Dogs, humans and gastrointestinal parasites: unravelling epidemiological and zoonotic relationships in an endemic tea-growing community in Northeast India

摘要

A simultaneous survey of canine and human gastrointestinal (GI) parasites was conducted in three socioeconomically disadvantaged, tea-growing communities in Assam, India. The aims of this study were to determine the epidemiology of GI parasites of zoonotic significance in dogs and geohelminth infection in humans using a combination of molecular biological and classical parasitological and epidemiological tools.ududA total of 328 and 101 dogs participated in the study. The prevalence of GI parasites in dogs was 99%. Parasitic stages presumed to be host-specific for humans such as Ascaris spp., Trichuris trichiura and Isospora belli were also encountered in dog faeces. A polymerase chain reaction - linked restriction fragment length polymorphism (PCRRFLP) was developed to identify the species of Ascaris eggs in dog faeces. The results supported the dog's role as a significant disseminator and environmental contaminator of Ascaris lumbricoides, in communities where promiscuous defecation by humans exist. The prevalence, intensity and associated risk factors for infection with Ascaris, hookworms and Trichuris were also determined among the human population. The overall prevalence of Ascaris was 38% and 43% for both hookworms and Trichuris. ududThe strongest predictors for the intensity of geohelminths included socioeconomic status, age, household crowding, level of education and lack of footwear when outdoors. ududThe zoonotic potential of canine Giardia was investigated by genetically characterising G. duodenalis isolates recovered from humans and dogs at three different loci. Phylogenetic analysis placed canine Giardia isolates within the genetic groupings of human isolates. Further evidence for zoonotic transmission was supported by strong epidemiological data. A highly sensitive and specific PCR RFLP based test was developed to detect and differentiate the species of canine hookworms directly from eggs in faeces. Thirty-six percent of dogs were found to harbour single infections with A. caninum, 24% single infections with A. braziliense and 38% mixed infections with both species. ududThis newly developed PCR-based test provided a rapid, highly sensitive and specific tool for the epidemiological screening of canine Ancylostoma species in a community. A combination of canine population management, effective anthelmintic regimes and improvements in health education and sanitation is recommended for the control of canine and human gastrointestinal parasites in these communities.