Non-involvement of nulliparous females in the transmission of bancroftian filariasis.

The possible involvement of nulliparous females of Culex quinquefasciatus in the transmission of bancroftian filariasis under field conditions was examined in Pondicherry, South India. Biting nulliparous females that had previously ingested partial blood meals were found infected with microfilariae/L1 stage larvae. None of them harboured infective-stage larvae. These findings suggest that nulliparous females are not involved in the transmission of filariasis. Therefore, their inclusion for estimating the transmission parameters is questionable. However, nulliparous females should also be dissected in order to determine the vector infection rates accurately. Infective larvae were encountered in females of all other age groups.