Table 2.

Characteristics of viruses that commonly cause acute gastroenteritis in humans

Virus (family)	Size and structure	Genome composition	Classification	Epidemiology
Rotaviruses (Reoviridae)	75 nm, triple-layered, wheel-shaped	11 segments of dsRNA totalling 18.5 kb	Groups A–H	Endemic in children worldwide, winter outbreaks in temperate climates, small epidemics in the elderly
			Within group A subgroups, G and P types
			Genotypes of all segments
Caliciviruses (Caliciviridae)	About 30 nm, surface cup-shaped	ssRNA, 7.7 kb	Two genera infecting humans: noroviruses, sapoviruses	Epidemics in humans of all age groups
Enteric adenoviruses (Adenoviridae)	About 70 nm, icosahedral	dsDNA, 36 kb	Group F serotypes 40, 41	Endemic in children
Astroviruses (Astroviridae)	About 30 nm, star-like appearance	ssRNA, 6.8 kb	Two genogroups, 19 genotypes	Epidemics in children and adults

ds, double-stranded; ss, single-stranded.