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Saldanha I, Lea R, Manangwa O, Garrod G, Haines LR, Acosta-Serrano Á, Auty H, Betson M, Lord JS, Morrison LJ, Mramba F, Torr SJ, Cunningham LJ. Caught in a trap: DNA contamination in tsetse xenomonitoring can lead to over-estimates of Trypanosoma brucei infection. PLoS Negl Trop Dis 2024; 18:e0012095. [PMID: 39133740 PMCID: PMC11341098 DOI: 10.1371/journal.pntd.0012095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 08/22/2024] [Accepted: 07/26/2024] [Indexed: 08/24/2024] Open
Abstract
BACKGROUND Tsetse flies (Glossina sp.) are vectors of Trypanosoma brucei subspecies that cause human African trypanosomiasis (HAT). Capturing and screening tsetse is critical for HAT surveillance. Classically, tsetse have been microscopically analysed to identify trypanosomes, but this is increasingly replaced with molecular xenomonitoring. Nonetheless, sensitive T. brucei-detection assays, such as TBR-PCR, are vulnerable to DNA cross-contamination. This may occur at capture, when often multiple live tsetse are retained temporarily in the cage of a trap. This study set out to determine whether infected tsetse can contaminate naïve tsetse with T. brucei DNA via faeces when co-housed. METHODOLOGY/PRINCIPLE FINDINGS Insectary-reared teneral G. morsitans morsitans were fed an infectious T. b. brucei-spiked bloodmeal. At 19 days post-infection, infected and naïve tsetse were caged together in the following ratios: (T1) 9:3, (T2) 6:6 (T3) 1:11 and a control (C0) 0:12 in triplicate. Following 24-hour incubation, DNA was extracted from each fly and screened for parasite DNA presence using PCR and qPCR. All insectary-reared infected flies were positive for T. brucei DNA using TBR-qPCR. However, naïve tsetse also tested positive. Even at a ratio of 1 infected to 11 naïve flies, 91% of naïve tsetse gave positive TBR-qPCR results. Furthermore, the quantity of T. brucei DNA detected in naïve tsetse was significantly correlated with cage infection ratio. With evidence of cross-contamination, field-caught tsetse from Tanzania were then assessed using the same screening protocol. End-point TBR-PCR predicted a sample population prevalence of 24.8%. Using qPCR and Cq cut-offs optimised on insectary-reared flies, we estimated that prevalence was 0.5% (95% confidence interval [0.36, 0.73]). CONCLUSIONS/SIGNIFICANCE Our results show that infected tsetse can contaminate naïve flies with T. brucei DNA when co-caged, and that the level of contamination can be extensive. Whilst simple PCR may overestimate infection prevalence, quantitative PCR offers a means of eliminating false positives.
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Affiliation(s)
- Isabel Saldanha
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Rachel Lea
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Oliver Manangwa
- Vector and Vector-borne Diseases Research Institute, Tanga, Tanzania
| | - Gala Garrod
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Lee R. Haines
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Álvaro Acosta-Serrano
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Harriet Auty
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Martha Betson
- School of Veterinary Medicine, University of Surrey, Guildford, United Kingdom
| | - Jennifer S. Lord
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Liam J. Morrison
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Furaha Mramba
- Vector and Vector-borne Diseases Research Institute, Tanga, Tanzania
| | - Stephen J. Torr
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Lucas J. Cunningham
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
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Tsolo A, Kore K, Sheferaw D. Bovine trypanosomosis, vector distribution and infection rate in three districts of Gamo Zone, southwestern Ethiopia. Parasite Epidemiol Control 2024; 26:e00374. [PMID: 39282215 PMCID: PMC11395718 DOI: 10.1016/j.parepi.2024.e00374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 06/03/2024] [Accepted: 08/13/2024] [Indexed: 09/18/2024] Open
Abstract
