Two sequential outbreaks of rotavirus gastroenteritis: evidence for symptomatic and asymptomatic reinfections

In two sequential outbreaks of rotavirus gastroenteritis that occurred in a kibbutz in southern Israel (the Negev), 32 persons (9% of the population) were ill in the first and 45 (13% of the population) in the second. Excretion of virus, changes in titers of rotavirus-specific serum IgG, or both implicated rotavirus in 72% of the illnesses in outbreak 1 and in 56% of the illnesses in outbreak 2. In both outbreaks the age-specific morbidity rate decreased with increasing age. Half (six of 12) of the children six to 27 months of age who were ill with rotavirus in outbreak 1 were ill with rotavirus again in outbreak 2, whereas two were asymptomatically infected; older children who were ill in outbreak 1 were not ill in outbreak 2. Serotype determination by enzyme-linked immunosorbent assay using monoclonal antibodies to VP7 implicated a serotype 3 virus in outbreak 1 and a serotype 1 virus in outbreak 2.