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African trypanosomiasis is caused by

Background Tsetse flies are cyclical vectors of African trypanosomiasis. They have established symbiotic associations with different bacteria, which influence certain aspects of their physiology. The vector competence of tsetse flies for different trypanosome species is highly variable and is suggested to be affected by various factors, amongst which are bacterial endosymbionts. Symbiotic interactions may provide an avenue for the disease control. The current study provided the prevalence of 3 tsetse symbionts in Glossina species from Cameroon, Chad and Nigeria.Results Tsetse flies were collected from five different locations and dissected. DNA was extracted and polymerase chain reaction PCR was used to detect the presence of Sodalis glossinidius, Spiroplasma sp and Wolbachia using specific primers. A total of 848 tsetse samples were analysed: Glossina morsitans submorsitans (47.52%), Glossina palpalis palpalis (37.26%), Glossina fuscipes fuscipes (9.08%) and Glossina tachinoides (6.13%). Only 95 (11.20%) were infected with at least one of the 3 symbionts. Among the infected, 6 (6.31%) were carrying mixed infection (Wolbachia and Spiroplasma). The overall symbiont prevalence was 0.88%, 3.66% and 11.00% respectively, for Sodalis, Spiroplasma and Wolbachia. Prevalence varied between countries and tsetse species. No Spiroplasma was detected in samples from Cameroon and no Sodalis was found in samples from Nigeria.Conclusion The present study revealed for the first time, the presence of infection by Spiroplasma in tsetse in Chad and Nigeria. These findings provide useful information to the repertoire of bacterial flora of tsetse flies and incite to more investigations to understand their implication in the vector competence of tsetse flies.

African trypanosomiasis is caused by Trypanosoma brucei subspecies and available drugs against it, are unsatisfactory due to poor pharmacokinetic properties. Trypanosomal Alternative Oxidase (TAO) is an attractive target for anti-trypanosome rational drug discovery because it is essential for parasite-specific ATP generation and absent in the mammalian host. In this study, 360 filtered ligands from the Universal Natural Product Database were virtually screened and docked on T. brucei brucei TAO (PDB-ID 3VVA). From the virtual screening, 10 ligands with binding energy from -10.6 to -9.0 kcal/mol were selected as hits and further subjected pharmacokinetic and toxicity analyses where all of them passed Lipinski's rule of five. Also, the compounds were non-mutagenic, non-tumorigenic and could cross the blood brain barrier. The two topmost hits (UNPD29179; megacerotonic acid and UNPD41551; a quinazoline derivative) interacted with `four glutamates (Glu123, Glu162, Glu213 and Glu266) close to di-iron (2 iron elements) at the catalytic site of the enzyme. Subsequently, 100 ns MD simulations of the two topmost hits were performed using GROMACS where high RMSD values of 0.75 nm (TAO-UNPD29179) and 0.52 nm (TAO- UNPD41551), low residues fluctuations and consistent values of radius of gyration were observed. Moreover, Solvent Accessible Surface Area showed a consistent value of 160 nm2 for both complexes while TAO-UNPD29179 had higher number of hydrogen bonds than the TAO-UNPD41551. Similarly, MM/PBSA calculations indicated that UNPD29179 had higher free binding energy with TAO than UNPD41551. The data suggest that megacerotonic acid and a quinazoline derivative could be potential inhibitors of TAO with improved pharmacokinetic properties.Communicated by Ramaswamy H. Sarma.

African Animal Trypanosomiasis (AAT) or nagana in animals, is caused by the blood-borne parasitic protozoa called trypanosomes, and is potentially fatal. It is estimated that Africa loses $4‒5 billion annually due to the death of livestock to nagana in the tsetse belt. Although The Gambia lies within this belt, there is scanty data regarding the epizootiology of nagana in The Gambia. Here, records of reported cases of nagana for the period 2010–2019 at the International Trypanotolerance Centre (ITC) in The Gambia were analyzed retrospectively. For insights into the current prevalence of AAT, blood samples of 384 cattle, 42 goats, and 59 sheep from the Central River Region (CRR) and Lower River Region (LRR) were analyzed microscopically for parasite identification. Furthermore, trypanosomes were characterized by polymerase chain reaction (PCR) using a panel of primers that identify trypanosomes to the level of the species and subspecies by targeting a portion of the internally transcribed spacer-one (ITS-1) of the ribosomal RNA. The retrospective study indicates that Trypanosoma vivax (66%) and T. congolense (33.4%) were the predominant species. Based on the archive records of ITC, the villages Touba, Misera, and Sambel Kunda all in the CRR of the Gambia are the most burdened with AAT. Microscopic examination of blood samples from cattle showed a prevalence of 1.56%, whereas the PCR-based analysis gave a higher prevalence of 12.5%. The molecular analysis revealed the presence of T. vivax (3.65%), T. congolense kilifi (2.6%), T. b. brucei (1.3%), T. congolense savannah/forest (0.52%), T. b. gambiense (0.52%). Interestingly, 4.43% of mixed infections i.e. multiple trypanosome species in individual animals were recorded. In 18% of the mixed infection cases, T. godfreyi, T. simiae were coinfecting cattle alongside T. congolense. The molecular identification including the phylogenetic analysis implicated T. congolense as the most predominant trypanosome species infecting animals in The Gambia. The incidence of nagana in The Gambia is documented and the prevalent trypanosomes identified to be T. vivax, different types of T. congolense, and T. brucei including the gambiense subspecie. Finally, nagana is less profound in sheep and goats compared to cattle, with seasonal and regional variations playing a significant role in the disease dynamics.

