Seroprevalence and participatory epidemiology of camelpox in Afar region of Ethiopia

Camelpox is endemic in most camel rearing regions of the world, causing significant economic losses. However, its epidemiology is not extensively investigated. We conducted a cross sectional seroprevalence study of camelpox in Amibara and Awash Fentale districts in Afar region of Ethiopia from November 2014 to May 2015. In addition, participatory epidemiology (PE) was conducted to identify seasonal occurrence of the disease in the study districts. Blood samples were collected from 384 dromedary camels from 31 herds distributed in five pastoral associations (PAs) in the two districts. Serum samples were separated from the blood samples and tested for the presence of viral antibodies using virus neutralization test. Seroprevalence data were analyzed using multilevel mixed effects logistic regression models accounting for the 4-level hierarchical data structure (camels nested in herds-herds in PA, and PA in district). For the participatory data, Kendall’s coefficient of concordance was used to assess agreements between the informants in identifying seasonal occurrences of the top five camel diseases. Camelpox antibodies were detected in 19.3% of camels (n = 384), 81% of herds (n = 31), and in all five PAs from the two districts in the Gabi Rasu zone of Afar region, Ethiopia. The seroprevalence did not significantly vary between herds, PAs or districts suggesting the widespread occurrence of the disease. Estimated age stratified basic reproduction number (R0) was 1.25 (95% CI: 0.62–2.19). Camelpox was identified as one of the top five common camel diseases in the area. The widespread occurrence of the disease can be attributed mainly to the commingling of camels from many herds during seasonal migration in search of feed and water, a practice very common under pastoral production systems. Although the PE informants indicated the clinical disease to be more common in young animals, seropositivity was higher in older animals. Camelpox commonly occurs during the minor and major rainy seasons. In conclusion, camelpox is found to be endemic in Afar pastoral region with sporadic outbreaks occurring during rainy seasons. Vaccination and improved camel management practices particularly during the high-risk period can be viable strategies to reduce the burden of the disease

A systematic review and meta-analysis of trypanosome prevalence in tsetse flies

Background: The optimisation of trypanosomosis control programs warrants a good knowledge of the main vector of animal and human trypanosomes in sub-Saharan Africa, the tsetse fly. An important aspect of the tsetse fly population is its trypanosome infection prevalence, as it determines the intensity of the transmission of the parasite by the vector. We therefore conducted a systematic review of published studies documenting trypanosome infection prevalence from field surveys or from laboratory experiments under controlled conditions. Publications were screened in the Web of Science, PubMed and Google Scholar databases. Using the four-stage (identification, screening, eligibility and inclusion) process in the PRISMA statement the initial screened total of 605 studies were reduced to 72 studies. The microscopic examination of dissected flies (dissection method) remains the most used method to detect trypanosomes and thus constituted the main focus of this analysis. Meta-regression was performed to identify factors responsible for high trypanosome prevalence in the vectors and a random effects meta-analysis was used to report the sensitivity of molecular and serological tests using the dissection method as gold standard. Results: The overall pooled prevalence was 10.3% (95% confidence interval [CI] = 8.1%, 12.4%) and 31.0% (95% CI = 20. 0%, 42.0%) for the field survey and laboratory experiment data respectively. The country and the year of publication were found to be significantly factors associated with the prevalence of trypanosome infection in tsetse flies. The alternative diagnostic tools applied to dissection positive samples were characterised by low sensitivity, and no information on the specificity was available at all. Conclusion: Both temporal and spatial variation in trypanosome infection prevalence of field collected tsetse flies exists, but further investigation on real risk factors is needed how this variation can be explained. Improving the sensitivity and determining the specificity of these alternative diagnostic tools should be a priority and will allow to estimate the prevalence of trypanosome infection in tsetse flies in high-throughput

Systematic review and meta-analysis on the global distribution, host range, and prevalence of Trypanosoma evansi