African animal trypanosomosis is one of the main obstacles to the development of livestock and agricultural output in Ethiopia. It usually results in a severe, frequently fatal sickness, and the infected animals were more weakened as the disease progress and become unfit for work. A cross sectional study design was conducted from December 2021 to April 2022 with the aim of estimating the prevalence of trypanosome infection both in Glossina spp. and cattle, and to assess apparent density of Glossina spp. A total of 298 cattle were selected and examined for trypanosome by using buffy coat technique. The overall prevalence of bovine trypanosomosis was 19.1%; and two species of trypanosomes, T. congolense and T. vivax, were identified in the study area. The prevalence of T. congolense and T. vivax were 15.8% and 2.3%, respectively. The prevalence of trypanosomosis was significantly higher in adult animals (OR = 2.7; p < 0.05) than in younger cattle and poor body condition (OR = 3.18; p < 0.05) than medium body condition animals. The mean PCV value of infected animals was 14.3% (13.3-15.4) significantly lower than the non-infected animals 18.5% (17.8-19.2). Glossina pallidipes is the only tsetse species encountered in all the study areas. In total, 2992 flies were caught of which 90.8% belong to G. pallidipes and 9.2% were other biting flies. The overall apparent density of G. pallidipes was 20.1 F/T/D and other biting flies were 2.0 F/T/D. A total of 307 live Glossina pallidipes were dissected. The overall prevalence of Glossina pallidipes infection rate was 9.1% (95% CI = 5.9-12.4). The prevalence of G. pallidipes infection was significantly higher in Kucha district (OR = 3.2, χ2 = 2.6, p < 0.05) than the other two districts, Daramalo and Arba Minch Zuria. Also it was significantly higher in flies trapped from riverine forest areas (OR = 5.5, χ2 = 2.86, p < 0.05). Therefore, to reduce the impact of trypanosomosis and Glossina, vector control and treating infected cattle with prophylactic or chemotherapeutic drugs and active community participation can play a key role.
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Affiliation(s)
- Amsayas Tsolo
- Daramalo District Livestock and Fisheries Resource Office, Gamo Zone, Ethiopia
| | - Kokeb Kore
- Animal Health Institution Arba-Minch Center, Ethiopia
| | - Desie Sheferaw
- Faculty of Veterinary Medicine, Hawassa University, Hawassa, Ethiopia
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3
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Mulat G, Maru M, Tarekegn ZS, Dejene H. A systematic review and meta-analysis on prevalence of bovine trypanosomosis in East Africa. Parasite Epidemiol Control 2024; 26:e00371. [PMID: 39184304 PMCID: PMC11341968 DOI: 10.1016/j.parepi.2024.e00371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 05/14/2024] [Accepted: 07/22/2024] [Indexed: 08/27/2024] Open
Abstract
Bovine trypanosomosis is an incapacitating and lethal ailment brought about by protozoan parasites of the genus Trypanosoma. The disease leads to losses in livestock and agricultural productivity, resulting in significant socio-economic repercussions. In East Africa, trypanosomosis has been endemic for an extensive period due to ecological factors and vector biology that facilitate the persistent circulation of trypanosomes. This investigation outlines the occurrence of bovine trypanosomosis in East Africa through a meta-analysis. A thorough search was conducted on PubMed, Google Scholar, Scopus, Web of Science and AJOL. Suitable studies were chosen using inclusion and exclusion criteria. The prevalence was estimated through a random effect model. Publication bias and the variation in prevalence estimates due to heterogeneity were also evaluated. The analysis was performed on 115 studies that contained relevant prevalence data. The collective estimate of bovine trypanosomosis prevalence across the studies stood at 12% (95% CI: 11, 13), ranging from 1% (95% CI: 0, 2) to 51% (95% CI: 45, 58). The subgroup analysis by country revealed considerable disparities in prevalence. The highest estimated prevalence was 24% (95% CI: 18, 30) in Somalia, whereas the lowest prevalence was observed in Ethiopia at 10% (95% CI: 9, 11). A significant level of heterogeneity was noted in most pooled estimates, even after conducting subgroup analysis. The visual examination of the funnel plot and the Egger's regression asymmetry coefficient (b = -5.13, 95% CI: -7.49, -2.76, p = 0.00) and Begg's plot (p = 0.00) indicate the presence of publication bias. In conclusion, bovine trypanosomosis is a pervasive and noteworthy malady affecting livestock. The findings of this investigation imply a high prevalence of bovine trypanosomosis in the majority of the countries under scrutiny. Despite the well-known hindrance that livestock trypanosomosis poses to livestock production in Africa, little attention has been devoted to the trypanosomosis situation, particularly in East African nations.