BackgroundAzadirachta indica,Khaya senegalensis,Anogeissus leiocarpusandTamarindus indicaare important ethnomedicinal plants used for health mitigation since the history of mankind. They are used discretionarily in folkloric medicine on the premise that they are natural products devoid of synthetic preservatives. However, nature endows plants with metabolites for warding off potential attacks from animals and the environment. Some of these metabolites are responsible for toxicity of some plants. Furthermore, drug-induced liver injuries and nephrotoxicity are the leading causes of pharmaceutical attrition of promising drug candidates in clinical trials. Thus, we aimed to evaluate the safety of four ethnomedicinal plants in short-, medium- and long-term usage.MethodsRats dosed once with 5000 mg/kg extracts of each of these plants served as acute study (AS) while rats dosed daily with 2000 mg/kg for 2, 12 and 14 weeks served as sub-acute (SAS), sub-chronic (SCS) and chronic (CS) studies, respectively. Rats administered distilled water served as the negative control (NC).ResultsA. leiocarpusandT. indicasignificantly reduced percentage weight gain in the SCS compared to the NC.A. leiocarpussignificantly (PK. senegalensissignificantly (PPA. indica and T. indicasignificantly (PA. leiocarpusandK. senegalensissignificantly (P+and K+were significantly higher in the SCS and CS studies compared to the NC. The histological lesions seen ranged from cellular degeneration, congestion, fibrosis to necrosis.ConclusionThus, nonlethal, reversible toxic insults occur in short-term usage (AS); while, insidious lethal toxic effects occur in medium-term (SAS) and long-term usage (SCS and CS). The ability of these plant to maintain adequate hematological parameters, bodyweight and absence of mortality may explain free usage of preparations made from these plants in folkloric medicine.

Background The analysis of single nucleotide polymorphism (SNPs) in drug-resistance associated genes is a commonly used strategy for the surveillance of anti-malarial drug resistance in populations of parasites. The present study was designed and performed to provide genetic epidemiological data of the prevalence of N86Y-Y184F-D1246Y SNPs in Plasmodium falciparum multidrug resistance 1 (pfmdr1) in the malaria hotspot of Northern Nigeria. Methods Plasmodium falciparum-positive blood samples on Whatman-3MM filter papers were collected from 750 symptomatic patients from four states (Kano, Kaduna, Yobe and Adamawa) in Northern Nigeria, and genotyped via BigDye (v3.1) terminator cycle sequencing for the presence of three SNPs in pfmdr1. SNPs in pfmdr1 were used to construct NYD, NYY, NFY, NFD, YYY, YYD, YFD and YFY haplotypes, and all data were analysed using Pearson Chi square and Fisher’s exact (FE) tests. Results The prevalence of the pfmdr1 86Y allele was highest in Kaduna (12.50%, 2 = 10.50, P = 0.02), whilst the 184F allele was highest in Kano (73.10%, 2 = 13.20, P = 0.00), and the pfmdr1 1246Y allele was highest in Yobe (5.26%, 2 = 9.20, P = 0.03). The NFD haplotype had the highest prevalence of 69.81% in Kano (2 = 36.10, P = 0.00), followed by NYD with a prevalence of 49.00% in Adamawa, then YFD with prevalence of 11.46% in Kaduna. The YYY haplotype was not observed in any of the studied states. Conclusion The present study suggests that strains of P. falciparum with reduced sensitivity to the lumefantrine component of AL exist in Northern Nigeria and predominate in the North-West region.

Equine piroplasmosis (EP) is an infectious, tick-borne disease caused by the hemoprotozoan parasites, Theileria equi, Babesia caballi, and a recently reported new species, T. haneyi. Infections by these apicomplexan parasites limit performance and cause economic losses for the horse industry. Equine piroplasmosis is widespread in the northern regions of Nigeria, where an increasing portion of the animal population is composed of horses. This disease has remained epidemiologically challenging, especially as the movement of horses increases across Nigeria. In this study, blood samples from 300 horses were collected in three states of northwestern Nigeria. The presence of piroplasms was screened by nested PCR targeting 18S rDNA and positive samples were analyzed using species-specific-nested PCR-targeting genes including ema1 (T. equi), rap1 (B. caballi), and a gene coding a protein of unknown function (T. haneyi). Species-specific-nPCR results demonstrated that the prevalence of T. equi was 13.0% (39/300), B. caballi was 3.3% (10/300) and T. haneyi was 2.7% (8/300). Mixed infections with T. equi and B. caballi was 2.7% (8/300) while T. equi, B. caballi, and T. haneyi multiple infection prevalence was 0.6% (2/300). We used 18S rDNA sequences to determine close relationships between T. equi by phylogenetic analysis and demonstrated that among 57 sequences of Theileria parasites, 28 samples belonged to clade A (49%), 13 samples were found to be clade C (22%), and 16 were clade D (28%). These results demonstrate the genetic diversity of T. equi circulating in horses from Nigeria.

