley & Sons Ltd.)
- Published
- 2021
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16. Infection by haemopathogens and tick infestation of sheep during summer season in Constantine region, Northeast Algeria.
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Foughali AA, Jedidi M, Dhibi M, Mhadhbi M, Sassi L, Berber A, Bitam I, and Gharbi M
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- Algeria epidemiology, Animals, Female, Male, Seasons, Sheep, Ixodidae, Theileria, Tick Infestations epidemiology, Tick Infestations veterinary
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A study on tick infestation of 43 sheep with clinical symptoms of piroplasmosis and anaplasmosis was carried out during summer seasons of 2016 and 2017 in 34 sheep flocks from Beni Hamidene locality, district of Constantine, Northeast Algeria. Only animals with clinical symptoms of piroplasmosis and/or anaplasmosis were checked for tick infestation. Among the 43 examined sheep, 58 ± 15% were infested by ticks. A total of 185 adult ticks (100 males and 85 females) were collected from the 25 sheep. Two tick genera, Rhipicephalus and Hyalomma consisting of four species were collected, Rhipicephalus bursa was the most frequent tick (164/185; 88.6 ± 4.6%), followed by Rhipicephalus sanguineus sensu lato (16/185; 8.6 ± 4%), Rhipicephalus (Boophilus) annulatus (4/185; 2.2 ± 2.1%) and Hyalomma scupense (1/185; 0.5 ± 1%). Mean overall tick infestation intensity was 7.4. Mixed infestations with two tick species were found in 10 sheep (23.3 ± 12.6%). All farmers (34/34) used ivermectin, and only 11% of them used acaricide to control ticks. The majority of R. bursa ticks (87/185; 45 ± 7%) were located on the ears 37/185; 20 ± 6%) and the testicles (50/185; 27 ± 6%). Giemsa-stained blood smears examination showed the presence of three haemopathogens: Anaplasma spp. (19/43; 44 ± 15%); Babesia spp. (6/43; 14 ± 10%) and Theileria spp. (1/43; 2 ± 4%). These results showed the presence of several low infestation burdens by ticks transmitting three haemopathogens., (© 2021 The Authors. Veterinary Medicine and Science published by John Wiley & Sons Ltd.)
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- 2021
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17. Tick Infestation and Piroplasm Infection in Barbarine and Queue Fine de l'Ouest Autochthonous Sheep Breeds in Tunisia, North Africa.
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Khamassi Khbou M, Rouatbi M, Romdhane R, Sassi L, Jdidi M, Haile A, Rekik M, and Gharbi M
- Abstract
As ticks and tick-borne pathogens affect the productivity of livestock, searching for genetically resistant breeds to infestation by ticks may represent an alternative to the overuse of chemical drugs. The aim of this study was to assess if there is a difference in tick infestation among the main sheep breeds in Tunisia. The study was carried out between April 2018 and January 2020 in 17 small to middle-sized sheep flocks from 3 regions across Tunisia. Four hundred and thirty-nine ear-tagged ewes from Barbarine (n = 288, 65.6%) and Queue Fine de l'Ouest (QFO) (n = 151, 34.4%) breeds were examined and sampled each trimester. Ticks were identified to the species level, and piroplasms were detected using PCR that targets a common sequence ARNr18S to both Babesia and Theileria genera using catch-all primers. Totally, 707 adult ticks were collected from animals; 91.4% (646/707) of them were Rhipicephalus sanguineus s.l. Queue Fine de l'Ouest animals were markedly less infested by ticks, and no one of them was infected by piroplasms compared to the Barbarine breed. Indeed, during the first four seasons, 21 animals, all from the Barbarine breed, were detected positive for piroplasms. This is the first study in Tunisia about the low susceptibility of QFO ewes to infestation by ticks and to infection by piroplasms. The QFO sheep breed could be raised preferably at high-risk areas of tick occurrence and could be considered in concrete control strategies, including a breeding program.
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- 2021
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18. Epidemiological investigation of Crimean-Congo haemorrhagic fever virus infection among the one-humped camels (Camelus dromedarius) in southern Tunisia.