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Affiliation(s)
- Getie Mulat
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Animal Sciences, University of Gondar, Ethiopia
| | - Moges Maru
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Animal Sciences, University of Gondar, Ethiopia
| | - Zewdu Seyoum Tarekegn
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Animal Sciences, University of Gondar, Ethiopia
| | - Haileyesus Dejene
- Department of Veterinary Epidemiology and Public Health, College of Veterinary Medicine and Animal Sciences, University of Gondar, Ethiopia
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Al-Ghafli H, Barribeau SM. Double trouble: trypanosomatids with two hosts have lower infection prevalence than single host trypanosomatids. Evol Med Public Health 2023; 11:202-218. [PMID: 37404250 PMCID: PMC10317189 DOI: 10.1093/emph/eoad014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 04/21/2023] [Indexed: 07/06/2023] Open
Abstract
Trypanosomatids are a diverse family of protozoan parasites, some of which cause devastating human and livestock diseases. There are two distinct infection life cycles in trypanosomatids; some species complete their entire life cycle in a single host (monoxenous) while others infect two hosts (dixenous). Dixenous trypanosomatids are mostly vectored by insects, and the human trypanosomatid diseases are caused mainly by vectored parasites. While infection prevalence has been described for subsets of hosts and trypanosomatids, little is known about whether monoxenous and dixenous trypanosomatids differ in infection prevalence. Here, we use meta-analyses to synthesise all published evidence of trypanosomatid infection prevalence for the last two decades, encompassing 931 unique host-trypansomatid systems. In examining 584 studies that describe infection prevalence, we find, strikingly, that monoxenous species are two-fold more prevalent than dixenous species across all hosts. We also find that dixenous trypanosomatids have significantly lower infection prevalence in insects than their non-insect hosts. To our knowledge, these results reveal for the first time, a fundamental difference in infection prevalence according to host specificity where vectored species might have lower infection prevalence as a result of a potential 'jack of all trades, master of none' style trade-off between the vector and subsequent hosts.
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Affiliation(s)
- Hawra Al-Ghafli
- Department of Evolution, Ecology and Behaviour, Institute of Infection, Veterinary, and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Seth M Barribeau
- Corresponding author. Department of Evolution, Ecology and Behaviour, Institute of Infection, Veterinary, and Ecological Sciences, University of Liverpool, Liverpool, UK. E-mail:
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Maxamhud S, Lindahl JF, Mugenyi A, Echodu R, Waiswa C, Roesel K. Seasonal Monitoring of Glossina Species Occurrence, Infection Rates, and Trypanosoma Species Infections in Pigs in West Nile Region, Uganda. Vector Borne Zoonotic Dis 2022; 22:101-107. [PMID: 35175139 DOI: 10.1089/vbz.2020.2744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Introduction: Trypanosomiasis is a parasitic infection caused by the protozoa Trypanosoma. It is exclusively associated with Glossina species habitats and, therefore, restricted to specific geographical settings. It affects a wide range of hosts, including humans. Animals may carry different Trypanosoma spp. while being asymptomatic. They are, therefore, potentially important in unpremeditated disease transmission. Aim: The aim of this study was to study the potential impact of the government tsetse fly control program, and to elucidate the role of pigs in the Trypanosoma epidemiology in the West Nile region in Uganda. Methods: A historically important human African trypanosomiasis (HAT) hotspot was selected, with sampling in sites with and without a government tsetse fly control program. Pigs were screened for infection with Trypanosoma and tsetse traps were deployed to monitor vector occurrence, followed by tsetse fly dissection and microscopy to establish infection rates with Trypanosoma. Pig blood samples were further analyzed to identify possible Trypanosoma infections using internal transcribed spacer (ITS)-PCR. Results: Using microscopy, Trypanosoma was detected in 0.56% (7/1262) of the sampled pigs. Using ITS-PCR, 114 of 341 (33.4%) pig samples were shown to be Trypanosoma vivax positive. Of the 360 dissected tsetse flies, 13 (3.8%) were positive for Trypanosoma under the microscope. The difference in captured tsetse flies in the government intervention sites in comparison with the control sites was significant (p < 0.05). Seasonality did not play a substantial role in the tsetse fly density (p > 0.05). Conclusion: This study illustrated the impact of a government control program with low vector abundance in a historical HAT hotspot in Uganda. The study could not verify that pigs in the area were carriers for the causative agent for HAT, but showed a high prevalence of the animal infectious agent T. vivax.
