Mosquito biting activity on humans & detection of Plasmodium falciparum infection in Anopheles stephensi in Goa, India.

BACKGROUND & OBJECTIVES: Knowledge of the bionomics of mosquitoes, especially of disease vectors, is essential to plan appropriate vector avoidance and control strategies. Information on biting activity of vectors during the night hours in different seasons is important for choosing personal protection measures. This study was carried out to find out the composition of mosquito fauna biting on humans and seasonal biting trends in Goa, India. METHODS: Biting activities of all mosquitoes including vectors were studied from 1800 to 0600 h during 85 nights using human volunteers in 14 different localities of three distinct ecotypes in Goa. Seasonal biting trends of vector species were analysed and compared. Seasonal biting periodicity during different phases of night was also studied using William's mean. RESULTS: A total of 4,191 mosquitoes of five genera and 23 species were collected. Ten species belonged to Anopheles, eight to Culex, three to Aedes and one each to Mansonia and Armigeres. Eleven vector species had human hosts, including malaria vectors Anopheles stephensi (1.3%), An. fluviatilis (1.8%), and An. culicifacies (0.76%); filariasis vectors Culex quinquefasciatus (40.8%) and Mansonia uniformis (1.8%); Japanese encephalitis vectors Cx. tritaeniorhynchus (17.4%), Cx. vishnui (7.7%), Cx. pseudovishnui (0.1%), and Cx. gelidus (2.4%); and dengue and chikungunya vectors Aedes albopictus (0.9%) and Ae. aegypti (0.6%). Two An. stephensi of the total 831 female anophelines, were found positive for P. falciparum sporozoites. The entomological inoculation rate (EIR) of P. falciparum was 18.1 and 2.35 for Panaji city and Goa, respectively. INTERPRETATION & CONCLUSIONS: Most of the mosquito vector species were collected in all seasons and throughout the scotophase. Biting rates of different vector species differed during different phases of night and seasons. Personal protection methods could be used to stop vector-host contact.

Sampling of adult mosquito vectors with Mosquito Magnet Pro in Panaji, Goa, India.

For mosquito vector population monitoring, a new commercial trap, Mosquito Magnet Pro (MM-PRO), was tested for its usefulness in Goa, India. Anopheles stephensi was tested for the presence of Plasmodium sporozoite infection in the salivary glands. Using the MM-PRO 24 h a day for 34 days, 2,329 mosquitoes belonging to 16 species were collected. These included 6 species each of the genera Anopheles and Culex, 2 species of Aedes, and 1 each of Mansonia and Armigeres. Most (91%) of the mosquitoes caught were females. Among these the number and percentage of each species were Anopheles stephensi 59 (2.78%), Culex quinquefasciatus 1013 (47.78%), Culex vishnui 551 (26.0%), Mansonia uniformis 216 (10.19%), and Aedes albopictus 1 (0.04%). Of the 54 An. stephensi females tested for the presence of circumsporozoite protein (CSP) by an ELISA technique, 1 was found to be Plasmodium falciparum CSP positive. The MM-PRO device was found useful for mosquito population sampling in the urban setting of Goa.