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Bouaicha F, Eisenbarth A, Elati K, Schulz A, Ben Smida B, Bouajila M, Sassi L, Rekik M, Groschup MH, and Khamassi Khbou M
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- Animals, Camelus, Enzyme-Linked Immunosorbent Assay veterinary, Female, Hemorrhagic Fever, Crimean virology, Male, Prevalence, RNA, Viral analysis, Real-Time Polymerase Chain Reaction veterinary, Seroepidemiologic Studies, Tunisia epidemiology, Hemorrhagic Fever Virus, Crimean-Congo isolation & purification, Hemorrhagic Fever, Crimean epidemiology, Ixodidae virology
- Abstract
Crimean-Congo haemorrhagic fever is a viral tick-borne zoonotic disease caused by a Nairovirus, Crimean-Congo haemorrhagic fever virus (CCHFV). The present survey aimed to determine the exposure of one-humped camels (Camelus dromedarius) from southern Tunisia to CCHFV. A total of 273 sera from extensively reared camels were collected from Tataouine district, Tunisia, and tested by CCHFV-specific enzyme linked immunosorbent assays. By combining the results of three serological tests, the overall seroprevalence of CCHFV was estimated as 89.7% (245/273). No viral RNA was detected from camel sera using quantitative real-time PCR (RT-qPCR). A total of 165 ticks were collected from camels and tested with RT-qPCR, and only one Hyalomma impeltatum tick was positive for virus RNA., (Copyright © 2020 Elsevier GmbH. All rights reserved.)
- Published
- 2021
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19. Presence of antibodies against tick-borne encephalitis virus in sheep in Tunisia, North Africa.
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Khamassi Khbou M, Romdhane R, Foughali AA, Sassi L, Suin V, Rekik M, and Benzarti M
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- Animals, Antibodies, Viral blood, Cross-Sectional Studies, Encephalitis, Tick-Borne epidemiology, Encephalitis, Tick-Borne immunology, Ixodes, Seroepidemiologic Studies, Sheep, Tunisia epidemiology, Encephalitis Viruses, Tick-Borne isolation & purification, Encephalitis, Tick-Borne veterinary, Sheep Diseases virology
- Abstract
Background: Tick-borne encephalitis virus (TBEv) is a flavivirus that circulates in a complex cycle involving small mammals as amplifying hosts and ticks as vectors and reservoirs. The current study aimed to investigate the presence of TBEv in Tunisian sheep. A sample of 263 adult sheep were selected from 6 localities where Ixodes ricinus is well established. Sera were screened using ELISA for TBEv IgG detection, then the doubtful and positive sera were tested by the seroneutralisation test (SNT) and screened for West Nile Virus (WNv) IgG for cross-reaction assessment., Results: The ELISA for TBEv IgG detected one positive serum and 17 borderlines. The SNT showed one positive serum among the 18 tested, giving an overall antibody prevalence of 0.38% (95% CI = 0.07-2.12%). All but one serum tested negative to WNv ELISA. None of the sheep farmers reported neurological signs among sheep or humans in their households., Conclusions: The results may indicate the circulation of TBEv for the first time in Tunisia and in North Africa. Further studies based on either virus isolation or RNA detection, are needed to confirm the presence of TBEv in North Africa.
- Published
- 2020
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20. Individual variability among autochthonous sheep in Northern Tunisia to infection by abomasum nematodes and Babesia/Theileria parasites.
