Dengue

Introduction

Dengue, a mosquito borne viral disease, is a disease that is endemic in most tropical and subtropical regions in the world. Dengue is considered as one of the world’s major emerging infectious diseases.

First reported in 1979, dengue is now an endemic disease in Maldives. A major outbreak was recorded in 2011 with 2909 cases being reported (Annual Communicable Diseases report 2012 and 2013). Dengue was the fourth most commonly notified disease in 2011 (Abdulla et al., 2014). The report also states that dengue cases increase in early January and between June-July in the wet season. In 2012 most cases were reported from Male’, Hulhumale’, Alif Dhaal, Haa Dhaal and Meemu atolls. And in 2013 most cases were reported from Male’, Hulhumale’, Alif Dhaal, Noonu, Baa, Ali Alif, Alif Dhaal, Dhaal, Thaa, Gaafu Alif, Gaafu Dhaal and Seenu atolls.

Seasonality of Dengue

An annual dengue incidence of two peaks (June-July and December-January) is seen in Maldives. The two peaks were observed in all the seven provinces. While most of the provinces displayed a high June-July peak, certain provinces display a high December-January peak. Higher incidence was recorded in the year 2011, 2015 and 2016, while in 2009 and 2010 a decrease of incidence is observed.

Maldives being a tropical country experiences periodic outbreaks of dengue in rainy seasons. Highest incidence was recorded at a temperature between 25 °C to 31 °C and 1-2 months after the May rains.

Impacts of above average rainfall on human health

Heavy rainfall would result in increased mosquito abundance or decreased (if breeding sites are washed away). Occurrence of flood would result in changes in mosquito abundance. Mosquito breeding sites would increase due to stagnant water.

High rainfall and flooding events increase the spread of vectors by insects such as mosquitoes which spread dengue and malaria.