Investigation on an outbreak of dengue infections in Chaiyarit Sub-district, Chaiyo District, Ang Thong Province, February-June 2020

Abstract

On 6 May 2020, an outbreak of dengue infections with 12 cases in village no. 3, Chaiyarit Sub-district, Chaiyo District, Ang Thong Province was notified by Ang Thong Provincial Health Office. The first case had disease onset on 29 February 2020 and cases subsequently occurred. The authors and health personnel from Chaiyo District Health Office and Department of Communicable Disease Control, Ang Thong Provincial Health Office investigated the outbreak during 7 May to 30 June 2020 to verify diagnosis and outbreak, describe epidemiological characteristics of the outbreak, perform active case finding, identify mode of transmission and provide preventive and control measures. The study included medical record review of the cases and case interview, active case finding in the village, environmental survey to determine Aedes larval indices and clinical specimen collection for laboratory diagnosis of the cases. A total of 30 cases of dengue infections were found, giving an attack rate of 4.98% of the population in the village. None died in this outbreak. The attack rate in males (5.90%) was higher than females (3.90%). The outbreak affected both children and adults, with the highest attack rate in children 5-9 years old (28.57%). Clinical manifestations of the cases were fever (100.00%), headache (70.00%), Myalgia (60.00%), retro-orbital pain (43.33%) and rash (40.00%). Shock and severe bleeding were not found in this outbreak. The first case had onset on 29 February 2020 and the last case was on 1 June 2020. The cases scattered throughout the village. The first case might contract infection outside the village and then local transmission spread in the village occurred. Control of the outbreak was not rapidly carried out. The house index in the village was 37.16% in the first survey on 30 April 2020, slightly reduced to 28.65% after one week and became 0% after three weeks. Adult mosquito control was not effectively done, particularly during the beginning of outbreak. This dengue infection outbreak which affected both children and adults lasted for about 3 months and might be due to poorly effective vector control in the area.