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Rouatbi M, Romdhane R, Bouaicha F, Saddem R, Sassi L, Dhibi M, Rekik M, Haile A, Mwacharo JM, Rischkowsky B, Darghouth MA, and Gharbi M
- Subjects
- Abomasum, Animals, Babesia isolation & purification, Babesiosis parasitology, Biological Variation, Individual, Female, Individuality, Male, Nematoda isolation & purification, Nematode Infections epidemiology, Nematode Infections parasitology, Sheep, Sheep Diseases parasitology, Sheep, Domestic, Theileria isolation & purification, Theileriasis parasitology, Tunisia epidemiology, Babesiosis epidemiology, Nematode Infections veterinary, Sheep Diseases epidemiology, Theileriasis epidemiology
- Abstract
In Tunisia, livestock plays an important role in the economy; unfortunately, Tunisian sheep population faces several health challenges. The aim of this trial was to study phenotypic variability of four local sheep breeds and strains to abomasum nematodes infection and to Babesia/Theileria parasites. Faeces, blood and abomasum contents were collected from 310 sheep slaughtered in eight commercial slaughterhouses across North Tunisia. Haematological and biochemical parameters were assessed. DNA was extracted and catch-all primers were used to detect both Theileria spp. and Babesia spp. DNA. Faecal egg counts (FEC) was quantitatively assessed using simple flotation technique followed by McMaster technique. Male and female worms were collected from all abomasum contents and counted under a stereomicroscope. The percentage of faeces samples positive for GIN's eggs was 30.82%. After worms' recovery, the infection prevalence was estimated to 75.90%. The overall infection prevalence by Babesia spp. and Theileria spp. was 4.21%. The dispersion of observations plots obtained by principal component analysis (PCA) showed two clusters of individuals. The first cluster contains animals having positive Babesia/Theileria PCR, presence of nematodes in the abomasum contents and relatively low total worm count (TWC < 500) expect one animal which was found bearing high TWC (>500). In this same group, with a suspected form of resistance, animals showed normal values of albumin and normal haematological parameters (red blood cell count [RBC], haemoglobin [Hb] and packed cell volume [PCV]). The second cluster represents all the other observations in which subgroups of animals were distinguished on the basis of their potential resistance to abomasum nematodes. Multiple correlations showed significant positive correlations between RBC/Hb, RBC/PCV, PCV/Hb and FEC/TWC. Significant negative correlations were observed between TWC/RBC and TWC/Hb. It is concluded that the phenotypic variability among local sheep breeds is essential for more advanced genetic and genomic studies., (© 2020 The Authors. Veterinary Medicine and Science published by John Wiley & Sons Ltd.)
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- 2020
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21. Seroprevalence of anti-Mycobacterium avium subsp. paratuberculosis antibodies in female sheep in Tunisia.
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Khamassi Khbou M, Romdhane R, Sassi L, Amami A, Rekik M, and Benzarti M
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- Animals, Female, Paratuberculosis microbiology, Prevalence, Seroepidemiologic Studies, Sheep, Sheep Diseases microbiology, Sheep, Domestic, Tunisia epidemiology, Antibodies, Bacterial blood, Mycobacterium avium subsp. paratuberculosis physiology, Paratuberculosis epidemiology, Sheep Diseases epidemiology
- Abstract
Paratuberculosis (Ptb) is a widespread chronic infection caused by Mycobacterium avium subsp. paratuberculosis (Map) that affects both domestic and wild ruminants. Most of the studies focused on cattle while, the prevalence of Ptb in sheep in different regions of the world is not well investigated. This study aimed to address this gap of knowledge by screening adult female sheep for paratuberculosis antibodies in different geographical regions of Tunisia. A total number of 338 female sheep from 15 small to middle-sized, extensively managed sheep farms in six regions across Tunisia were sampled. Animals were clinically examined before blood sampling. Sera were tested for the presence of anti-Mycobacterium avium subsp. paratuberculosis antibodies using a commercial ELISA kit. Six farms out of 15 comprised at least one seropositive animal and 11 female sheep out of 338 tested animals (3.25%; 95% CI = [1.83-5.73]) were seropositive to M. avium subsp. paratuberculosis. The seroprevalence was significantly lower in 5-year-old females (p = .04) and animals that do not graze (p = .02). Due to its huge economic and social impacts, paratuberculosis represents a health problem in Tunisia and several other countries Further investigations are needed to rank sheep Ptb in Tunisia among other diseases and to assess the main risk factors using a larger nation-wide survey., (© 2020 The Authors. Veterinary Medicine and Science Published by John Wiley & Sons Ltd.)
- Published
- 2020
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22. Purification and characterization of a novel high molecular weight alkaline protease produced by an endophytic Bacillus halotolerans strain CT2.
