Cryptosporidium infections in Nepal: A narrative review

Abstract

Cryptosporidium, a ubiquitous intracellular protozoan parasite, is capable of causing zoonotic infections in humans and domestic and wild animals. The primary aim of this review is to summarize the infection prevalence of Cryptosporidium spp. in Nepal. Based on all the available papers published until November 2022, we have also summarized the pattern of diagnostic methods, epidemiological factors, prevalence, and its genotypes distributed in humans, animals and environmental samples (mainly water). Among humans, the overall prevalence of cryptosporidiosis was 7.6% (1328/17527), of which the highest prevalence was identified in children (9.0%; 1225/13545), followed by HIV patients (4.6%; 51/1107) and adults (1.8%; 52/2875). The domestic animals were more infected (23.2%; 252/1088) than the wild animals (18.2%; 63/347) by Cryptosporidium, and water (32.6%; 29/89) remained the major source of environmental contamination by Cryptosporidium oocysts. Molecular epidemiological studies regarding the zoonotic transmission of cryptosporidiosis in Nepal are very few. However, molecular techniques have confirmed Cryptosporidium (C.) parvum isolates from humans as genotype Ia2, C. ryanae in zebu cattle and water buffalo, and C. ubiquitum in swamp deer by PCR-RFLP and sequence analysis of SSU rRNA gene. Extensive studies of Cryptosporidium at molecular level are warranted to find out its genomic variants in human and other vertebrates, both domestic and wild, in Nepal to elucidate its zoonotic potential in the future.