Evidence for camels (Camelus bactrianus) as the main intermediate host of Echinococcus granulosus sensu lato G6/G7 in Mongolia
Cystic echinococcosis (CE), the parasitic disease caused by the larval stage of Echinococcus granulosus sensu lato (s.l.), is a global public health problem. In Mongolia, despite wide distribution of human CE, not enough information is available on the prevalence and molecular characterization of CE in livestock and its zoonotic linkage with human cases. We investigated the distribution of human CE cases and livestock population using statistical models to get insight into the zoonotic linkage. The incidence of human CE cases increased by a factor of 1.71 for one interquartile range increment in the density of the camel population. No significant association was observed with other livestock species. The samples collected from 96 camels and 15 goats in an endemic region showed a CE prevalence of 19.7% and 6.7%, respectively. All livestock CE were E. granulosus s.l. G6/G7 species of the E. granulosus s.l. complex. The genetic diversity was investigated using the haplotype network based on full cox1 gene analysis of the samples collected from livestock CE and nucleotide sequences previously reported from human CE and wild canids infection in Mongolia. Four haplotypes were identified within the livestock samples, two of which had not been previously reported. A common haplotype was identified among humans, camels, goats, and a wolf, all of which were within the same geographical area. A mixed infection of E. granulosus s.l. G6/G7 with different haplotypes in the intermediate host was identified. To the best of our knowledge, this is the most comprehensive description of the current epidemiological situation of CE in Mongolia with substantial evidence that camels might be the main intermediate host of E. granulosus s.l. G6/G7 in Mongolia. Moreover, our result presents the first report in the country to provide insight into the prevalence of E. granulosus s.l. G6/G7 in livestock.
KeywordsEchinococcus granulosus s.l. G6/G7 Cystic echinococcosis Camel Goat Mongolia
The authors are greatly thankful to the team of the local veterinary office in Omnogobi province which helped us to collect samples. We also thank Vanessa Bastid and Carine Peytavin de Garam from Anses LRFSN for their skilled technical assistance in the molecular analyses.
This work was supported by the Neglected Zoonotic Diseases unit in Department of the Control of Neglected Tropical Diseases, WHO.
Funding source(s) had no involvement in study design, the collection, analysis and interpretation of data, the writing of the report, and in the decision to submit the article for publication.
Compliance with ethical standards
This work presented here was approved by the Medical Ethics committee of Mongolia (July 2014) and WHO ERC (27 Nov 2015).
The animals were being processed as part of the normal work of the abattoir. The routine investigation of local veterinary office on animal carcass do not require ethical approval in Mongolia.
Conflict of interest
The authors declare that there is no conflict of interest.
Statistical data of hospital discharge is available upon request from the National Center for Zoonotic Disease (NCZD). The director of NCZD, Dr. Tsogbadrakh Nyamdorj, is the point of contact. Email address is: email@example.com.
All relevant data regarding animal sample is within the manuscript and its Supporting Information files.
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