- Author
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Dorra G, Ines K, Imen BS, Laurent C, Sana A, Olfa T, Pascal C, Thierry J, and Ferid L
- Subjects
- Bacillus chemistry, Bacillus genetics, Bacterial Proteins chemistry, Bacterial Proteins genetics, Calcium chemistry, Endopeptidases chemistry, Endopeptidases genetics, Enzyme Stability, Hydrolysis, Ions chemistry, Kinetics, Manganese chemistry, Molecular Weight, Protease Inhibitors chemistry, RNA, Ribosomal, 16S genetics, Substrate Specificity, Temperature, Bacillus enzymology, Bacterial Proteins isolation & purification, Endopeptidases isolation & purification, Endophytes chemistry
- Abstract
A protease-producing strain CT2 isolated from Tunisian potatoes, exhibiting a potent protease activity (prot CT2), was identified as Bacillus halotolerans according to 16S ribosomal DNA sequence analysis. Maximum prot CT2 production was obtained in medium supplemented with bean seed proteins. Proteolytic activity was purified by ammonium sulphate precipitation, Sephacryl S-200 gel filtration and SP-sepharose cation-exchange chromatography. Optimal enzyme activity was reached at pH 9 and temperature of 50 °C. Proteolytic activity was enhanced by Ca
2+ and Mn2+ ions, completely inhibited by PMSF suggesting a serine protease nature and exhibited high stability in the presence of commercial detergents. Prot CT2 showed broad substrate specificity towards both synthetic and natural substrates, with a high capacity to hydrolyze legume seed proteins. Using electrophoretic analysis, its molecular weight was around 250 kDa with two major subunit showing important homologies with serine proteases belonging to the subtilisin-like serine proteases. Based on the Lineweaver-Burk plots Km and Vmax values were 10 mg/ml and 50,000 U/mg respectively. This newly described prot CT2 displays relevant properties which highlight its potential use in various industrial and biotechnological applications., (Copyright © 2018 Elsevier B.V. All rights reserved.)- Published
- 2018
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23. Illicit substance use among Tunisian college students: prevalence and risk factors.
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Chekib Z, Zammit N, Manel L, Menel M, Elghardallou M, Jihen S, Ali M, and Thouraya A
- Abstract
Background Illicit substance use among college students represents one of the most complicated social problems. Studying its predictors could help deal with this problem more efficiently. Aims To determine the prevalence of life time illicit substance use and its predictors among Tunisian college students. Methods A cross-sectional study was conducted in five colleges in the region of Sousse, Tunisia in the 2012-2013 school year. A sample of 556 college students responded to an anonymous self-administrated questionnaire. Collected data concerned socio-demographic characteristics and substances use. Results The mean age of students was 21.8 ± 2.2 years. Females represented 51.8% of participants. Among respondents: 31 (5.6%) had used illicit substance at least once. Cannabis was the main substance used by 26 (4.7%) students. The average age of the illicit substance use initiation was 19 (±2.5) years while it was almost 17 (±3) years for both tobacco and alcohol use initiations. Proportions of male students and academic failure were significantly more important among illicit substance users than among non users. While the most influential factors on illicit substance use were: alcohol use, tobacco use and low socioeconomic level. Conclusion This study highlights the strong association between the other risk behaviors and illicit drug use. Future interventions should focus on the whole risk behaviors simultaneously at late adolescence with regard to the environmental context.
- Published
- 2017
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24. Molecular prevalence of Toxoplasma gondii DNA in goats' milk and seroprevalence in Northwest Tunisia.
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Amairia S, Rouatbi M, Rjeibi MR, Nouasri H, Sassi L, Mhadhbi M, and Gharbi M
- Abstract
Toxoplasmosis is a worldwide zoonosis with high impact on human and animal health. Consumption of unpasteurized milk is a risk factor of human toxoplasmosis. The aim of this study was to estimate the seroprevalence and molecular prevalence of T. gondii in goats' milk in Northwest of Tunisia (Jendouba Governorate). A total number of 77 blood samples were collected from six herds were screened with a commercial ELISA kit for T. gondii antibodies. For the same goats' samples, a nested PCR was performed to detect T. gondii DNA in milk. The seroprevalence of T. gondii infection was 31.2% (±0.05) while the molecular prevalence of this parasite in milk was estimated to 7.8% (±0.03). A very low value of kappa showed that there is not agreement between seroprevalence and parasite prevalence in milk. These results suggest that the consumption of raw milk from naturally infected goats is a potential source of human infection. An extension programme should be implemented to decrease related to goats' raw milk consumption.
- Published
- 2016
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25. Protective effect of grape seed and skin extract on cerebral ischemia in rat: implication of transition metals.