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Affiliation(s)
- Sadiya Maxamhud
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Johanna F Lindahl
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.,Department of Biosciences, International Livestock Research Institute, Nairobi, Kenya.,Department of Clinical Sciences, Swedish University of Agricultural Science, Uppsala, Sweden
| | - Albert Mugenyi
- Coordinating Office for Control of Trypanosomiasis in Uganda, Ministry of Agriculture, Animal Industry and Fisheries, Makerere, Uganda
| | - Richard Echodu
- Department of Biology, Faculty of Science, Gulu University, Gulu, Uganda
| | - Charles Waiswa
- Coordinating Office for Control of Trypanosomiasis in Uganda, Ministry of Agriculture, Animal Industry and Fisheries, Makerere, Uganda.,Department of Pharmacy, Clinical and Comparative Studies, School of Veterinary Medicine and Animal Resources, Makerere University, Kampala, Uganda
| | - Kristina Roesel
- Department of Biosciences, International Livestock Research Institute, Nairobi, Kenya.,Department of Veterinary Medicine, Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
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Metabolic drug targets of the cytosine metabolism pathways in the dromedary camel (Camelus dromedarius) and blood parasite Trypanosoma evansi. Trop Anim Health Prod 2020; 52:3337-3358. [PMID: 32926292 DOI: 10.1007/s11250-020-02366-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 07/31/2020] [Indexed: 10/23/2022]
Abstract
Trypanosomiasis is a major illness affecting camels in tropical and subtropical regions. Comparisons of camel and Trypanosoma evansi genomes can lead to the discovery of new drug targets for treating Trypanosoma infections. The synthesis pathways of cytosine, cytidine, cytidine monophosphate (CMP), cytidine diphosphate (CDP), cytidine triphosphate (CTP) deoxycytidine, deoxycytidine monophosphate (dCMP), deoxycytidine diphosphate (dCDP), and deoxycytidine triphosphate (dCTP) were compared in the dromedary camel (Camelus dromedarius) and T. evansi. None of the enzymes involved in cytosine pathway were detected in camels and T. evansi. Notably, cytidine kinase (CK) and 5'-nucleotidase, which interconverts cytidine to CMP, were not detected in T. evansi but were present in camels. UMP/CMP kinase was not predicted in T. evansi. Therefore, the presence of enzymes involved in the CTP synthesis cascade was not predicted in T. evansi. CMP synthesis might also be encoded by other enzymes, e.g., purine nucleotides kinases. Both camel and T. evansi share an efficient enzyme system for converting CDP to CTP. In conclusion, CTP synthase is important for homeostasis of cytosine nucleotides in T. evansi and could be a potential drug target against the parasite. In addition, the inhibition of UMP synthesis might contribute to parasite death as it is a shared source for CTP synthesis.
