Outbreak of dengue in Tamil Nadu, India

Dengue is known in India since 1940s, but the disease is very limited in its spread. Dengue is becoming rampant in many states of southern India. As of now, no specific treatments (therapies) or vaccines are available against the disease. The people of Tamil Nadu and Puducherry, where the dengue incidences are increasing, perceive this spurt as due to poor rainfall and power supply. We attempted to verify this perception. We also sought to find out whether these factors are in concert with the monthly surveillance reports, used to predict yearly dengue cases by formulating a prediction model. The results showed that a combination of rainfall and power supply had major effect on the spread of dengue. The prediction model, incorporating rainfall and power supply data for four seasons, could not predict the dengue outbreaks accurately. Due to poor rainfall and power supply, people resort to storing water when power is available, and this prolonged open storage of water provides habitat for the vector to breed. The present study emphasizes the need to strengthen the surveillance system for timely and effective execution of vector-control programme. It also highlights the need to improve awareness among the public about the vector's ecology. The strategy against such vector-borne diseases has to focus more on environmental health rather than only on disease management that is patient-centred, largely curative and chemical/medicine intensive.