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Safwen K, Selima S, Mohamed E, Ferid L, Pascal C, Mohamed A, Ezzedine A, and Meherzia M
- Subjects
- Animals, Brain metabolism, Brain Ischemia etiology, Calcium metabolism, Calpain metabolism, Cerebral Infarction etiology, Female, Malondialdehyde metabolism, Nitrites metabolism, Oxidoreductases metabolism, Rats, Rats, Wistar, Reactive Oxygen Species metabolism, Reperfusion Injury complications, Antioxidants therapeutic use, Brain Ischemia prevention & control, Plant Extracts therapeutic use, Seeds chemistry
- Abstract
Ischemic stroke is a leading cause of long lasting disability in humans and oxidative stress an important underlying cause. The present study aims to determine the effect of short term (seven-days) administration of high dosage grape seed and skin extract (GSSE 2.5 g/kg) on ischemia/reperfusion (I/R) injury in a rat model of global ischemia. Ischemia was induced by occlusion of the common carotid arteries for 30 min followed by one-hour reperfusion on control or GSSE treated animals. I/R induced a drastic oxidative stress characterized by high lipid and protein oxidation, a drop in antioxidant enzyme defenses, disturbed transition metals as free iron overload and depletion of copper, zinc and manganese as well as of associated brain enzyme activities as glutamine synthetase and lactate dehydrogenase. I/R also induced NO and calcium disruption and an increase in calpain activity, a calcium-sensitive cysteine protease. Interestingly, almost all I/R-induced disturbances were prevented by GSSE pretreatment as oxidative stress, transition metals associated enzyme activities, brain damage size and histology. Owing to its antioxidant potential, high dosage GSSE protected efficiently the brain against ischemic stroke and should be translated to humans., (© 2014 World Stroke Organization.)
- Published
- 2015
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26. Prevalence of piroplasms in small ruminants in North-West Tunisia and the first genetic characterisation of Babesia ovis in Africa.
- Author
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Rjeibi MR, Gharbi M, Mhadhbi M, Mabrouk W, Ayari B, Nasfi I, Jedidi M, Sassi L, Rekik M, and Darghouth MA
- Subjects
- Animals, Arachnid Vectors parasitology, Babesia isolation & purification, Base Sequence, DNA, Protozoan genetics, DNA, Protozoan isolation & purification, Goat Diseases parasitology, Goats parasitology, Molecular Sequence Data, Parasitemia epidemiology, Parasitemia parasitology, Phylogeny, Prevalence, Rhipicephalus parasitology, Seasons, Sequence Alignment, Sequence Homology, Nucleic Acid, Sheep parasitology, Sheep Diseases parasitology, Theileria isolation & purification, Tick Infestations complications, Tick Infestations epidemiology, Tick Infestations veterinary, Tunisia epidemiology, Babesia genetics, Babesiosis epidemiology, Goat Diseases epidemiology, Parasitemia veterinary, Sheep Diseases epidemiology, Theileriasis epidemiology
- Abstract
In this study, the prevalence of piroplasms in sheep and goats was assessed with Giemsa-stained blood smear examination, PCR and nested PCR-restriction fragment length polymorphism (RFLP) to identify Babesia and Theileria species, respectively, in 338 small ruminants (172 sheep and 166 goats) from three sites in North-West Tunisia during the 2011 summer season. The overall infection prevalence of piroplasms in Giemsa-stained blood smears was 3.2% (11/338), with a parasitaemia ranging from 0.01 to 0.05%. PCR detected two species, namely Babesia ovis (in sheep and goats) and Theileria ovis (in sheep), with an overall prevalence of 16.3%. The molecular prevalence of B. ovis was significantly higher in sheep than in goats (17.4% and 9%, respectively, p = 0.034). The same trend was observed for T. ovis in sheep and goats (5.8% and 0%, respectively, p = 0.004). Comparison of the partial sequences of the 18S ssu rRNA gene revealed 100% similarity amongst Babesia from sheep and goats. The single Theileria sequence in this study showed 100% similarity to T. ovis. A high similarity with all the blasted genotypes was reported for Theileria and Babesia sequences. This is the first molecular detection of B. ovis and genetic characterisation of small ruminants' piroplasms in Africa., (© M.R. Rjeibi et al., published by EDP Sciences, 2014.)
- Published
- 2014
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27. Population dynamics of ticks infesting the one-humped camel (Camelus dromedarius) in central Tunisia.
