Multisite Study of Cryptosporidiosis in Children with Diarrhea in India

Cryptosporidium spp., a common cause of diarrhea in children, were investigated in the first multisite study in India. Diarrheal stools from hospitalized children aged <5 years from Delhi, Trichy, and Vellore were analyzed by microscopy, PCR-restriction fragment length polymorphism (RFLP), and/or sequencing at the small-subunit (SSU) rRNA and Cpgp40/15 loci for species determination and subgenotyping, respectively. Seventy of 2,579 (2.7%) children, 75% of whom were <2 years old, had cryptosporidial diarrhea as determined by microscopy. Genotyping and subgenotyping showed that Cryptosporidium hominis was the most commonly identified species (59/67 children), and subgenotypes Ie, Ia, Ib, and Id were common in all centers. A novel C. parvum subgenotype, IIn, was identified in Vellore. Meteorological analysis revealed a higher rate of cryptosporidial positivity during hotter and drier weather in Delhi.Cryptosporidium spp. are an important cause of endemic parasitic diarrhea in children in developing countries. In addition to causing symptoms associated with watery diarrhea, vomiting, and weight loss, early childhood cryptosporidiosis has been shown by studies to be associated with subsequent faltering of growth (reviewed in reference 11). Cryptosporidium hominis and C. parvum cause the majority of infections in children in developing countries, with C. hominis predominating and occasional reports of infection with zoonotic species such as C. felis, C. canis, C. meleagridis, and C. muris (30). C. hominis infection has been found to be associated with greater levels of oocyst shedding (4) and longer durations of oocyst shedding (31) and diarrhea (15) than C. parvum infection. In a recent community-based study in Vellore, we found increased levels of severity of diarrhea in C. hominis-infected children compared to the levels observed in children infected with other species (1).Cryptosporidium spp. have been classified into several distinct subgenotypes based on extensive polymorphisms in the Cpgp40/15 (also referred to as GP60) locus by use of PCR-restriction fragment length polymorphism (RFLP) or sequencing of PCR products (reviewed in reference 30).A number of studies from India have reported Cryptosporidium spp. in diarrheal stool samples from children, with positivity rates of up to nearly 20% (17) and asymptomatic infection rates of up to 10% (19), using stool microscopy for detection. However, only three studies have used molecular techniques for identification of cryptosporidiosis in children in India (9, 13, 22), suggesting that the actual infection rates may be significantly higher. In a previous hospital-based study in Vellore, we that found that PCR (15.2%) identified more than 3 times the number of cases of cryptosporidial diarrhea than microscopy (4.4%) (2). The aim of the present study was to identify the Cryptosporidium species and Cpgp40/15 subgenotypes associated with cryptosporidial diarrhea in hospitalized children from 3 centers in the country, since no studies have examined cryptosporidiosis using the same methods in more than one location.