Estimation of anopheline survival rate, vectorial capacity and mosquito infection probability from malaria vector infection rates in villages near Madang, Papua New Guinea.
Abstract
Indices of the intensity of malaria transmission (mosquito survival per feeding cycle, survival per extrinsic incubation period, vectorial capacity and mosquito infection probability) were measured in 3 villages near Madang, Papua New Guinea, over an 18-month period in 1984-85. The parameters were estimated from mosquito infection rates (Plasmodium sporozoite rates and delayed oocyst rates) and human blood indices from different types of catch using the novel cyclical feeding model of vector transmission of A.J. Saul et al. (1990) [see Journal of Applied Ecology, 27: 123-133]. Approximate variance formulae are given for the estimates from the Saul model, and assessed through a computer simulation study. Estimates of survival through the feeding cycle for the 3 different species of the Anopheles punctulatus complex in the 3 villages ranged form 0.580 to 0.608, and were consistent with estimates made over the same period from the mean parous rates. Probability of survival through the extrinsic incubation period was significantly higher for A. punctulatus in Butelgut village (0.294) than for A. farauti in Maraga (0.151) or A. koliensis in Mebat (0.171). Individual vectorial capacity was significantly lower for A. farauti in Maraga (0.027) than for A. koliensis in Mebat (0.252) and Butelgut (0.154). The mosquito infection probability for A. koliensis ranged from 0.049 to 0.174, with significant variation between 2 villages. The infection probability was also higher for this species in Butelgut than for A. punctulatus in the same village.