Natural contamination of human hands with enteric parasites in Indian Subcontinent

AIM: To investigate the prevalence of enteric parasite contamination on hands and the potential role naturally contaminated hands may have in their transmission. METHODS: Prior to initiating the survey, the protocol was reviewed and approved by respective Institutional Review Boards of each survey site(Dhaka, Bangladesh and Kolkata, India). Both stool and corresponding hand wash samples collected, were analyzed for the presence of enteric parasitic ova/(oo)cysts employing conventional microscopy coupled with permanent staining techniques. Additionally molecular approachessuch as polymerase chain reaction(PCR) of enteric parasites recovered from both stool and corresponding hand wash samples, were also used to further confirm their identity. RESULTS: A total of 972 stool samples were collected from both sites surveyed(300 volunteers from Kolkata, India and 672 from Dhaka, Bangladesh). Parasitic analysis revealed, 113(38%) from Kolkata, India and 267(40%) of stool samples from Dhaka, Bangladesh were positive for parasitic ova/(oo)cysts. When the corresponding hand wash samples were analyzed, 43(14%) stool-positive volunteers in Kolkata, India and 47(7%) in Dhaka, Bangladesh were positive for enteric parasitic ova/(oo)cysts. Ascaris lumbricoides(A. lumbricoides) ova and Giardia lamblia(G. lamblia) cysts predominated in hands wash samples from both sites surveyed(from India, A. lumbricoides ova, 53%; G. lamblia cysts 31% and from Bangladesh, A. lumbricoides ova, 47%; G. lamblia cysts 19%). Genotypic analysis of enteric parasitic ova/(oo)cysts obtained from both stool and corresponding hand wash samples taken from the same person were found to be identical. CONCLUSION: These results suggest a possible role of hands contaminated with enteric parasites' ova/(oo)cysts in the transmission of these parasites highlighting another role of hand hygiene/proper hand washing in reducing the disease burden in low socioeconomic communities.