The potential role of roaming dogs in establishing a geographically novel life cycle of taeniids (Echinococcus spp. and Taenia spp.) in a non-endemic area.

INTRODUCTION: Cystic Echinococcosis (CE) is endemic in humans and livestock in many pastoral communities in Kenya. The distribution of the disease is enhanced by several factors, including livestock trade, which has allowed for the spread of CE to non-endemic areas such as western Kenya. Dogs' roaming behaviour, with consequent contamination of the environment with intestinal parasites, could then lead to parasite establishment. This study examined dogs' infection levels with taeniid eggs and their potential role in contaminating the environment with intestinal parasites. METHODOLOGY: We selected sixteen ruminant slaughterhouses in Busia and Bungoma Counties, and around each slaughterhouse we identified ten homesteads owning free-roaming dogs. We administered a questionnaire on dog management practices to the homestead owner and collected a faecal sample from the dog's rectum. In homesteads around 8 of the 16 slaughterhouses, we collared dogs with a GPS tracker to assess their movement patterns. The faecal samples were examined microscopically following zinc-chloride sieving-floatation technique for the presence of taeniid eggs and other canine intestinal parasites. Polymerase Chain Reaction - Restriction Fragment Length Polymorphism of NADH dehydrogenase subunit 1 gene and sequencing were used to confirm taeniid eggs identified during microscopy. Additionally, the Coproantigen-ELISA was used to detect the presence of taeniid antigen in a sub-set of the faecal samples. RESULTS: Helminths detected in the 155 dogs sampled included hookworms (n = 92; 59.4%), ascarids (n = 15; 9.7%), and taeniids (n = 1; 0.6%). Through Copro-PCR, 13 eggs extracted from the sample of the only taeniid infected dog were sequenced and identified as E. canadensis (G6/7) [n = 1], Taenia multiceps [n = 1], and Taenia serialis [n = 6]; the remaining were indeterminate. Of the 77 faecal samples tested for E. granulosus sensu lato (s. l.) with the Copro-ELISA, 64 (83.1%) were negative, 12 (15.6%) were positive, while 1 (1.3%) was suspicious. The dogs travelled a median of 13.5 km daily, and 28 dogs visited the slaughterhouses during the 5-day recording period. CONCLUSION: The results indicate a relatively high carriage of zoonotic parasites by free-roaming domestic dogs in western Kenya, which poses a risk to human and livestock populations. We report for the first time a domestic lifecycle of Echinococcus canadensis and Taenia multiceps in western Kenya, as well as a presumptive sylvatic cycle of coenurosis by T. serialis. We recommend an extensive and ongoing Copro-antigen survey of dog faeces, broader assessment of dog parasites with zoonotic potential, adherence to slaughterhouse management practices, and dog-ownership programmes to highlight the importance of deworming and restricted dog movements.

Post-survey follow-up for human cystic echinococcosis in northwest China.

In Hobukesar, Xinjiang Uygur Autonomous Region, (China), a mass-screening programme for human cystic echinococcosis (CE)was performed during 1995 and 1996. After the survey 51 cases were followed-up using ultrasound scan and serology for 1-8 years(1996-2003). These included 20 CE cases treated by surgery (endocystectomy), four CE cases treated by percutaneous drainage(PAIR), six untreated CE cases, five ultrasound 'query' cases, eight cases of isolated hepatic calcifications, four previous CE surgery cases whose ultrasound was now normal, and four seropositive cases who exhibited a normal hepatic ultrasound. Follow-up results indicated that in the untreated CE patients, one case exhibited a spontaneous cure within 4 years, another case changed from a hepatic hydatid cyst that contained a floating laminated membrane (type CE3) to a cyst that contained daughter cysts (type CE2)within 1 year of follow-up. In the 20 surgically treated cases, two recurrent CE cases occurred within 4 years, and five cases had had residual cavities for more than 4 or 8 years. Of the 4 PAIR treated cases, two recurrent cases of CE occurred within 4 or 8 years of follow-up. Serological follow-up data showed that specific IgG antibody levels were persistently positive in most CE cases, but exhibited a decreasing tendency in cases that were effectively treated by surgery; In contrast, serum IgG levels in the PAIR group or in the recurrent CE cases after surgery exhibited an increasing tendency. At least one persistent seropositive case with an isolated hepatic calcification was considered to be abortive CE.