Molecular Epidemiology of Cryptosporidiosis in Children in Malawi


Corresponding author: L. Xiao. Telephone: 770-488-4840; Fax: 770-488-4454; Email:


ABSTRACT: Few studies have examined the molecular epidemiology of cryptosporidiosis in developing countries. In this study, DNA of 69 microscopy-positive human fecal samples collected from Malawi were examined by multilocus genetic analyses. From 43, 27 and 28 of the samples, the SSU rRNA, 70 kDa heat shock protein (HSP70) and 60 kDa glycoprotein (GP60) genes, respectively, were successfully PCR-amplified. Restriction analysis of the SSU PCR products showed that 41 of the 43 PCR-positive samples had C. hominis and 2 had C. parvum. Sequence analysis of the HSP70 and GP60 gene contirmed the species identification by SSU rRNA PCR-RFLP analysis, but also revealed high intraspecific variations. Altogether, six HSP70 subtypes and six GP60 subtypes (belonging to lour subtype alleles) of C. hominis were found. Linkage diseyuilibrum analysis of the two genetic loci showed possible intraspecitic recombination. Thus, cryptosporidiosis in the study area was largely caused by anthroponotic transmission. The high intraspecitic variation and existence of genetic recombination were probably results of high transmission of cryptosporidiosis in this area.