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Confirmation that Plasmodium falciparum has aperiodic infectivity to Anopheles gambiae
A K Githeko1, A D Brandling-Bennett, M Beier
1Kenya Medical Research Institute (KEMRI), Vector Biology and Control Research Centre (VBCRC), Kisumu.
Insights
Afternoon mosquito feeding on Plasmodium falciparum infected humans yields similar results to nighttime feeding. This finding simplifies experimental malaria vaccine studies by allowing daytime mosquito infections.
Area of Science:
- Medical Entomology
- Infectious Diseases
- Vaccinology
Background:
- Field studies for transmission-blocking malaria vaccines require controlled mosquito infections.
- Plasmodium falciparum is the deadliest malaria parasite, transmitted by Anopheles gambiae mosquitoes.
- Mosquito feeding times can potentially influence infection rates and parasite development.
Purpose of the Study:
- To compare the quantitative similarity of Plasmodium falciparum infections in Anopheles gambiae mosquitoes fed on infected humans during the afternoon (16:00) versus nighttime (23:00).
- To determine if daytime mosquito feeding is a viable alternative for experimental malaria transmission studies.
Main Methods:
- Colony-bred Anopheles gambiae females were fed on Plasmodium falciparum-positive children (aged 5-12) in Kenya.
- Two feeding batches were conducted: one at 16:00 hours and another at 23:00 hours.
- Infection rates, number of infectious children, and oocyst development in mosquitoes were analyzed.
Main Results:
- No statistically significant differences were observed between afternoon and nighttime feeding groups.
- Proportions of infected mosquitoes were comparable.
- Mean oocyst burdens in mosquitoes did not differ significantly based on feeding time.
Conclusions:
- Experimental Plasmodium falciparum infections in Anopheles gambiae are quantitatively similar regardless of whether mosquitoes feed during the afternoon or at night.
- Afternoon feeding is a convenient and equivalent alternative for conducting mosquito infections in malaria vaccine research.
- This simplifies experimental protocols, enabling more flexible scheduling for field studies.
Abstract:
In preparation for field studies of transmission-blocking malaria vaccines, a study was carried out to determine whether P. falciparum infections obtained in An. gambiae blood-fed at 16.00 hours were quantitatively similar to infections obtained at 23.00 hours. Using a group of children aged 5-12 years from villages at Ahero, near Kisumu in Kenya, 71/74 (96%) of whom were found to be positive for P.falciparum parasitaemia, one batch of fifty colony-bred An.gambiae females were fed on volunteers at 16.00 hours and another batch at 23.00 hours. No statistically significant differences were found in the proportions of mosquitoes becoming infected, the numbers of children infecting mosquitoes or the mean numbers of malaria oocysts developing in mosquitoes blood-fed at the different times. Because mosquito infections obtained by day (16.00 hours) are equivalent in quantity to those obtained at night (23.00 hours), experimental infections can be carried out in the afternoon, when it is most convenient, rather than during the night.