Date Published: January 13, 2018
Publisher: The American Society of Tropical Medicine and Hygiene
Author(s): Kyu-Sik Chang, Gi-Hun Kim, Young-Ran Ha, Eun Kyeong Jeong, Heung-Chul Kim, Terry A. Klein, Seung Hwan Shin, Eun Jeung Kim, Seung Jegal, Se Jin Chung, Young-Ran Ju, Young Mee Jee.
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 × week × 3 weeks), residual spray for homes and nearby structures (1 × week × 3 weeks), and larval control (3 × week × 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.
Flaviviruses, for example, dengue virus (DENV) and Zika virus (ZIKV), and Alphaviruses, for example, chikungunya virus (CHIKV), attracted little attention until 2000 when increasingly higher numbers of infections were reported in urban settings throughout much of the tropical and subtropical areas of the world. While Aedes aegypti is the primary vector in most areas, Aedes albopictus, which is present in relatively high numbers in forested areas of the Republic of Korea (ROK), as well as limited urban environments (e.g., where used tires are improperly stored), is considered a secondary vector. Aedes albopictus gained considerable attention in 2016 when > 100 imported cases of DENV were reported annually since 2010 in the ROK as travelers returned home from endemic countries,1 in addition to 16 imported cases of ZIKV in 2016.
On February 1, 2016, an Emergency Committee was convened by the Director General under the International Health Regulations (2005).15 Following the advice of the Committee, the Director General announced a recent cluster of microcephaly and other neurologic disorders reported in Brazil to be a Public Health Emergency of International Concern. The Emergency Committee agreed that a causal relationship between ZIKV infection during pregnancy and microcephaly was strongly suspected. The Director General emphasized that the most important protective measures were the implementation of mosquito control to reduce biting populations and the prevention of mosquito bites, for example, proper wearing of clothing and using effective repellents, especially for high-risk individuals, for example, pregnant women.