Background Vaccines are the most reliable alternative to elicit sterile immunity against malaria but their development has been hindered by polymorphisms and strain-specificity in previously studied antigens. New vaccine candidates are therefore urgently needed. Highly conserved Plasmodium falciparum reticulocyte-binding protein homologue-5 (PfRH5) has been identified as a potential candidate for anti-disease vaccine development. PfRH5 is essential for erythrocyte invasion by merozoites and crucial for parasite survival. However, there is paucity of data on the extent of genetic variations on PfRH5 in field isolates of Plasmodium falciparum. This study described genetic polymorphisms at the high affinity binding polypeptides (HABPs) 36718, 36727, 36728 of PfRH5 in Nigerian isolates of P. falciparum. This study tested the hypothesis that only specific conserved B and T cell epitopes on PfRH5 HABPs are crucial for vaccine development. Methods One hundred and ninety-five microscopically confirmed P. falciparum samples collected in a prospective cross-sectional study of three different populations in Lagos, Nigeria. Genetic diversity and haplotype construct of Pfrh5 gene were determined using bi-directional sequencing approach. Tajima’s D and the ratio of nonsynonymous vs synonymous mutations were utilized to estimate the extent of balancing and directional selection in the pfrh5 gene. Results Sequence analysis revealed three haplotypes of PfRH5 with negative Tajima’s D and dN/dS value of − 1.717 and 0.011 ± 0.020, respectively. A single nucleotide polymorphism, SNP (G → A) at position 608 was observed, which resulted in a change of the amino acid cysteine at position 203 to tyrosine. Haplotype and nucleotide diversities were 0.318 ± 0.016 and 0.0046 ± 0.0001 while inter-population genetic differentiation ranged from 0.007 to 0.037. Five polypeptide variants were identified, the most frequent being KTKYH with a frequency of 51.3%. One B-cell epitope, 151 major histocompatibility complex (MHC) class II T-cell epitopes, four intrinsically unstructured regions (IURs) and six MHC class I T-cell epitopes were observed in the study. Phylogenetic analysis of the sequences showed clustering and evidence of evolutionary relationship with 3D7, PAS-2 and FCB-2 RH5 sequences. Conclusions This study has revealed low level of genetic polymorphisms in PfRH5 antigen with B- and T-cell epitopes in intrinsically unstructured regions along the PfRH5 gene in Lagos, Nigeria. A broader investigation is however required in other parts of the country to support the possible inclusion of PfRH5 in a cross-protective multi-component vaccine.

African trypanosomiasis, sleeping sickness in humans or nagana in animals, is a potentially fatal neglected tropical disease and a threat to 65 million human lives and 100 million small and large l...

The alternative oxidase (AOX) is a monotopic diiron carboxylate protein which catalyzes the four-electron reduction of dioxygen to water by ubiquinol. Although we have recently determined the crystal structure of Trypanosoma brucei AOX (TAO) in the presence and absence of ascofuranone (AF) derivatives (which are potent mixed type inhibitors) the mechanism by which ubiquinol and dioxygen binds to TAO remain inconclusive. In this article, ferulenol was identified as the first competitive inhibitor of AOX which has been used to probe the binding of ubiquinol. Surface plasmon resonance reveals that AF is a quasi-irreversible inhibitor of TAO whilst ferulenol binding is completely reversible. The structure of the TAO-ferulenol complex, determined at 2.7 A, provided insights into ubiquinol binding and has also identified a potential dioxygen molecule bound in a side-on conformation to the diiron center for the first time.

The alternative oxidase (AOX) is a ubiquitous terminal oxidase of plants and many fungi, catalyzing the four-electron reduction of oxygen to water alongside the cytochrome-based electron transfer chain. Unlike the classical electron transfer chain, however, the activity of AOX does not generate adenosine triphosphate but has functions such as thermogenesis and stress response. As it lacks a mammalian counterpart, it has been investigated intensely in pathogenic fungi. However, it is in African trypanosomes, which lack cytochrome-based respiration in their infective stages, that trypanosome alternative oxidase (TAO) plays the central and essential role in their energy metabolism. TAO was validated as a drug target decades ago and among the first inhibitors to be identified was salicylhydroxamic acid (SHAM), which produced the expected trypanocidal effects, especially when potentiated by coadministration with glycerol to inhibit anaerobic energy metabolism as well. However, the efficacy of this combination was too low to be of practical clinical use. The antibiotic ascofuranone (AF) proved a much stronger TAO inhibitor and was able to cure Trypanosoma vivax infections in mice without glycerol and at much lower doses, providing an important proof of concept milestone. Systematic efforts to improve the SHAM and AF scaffolds, aided with the elucidation of the TAO crystal structure, provided detailed structure-activity relationship information and reinvigorated the drug discovery effort. Recently, the coupling of mitochondrion-targeting lipophilic cations to TAO inhibitors has dramatically improved drug targeting and trypanocidal activity while retaining target protein potency. These developments appear to have finally signposted the way to preclinical development of TAO inhibitors., Funding from the Spanish Ministerio de Economia, Industria y Competitividad (grant SAF2015‐66690‐R) and the Japan Society for the Promotion of Science (JSPS grant 17F17420) is gratefully acknowledged.

