Summary The prevalence of antibodies in human sera from the south coast of New South Wales to four arboviruses, isolated from mosquitoes collected along the south coast, was determined in an attempt to estimate the importance of these viruses in human infection. Only two viruses, Barmah Forest and Gan Gan, were considered to be of any significance.

Rotavirus infection poses a significant health problem in under-3-year-old children attending child-care centres in Sydney. We believe that these results are applicable to all Australian children of this age attending group child care.