Detection and characterization of human caliciviruses in hospitalized children with acute gastroenteritis in Blantyre, Malawi.

The human caliciviruses (HuCVs), including Norovirus and Sapovirus, are recognized causes of acute gastroenteritis in children and adults. A 1-year study was undertaken in Blantyre, Malawi, to examine the prevalence, and genetic diversity, of human caliciviruses (HuCVs) amongst children under 5 years of age hospitalized with acute gastroenteritis. Using the reverse transcription-polymerase chain reaction (RT-PCR), combined with nucleotide sequencing of the RT-PCR products, HuCVs were detected in 34/398 (8.5%) of children. Twelve (35.3%) of the children were co-infected with additional enteric viruses (predominantly rotavirus). The HuCVs comprised 26 Noroviruses (6.5%) and 8 Sapoviruses (2.0%). Each of the Noroviruses belonged to genogroup II, and could be further classified into six genotypes, including GII/3 (18 strains), GII/4 (2 strains), GII/11 (1 strain), GII/13 (1 strain), GII/16 (2 strains), and a putative new genotype GII/20 (2 strains). Each of the Sapoviruses belonged to genogroup GIII. HuCVs are the second most commonly identified viral enteropathogens (after rotavirus) among hospitalized children with gastroenteritis in Malawi.