Schistosomiasis is prevalent in Nigeria, and the foremost pathogen is Schistosoma haematobium, which affects about 29 million people. Single dose of the drug praziquantel is often recommended for treatment but the efficacy has not been documented in certain regions. Therefore, this study was designed to assess the impact of single dose praziquantel treatment on S. haematobium infection among school children in an endemic community of South-Western Nigeria. Urine samples were collected from 434 school children and 10 ml was filtered through Nucleopore filter paper before examination for egg outputs by microscopy. The prevalence was 24.9% at pre-treatment. There was no statistically significant difference for the prevalence of infection between males (14.7%) and females (10.2%), although the mean egg count for the females (9.87) was significantly more (Plt; 0.05) than the males (6.06). At 6 and 12 months post-treatment there was 74.4% and 86.4% reduction in the mean egg count, respectively. Interestingly, an increased prevalence of infection from 2.1% at 6 months to 7.7% at 12 months post-treatment was observed, nonetheless the mean egg count was reduced to 0.27 at 12th month from 1.98 at 6 months post-treatment. Resurgence in the prevalence rate between 6 and 12 months post-treatment with praziquantel is herein reported and the need for a follow-up treatment in endemic areas for adequate impact on schistosomiasis control is discussed.

Equine piroplasmosis, an economically important disease of equids caused by the hemoprotozoan parasites Theileria equi, T. haneyi, and Babesia caballi, has a worldwide distribution. These parasites are transmitted by ixodid ticks. To improve the detection of horses in Nigeria exposed to piroplasm parasites, 72 horses with variable clinical signs of piroplasmosis were sampled from Northwest and Northcentral Nigeria and tested by nPCR and cELISA. Blood and serum samples were collected from each horse via jugular venesection. Individually, nPCR or cELISA failed to identify all horses exposed to piroplasms. A combination of species-specific nPCR and the OIE-approved T. equi and B. caballi cELISAs enhanced the detection of horses exposed to parasites. The results also demonstrated horses showing abnormal hematology were positive for only T. equi, except for one sample that was coinfected with T. equi and T. haneyi. We also identified ticks collected from some of the horses, with Rhipicephalus evertsi evertsi being the most prevalent. This study shows that a larger proportion of horses in the sample set were exposed to T. equi than B. caballi or T. haneyi. Additionally, ticks that have been previously reported as potential vectors for these parasites were found to have infested sampled horses. Further studies are needed to investigate which tick species are competent vectors for Theileria spp. and Babesia caballi in Nigeria.

African Animal Trypanosomiasis (AAT) or nagana in animals, is caused by the blood-borne parasitic protozoa called trypanosomes, and is potentially fatal. It is estimated that Africa loses $4‒5 billion annually due to the death of livestock to nagana in the tsetse belt.Although The Gambia lies within this belt, there is scanty data regarding the epizootiology of nagana in The Gambia. Here, records of reported cases of nagana for the period 2010-2019 at the International Trypanotolerance Centre (ITC) in The Gambia were analyzed retrospectively.For insights into the current prevalence of AAT, blood samples of 384 cattle, 42 goats, and 59 sheep from the Central River Region (CRR) and Lower River Region (LRR) were analyzed microscopically for parasite identification. Furthermore, trypanosomes were characterized by polymerase chain reaction (PCR) using a panel of primers that identify trypanosomes to the level of the species and subspecies by targeting a portion of the internally transcribed spacer-one (ITS-1) of the ribosomal RNA.The retrospective study indicates that Trypanosoma vivax (66%) and T. congolense (33.4%) were the predominant species. Based on the archive records of ITC, the villages Touba, Misera, and Sambel Kunda all in the CRR of the Gambia are the most burdened with AAT. Microscopic examination of blood samples from cattle showed a prevalence of 1.56%, whereas the PCR-based analysis gave a higher prevalence of 12.5%. The molecular analysis revealed the presence of T. vivax (3.65%), T. congolense kilifi (2.6%), T. b. brucei (1.3%), T. congolense savannah/forest (0.52%), T. b. gambiense (0.52%). Interestingly, 4.43% of mixed infections i.e. multiple trypanosome species in individual animals were recorded. In 18% of the mixed infection cases, T. godfreyi, T. simiae were coinfecting cattle alongside T. congolense. The molecular identification including the phylogenetic analysis implicated T. congolense as the most predominant trypanosome species infecting animals in The Gambia.The incidence of nagana in The Gambia is documented and the prevalent trypanosomes identified to be T. vivax, different types of T. congolense, and T. brucei including the gambiense subspecie. Finally, nagana is less profound in sheep and goats compared to cattle, with seasonal and regional variations playing a significant role in the disease dynamics.

Background: The analysis of single nucleotide polymorphism (SNPs) in drug-resistance associated genes is a commonly used strategy for the surveillance of antimalarial drug resistance in populations of parasites. The present study was designed and performed to provide genetic epidemiological data of the prevalence of N86Y-Y184F-D1246Y SNPs in Plasmodium falciparum multidrug resistance 1 (pfmdr1) in the malaria hotspot of Northern Nigeria.Methods: Plasmodium falciparum-positive blood samples on Whatman-3MM filter papers were collected from 750 symptomatic patients from four states (Kano, Kaduna, Yobe and Adamawa) in Northern Nigeria, and genotyped via BigDye (v3.1) terminator cycle sequencing for the presence of three SNPs in pfmdr1. SNPs in pfmdr1 were used to construct NYD, NYY, NFY, NFD, YYY, YYD, YFD and YFY haplotypes, and all data were analyzed using Pearson Chi-square and Fisher's exact (FE) tests.Results: The prevalence of the pfmdr1 86Y allele was highest in Kaduna (12.50%, 𝜒² = 10.50, P = 0.02), whilst the 184F allele was highest in Kano (73.10%, 𝜒² = 13.20, P = 0.00), and the pfmdr1 1246Y allele was highest in Yobe (5.26%, 𝜒² = 9.20, P = 0.03). The NFD haplotype had the highest prevalence of 69.81% in Kano (𝜒² = 36.10, P = 0.00), followed by NYD with a prevalence of 49.00% in Adamawa, then YFD with prevalence of 11.46% in Kaduna. The YYY haplotype was not observed in any of the studied states.Conclusion: The present study shows that P. falciparum strains with potential reduced susceptibility to the lumefantrine component of AL exist in Northern Nigeria and predominate in the North-West region.

