Van Kesteren, F
Canine echinococcosis in the Alay Valley, southern Kyrgyzstan
, PhD thesis, University of Salford.
Echinococcosis is a serious and often fatal zoonotic disease caused by parasites in the genus Echinococcus. Echinococcus spp. cycle between intermediate and final hosts, and it is the accidental ingestion of eggs in faeces of final hosts (usually canids) that causes the disease in humans. There is evidence that echinococcosis is re-emerging in Kyrgyzstan, with increasing numbers of human cases reported from the south of the country. However, little is known about canine echinococcosis in the local domestic dog population, despite the fact that dogs are the main source of human infection. As such, this thesis focuses on canine echinococcosis in the Alay Valley, southern Kyrgyzstan.
In order to study canine echinococcosis, reliable tools for diagnosing infection in dogs are needed. Previous studies have found that coproELISAs measuring Echinococcus spp. antigens in faecal samples can accurately detect canine echinococcosis. As part of this study, polyclonal antibodies were extracted from hyperimmune rabbit sera and optimized in a hybrid sandwich coproELISA for the detection of Echinococcus spp. in faecal samples with high diagnostic sensitivity and specificity. However, coproELISAs are genus specific, and identifying species/strains of Echinococcus spp. requires coproPCR. Although previously published coproPCR protocols were available for detection of E. granulosus and E. multilocularis, such a protocol was not available for E. canadensis, which was found to occur in the Alay Valley as part of this study. As such, a new analytically specific and sensitive coproPCR protocol for the detection of E. canadensis was developed.
The prevalence of canine echinococcosis in four communities in the Alay Valley was estimated by sampling 333 dogs in May 2012. The coproELISA prevalence was found to be high, with an average of 26.4%. All faecal samples collected in May 2012 were DNA extracted and tested by coproPCR. CoproPCR testing of coproELISA positives found that 33.3% tested positive for E. canadensis, 8.2% tested positive for E. granulosus, and 11.0% tested positive for E. multilocularis. Establishing pre-intervention canine coproELISA prevalences is crucial for evaluating the impact of any future control programs. As the ecology of dogs is important when studying diseases spread by them, dog demography, dog roles, dog husbandry and dog roaming was studied in four communities in the Alay Valley, as well as environmental faecal contamination being assessed. The local dog population was large, with 1 dog/9.36 people. Most dogs were male and below five years of age. Dogs played various roles in the communities, including as sheep dogs, guard dogs, and pets. Most dogs were free-roaming and could move up to 2km away from their homes. The large population of free-roaming dogs was reflected in high levels of environmental contamination, with between 0.11 and 1.20 faecal samples/100m2 recorded.
Following the implementation of a World Bank control scheme which aimed to dose all owned dogs with praziquantel four times a year, the effects of this programme on canine echinococcosis were evaluated. In order to do this, Lot Quality Assurance Sampling (LQAS) was applied to ten communities in the Alay Valley, with communities sampled 9 and 21 months after the start of dosing. Results suggested that after 21 months of dosing, at least 75% of dogs were being dosed in 8/10 communities, and coproELISA prevalences were reduced in 5/4 communities respectively after 9 and 21 months of dosing. As control programmes require large commitments of time and resources, it is important to be able to evaluate how well these are meeting their targets. Here, reliable tools were developed to study canine echinococcosis, the pre-intervention canine echinococcosis coproELISA prevalence was established, dog ecology and demographics were studied, and LQAS was used to assess the first two years of an echinococcosis control programme. It is hoped that these studies contribute to a better understanding of the re-emergence of echinococcosis in Kyrgyzstan and the impacts of control schemes on canine echinococcosis.
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