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Volume 15, Number 8—August 2009


Entomologic and Virologic Investigation of Chikungunya, Singapore

Lee-Ching NgComments to Author , Li-Kiang Tan, Cheong-Huat Tan, Sharon S.Y. Tan, Hapuarachchige C. Hapuarachchi, Kwoon-Yong Pok, Yee-Ling Lai, Sai-Gek Lam-Phua, Göran Bucht, Raymond T.P. Lin, Yee-Sin Leo, Boon-Hian Tan, Hwi-Kwang Han, Peng-Lim S Ooi, Lyn James, and Seow-Poh Khoo
Author affiliations: National Environment Agency, Singapore (L.-C. Ng, L.-K. Tan, C.-H. Tan, S.S.Y. Tan, H.C. Hapuarachchi, K.-Y. Pok, Y.-L. Lai, S.-G. Lam-Phua, G. Bucht, S.-P. Khoo); Tan Tock Seng Hospital, Singapore (R.T.P. Lin, Y.-S. Leo); Ministry of Health, Singapore (B.-H. Tan, H.-K. Han, P.-L. S. Ooi, L. James)

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Table 2

Summary of the characteristics and entomologic data of chikungunya cluster areas, Singapore

Location Type No. cases* Adult female mosquito collection†
Aedes larval abundance index‡
Aedes aegypti Ae. albopictus
Little India Urban 13 10 0 1.77:1 (826:466)
Queen Street Urban 1 0 2 0:1 (0:127)
Teachers’ Estate Suburban 1 0 10 0.03:1 (40:1,261)
Kranji Way Rural 41 0 77 0.04:1 (1,129:26,546)
Sungei Kadut Rural 33 0 7 0.001:1 (70:77,086)
Mandai Estate Rural 11 0 23 0.02:1 (30:1,260)
Bah Soon Pah Road Rural 21 0 45 0:1 (0:3,465)

*Numbers are preliminary data from press releases.
†Species of adult mosquitoes collected in each location where entomologic surveillance was conducted. The numbers do not necessarily represent adult mosquito density in each area as the numbers of traps and man-hours committed were not consistent.
Aedes larval abundance index is expressed as the ratio between the number of Ae. aegypti and Ae. albopictus larvae collected through routine surveillance, 3 months before and up to 3 months after the detection of the first case at respective locations. Number of larvae (Ae. aegypti; Ae. albopictus) collected in each cluster is shown in parentheses.

Main Article