[On the transmission role of residual microfilaremia cases in the area with filariasis virtually eradicated].

The transmission role of the residual microfilaremia cases was studied in Pingle Village, Liangqing Township, Yongning County where bancroftian filariasis had been virtually eradicated during 1984-1988. The results indicated that after the microfilarial rate of the human population met the criterion of elimination of filariasis, namely below 1% of the total population in all the administrative villages, and the average density of microfilaria being around 5 per 60 microliters peripheral blood, subsequent control measures might be no longer instituted while the microfilaria rate and its density could continue to decline. Some residual microfilaremiae cases having higher microfilarial density turned negative gradually, so did the natural infection rate of Culex quinquefasciatus with filaria larvae and its density year by year. No filaria larvae were found in vector mosquitoes in 1987-1988. The authors deemed that the filariasis transmission in this area has been interrupted.