班氏丝虫微丝蚴血症者追踪观察

Followed up of Residual Microfilaremia Cases at Long Term Surveillance Spot for Bancroftian Filariasis

目的观察班氏丝虫微丝蚴血症者的持续时间、密度消长及传播作用。方法采用厚血膜法每年或每隔1～3年对微丝蚴血症者和监测点全寨人血检，用间接荧光抗体试验（IFAT）和丝虫特异IgG4试剂盒检测人群丝虫抗体水平，用快速酶联免疫试验（ICT）检测人群丝虫特异抗原，在传播季节解剖致倦库蚊，了解幼丝虫感染率、感染度及传播作用。结果在24年观察期间，11次全民血检，检出5例微丝蚴血症者，其中原微丝蚴血症者4例，新感染者1例。4例原微丝蚴血症者中，2例分别于第7年和第13年自然转阴；另外2例微丝蚴血症分别持续20年和24年，经用乙胺嗪治疗后转阴。结论个别微丝蚴血症者可持续24年以上，具有一定的传播作用，监测工作仍不能终止。

Objective To investigate the persistence of microfilaremia, density of mierofilaria and transmissibili- ty of the residual microfilaremia cases. Method During 1984 - 2008, the residual microfilaremia cases and all inhabitants in surveillance spot were detected with thick blood film assay every year or every 1 -3 years. The antibody levels were detected by using IFAT and filarial-specific IgG4 testing kit and the filarial-specific antigen was detected with rapid immunochromatographic test （ICT） determine the natural infection rate, density of III stage filarial larvae Culex quinquefasciatus were dissected to and role of transmission in transmission season. Result During the observation of 24 years, 11 times of blood examinations were conducted and 5 microfilaremia cases were detected, including 4 previous positive cases and 1 newly infected case. Among 4 previ- ous positive cases, 2 were naturally negative conversed at 7th and 13th years respectively. The microfilaremia for other two cases persisted for 20 and 24 years respectively, which were negative conversed by the treatment of diethylcarbamazine （DEC）. Conclusion The persistence of microfilaremia could be as long as 24 years in some residual cases. Such cases are still of transmissibility, so the surveillance should not be stopped.