[Observation on malaria transmission intensity at a stone-pit of the mountain area in Baoan County, Guangdong Province].

Zhangshubu stone-pit in Baoan County is located in the mountain area. The workers' camps are 2-3 km away from the village. In a recent survey, in malaria peak season (June, July, August) An. anthropophagus accounted for 87.7% (1059/1207) of the total anopheline population and the average man-biting rate was 10.90, 24.88 and 8.71 respectively. The sporozoite positive rate, the human blood index and the daily survival rate were 0.54% (3/554), 1.0 and 0.803 respectively. The parasitaemia rate, the rate of gametocyte carriers, and the rate of persons with malaria history within 1-2 months were 45.5% (10/22), 13.6% (3/22) and 50.0% (11/22), respectively. On average, the entomological inoculation rate A, B and C calculated by three methods were 0.084, 0.665 and 0.215, respectively, indicating that the workers might get malaria infection if they stayed at the camp for 1.5-11.9 days. An analysis of the malaria onset time of the patients suggested that the time calculated from the inoculation rate A was closer to the real situation than those calculated from the inoculation rate B or C. The prevalence trend of malaria could be predicted through the monitoring of the entomological inoculation rate.