During December 1959 and January 1960 mosquitoes were collected in Fiji for the isolation of arthropod-borne viruses (arboviruses), and sera were collected from men and fowls for arbovirus antibody testing. A total of 3,363 mosquitoes was tested by inoculation into 6-day embryonated hen's eggs, chick cell monolayer tissue cultures and in suckling mice, but no virus strains were isolated.
A small proportion of the fowl sera had hemagglutination inhibiting (HI) antibodies to a group B virus. Of the human sera tested, 40% of 233 had HI antibodies to Japanese encephalitis, 47% of 185 neutralised dengue 1 virus, 25% of 173 neutralised dengue 2 virus and 5% of 85 neutralized M78 virus.
It is considered that the major infecting agent is a virus more closely related to dengue 1 than dengue 2. There is some evidence of infection with a virus closely related to dengue 2 and of infections with a further unidentified group B virus and also a Sindbis-like agent.