Endemic malaria in four villages of the Pakistani province of Punjab.

The prevalence of malaria in 4 villages 60 km south of Lahore, Punjab, where Anopheles culicifacies is the vector was estimated from blood films made during three mass malaria surveys (MS) and at 204 clinics (CS) held over 18 consecutive months. The highest parasite rate occurred during October 1984 when 43% of the CS population had parasitaemias. Plasmodium vivax predominated early in the major transmission season (23% and 15% vivax parasitaemias in August 1983 and 1984 respectively) whereas P. falciparum was the most common species later in the transmission season (an average falciparum prevalence of 37% in October and November 1984) and following the transmission season through March. Despite the proximity and habitat similarity of the 4 villages, both total and species malaria prevalence rates showed inter-village differences. Asexual stage and gametocyte parasite rates in children were 2 to 5 times higher than in adults. No increased mortality due to malaria was detected among the 4000 study population. Malaria was stable and endemic, albeit seasonally transmitted, in these 4 villages during 1983 and 1984.