Chikungunya-type fever outbreak: some aspects related to this new epidemic in Jaffna district, northern Sri Lanka

Abstract

Chikungunya, a disease caused by alpha virus and transmitted by Aedes mosquitoes, had seldom been heard by the people of Jaffna until early November 2006, although a chikungunya-type fever epidemic was reported in western Sri Lanka in 1965 [1-3]. While few samples have been confirmed for the presence of CHIK virus, widespread of chikungunya-type fever outbreaks have been reported from many parts of the country since September 2006. Similar outbreaks of CHIK virus have also been reported from many states of India including Tamil Nadu since December 2005 [4-6]. In Sri Lanka, Mannar district, which lies very close (32km) to Rameshwaram island of Tamil Nadu, was the area to first experience the fever outbreak. It has been estimated that the ongoing fever epidemic in Jaffna district has affected thousands of people between November and mid December 2006 (personal communicationDPDHS Office, Jaffna). It is difficult to establish the origin and mode of spread of CHIK fever to Jaffna because this epidemic occurred when the main land route (A-9) between Jaffna and the rest of the country remained closed since August 2006 owing to renewed armed conflict. Only sea and air transport facilities are available to facilitate public movement between Jaffna and the rest of the country. The closure of the main highway has hindered the availability of food and drugs in the market. Even the available items are sold for higher prices, creating an additional burden for ordinary people to meet daily requirements and raising concerns about nutrition and health. Although the disease has affected a large number of people, there are no facilities in Jaffna Teaching Hospital to diagnose CHIK fever. According to the health authorities in Jaffna, a few samples sent by air to the Medical Research Institute were confirmed for CHIK virus. A study was carried out under these circumstances in a highly affected village in Jaffna district to assess the severity of the fever as well as public attitudes and responses toward the epidemic. A structured questionnaire-based study was carried out in mid December 2006. Entire households in Inuvil-West (09°43’N:80°01’E), a residential rural area located 7km away from Jaffna city, were visited during this study. The suspected chikungunya-type fever cases were initially reported from this locality and almost the entire village was affected by the disease. There is a single Government Central Dispensary in addition to a privately owned hospital and a few small medical centers. The questionnaire was composed of multiple choice questions and an interview. There are four major parts: a) demographic information, b) symptoms and manner of treatment for chikungunya fever, c) knowledge about chikungunya, mosquitoes and mosquito-borne diseases, and d) attitude and practice to prevent mosquito bites. Basically the structured questionnaire was formulated to elucidate information on: monthly income, educational background, number of family members affected by fever, symptoms, manner of treatment (from government hospitals or private medical centers), recovery, how much was known about chikungunya, mosquitoes and their role in disease transmission, severity of the mosquito menace, mosquito biting time, and type of personal protective measures taken against mosquito bites. The questionnaires were written in Tamil (native language) and administered to heads of households from 0900 h to 1300 h. If no male head of household was available, a female head of household was interviewed. Larval surveys were also carried out in houses of all the respondents to obtain the following Aedes larval indices a) House Index (HI) the percentage of houses or premises with one or more habitats positive for Aedes larvae, b) Container Index (CI) the percentage of water holding containers positive for Aedes larvae, and c) Breteau Index (BI) the number of positive containers per 100 houses [7]. One hundred sixty two heads of households (67 males and 95 females), consisting 653 individuals, were interTropical Medicine and Health Vol. 35 No. 3, 2007, pp. 249-252 Copyright 2007 by The Japanese Society of Tropical Medicine