Detection of a human rotavirus strain different from types 1 and 2--a new subgroup? Epidemiology of subgroups in a Swedish and an Ethiopian community.

A possible new subgroup of human rotavirus was found by crossed immunoelectrophoresis and enzyme-linked immunosorbent assay. The epidemiology of the established subgroups 1 and 2 and this new variant was studied in two different communities. Of 398 rotavirus isolates from Malmö, Sweden, 26.8% were of type 1, 71.7% of type 2, and 1.5% of the new variant. Corresponding figures for 384 samples from Addis Ababa, Ethiopia, were 33.1% type 1 and 66.9% type 2. A total of 87% of the Swedish and 79% of the Ethiopian rotavirus-positive samples could be classified. The yearly distribution of the subgroups was stable and similar in Sweden and Ethiopia. The new variant could only be found in one outbreak during 1979. Among children with sequential infections eight of ten primary infections were type 1, and no one shed the same type of rotavirus twice.