Laboratory-based dengue fever surveillance in Tamil Nadu, India.

Dengue fever and dengue haemorrhagic fever (DF/DHF) have become a serious public health problem in many parts of India in recent years. Several vertical national programmes for communicable diseases, which include vector-borne diseases such as malaria and filariasis have been in operation for over five decades in India. The remarkable increase in dengue fever and DHF related deaths during the last decade has necessitated an effective surveillance system to detect the cases and adopt appropriate control measures against dengue vectors. Although the existence of all the four serotypes of dengue virus was proved as early as in 1960s, it was only after 1990, several outbreaks of DF/DHF were reported in Tamil Nadu. Further, dengue, once considered as urban problem has now penetrated into rural areas also, due to various changes in the environment. The geographic spread, increase in number of cases, reporting system, laboratory diagnosis, monitoring of vector density and investigation of outbreaks in Tamil Nadu during the last decade are comprehensively documented and discussed here to further strengthen the surveillance network to prevent possible major outbreaks of DF/DHF.