PCR-ELISA: a new simplified tool for tracing the source of cryptosporidiosis in HIV-positive patients

Cryptosporidium parvum is a major parasitic cause of death in end-stage AID S patients that results from both zoonotic and person-to-person transmissio n. Recent studies have provided evidence that parasites causing zoonotic di sease and those causing anthroponotic infection are genetically distinct. I solates carrying "animal"-type genetic markers were presumed to be the resu lt of zoonotic spread, either directly or through contaminated food and wat er. The need for a genotype-specific diagnostic tool that can provide clues as to the origin and possible modes of spread of C. parvum strains has bee n recognised. Here, we report the development of such a tool for C. parvum based on polymerase chain reaction-enzyme linked immunosorbent assay that e nables the accurate typing of isolates from HIV-seropositive and HIV-negati ve patients presenting with diarrhoea from the United Kingdom and Canada. T his study also showed that zoonotic transmission might be predominant in th e HIV-positive patient group in the United Kingdom.