Background The analysis of single nucleotide polymorphism (SNPs) in drug-resistance associated genes is a commonly used strategy for the surveillance of antimalarial drug resistance in populations of parasites. The present study was designed and performed to provide genetic epidemiological data of the prevalence of N86Y-Y184F-D1246Y SNPs in Plasmodium falciparum multidrug resistance 1 (pfmdr1) in the malaria hotspot of Northern Nigeria. Methods Plasmodium falciparum-positive blood samples on Whatman-3MM filter papers were collected from 750 symptomatic patients from four states (Kano, Kaduna, Yobe and Adamawa) in Northern Nigeria, and genotyped via BigDye (v3.1) terminator cycle sequencing for the presence of three SNPs in pfmdr1. SNPs in pfmdr1 were used to construct NYD, NYY, NFY, NFD, YYY, YYD, YFD and YFY haplotypes, and all data were analyzed using Pearson Chi-square and Fisher's exact (FE) tests. Results The prevalence of the pfmdr1 86Y allele was highest in Kaduna (12.5%, 𝜒² = 10.47, P pfmdr1 1246Y allele was highest in Yobe (5.26%, 𝜒² = 9.18, P P. falciparum strains with reduced sensitivity to artemether-lumefantrine exist in Northern Nigeria and predominate in the North-West region.

Protozoan parasites of the Order Trypanosomatida infect a wide range of multicellular plants and animals, causing devastating and potentially fatal diseases. Trypanosomes are the most relevant members of the order in sub-Saharan Africa because of mortalities and morbidities caused to humans and livestock. There are growing concerns that trypanosomes are expanding their reservoirs among wild animals, which habours the parasites, withstand the infection, and from which tsetse flies transmit the parasites back to humans and livestock. This study was designed to investigate the potentials of the African hedgehog serving as reservoir for African animal trypanosomes. Five adult hedgehogs alongside five laboratory mice were intraperitoneally inoculated with 106 and 104 of Trypanosoma congolense cells, respectively, and monitored for parasitemia and survival. Serum from twenty hedgehogs was subjected to trypanocidal activity-guided fractionation by successive ion-exchange and gel-filtration chromatographies, followed by characterization with Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis (SDS-PAGE). Hedgehogs were resistant to the infection as no parasite was detected and none died even after 60 days, while all the mice died within 12 days. Both the serum and plasma prepared from hedgehogs demonstrated trypanocidal activity- rapidly killed trypanosomes even when diluted 1000 times. The trypanolytic factor was identified to be proteinaceous with an estimated molecular weight of 115-kDa. For the first time, it is here demonstrated that hedgehog blood has significant trypanolytic activity against T. congolense. The potential application of the hedgehog protein for the breeding of trypanosomosis-resistant livestock in tsetse fly belt is discussed.

BackgroundRift Valley fever (RVF) is a zoonotic disease that has become emerging and re-emerging in some regions of the world, infecting livestock and humans. One-humped camels are important economic livestock species in Africa used for traction, transportation, and food. Regional and international trade has continued to increase the risk of this disease, spreading widely and causing severe economic and public health catastrophes in affected regions. In spite of these risks, there is a dearth of information about the status of RVF in camels in Nigeria. This study was carried out to determine the prevalence of the RVF virus in one-humped camels in Nigeria and identify the risk factors associated with the disease.MethodsA cross-sectional study with simple random sampling was carried out in seven local government areas of Jigawa and Katsina States. The sera from camels were tested for anti-RVFV IgG. Camel owners were administered a structured questionnaire to ascertain their knowledge, attitude, and practice.ResultsAn overall prevalence of 19.9% (95% CI; 17.07-22.90) was recorded. Based on age groups, the highest prevalence of 20.9% (95% CI; 17.00-25.31) was obtained among older camels (6-10 years), while female camels recorded a high prevalence of 20.4% (95%CI; 15.71-25.80). Sule Tankar-kar recorded the highest prevalence with 33% (95%CI; 1.31-4.72, p= 0.007) and OR 2.47 in Jigawa State while Mai’adua had 24.7% (95%CI; 0.97-2.73, p=0.030) with OR 1.62 in Katsina State respectively. From the risk map, local government areas bordering Niger Republic were at a high risk of RVF. Only high rainfall was not significantly linked with RVF occurrence among nomadic camel pastoralists (95%CI 0.93-5.20; p=0.070).ConclusionThere is a need for the country to have quarantine units across borders for screening animals coming from neighbouring countries for transboundary infectious diseases such as RVF.Author SummaryRift Valley fever is a viral haemorrhagic fever that affects animals and humans with high mortality. Recently there has been increased demand in camel meat and products for food and therapeutic purposes. Climate change, coupled with insecurity in the Sahel, has had a significant impact on transhumance activities where camels and their owners move to different countries in search of pasture for their animals. Though Nigeria has not reported an outbreak of Rift Valley fever despite serological evidence in various animal species, there is a need to assess RVF in camels, which is a critical animal species, involved in transhumance with the potential of introducing transboundary diseases into new areas. The study assessed the presence of antibodies in camels, identified risk factors associated with the disease in camels and areas at risk for the disease. Our study found a seroprevalence of 19.9% in camels in two northern states of Nigeria, which shares a boundary with the Niger Republic that recently reported an outbreak. Our findings suggest that areas in proximity to Niger Republic are at a high risk to the disease and camels belonging to transhumance pastoralists are highly likely to contract Rift Valley fever since they are exposed to various ecological and environmental factors that precipitate the disease.

