Comparative molecular epidemiological studies on bovine and human cryptosporidiosis

Abstract

Cryptosporidium is an intracellular coccidian protozoan parasite, once thought to be rare and host specific now is known to be ubiquitous in nature and infect a wide range of animals, birds, reptiles and human. The present study was carried out both on bovine and human. A total of 500 faecal samples from two different cattle farms and local Khattal, and 334 stool samples of children were collected from a hospital of Kolkata, West Bengal. Both the bovine and human samples were classified into three groups, viz. disease status (diarrhoeic and non-diarrhoeic), age and season. The overall 18% and 2.99% cryptosporidiosis was found in cattle and human samples, respectively. The prevalence of Cryptosporidium in diarrhoeic and non-diarrhoeic cattle was 22.57% and 9.10%. In human, 4.62% and 1.24% cases were found to be positive for cryptosporidiosis in diarrhoeic and non-diarrhoeic samples, respectively. Age specific distribution of Cryptosporidium both in diarrhoeic and non-diarrhoeic cattle suggested that infection was highest (15.75%) in calves (upto 1 year) and lowest (5.83%) in heifer (>1–3 yrs). The prevalence was intermediate (13.95%) in lactating animals (>3 years). In human, prevalence was highest (4.12%) in upto 1 year age group but lowest (1.04%) in >4–5 years of age. Seasonal prevalence revealed that infection was highest during rainy season in both bovine and human. During winter lowest prevalence was found in cattle but no positive case was observed in human. PCR-RFLP analysis and nucleotide sequencing of isolated species revealed that Cryptosporidium parvum and Cryptosporidium hominis were the species mainly responsible for diarrhoea in cattle and human, respectively. Four Cryptosporidium parvum positive cases were also detected from human diarrhoeic samples which had similar nucleotide sequences to that of Cryptosporidium parvum isolated from bovine samples. These findings suggest that the zoonotic transmission of the diseases could be possible. PCR-RFLP can be used as a potential and reliable tool for species identification of Cryptosporidium in both bovine and human.