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7
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Morenikeji OB, Hawkes ME, Hudson AO, Thomas BN. Computational Network Analysis Identifies Evolutionarily Conserved miRNA Gene Interactions Potentially Regulating Immune Response in Bovine Trypanosomosis. Front Microbiol 2019; 10:2010. [PMID: 31555241 PMCID: PMC6722470 DOI: 10.3389/fmicb.2019.02010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 08/16/2019] [Indexed: 12/19/2022] Open
Abstract
Bovine trypanosomosis is a devastating disease that causes huge economic loss to the global cattle industry on a yearly basis. Selection of accurate biomarkers are important in early disease diagnosis and treatment. Of late, micro-RNAs (miRNAs) are becoming the most useful biomarkers for both infectious and non-infectious diseases in humans, but this is not the case in animals. miRNAs are non-coding RNAs that regulate gene expression through binding to the 3'-, 5'-untranslated regions (UTR) or coding sequence (CDS) region of one or more target genes. The molecular identification of miRNAs that regulates the expression of immune genes responding to bovine trypanosomosis is poorly defined, as is the possibility that these miRNAs could serve as potential biomarkers for disease diagnosis and treatment currently unknown. To this end, we utilized in silico tools to elucidate conserved miRNAs regulating immune response genes during infection, in addition to cataloging significant genes. Based on the p value of 1.77E-32, we selected 25 significantly expressed immune genes. Using prediction analysis, we identified a total of 4,251 bovine miRNAs targeting these selected genes across the 3'UTR, 5'UTR and CDS regions. Thereafter, we identified candidate miRNAs based on the number of gene targets and their abundance at the three regions. In all, we found the top 13 miRNAs that are significantly conserved targeting 7 innate immune response genes, including bta-mir-2460, bta-mir-193a, bta-mir-2316, and bta-mir-2456. Our gene ontology analysis suggests that these miRNAs are involved in gene silencing, cellular protein modification process, RNA-induced silencing complex, regulation of humoral immune response mediated by circulating immunoglobulin and negative regulation of chronic inflammatory response, among others. In conclusion, this study identifies specific miRNAs that may be involved in the regulation of gene expression during bovine trypanosomosis. These miRNAs have the potential to be used as biomarkers in the animal and veterinary research community to facilitate the development of tools for early disease diagnosis/detection, drug targeting, and the rational design of drugs to facilitate disease treatment.
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Affiliation(s)
- Olanrewaju B. Morenikeji
- Department of Biomedical Sciences, Rochester Institute of Technology, Rochester, NY, United States
| | - Megan E. Hawkes
- Department of Biomedical Sciences, Rochester Institute of Technology, Rochester, NY, United States
| | - André O. Hudson
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, NY, United States
| | - Bolaji N. Thomas
- Department of Biomedical Sciences, Rochester Institute of Technology, Rochester, NY, United States
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Abstract
Parasites elicit several physiological changes in their host to enhance transmission. Little is known about the functional association between parasitism and microbiota-provisioned resources typically dedicated to animal hosts and how these goods may be rerouted to optimize parasite development. This study is the first to identify a specific symbiont-generated metabolite that impacts insect vector competence by facilitating parasite establishment and, thus, eventual transmission. Specifically, we demonstrate that the tsetse fly obligate mutualist Wigglesworthia provisions folate (vitamin B9) that pathogenic African trypanosomes exploit in an effort to successfully establish an infection in the vector’s MG. This process is essential for the parasite to complete its life cycle and be transmitted to a new vertebrate host. Disrupting metabolic contributions provided by the microbiota of arthropod disease vectors may fuel future innovative control strategies while also offering minimal nontarget effects. Many symbionts supplement their host’s diet with essential nutrients. However, whether these nutrients also enhance parasitism is unknown. In this study, we investigated whether folate (vitamin B9) production by the tsetse fly (Glossina spp.) essential mutualist, Wigglesworthia, aids auxotrophic African trypanosomes in completing their life cycle within this obligate vector. We show that the expression of Wigglesworthia folate biosynthesis genes changes with the progression of trypanosome infection within tsetse. The disruption of Wigglesworthia folate production caused a reduction in the percentage of flies that housed midgut (MG) trypanosome infections. However, decreased folate did not prevent MG trypanosomes from migrating to and establishing an infection in the fly’s salivary glands, thus suggesting that nutrient requirements vary throughout the trypanosome life cycle. We further substantiated that trypanosomes rely on symbiont-generated folate by feeding this vitamin to Glossina brevipalpis, which exhibits low trypanosome vector competency and houses Wigglesworthia incapable of producing folate. Folate-supplemented G. brevipalpis flies were significantly more susceptible to trypanosome infection, further demonstrating that this vitamin facilitates parasite infection establishment. Our cumulative results provide evidence that Wigglesworthia provides a key metabolite (folate) that is “hijacked” by trypanosomes to enhance their infectivity, thus indirectly impacting tsetse species vector competency. Parasite dependence on symbiont-derived micronutrients, which likely also occurs in other arthropod vectors, represents a relationship that may be exploited to reduce disease transmission.