Acetate:succinate CoA transferase (ASCT) is a mitochondrial enzyme that catalyzes the production of acetate and succinyl-CoA, which is coupled to ATP production with succinyl-CoA synthetase (SCS) in a process called the ASCT/SCS cycle. This cycle has been studied in Trypanosoma brucei (T. brucei), a pathogen of African sleeping sickness, and is involved in (i) ATP and (ii) acetate production and proceeds independent of oxygen and an electrochemical gradient. Interestingly, knockout of ASCT in procyclic form (PCF) of T. brucei cause oligomycin A-hypersensitivity phenotype indicating that ASCT/SCS cycle complements the deficiency of ATP synthase activity. In bloodstream form (BSF) of T. brucei, ATP synthase works in reverse to maintain the electrochemical gradient by hydrolyzing ATP. However, no information has been available on the source of ATP, although ASCT/SCS cycle could be a potential candidate. Regarding mitochondrial acetate production, which is essential for fatty acid biosynthesis and growth of T. brucei, ASCT or acetyl-CoA hydrolase (ACH) are known to be its source. Despite the importance of this cycle, direct evidence of its function is lacking, and there are no comprehensive biochemical or structural biology studies reported so far. Here, we show that in vitro–reconstituted ASCT/SCS cycle is highly specific towards acetyl-CoA and has a higher kcat than that of yeast and bacterial ATP synthases. Our results provide the first biochemical basis for (i) rescue of ATP synthase-deficient phenotype by ASCT/SCS cycle in PCF and (ii) a potential source of ATP for the reverse reaction of ATP synthase in BSF., Highlights • First biochemical and structural characterization of mitochondrial ASCT/SCS cycle • It is essential for mitochondrial acetate/ATP production and T. brucei BSF growth • TbASCT/SCS cycle shows higher k cat than that of yeast and bacterial ATP synthases • Detailed comparative biochemical analysis between ASCT and human SCOT • Active site residue and X-CoA binding site determined by site-directed mutagenesis

Rift Valley fever (RVF) is a complex emerging arboviral hemorrhagic disease that causes significant illness in animals and humans. Camel trade across the land borders between Nigeria and the Niger Republic occurs frequently and poses a significant risk for RVF transmission to pastoralists and traders. We carried a cross-sectional study between November 2016 and April 2017 in two northern States (Katsina and Jigawa) known for camel trade in Nigeria to investigate the seroprevalence and potential risk factors for RVFV occurrence. We collected 720 sera and administered questionnaire to pastoralists. We used the competitive enzyme-linked immunosorbent assay (c-ELISA) to determine the previous exposure to RVFV infection. We retrieved environmental information from public data sources that might explain RVFV seropositivity at the LGA level. To asses potential risk factors,we categorized LGAs with RVFV as "1" and those without a case" 0". We fitted a logistic model to the data and estimated odds ratios and 95% confidence intervals. An overall 19.9% prevalence was reported among camel herd—the highest seropositivity (33.3%) was recorded in SuleTankarkar LGA. In the multivariable model, only rain-fed croplands was significantly associated with RVFV antibodies occurrence p = 0.048 (OR = 0.87, 95% CI: 0.76–0.99). Only a minority of the respondents, 19.3% (n = 17/88), knew that RVF is zoonotic. Separation of healthy animals from the infected animals was carried out by 53.4% (47/88) pastoralists while 59.1% (52/88) pastoralists still use ethnoveterinary practices to control or mitigate disease outbreaks. Our study demonstrates the presence of RVFV antibodies among camel in Nigeria and the associated risk factors. These findings highlight the need for enhancing surveillance and control efforts and the public health education of camel pastoralists. Further investigation to unravel the zoonotic transmission potential to pastoralists and other animal species is pertinent., Highlights • An overall seroprevalence of 19.9% was recorded in our study. • Rain-fed croplands were significantly associated with RVFV. • There is need for public health education among pastoralists.

