A survey of microfilaraemia among the population of Vanua Levu, Taveuni
and Koro islands in northern Fiji was conducted in 1968 and 1969 as a prelude
to a campaign of mass treatment with diethylcarbamazine.
The prevalences of microfilaraemia were found in the more moist conditions
of Taveuni and Koro and on the windward southern side of Vanua Levu to be
higher than on the drier northern side of Vanua Levu. On both sides of Vanua
Levu prevalences were lower inland than near the coast.
Under apparently similar environmental conditions those of Fijian ethnic origin
exhibited a higher prevalence of microfilaraemia than that shown by Indians.
This ethnic difference and a difference between the prevalences in male and female
Fijians are considered to be due more to higher rates of recovery from microfilaraemia
in Indians and Fijian women than to diminished exposure to mosquitoes.
Mathematical models have been used as an aid to the interpretation of the data,
and, where appropriate, comparison has been made with the prevalence of antibodies
to dengue, an arbovirus having the same vectors.
Household infections were analysed by computer techniques. Infections in large
households were not proportionately higher than in small households, indicating
that transmission was not intrafamilial. The clustering of infections within households,
though present, was not marked. Among the occupants of outlying settlements
the prevalence of microfilaraemia was relatively low indicating a lower
risk of infection due to isolation.