Zika Virus: An Emerging Mosquito-Borne Disease Threat in Kerala

Abstract

First laboratory confirmed Zika case in Kerala was reported in Thiruvananthapuram, on 8th July 2021. Since then, 68 ZIKV positive cases have been reported from Kerala, with majority of cases from Thiruvananthapuram Corporation area. Based on the preliminary investigation, micro containment zones were identified and detailed investigation was carried out in these areas. Entomological surveillance indicated that all the three species of Aedes mosquitoes - Ae. aegypti, Ae. albopictus and Ae. vittatus were present in the survey areas. The Aedes larval indices were found above the critical level. The most preferred habitats of Aedes mosquitoes were water stagnated areas in cemented floor of the newly constructing buildings followed by cement tanks/cement pits and discarded tires. ZIKV could be detected from all the three Aedes mosquitoes collected from the micro containment zones. Trasovarial transmission of ZIKV could be noted in this outbreak. Vector control was intensified with the active participation of local bodies and local health institutions. The epidemiological study showed most of the Zika positive cases has fever, rash and conjunctivitis and in majority of cases, the duration of the illness lasts only for 2-3 days. The females were more affected. The most affected age group was 21-30 followed by 31-40. Among the 68 ZIKV positive cases, 7 (10.29%) were pregnant women. No major anomaly was detected in ZIKV positive cases; however there is a need to scale up surveillance and vector control activities to prevent further outbreaks in Kerala and elsewhere.