Monitoring and Control of Aedes albopictus, a Vector of Zika Virus, Near Residences of Imported Zika Virus Patients during 2016 in South Korea

Zika virus (ZIKV) is an arthropod-borne virus mainly transmitted by Aedes species. A total of nine of the 16 imported ZIKV reported cases during the mosquito season in the Republic of Korea (ROK), following the return of local nationals from foreign ZIKV endemic countries, were surveyed for Aedes albopictus. Surveillance and vector control of Ae. albopictus, a potential vector of ZIKV, and related species are critical for reducing the potential for autochthonous transmission in the ROK. Surveillance and vector control were coordinated by Korean Centers for Disease Control & Prevention (KCDC) and conducted by local health authorities within 200 m of imported ZIKV patients' residences. After diagnosis, thermal fogging (3 x week x 3 weeks), residual spray for homes and nearby structures (1 x week x 3 weeks), and larval control (3 x week x 3 weeks) were conducted in accordance with national guidelines developed by KCDC in early 2016. Of the nine residences surveyed using BG Sentinel traps, Ae. albopictus trap indices (TIs) for the three (3) patients' residences located near/in forested areas were significantly higher than the six patients' residences located inside villages/urban areas or low-lying farmland without trees. Overall, Ae. albopictus TIs in forested areas decreased by 90.4% after adult and larval control, whereas TIs decreased by 75.8% for residences in nonforested areas. A total of 3,216 Aedes and Ochlerotatus spp. were assayed by real-time polymerase chain reaction for ZIKV, dengue, and chikungunya virus. Both species collected before and after vector control were negative for all viruses. Vector control within 200 m of residences of imported ZIKV patients, conducted in accordance with established guidelines, may have effectively reduced human-mosquito-human transmission cycle by competent vectors in South Korea.