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Gharbi M, Moussi N, Jedidi M, Mhadhbi M, Sassi L, and Darghouth MA
- Subjects
- Animals, Female, Ixodidae physiology, Male, Population Dynamics, Prevalence, Rhipicephalus classification, Rhipicephalus physiology, Seasons, Sex Ratio, Tick Infestations epidemiology, Tunisia epidemiology, Camelus parasitology, Ixodidae classification, Tick Infestations veterinary
- Abstract
A tick population was monitored on 30 camels (Camelus dromedarius) over one year in Kairouan region, Central Tunisia. A total of 1630 ticks was collected and identified resulting in an estimate of different parasitological indicators. The ticks belonged to 2 genera and 5 species: Hyalomma impeltatum (53%) and Hyalomma dromedarii (45%) were the dominant species followed by Hyalomma excavatum (1%), Hyalomma marginatum (0.5%), and Rhipicephalus turanicus (0.5%) (p<0.001). Mean infestation prevalence was 90.6%; all the animals were infested by at least one tick from May to September. The highest mean prevalence was observed in H. impeltatum (60%), the lowest was reported in R. turanicus (0.03%) (p<0.05). Mean overall intensity of infestation was 4.4 ticks/animal. The highest mean intensity was observed in H. impeltatum (2.7 ticks/animal). Overall mean abundance of ticks was 4.4 ticks/animal. Different abiotic factors, namely monthly mean minimum and monthly mean maximum temperatures and the number of sunny days were positively correlated with overall monthly tick burdens which were in turn negatively correlated with the monthly mean relative humidity. This is the first study on camel tick dynamics in Tunisia., (Copyright © 2013 Elsevier GmbH. All rights reserved.)
- Published
- 2013
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28. Hyalomma scupense (Acari, Ixodidae) in northeast Tunisia: seasonal population dynamics of nymphs and adults on field cattle.
- Author
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Gharbi M, Hayouni ME, Sassi L, Dridi W, and Darghouth MA
- Subjects
- Age Factors, Analysis of Variance, Animals, Cattle, Cattle Diseases epidemiology, Feeding Behavior, Female, Male, Nymph growth & development, Population Dynamics, Seasons, Sentinel Surveillance veterinary, Sex Factors, Tick Infestations epidemiology, Tick Infestations parasitology, Tunisia epidemiology, Cattle Diseases parasitology, Ixodidae growth & development, Tick Infestations veterinary
- Abstract
Hyalomma scupense is a two-host tick infesting mainly cattle representing in North Africa the vector of tropical theileriosis (Theileria annulata infection), a major tick-borne disease affecting cattle. Any effective control programme of ticks requires a good knowledge of the biology of the target species. In the present study, three cattle farms in northeast Tunisia were surveyed during the activity seasons for adult and nymphs of Hyalomma scupense. Several indicators were studied, including chronological indicators, infestation prevalence, infestation intensity and feeding predilection sites of the ticks. The adult ticks were present from mid-June to late November. Nymphs were observed on animals from early September to late November. A large proportion of the ticks were attached in the posterior udder quarters: 41% and 64% of adult ticks and nymphs, respectively. The animals that were heavily infested by adult ticks were also heavily infested by nymphs. Moreover, 17% of adult ticks and 53% of nymphs were present on only 5% of cattle population. These data are important for the success of targeted acaricide application leading to a dramatic decrease of acaricide quantity needed for the treatment. When the preferential sites of attachment are known, the effectiveness of manual removal of ticks can be improved. The presence of highly infested animals is to be considered when any control programme is implemented, since these animals harbour a high proportion of the ticks., (© M. Gharbi et al., published by EDP Sciences, 2013.)
- Published
- 2013
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29. Acute effects of a partially purified fraction from garlic on plasma glucose and cholesterol levels in rats: putative involvement of nitric oxide.
- Author
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Mehrzia M, Ferid L, Mohamed A, and Ezzedine A
- Subjects
- Animals, Female, Male, Plant Extracts administration & dosage, Plant Extracts isolation & purification, Rats, Rats, Wistar, Blood Glucose drug effects, Cholesterol blood, Garlic chemistry, Nitric Oxide physiology
- Abstract
Garlic has been extensively used as a medicinal plant. Most of its numerous beneficial effects such as antioxidant, antibacterial, antitumoral involve sulfur-derived amino acids. In the present work, we reevaluated the acute effects of aqueous extract of garlic on plasma glucose and cholesterol levels in normal rats. Control (vehicle H2O) or garlic extract-treated group at 100-120 mg protein/kg body wt were intraperitoneally injected (IP) and glucose, cholesterol, insulin and nitric oxide metabolites levels were determined after a short-term duration of 6 h. We confirmed that garlic contained an active fraction, exerting both glucose and cholesterol-lowering activity. The glucose-lowering effect was triggered by an increase in insulinemia. Preliminary study indicated that the active agent was different from S-allyl-cysteine-sulfoxide, the active principle implicated in hypoglycaemic and hypolipidemic effects of garlic or arginine. The mechanism of action seemed to involve nitric oxide (NO), which increased time and dose-dependently. The garlic effects were abolished by diphenyleneiodonium chloride (DPI = 1 mg/kg body wt), a specific inhibitor of NO production, suggesting the involvement of constitutive nitric oxide synthase.
