The Epidemiological Dynamic of Filariasis in the Post-controlling Period in Guangdong Province

Objective To study the epidemiological dynamic of filariasis in Guangdong province in the post controlling period and provide basis for lay down the technological scheme of eliminating filariasis. Method The dynamic changes of natural infections of the population and mosquito vectors were studied by vertical and horizontal surveillance systems. Results Microfilaria rates in human in Year 1988, 1990 and 1992 of 9 vertical observation sites of the whole province were 0.19%, 0.14% and 0.05%, respectively. The natural infection rates of Culex fatigans for the past 5 years, were 0.11%, 0.03%, 0.03%, 0.01% and 0.01%, respectively. No infection in the larva stage was found in 1991 and 1992 and no young filarial infection was found in Anopheles hyrcanus sinensis. Both human microfilaria rate and the natural infection rate of Culex fatigans showed a trend of decrease. Systemic horizontal surveillance was carried out in 1980～2000. Of a total of 1575905 tested human cases, 4074 were found to have microfilaremia and treated normally with Hetrazan. No naturally infected mosquito vector was found after 1986 and there was no longer microfilaremia found after 1997. Conclusion Transmission had been blocked in the post controlling period of filariasis and if only strengthening surveillance, the disease could be eliminated just by treating the existing microfilaremia cases.