a1 Papua New Guinea Institute of Medical Research, P.O. Box 378, Madang, Papua New Guinea
a2 Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Md 20792, USA
a3 London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, England
The proportion of blood meals taken on humans which are infectious to mosquitoes in the Madang area, Papua New Guinea was estimated by two methods. In the first, laboratory reared Anopheles farauti were fed on individuals of all ages at village surveys. The results showed that 3·8% of people were infectious and that the mean percentage of mosquitoes which became infected by feeding on these people was 37·9%. From the average proportion of mosquitoes infected, the probability that a mosquito feeding on a human would pick up infection was 0·013±0·005. In the second approach mosquitoes were fed on identified Plasmodium falciparum, P. vivax and P. malariae gametocyte carriers. The results indicated that 46% of gametocyte carriers were infectious and that the mean probability of a mosquito becoming infected after feeding on a gametocyte carrier was 0·151±0·029. Gametocyte prevalence rates in all ages measured over 18 months in three villages averaged 3·3% P. falciparum, 4·0% P. vivax and 0·7% P. malariae, totalling 8·0±0·7%. Combining gametocyte prevalence rates with the probability of a mosquito becoming infected from a gametocyte carrier, the probability of a mosquito becoming infected following a blood meal on a member of the human population was estimated to be 0·012±0·003.
(Accepted October 01 1987)
p1 Queensland Institute of Medical Research, Bramston Terrace, Herston, Brisbane, Queensland, Australia 4006.
p2 Institute of Animal Genetics, West Mains Rd, Edinburgh EH9 3JN, Scotland.
p3 Department of Tropical Public Health, Harvard School of Public Health, 665 Huntingdon Ave., Boston, MA 02115, USA.