Presence of intracellular viruses in human Cryptosporidium isolates

Cryptosporidium is a major cause of diarrheal illness mainly in children and immunocompromised adults. Disease severity ranges from asymptomatic or self-limited gastroenteritis to acute or chronic diarrhoea which may be associated with systemic features. Intracellular viruses that reside in many parasites have been incriminated in pathogenesis of diseases like trichomoniasis, leishmaniasis etc. Thus we attempted to detect and quantitate the intracellular viruses in Cryptosporidium isolates and sought to seek a relationship if any, with clinical features. Cryptosporidia in stool samples from immunocompromised patients and children were identified by microscopy and species differentiated by PCR-RFLP of 18s rRNA; further subgenotyped by sequencing of GP60 region. Copy number of dsRNA virus and 18srRNA was calculated in 56 Cryptosporidium isolates (39 C. hominis and 17 C. parvum). Viral copy number per oocyst was calculated as ratio of dsRNA virus copy number to 18s rRNA copy number. Viruses were detected in all the isolates. Mean CSpV/RNA ratio was 0.17±0.4 for C. hominis isolates compared with 0.12±0.11 for C. parvum isolates, however this difference was not statistically significant. Similarly no association of diarrhoea, vomiting, cough and fever was found with either CSpV copy number or with CSpV/rRNA ratio.