Malaria outbreak in the Indira Gandhi Nahar Pariyojna command area in Jaisalmer district, Thar Desert, India.

A focal outbreak of malaria occurred in the villages situated close to the main Indira Gandhi canal near Ramgarh in Jaisalmer district, western Rajasthan. Stagnation of water over a month's period in the main canal as well as long standing rain water in the form of expansive lakes near these villages formed vast breeding grounds for the vectors like Anopheles culicifacies, along with A. stephensi already breeding in the 'tanka' and 'beri' in the epidemichit villages. Rapid mass blood surveys along with other entomological and parasitological investigations were conducted in four of the ten affected villages, viz., Seuva, Raghwa, Raimala and Sadhna. A total of 992 specimens belonging to four vector species were sampled, namely, A. stephensi (47.4%), A. culicifacies (41.0%), A. subpictus (11.2%) and A. annularis (0.4%). Epidemiologically, about one-fourth of the examined persons were positive (SPR 25.5%), although Plasmodium falciparum dominated the parasitaemia (49.5%). Available data are indicative of changed malariological scenario in the Indira Gandhi Nahar Pariyojna command area, where epidemics are regular features every year.