- Published
- 2006
30. Vaccination of calves with an attenuated cell line of Theileria annulata and the sporozoite antigen SPAG-1 produces a synergistic effect.
- Author
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Darghouth MA, Boulter NR, Gharbi M, Sassi L, Tait A, and Hall R
- Subjects
- Animals, Cattle, Cattle Diseases epidemiology, Cattle Diseases prevention & control, Cell Line, Disease Susceptibility, Male, Random Allocation, Theileriasis epidemiology, Theileriasis prevention & control, Vaccination veterinary, Antigens, Protozoan immunology, Cattle Diseases immunology, Protozoan Proteins immunology, Protozoan Vaccines immunology, Theileria annulata immunology, Theileriasis immunology
- Abstract
The sporozoite surface antigen, SPAG-1 and the attenuated schizont infected Tunisian line CL1 of Theileria annulata have been shown, in previous studies, to induce variable levels of protection against homologous and heterologous sporozoite challenge, respectively. We report here the result of a vaccination trial comparing the protection level induced by the SPAG-1 antigen (as a recombinant full length His tagged protein) and the attenuated cell line, used singly or in combination. The results, after challenge of immunised calves with a lethal dose of sporozoites, show that SPAG-1 provides limited protection (one out of seven calves surviving), while the attenuated cell line provides moderate protection (three out of seven calves recovered). The combination of SPAG-1 and the attenuated cell line induced the best protection as indicated by the survival of all the vaccinated calves. These results, together with a range of parasitological and clinical parameters, demonstrate the enhanced protection provided by combining sporozoite and schizont antigens in vaccination against tropical theileriosis.
- Published
- 2006
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31. Infection of calves with Theileria annulata in Tunisia: Economic analysis and evaluation of the potential benefit of vaccination.
- Author
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Gharbi M, Sassi L, Dorchies P, and Darghouth MA
- Subjects
- Anemia economics, Anemia epidemiology, Anemia etiology, Anemia veterinary, Animals, Antiprotozoal Agents economics, Cattle, Cattle Diseases economics, Cattle Diseases epidemiology, Cattle Diseases etiology, Cost-Benefit Analysis, Female, Male, Seasons, Theileriasis complications, Theileriasis epidemiology, Theileriasis prevention & control, Tunisia epidemiology, Antiprotozoal Agents therapeutic use, Protozoan Vaccines economics, Theileria annulata, Theileriasis economics, Veterinary Medicine economics
- Abstract
A field study aiming to estimate the costs of tropical theileriosis was carried out in an endemic region of the North of Tunisia. Three farms were monitored for two successive summer seasons. A total number of 56 calves and 12 sentinel cows were monitored. Calves were ranked into four groups: non infected animals, diseased animals with clinical tropical theileriosis, sub-clinical Theileria annulata infected animals with anaemia and sub-clinical T. annulata infected animals without anaemia. The total costs due to disease and infection were estimated to be 15,115.058 TD (Euro 9388.20). A high proportion of these costs (50.81%) is accounted for by asymptomatic infection. Sub-clinical infections with anaemia showed the highest losses in live weight, while disease cases (prevalence 42.86%) are responsible for 23.64% of the losses with death as the most important element. A cost-benefit analysis of vaccination using a Tunisian attenuated cell line vaccine was also undertaken. Considering that the vaccine would cost 5 TD (Euro 3.10), the cost-benefit ratio of vaccination is 23.7. Sensitivity analysis of the vaccination costs shows that the indifference decision point is around 118 TD (Euro 73.29).
- Published
- 2006
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32. A beta-glucosidase from Sclerotinia sclerotiorum: biochemical characterization and use in oligosaccharide synthesis.