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Ebhodaghe F, Isaac C, Ohiolei JA. A meta-analysis of the prevalence of bovine trypanosomiasis in some African countries from 2000 to 2018. Prev Vet Med 2018; 160:35-46. [PMID: 30388996 DOI: 10.1016/j.prevetmed.2018.09.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 08/13/2018] [Accepted: 09/18/2018] [Indexed: 01/24/2023]
Abstract
Bovine trypanosomiasis is a disease of cattle. In sub-Saharan Africa, the disease mean prevalence estimates are unknown in most endemic countries. We therefore performed a meta-analysis with the aim of estimating national mean prevalence of bovine trypanosomiasis in endemic countries across sub-Saharan Africa. Relevant articles reporting bovine trypanosomiasis prevalence were retrieved through systematic literature search and scanning of articles reference-lists. Eligibility criteria included that articles reported sample size, prevalence, and diagnostic technique adopted. Overall, data from 180 eligible articles from 19 countries satisfied the inclusion criteria. Meta-analysis of prevalence data based on the random-effects model resulted in an overall mean prevalence of 15.10% (95% CI: 13.22-17.08). National prevalence estimates were generally high except those of Benin and Senegal where estimates ranked below 10.00%. Significant heterogeneity (I2 = 98.75%. p = <0.0001) was noted between studies, and univariate meta-regression analysis identified choice of diagnostic method being major contributor to observed heterogeneity (R2 = 36.37%); while country of study (R2 = 9.57%) and sample size (R2 = 3.47%) had marginal effect on heterogeneity. In spite of past and ongoing control activities, bovine trypanosomiasis remains highly prevalent in most endemic sub-Saharan African countries. Nevertheless, dearth of epidemiological data in some countries and the use of less sensitive diagnostic tools limit reliable estimation of the disease prevalence. Therefore, there is the need to intensify efforts in aspects of surveillance and increased application of molecular diagnostic tool(s) across endemic locations as this would raise the chances of achieving a near-accurate estimate of the disease prevalence which is the first step to attempting eradication.
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Affiliation(s)
- F Ebhodaghe
- African Regional Postgraduate Programme in Insect Science, West African Sub-Regional Centre, University of Ghana Legon, Accra, Ghana; Department of Zoology, Ambrose Alli University, Ekpoma, Nigeria.
| | - C Isaac
- Department of Zoology, Ambrose Alli University, Ekpoma, Nigeria.
| | - J A Ohiolei
- Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China.
