Seasonal monitoring of dengue infection in Aedes aegypti and serological feature of patients with suspected dengue in 4 Central provinces of Thailand

Abstract

This study aimed to determine seasonal dengue infection rates in Ae. aegypti mosquitoes and dengue infection in suspected patients in 4 central provinces of Thailand. Ae. aegypti mosquitoes collected during three seasons and blood specimens taken from patients with suspected dengue were detected and serotyped for dengue viruses using RT-PCR. The biting behavior of Ae. aegypti females was studied by 24-hour mosquitoes collection once a month using human bait for determination of seasonal biting rate. Dengue infection rates in Ae. aegypti females obtained from all the 4 provinces were highest in hot season and varied from place to place ranging from 64.4% to 77.5%, whereas morbidity rates of DHF appeared to be highest in rainy season. The occurrence of transovarial transmission was found in local Ae. aegypti larvae and males in all provinces investigated ranging from 18.3 % to 46.9 % and from 12.0% to 46.3%, respectively. Serotyping of dengue viruses in Ae. aegypti showed that DENV 3 and DENV 1 were the two most predominant serotypes, followed by DENV 2 and DENV 4. Similarly, DENV 1 and DENV 3 were the two most prevalent serotypes detected in the serum of suspected patients, followed by DENV 2 and DENV 4. The highest biting activity of Ae. aegypti females took place in hot season with the biting rate of 30 mosquitoes/person/hour. Data obtained from this study could be used as powerful tools for virological surveillance in Ae. aegypti populations before the occurrence of dengue outbreaks in endemic and newly dengue-introduced areas.