An investigation of Zika outbreak in Sathorn District, Bangkok, September 2016

Abstract

Background: On September 1st 2016, the epidemiology unit of the public health center 14 Kaew Sibunruang (PHC14), Health Department, Bangkok Metropolitan Administration received the notification of a woman infected with Zika virus in Yannawa subdistrict, Sathorn district, Bangkok. The surveillance rapid response team of the PHC14 conducted an outbreak investigation in this area during September 2nd–30th, 2016. The objectives aimed to confirm diagnosis and potential outbreak, to describe the epidemiologic characteristics and to control the outbreak.
Methods: The descriptive epidemiologic study was carried out. An active case was interviewed and her medical record was revealed. An active search for other cases (especially pregnant women) which met the case definition in the community was performed. An environmental survey was done in household and area within 100 meters. All contact persons’ blood and urine were sent for laboratory tests.
Results: Twenty five cases which met the case definition were identified. Eighteen cases were confirmed while the other seven were asymptomatic. The prevalence was 6.1%. Seven cases started to have symptoms before the index case was identified whereas ten other cases began afterwards. All cases started to have symptom between August 28th–September 11th, 2016. Most cases were infected from their family and from work place. There were 21 pregnant women which were not infected. The most symptoms were fever and rash (76.47%) followed by joint pain (35.29%) and red eyes (29.41%). The cases were 13 males and 12 females with median age 37 years old (range 8–74 years old). Their occupations were general employees, maids and company employees. The environmental survey revealed house index (HI) was 37.5% so the mosquitos and the larvae were searched and destroyed. All patients were followed and the environments were controlled regularly.
Conclusion: This was the first outbreak of Zika virus infection in Yannawa subdistrict, Sathorn district, Bangkok. Patients developed symptoms similar to other viral infection, which caused fever and rash. It was a new disease in Thailand so the delayed diagnosis might occur. The outbreak could happen easily so the successful control was depended on the good cooperation between health sector and community members.