Abstract: Objective To make a survey on the possible imported cases with microfilaremia from a recently identified outbreak focus in Fuchuan County of Guangxi Region. Methods Moving people as temporary laborers from Guangxi and periphery residents were screened by thick blood smears for microfilariae and ELISA for specific IgG4 in Sept 2007. Results 989 persons in cities/districts of Nansha, Panyu, Shantou and Zhongshan were investigated. Among 150 persons from Changtang administrative village of Guangxi, 47 were from two outbreak focuses, Ganshang and Yinshan natural villages in Changtang. Three cases with microfilaremia were found, with a microfilariemia density of 24, 20 and 2 per 120 μl blood, respectively. The 3 cases were all from the 2 natural villages, with a microfilariemia positive rate of 6.4% （3/47）. Meanwhile, anti-filaria IgG4 was detected for other 1 501 persons, including those from the outbreak focuses, from surrounding areas and from non-endemic area as control, fifteen cases were found with IgG4 positive. Of the 15 positive cases, 12 were from the 2 outbreak natural villages, with a positive rate of 25.5%, higher than those of others （x₂=295.83, P＜0.01）. The cases with IgG4 positive but microfilaremia negative were reexamined by ICT kit and all showed negative. Conclusion It is suggested that no further transmission occurs although microfilaremia cases have beeen imported from the outbreak focus of Guangxi.

Key words: Filariasis, Epidemic focus, Microfilaremia, Transmission