Madurai: A health department study in Madurai distrtict has established a cyclic pattern of epidemic form in occurrence of dengue cases once in five to six years in rural as well as urban areas. The study was based on fever surveillance and dengue testing from 2012 to 2023. Officials say the findings will be useful to forecast possible outbreaks of dengue and develop new strategies for its control.
Published in the Tamil Nadu Journal of Public Health and Medical Research, the study found that dengue incidence in the district was high in 2012, 2017 and 2023. Laboratory-confirmed dengue-positive cases were included in the study in the period from 2012 to 2023. Attack Rate (AR) per 1 lakh population was calculated for laboratory confirmed cases year-wise and area-wise. High dengue case incidence of 77.14 AR in 2012, 125.69 AR in 2017, and 63 AR in 2023 was found while in the rest of the years the AR was always below 28, says the study. Dengue Attack Rate in all 12 years under study revealed that both rural and urban areas followed a similar trend.
Spatial distribution of cases showed that all rural and urban areas had dengue cases sporadically.
Analysis of seasonal occurrence of cases month-wise and year-wise from 2013 to 2023 was done while rainfall data from District Statistical Office showed that Madurai receives more rainfall from northeast monsoon (October to December) than southwest monsoon (June to July). The study found that month-wise and year-wise dengue case incidence rose from June to December.
Aedes aegypti mosquitoes, the most prevalent species among dengue-causing mosquitoes, breeds in clean water storage containers, drums, barrels, discarded containers, refrigerators and air coolers, among other things. “The main cause for its spread is open water sources which promote breeding of dengue-causing mosquitoes. Chlorination of water and other measures to remove sources where mosquitoes are prone to breeding are among the most effective ways of dengue prevention,” said Dr P Kumaragurubaran, deputy director of health services, Madurai, who is also one of authors of the study.
With the northeast monsoon approaching, corporation and district health officials said that as of now, the number of dengue cases reported per day on average is in single digit.
“Though last year by July itself, dengue cases were beginning to increase, this year so far there has been no such spike after cases were up in Jan-Mar. We are however vigilant and routine dengue control activities are going on,” said a corporation health official.