- Author
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Issam SM, Mohamed G, Dominique LM, Thierry M, Farid L, and Nejib M
- Subjects
- Ascomycota growth & development, Cellobiose chemistry, Chromatography, Gel, Chromatography, High Pressure Liquid, Chromatography, Ion Exchange, Electrophoresis, Polyacrylamide Gel, Fungal Proteins chemistry, Fungal Proteins isolation & purification, Glucose chemistry, Oligosaccharides analysis, Substrate Specificity, beta-Glucosidase isolation & purification, Ascomycota enzymology, Oligosaccharides chemical synthesis, beta-Glucosidase chemistry
- Abstract
The filamentous fungus Sclerotinia sclerotiorum, grown on a xylose medium, was found to excrete one beta-glucosidase (beta-glu x). The enzyme was purified to apparent homogeneity by ammonium sulfate precipitation, gel filtration, anion-exchange chromatography, and high-performance liquid chromatography (HPLC) gel filtration chromatography. Its molecular mass was estimated to be 130 kDa by HPLC gel filtration and 60 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis, suggesting that beta-glu x may be a homodimer. For p-nitrophenyl beta-d-glucopyranoside hydrolysis, apparent Km and Vmax values were found to be 0.09 mM and 193 U/mg, respectively, while optimum temperature and pH were 55-60 degrees C and pH 5.0, respectively. beta-Glu x was strongly inhibited by Fe2+ and activated about 35% by Ca2+. beta-Glu x possesses strong transglucosylation activity in comparison with commercially available beta-glucosidases. The production rate of total glucooligosaccharides (GOSs) from 30% cellobiose at 50 degrees C and pH 5.0 for 6 h with 0.6 U/mL of enzyme preparation was 80 g/L. It reached 105 g/L under the same conditions when using cellobiose at 350 g/L (1.023 M). Finally, GOS structure was determined by mass spectrometry and 3C nuclear magnetic resonance spectroscopy.
- Published
- 2004
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33. Production, purification, and biochemical characterization of two beta-glucosidases from Sclerotinia sclerotiorum.
- Author
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Issam SM, Mohamed G, Farid L, Sami F, Thierry M, Dominique LM, and Nejib M
- Subjects
- Ascomycota growth & development, Cellobiose, Cellulases chemistry, Cellulases isolation & purification, Cellulose, Chromatography, Gel, Chromatography, High Pressure Liquid, Chromatography, Ion Exchange, Culture Media, Electrophoresis, Polyacrylamide Gel, Enzyme Stability, Glucose, Hydrogen-Ion Concentration, Isoenzymes biosynthesis, Kinetics, Molecular Weight, Temperature, Xylose, Ascomycota enzymology, Cellulases biosynthesis
- Abstract
The filamentous fungus Sclerotinia sclerotiorum produces beta-glucosidases in liquid culture with a variety of carbon sources, including cellulose (filter paper), xylan, barley straw, oat meal, and xylose. Analysis by native polyacrylamide gel electrophoresis (PAGE) followed by an activity staining with the specific chromogenic substrate, 5-bromo 4-chloro 3-indolyl beta-1,4 glucoside (X-glu) showed that two extracellular beta-glucosidases, designated as beta-glu1 and beta-glu2, were in the filter paper culture filtrate. Only one enzyme designated as beta-glu x was revealed by the same method in the xylose culture filtrate. Beta-glu1 and beta-glu2 were purified to homogeneity. The purification procedure consist of a common step of anion-exchange chromatography on DEAE-Sepharose CL6B, both high-performance liquid chromatography (HPLC) anion-exchange and gel filtration columns for beta-glu1 and only HPLC gel filtration for beta-glu2. Beta-glu1 has a molecular mass of 196 kDa and 96.5 kDa, as estimated by gel filtration and sodium dodecyl sulfate (SDS)-PAGE, respectively, suggesting that the native enzyme may consist of two identical subunits. The same analysis showed that beta-glu2 is a monomeric protein with an apparent molecular mass of about 76.5 kDa. Beta-glu1 and beta-glu2 hydrolyses PNPGlc and cellobiose, with apparent Km values respectively for PNPGlc and cellobiose of 0.1 and 1.9 mM for beta-glu1 and 2.8 and 8 mM for beta-glu2. Both enzymes exhibit the same temperature and pH optima for PNPGlc hydrolysis (60 degrees C and pH 5.0). beta-glu1 was stable over a pH range of 3-8 and kept 50% of its activity after 30 min of heating at 60 degrees C without substrate. It was further characterized by studying the effect of some cations and various reagents on its activity.
- Published
- 2003
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