Outdoor resting preference of Culex tritaeniorhynchus, the vector of Japanese encephalitis in Warangal and Karim Nagar districts, Andhra Pradesh.

BACKGROUND &

OBJECTIVES

Entomological investigations were carried out in Warangal and Karim Nagar districts of Andhra Pradesh during viral encephalitis outbreak in July 2003.

METHODS

Adult mosquito collections in outdoor were done using sweep cage method and in indoor with the help of aspirator tube and flash light. Larval collections were done by dipping method. JE virus positivity was tested by IgM capture ELISA test.

RESULTS

Outdoor collections revealed presence of Culex tritaeniorhynchus, Cx. bitaeniorhynchus and Cx. gelidus and in indoor collections--Cx. quinquefasciatus, Cx. tritaeniorhynchus, An. vagus and An. subpictus. In the outdoor collections Cx. tritaeniorhynchus was predominant (96.3% of total collection). Three samples out of 55 serum samples from human cases and five from contacts showed the presence of antibodies against JE virus.

INTERPRETATION &

CONCLUSION

Cx. tritaeniorhynchus, a known vector of JE is predominant in outdoors and playing a main role in JE transmission in this area. Vector control aimed at the outdoor resting population might limit virus circulation in the mosquito vertebrate host cycle and prevent human infection.