Background In general, glycerol kinases (GKs) are transferases that catalyze phospho group transfer from ATP to glycerol, and the mechanism was suggested to be random bi-bi. The reverse reaction i.e. phospho transfer from glycerol 3-phosphate (G3P) to ADP is only physiologically feasible by the African trypanosome GK. In contrast to other GKs the mechanism of Trypanosoma brucei gambiense glycerol kinase (TbgGK) was shown to be in an ordered fashion, and proceeding via autophosphorylation. From the unique reaction mechanism of TbgGK, we envisaged its potential to possess phosphatase activity in addition to being a kinase. Methods Our hypothesis was tested by spectrophotometric and LC-MS/MS analyses using paranitrophenyl phosphate (pNPP) and TbgGK's natural substrate, G3P respectively. Furthermore, protein X-ray crystallography and site-directed mutagenesis were performed to examine pNPP binding, catalytic residues, and the possible reaction mechanism. Results In addition to its widely known and expected phosphotransferase (class II) activity, TbgGK can efficiently facilitate the hydrolytic cleavage of phosphoric anhydride bonds (a class III property). This phosphatase activity followed the classical Michaelis-Menten pattern and was competitively inhibited by ADP and G3P, suggesting a common catalytic site for both activities (phosphatase and kinase). The structure of the TGK-pNPP complex, and structure-guided mutagenesis implicated T276 to be important for the catalysis. Remarkably, we captured a crystallographic molecular snapshot of the phosphorylated T276 reaction intermediate. Conclusion We conclude that TbgGK has both kinase and phosphatase activities. General significance This is the first report on a bifunctional kinase/phosphatase enzyme among members of the sugar kinase family.

We investigated a chemical strategy to boost the trypanocidal activity of 2,4-dihydroxybenzoic acid (2,4-DHBA)- and salicylhydroxamic acid (SHAM)-based trypanocides with triphenylphosphonium and quinolinium lipophilic cations (LC). Three series of LC conjugates were synthesized that were active in the submicromolar (5a-d and 10d-f) to low nanomolar (6a-f) range against wild-type and multidrug resistant strains of African trypanosomes (Trypanosoma brucei brucei and T. congolense). This represented an improvement in trypanocidal potency of at least 200-fold, and up to >10 000-fold, compared with that of non-LC-coupled parent compounds 2,4-DHBA and SHAM. Selectivity over human cells was >500 and reached >23 000 for 6e. Mechanistic studies showed that 6e did not inhibit the cell cycle but affected parasite respiration in a dose-dependent manner. Inhibition of trypanosome alternative oxidase and the mitochondrial membrane potential was also studied for selected compounds. We conclude that effective mitochondrial targeting greatly potentiated the activity of these series of compounds., The logistical collaboration of Drs. Jagerovic, Goya, and Herranz is gratefully acknowledged. This work was funded by the Spanish Ministerio de Economia y Competitividad (SAF2015-66690-R). G.U.E. was supported by a TET-fund studentship from the government of Nigeria and by a Mac Robertson Travel Scholarship from the College of Medical, Veterinary and Life Sciences of the University of Glasgow

African trypanosomiasis, sleeping sickness in humans or nagana in animals, is a potentially fatal neglected tropical disease and a threat to 65 million human lives and 100 million small and large livestock animals in sub-Saharan Africa. Available treatments for this devastating disease are few and have limited efficacy, prompting the search for new drug candidates. Simultaneous inhibition of the trypanosomal glycerol kinase (TGK) and trypanosomal alternative oxidase (TAO) is considered a validated strategy toward the development of new drugs. Our goal is to develop a TGK-specific inhibitor for coadministration with ascofuranone (AF), the most potent TAO inhibitor. Here, we report on the identification of novel compounds with inhibitory potency against TGK. Importantly, one of these compounds (compound 17) and its derivatives (17a and 17b) killed trypanosomes even in the absence of AF. Inhibition kinetics revealed that derivative 17b is a mixed-type and competitive inhibitor for TGK and TAO, respectively. Structural data revealed the molecular basis of this dual inhibitory action, which, in our opinion, will aid in the successful development of a promising drug to treat trypanosomiasis. Although the EC

Hard ticks are not only haematophagus ectoparasites of vertebrates, but vectors of several micro-organisms that cause severe diseases around the world. In Sub-Saharan Africa, particularly Nigeria, tick infestation is major setback to improvement of livestock and companion animals due to misdiagnoses. The combination of morphological and molecular approach have been documented as a reliable and most appropriate procedure for accurate identification of tick species. Therefore, this study aimed to identify ticks that infest dogs across the six Area Councils of Federal Capital Territory (FCT), Abuja-Nigeria. Ticks (n=2041) were collected from dogs sampled (n=480) for a period of one year and identified morphologically. Genomic DNA was extracted from representative identified tick specimen (n=30) and were amplified in Polymerase Chain Reaction (PCR) using genus specific primers targeting 18S rRNA gene. The products were electrophoresed on 1.5% agarose gel, purified and sequenced bidirectionally. The nucleotide sequences were analysed in BLASTn in NCBI data base. A phylogenetic tree was constructed using Neighbour-Joining Algorithms. The identification by morphology showed that ticks were belonging to 2 Genera: Rhipicephalus and Amblyomma. The most abundant species was Rhipicephalus (99.9%), and then Amblyomma (0.1%). DNA amplification showed bands size of 173 bp and the BLASTn search analysis revealed 99-100% identity with R. sanguineus in the GenBank. The phylogenetic analysis showed that strains of the R. sanguineus were similar to those previously reported in Israel and Cuba. In conclusion, Rhipicephalus sanguineus was the most abundant tick found among dogs screened in Abuja, Nigeria, irrespective of their use. This is the first molecular identification of dog ticks in the FCT and may have epidemiological significance in the control of ticks and tick-borne disease in the region.