Abstract Background Surra is an animal trypanosomosis, caused by infection with Trypanosoma evansi and leading to severe economic loss due to mortality and morbidity. Compared to tsetse-transmitted animal trypanosomoses, little attention is given to the epidemiology and control of surra. Understanding its epidemiology is a first step in local and global efforts to control the disease. We conducted a systematic review and meta-analysis of published studies on distribution, host ranges and prevalence of T. evansi infection. Methods Four electronic databases were searched for publications on T. evansi that met our inclusion criteria for the systematic review. Subsets of publications were subjected to meta-analysis for the pooled prevalence of T. evansi in various hosts as determined by multiple detection methods. Results A total of 272 references published between 1906–2017 were included. Trypanosoma evansi was reported from 48 countries; largely confined to Africa and Asia with publications on natural T. evansi infections from 77% (n = 48) of countries, contrasting with seven countries in South America, and four in Europe where T. evansi is not endemic but was imported with infected animals. Although surra is a notifiable disease, many countries do not report surra cases to OIE. Trypanosoma evansi was mainly reported from dromedary camels in Africa and the Middle East, water buffaloes, cattle, dogs and horses in East and Southeast Asia. In South America, the acute form of the disease was reported in horses and dogs. Surra was also reported in a wide range of wild animals. Some rare human cases occurred in India and Vietnam. Meta-analysis on a subset of 165 publications indicated pooled prevalence of T. evansi in domestic animals ranging from 14–31%, 6–28% and 2–9% using respectively antibody detection, molecular and parasitological tests, with camels as the most affected, followed by buffalo and cattle. Conclusions This study illustrates that T. evansi affects a wide range of domestic and wild animals in Africa, Asia and South America with highest prevalence observed in dromedary camels. For successful control of T. evansi, both locally and globally, the role of wild animals in the epidemiology of surra needs further investigation

The fertility and viability of <i>Echinococcus s</i>.<i>l</i>. cysts in animal intermediate hosts reported in the GHA between 2000 and 2022.

The fertility and viability of Echinococcus s.l. cysts in animal intermediate hosts reported in the GHA between 2000 and 2022.</p

Number of records on <i>Echinococcus granulosus s</i>.<i>l</i>. reported in the GHA between 2000 and 2022.

Shapefiles were republished from the DIVA-GIS database (https://www.diva-gis.org/gdata) under a CC BY 4.0 license, with permission from Global Administrative Areas (GADM), original copyright 2018.</p

Species/genotypes distribution of CE in animal intermediate host species reported in the GHA between 2000 and 2022.

Species/genotypes distribution of CE in animal intermediate host species reported in the GHA between 2000 and 2022.</p

Prevalence ranges of CE in animal intermediate hosts species reported in the GHA between 2000 and 2022.

aExported animals from Sudan and Somalia to Saudi Arabia revealing zero prevalence estimates.</p

Distribution of included records in the systematic review of <i>E</i>. <i>granulosus</i> infection in the GHA by publication year (2000 to 2022).

Distribution of included records in the systematic review of E. granulosus infection in the GHA by publication year (2000 to 2022).</p

PRISMA 2020 checklist.

BackgroundCystic echinococcosis (CE) is a neglected zoonotic disease that is caused by Echinococcus granulosus sensu lato (s.l.), the life cycle of which involves multiple hosts. We conducted a systematic review (SR) on E. granulosus s.l. in the Greater Horn of Africa (GHA), to provide a picture of its recent epidemiology across all hosts.MethodsFor this SR, conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, five electronic databases, as well experts in the region were consulted to retrieve records published between 2000 and 2022, reporting the presence of E. granulosus s.l. infections in any natural host in the GHA (Djibouti, Eritrea, Ethiopia, Kenya, Sudan, Somalia, South Sudan, Tanzania and Uganda).Principal findingsA total of 247 records were retained, describing the presence of E. granulosus s.l. throughout the GHA, except for Djibouti. Only few population surveys on human CE were conducted in the area, with the prevalence ranging between 0.3 and 11.3%. In animals, the reported prevalence ranged up to 61.6% in camels, 88.4% in cattle; 65.2% in goats, 9.9% in pigs, 67.8% in sheep and 94.5% in dogs. In addition, E. granulosus s.l. was also reported in wildlife. A total of five species were reported in the different hosts, namely E. granulosus sensu stricto (G1, G3, GOmo), E. canadensis (G6/7), E. ortleppi (G5), E. felidis, and E. equinus (G4).ConclusionsWe confirm that E. granulosus s.l. is prevalent throughout the GHA. Nevertheless, despite our efforts to screen grey literature, an accurate assessment of the epidemiology in GHA remains challenging, due to the lack of combined host, in-depth risk factor and behavioural studies, as well as the wide diversity in subpopulations studied and diagnostic tools used. Interdisciplinary and transboundary partnerships would be essential for the design of effective control strategies, tuned to the GHA setting.</div