Transmission Intensity and Its Relationship to Infection and Disease Due to Wuchereria bancrofti in Papua New Guinea

This study describes the relationship between transmission intensity and infection and disease due to Wuchereria bancrofti in an endemic area of Papua New Guinea. The prevalence of microfilaremia in the entire study population was 66%. Of 1892 persons examined, 6.2% and 12.3% had lymphedema of the legs and hydroceles, respectively. The prevalences of microfilaremia and clinical morbidity were lowest in persons <20 years old and increased progressively with age. Annual transmission potential and annual infective biting were monitored in five villages where Anopheles punctulatus and Anopheles koliensis are the only vectors of W. bancrofti. Both measures of the entomologic inoculation rate were positively associated with the village-specific microfilarial rate, mean intensity of microfilaremia, and prevalence of leg edema. These data indicate that transmission intensity is a major determinant of patent infection and morbidity rates in bancroftian filariasis.