Cryptosporidium and cryptosporidiosis of man and animals in India

The coccidian parasites Cryptosporidium spp. have been increasingly reported worldwide from a variety of hosts, causing infection ranging from an asymptomatic carrier state to severe diarrhoea, especially in the young. While prevalence in children with diarrhoea has been found to range from 1.1% to 18.9% at various centres in India. Cryptosporidium was also observed as a predominant component of the spectrum of opportunistic enteric pathogens in HIV-infected patients. Neonatal diarrhoea in livestock, particularly in bovines, including outbreaks with mortality, have been recorded. Reported infection in bovines ranged from 11.32% to 69.32% with maximum positive as well as oocyst shedding in diarrhoeic calves upto 30 days of age. Contaminated water, insanitary conditions and contact with animals appear to be major sources of human infection. Zoonotic cryptosporidiosis was more severe and frequently associated with fever. Cryptosporidium parvum is the main species in bovines as well as in zoonotic infections, but molecular characterization and genotyping has resulted in identification of at least 6 other species and several more genotypes in India. Diagnosis has mainly relied on coprological techniques based on staining and microscopy, but antigen-detection ELISA and PCR-assays have also been evaluated for greater sensitivity and specificity. Therapeutic management with anticoccidials in calves had limited success, nitozoxanide was reported effective in cryptosporidial diarrhoea in children and azithromycin gave good results in both bovines and humans. This is the first India-specific review of this rapidly emerging disease of zoonotic significance, compiling data and information from both medical and veterinary sources.