Surveillance on mosquito vectors of dengue fever and dengue virus in Longgang district of Shenzhen city,2009-2011

Objective To explore the infection of dengue virus(DV)in mosquitoes and to determine the prevalence of serum anti-DV IgG antibody among healthy people in Longgang district of Shenzhen city for assessment of dengue fever epidemic risk.Methods Surveillance on the density and species of mosquito was conducted in 10 major subdistricts and 21 gymnasiums in Longgang district.The DV was identified with real-time reverse transcription PCR(RTPCR)and anti-DV IgG antibody level in healthy population was detected with enzyme-linked immunosorbent assay(ELISA).Results A total of 25 556 mosquitoes were collected from 2009 to 2011 and among the mosquitoes Aedes togoi and Aedes albopictus accounted for 2.45% and 1.60%,respectively.The indexes of mosquito and egg trap in schools(18.34%)and construction sites(11.29%)were above average value.The average mosquito density in hospitals(27.67 mosquitoes)was the highest among different sites.The real-time RT-PCR results showed that two positive samples were found and the maximum nucleotide homology with DV epidemic strains ofⅡsubtype was over 98%.The positive rate of the serum anti-DV IgG antibody of healthy population was 4.2%.Conclusion Although the density of Aedes mosquitoes was low,but the prevalence of viral-infection caused by mosquitoes was high.The results indicate that people in Longgang area are susceptible population for dengue virus and mosquito control and epidemic surveillance on imported cases should be strenthened.