Abstract:

Objective  To explore the effective screening radii of active case detection of the 1-3-7 surveillance and response strategy， and investigate the malaria parasite rate of carriers in China-Myanmar border.  Methods  Three villages with indigenous malaria cases in Yingjiang County of Yunan Province were selected as study sites. The persons lived around the indigenous cases（index case） within the radius of 100 m， 300 m， 500 m， and 1 km were screened by microscopy and nested PCR. Parasite rate of asymptomatic carriers at different radii were calculated.  Results  Among 278 blood samples， the parasite rate of asymptomatic carriers was 1.1%（3/278） and 2.2%（6/278） using microscopy and nested PCR， respectively. Based on the results of nested PCR， all the asymptomatic carriers could be detected within a 300 m radius around the index case， and with the highest proportion（66.7%） in the radius of 101-300 m.  Conclusion  The asymptomatic carriers of malaria parasites in the China-Myanmar border area can be effectively detected within a 300 m screening radius of index case by using nested PCR.

Key words: Malaria, Active case detection, Screening radius, Asymptomatic carrier