A non-destructive sugar-feeding assay for parasite detection and estimating the extrinsic incubation period of Plasmodium falciparum in individual mosquito vectors

Abstract

Despite its epidemiological importance, the time Plasmodium parasites take to achieve development in the vector mosquito (the extrinsic incubation period, EIP) remains poorly characterized. A novel non-destructive assay designed to estimate EIP in single mosquitoes, and more broadly to study Plasmodium–Anopheles vectors interactions, is presented. The assay uses small pieces of cotton wool soaked in sugar solution to collect malaria sporozoites from individual mosquitoes during sugar feeding to monitor infection status over time. This technique has been tested across four natural malaria mosquito species of Africa and Asia, infected with Plasmodium falciparum (six field isolates from gametocyte-infected patients in Burkina Faso and the NF54 strain) and across a range of temperatures relevant to malaria transmission in field conditions. Monitoring individual infectious mosquitoes was feasible. The estimated median EIP of P. falciparum at 27 °C was 11 to 14 days depending on mosquito species and parasite isolate. Long-term individual tracking revealed that sporozoites transfer onto cotton wool can occur at least until day 40 post-infection. Short individual EIP were associated with short mosquito lifespan. Correlations between mosquito/parasite traits often reveal trade-offs and constraints and have important implications for understanding the evolution of parasite transmission strategies.

Intervention reducing malaria parasite load in vector mosquitoes: no impact onPlasmodium falciparumextrinsic incubation period and the survival ofAnopheles gambiae

“…It is made available under a preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in The copyright holder for this this version posted December 31, 2022. ; https://doi.org/10.1101/2022.12.28.522076 doi: bioRxiv preprint thresholds. A consequence is that higher sporozoite loads are more likely to be detected so that our technique may have overestimated the extrinsic incubation time in mosquitoes carrying low sporozoite loads [43]. Thus, despite the observed trend, which remains non-significant and likely to be due to the expected technical bias, our results highlight that the EIP does not depend on the parasite density in the system tested here.…”

Adapting field-mosquito collection techniques in a perspective of near-infrared spectroscopy implementation

“…gambiae and An. coluzzii were obtained from an outbred colony established [ 15 ] in 2015 and 2016, respectively, and routinely identified by conventional PCR assays [ 16 ]. These two Anopheles species were repeatedly replenished with F 1 s from wild-caught female mosquitoes.…”

Contrasting effects of the alkaloid ricinine on the capacity of Anopheles gambiae and Anopheles coluzzii to transmit Plasmodium falciparum

“…Given the daily frequency of mosquito sugar feeding at 27 °C (i.e. about 75% [ 26 ]) by 2–3 days, all mosquitoes would have acquired their sugar meal treatment at least once. Male and female mosquitoes were kept together to ensure insemination.…”

“…Oocyst rupture in the mosquito midgut and sporozoite invasion of salivary glands are highly asynchronous. While some oocysts are intact and keep developing on 9–12 dpbm, others have already ruptured and released their sporozoites [ 26 , 27 ]. To explore possible differences in the timing of sporozoite dissemination in mosquito salivary glands between ricinine-fed and control females, three metrics were measured [ 26 , 27 ]: The proportion of infected mosquitoes with ruptured oocysts on 10–12 dpbm; the number of mosquitoes with at least one ruptured oocyst in their midguts out of the total number of infected mosquitoes (i.e.…”