5-Aminolevulinic acid (ALA) is a naturally occurring amino acid present in diverse organisms and a precursor of heme biosynthesis. ALA is commercially available as a component of cosmetics, dietary supplements, and pharmaceuticals for cancer diagnosis and therapy. Recent reports demonstrated that the combination of ALA and ferrous ion (Fe 2+ ) inhibits the in vitro growth of the human malaria parasite Plasmodium falciparum . To further explore the potential application of ALA and ferrous ion as a combined antimalarial drug for treatment of human malaria, we conducted an in vivo efficacy evaluation. Female C57BL/6J mice were infected with the lethal strain of rodent malaria parasite Plasmodium yoelii 17XL and orally administered ALA plus sodium ferrous citrate (ALA/SFC) as a once-daily treatment. Parasitemia was monitored in the infected mice, and elimination of the parasites was confirmed using diagnostic PCR. Treatment of P. yoelii 17XL-infected mice with ALA/SFC provided curative efficacy in 60% of the mice treated with ALA/SFC at 600/300 mg/kg of body weight; no mice survived when treated with vehicle alone. Interestingly, the cured mice were protected from homologous rechallenge, even when reinfection was attempted more than 230 days after the initial recovery, indicating long-lasting resistance to reinfection with the same parasite. Moreover, parasite-specific antibodies against reported vaccine candidate antigens were found and persisted in the sera of the cured mice. These findings provide clear evidence that ALA/SFC is effective in an experimental animal model of malaria and may facilitate the development of a new class of antimalarial drug.

African trypanosomiasis is a neglected parasitic disease that is still of great public health relevance, and a severe impediment to agriculture in endemic areas. The pathogens possess certain unique metabolic features that can be exploited for the development of new drugs. Notably, they rely on an essential, mitochondrially-localized enzyme, Trypanosome Alternative Oxidase (TAO) for their energy metabolism, which is absent in the mammalian hosts and therefore an attractive target for the design of safe drugs. In this study, we cloned, expressed and purified the physiologically relevant form of TAO, which lacks the N-terminal 25 amino acid mitochondrial targeting sequence (ΔMTS-TAO). A new class of 32 cationic and non-cationic 4-hydroxybenzoate and 4-alkoxybenzaldehyde inhibitors was designed and synthesized, enabling the first structure-activity relationship studies on ΔMTS-TAO. Remarkably, we obtained compounds with enzyme inhibition values (IC) as low as 2 nM, which were efficacious against wild type and multidrug-resistant strains of T. brucei and T. congolense. The inhibitors 13, 15, 16, 19, and 30, designed with a mitochondrion-targeting lipophilic cation tail, displayed trypanocidal potencies comparable to the reference drugs pentamidine and diminazene, and showed no cross-resistance with the critical diamidine and melaminophenyl arsenical classes of trypanocides. The cationic inhibitors 15, 16, 19, 20, and 30 were also much more selective (900 - 344,000) over human cells than the non-targeted neutral derivatives (selectivity >8-fold). A preliminary in vivo study showed that modest doses of 15 and 16 reduced parasitaemia of mice infected with T. b. rhodesiense (STIB900). These compounds represent a promising new class of potent and selective hits against African trypanosomes., This work was funded by the Spanish Ministerio de Economia y Competitividad (SAF2015-66690-R). This investigation also received financial support (ID No. B40103 to EOB) from TDR, the Special Programme for Research and Training in Tropical Diseases (co-sponsored by UNICEF, UNDP, the World Bank and WHO). G. U. Ebiloma was supported by a TET-Fund studentship from the government of Nigeria and by a Mac Robertson Travel Scholarship from the College of Medical, Veterinary and Life Sciences of the University of Glasgow.

In Trypanosoma brucei, a parasite that causes African trypanosomiasis in humans (sleeping sickness) and in livestock (nagana) throughout sub-Saharan Africa, the trypanosome alternative oxidase (TAO) is essential for the respiration of bloodstream form parasites (i.e. the human-infective form). Since TAO has no counterpart in mammalian cells and it is conserved among T. brucei subspecies, it has been validated as a promising target for the chemotherapy of African trypanosomiasis. We present here a successful approach to boost the activity of TAO inhibitors based on the conjugation of the inhibitor with lipophilic cations (LC) that can cross lipid bilayers by non-carrier mediated transport, and thus accumulate specifically into mitochondria, driven by the plasma and mitochondrial transmembrane potentials (negative inside). This design afforded several LC–TAO inhibitor conjugates active in the submicromolar to low nanomolar range against wild type and resistant strains of African trypanosomes (T. b. brucei, T. congolense), with selectivity over human cells >500.

Recent studies on the respiratory chain of Ascaris suum showed that the mitochondrial NADH-fumarate reductase system composed of complex I, rhodoquinone and complex II plays an important role in the anaerobic energy metabolism of adult A. suum. The system is the major pathway of energy metabolism for adaptation to a hypoxic environment not only in parasitic organisms, but also in some types of human cancer cells. Thus, enzymes of the pathway are potential targets for chemotherapy. We found that flutolanil is an excellent inhibitor for A. suum complex II (IC50 = 0.058 μM) but less effectively inhibits homologous porcine complex II (IC50 = 45.9 μM). In order to account for the specificity of flutolanil to A. suum complex II from the standpoint of structural biology, we determined the crystal structures of A. suum and porcine complex IIs binding flutolanil and its derivative compounds. The structures clearly demonstrated key interactions responsible for its high specificity to A. suum complex II and enabled us to find analogue compounds, which surpass flutolanil in both potency and specificity to A. suum complex II. Structures of complex IIs binding these compounds will be helpful to accelerate structure-based drug design targeted for complex IIs.