A study on the infectivity of patients to mosquitoes in the early stages of primary plasmodium vivax malaria (madagascar strain)

Abstract

1. (1) Daily feedings of laboratory-bred Anopheles atroparvus were carried out on 54 patients during the early stages of primary P. vivax malaria (Madagascar strain). 2. (2) One hundred mosquitoes were fed daily on each patient from the onset of symptoms or parasitaemia, and continued until the patient was given suppressive or curative therapy. 3. (3) On the 7th day after feeding, 40 mosquitoes from each batch were dissected to determine the percentage of mosquitoes infected and the number of oocysts per gut. 4. (4) The earliest infection in the mosquito occurred 2 days after fever or parasitaemia, and the latest 7 days after. 5. (5) The percentage of mosquitoes which became positive on the 1st day of infection varied between five and 100. 6. (6) From 32 patients, mosquitoes became infected before gametocytes were detected in blood films; and from 22 patients, mosquitoes became infected on the 1st day that male gametocytes were found. 7. (7) It is well known that in primary untreated P. vivax infections, maximum gametocyte density is reached on or about the 10th day. The work described in this paper shows that ripe gametocytes may be present in sufficient numbers to infect mosquitoes as early as the 3rd, and even in one case, on the 2nd day. 8. (8) In P. vivax endemic areas, even where there are good medical services, not many patients would be admitted to hospital or treated, as early as the 3rd day of a primary attack, by which time they might have infected mosquitoes. 9. (9) We believe that in malaria eradication and control schemes, success is more likely to be achieved if gametocytocidal drugs are given to coincide with mosquito control.