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Krafsur ES, Maudlin I. Tsetse fly evolution, genetics and the trypanosomiases - A review. INFECTION GENETICS AND EVOLUTION 2018; 64:185-206. [PMID: 29885477 DOI: 10.1016/j.meegid.2018.05.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 05/30/2018] [Accepted: 05/31/2018] [Indexed: 01/27/2023]
Abstract
This reviews work published since 2007. Relative efforts devoted to the agents of African trypanosomiasis and their tsetse fly vectors are given by the numbers of PubMed accessions. In the last 10 years PubMed citations number 3457 for Trypanosoma brucei and 769 for Glossina. The development of simple sequence repeats and single nucleotide polymorphisms afford much higher resolution of Glossina and Trypanosoma population structures than heretofore. Even greater resolution is offered by partial and whole genome sequencing. Reproduction in T. brucei sensu lato is principally clonal although genetic recombination in tsetse salivary glands has been demonstrated in T. b. brucei and T. b. rhodesiense but not in T. b. gambiense. In the past decade most genetic attention was given to the chief human African trypanosomiasis vectors in subgenus Nemorhina e.g., Glossina f. fuscipes, G. p. palpalis, and G. p. gambiense. The chief interest in Nemorhina population genetics seemed to be finding vector populations sufficiently isolated to enable efficient and long-lasting suppression. To this end estimates were made of gene flow, derived from FST and its analogues, and Ne, the size of a hypothetical population equivalent to that under study. Genetic drift was greater, gene flow and Ne typically lesser in savannah inhabiting tsetse (subgenus Glossina) than in riverine forms (Nemorhina). Population stabilities were examined by sequential sampling and genotypic analysis of nuclear and mitochondrial genomes in both groups and found to be stable. Gene frequencies estimated in sequential samplings differed by drift and allowed estimates of effective population numbers that were greater for Nemorhina spp than Glossina spp. Prospects are examined of genetic methods of vector control. The tsetse long generation time (c. 50 d) is a major contraindication to any suggested genetic method of tsetse population manipulation. Ecological and modelling research convincingly show that conventional methods of targeted insecticide applications and traps/targets can achieve cost-effective reduction in tsetse densities.
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Affiliation(s)
- E S Krafsur
- Department of Entomology, Iowa State University, Ames, IA 50011, USA.
| | - Ian Maudlin
- School of Biomedical Sciences, The University of Edinburgh, Scotland, UK
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Odeniran PO, Ademola IO. A meta-analysis of the prevalence of African animal trypanosomiasis in Nigeria from 1960 to 2017. Parasit Vectors 2018; 11:280. [PMID: 29720251 PMCID: PMC5930763 DOI: 10.1186/s13071-018-2801-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 03/19/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND African animal trypanosomiasis is an economically significant disease that affects the livestock industry in Nigeria. It is caused by several parasites of the genus Trypanosoma. National estimates of the disease prevalence in livestock and tsetse flies are lacking, therefore a systematic review and meta-analysis were performed to understand the trend of the disease prevalence over the years. METHODS Publications were screened in Web of Science, Ovid MEDLINE, Global Health, EMBASE and PubMed databases. Using four-stage (identification, screening, eligibility and inclusion) process in the PRIMSA checklist, only studies that met the inclusion criteria for AAT and tsetse infections were analysed. Point estimates prevalence and subgroup analyses based on diagnostic techniques in livestock were evaluated at 95% confidence interval (CI). RESULTS A total of 74 eligible studies published between 1960 and 2017 were selected for meta-analysis. This covers the six geopolitical zones, involving a total of 53,924 animals. The overall prevalence of AAT was 16.1% (95% CI: 12.3-20.3%). Based on diagnostic techniques, the prevalence of AAT in cattle was highest in PCR followed by serology and microscopy while the highest prevalence in pigs was observed with serology. Out of 12,552 tsetse flies examined from 14 eligible studies, an overall prevalence of 17.3% (95% CI: 4.5-36.0%) and subgroup prevalence of 49.7% (95% CI: 30.7-68.8%), 11.5% (95% CI: 6.1-18.5) and 4.5% (95% CI: 1.8-8.8%) in G. morsitans, G. tachinoides and G. palpalis, respectively, were observed using the random effects-model. CONCLUSIONS The prevalence of trypanosomes in both vectors and animal hosts was high in Nigeria. Therefore, further research on risk factors, seasonal and transhumance effects, vectoral capacity and competence are warranted for an effective control of AAT in Nigeria.
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Affiliation(s)
- Paul Olalekan Odeniran
- Department of Veterinary Parasitology, Faculty of Veterinary Medicine, University of Ibadan, Ibadan, Nigeria.,Division of Infection and Pathway Medicine, Deanery of Biomedical Sciences, University of Edinburgh, Edinburgh, EH8 9JZ, UK
| | - Isaiah Oluwafemi Ademola
- Department of Veterinary Parasitology, Faculty of Veterinary Medicine, University of Ibadan, Ibadan, Nigeria.
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