Blood meals from ‘dead-end’ vertebrate hosts enhance transmission potential of malaria-infected mosquitoes

Abstract

Ingestion of an additional blood meal(s) by mosquitoes can accelerate parasite migration to the salivary glands in infected mosquitoes. Most studies, however, offer blood from the same vertebrate host species as the original challenge (for e.g., human for primary and additional blood meals). Here, we show a second blood meal from bovine and canine hosts can also enhance sporozoite migration inAnopheles stephensimosquitoes infected with the human– and rodent–restrictedPlasmodium falciparumandP. bergheirespectively. The extrinsic incubation period (time to sporozoite appearance in salivary glands) showed more consistent reductions with blood from human and bovine donors than canine blood, although the latter′s effect may be confounded by the toxicity, albeit non-specific, associated with the anti–coagulant used to collect whole blood from donors. The complex patterns of enhancement highlight the limitations of a laboratory system but are nonetheless reminiscent of parasite host–specificity and mosquito adaptations, and the genetic predisposition ofAn. stephensifor bovine blood. We suggest that in natural settings, a blood meal from any vertebrate host could accentuate the risk of human infections byP. falciparum, although our observations should also be applicable to other species ofPlasmodiumand indeed other vector-borne diseases such as arboviruses for instance.

Mosquito aging modulates the development, virulence and transmission potential of pathogens

“…This emphasizes the consistency of EIP in the context of mosquito age and further suggest that the beneficial effects of lengthy EIPs must be under strong selective pressures [94,95]. That being said, recent studies have demonstrated that providing one or more noninfectious blood meals after the initial infectious meal significantly shorten the EIP [29,31,[96][97][98]. It is common practice in laboratory studies on mosquito-Plasmodium interactions to maintain specimens on a sugar solution alone to prevent the decrease in sample size associated with each blood-feeding episode (non-fed individuals being excluded).…”

Mosquito ageing modulates the development, virulence and transmission potential of pathogens

“…This emphasizes the consistency of EIP in the context of mosquito age and further suggests that the beneficial effects of lengthy EIPs must be under strong selective pressures [94,95]. That being said, recent studies have demonstrated that providing one or more non-infectious blood meals after the initial infectious meal significantly shortened the EIP [28,30,[96][97][98]. It is common practice in laboratory studies on mosquito-Plasmodium interactions to maintain specimens on a sugar solution alone to prevent the decrease in sample size associated with each blood-feeding episode (non-fed individuals being excluded).…”

Multiple hosts, multiple impacts: the role of vertebrate host diversity in shaping mosquito life history and pathogen transmission

“…2017). In another study, a second blood meal shortened parasite development in P. falciparum with no group specific differences, while a marginal increase was observed with human blood compared to unfed controls for P. berghei development (Pathak et al . 2022).…”

“…1989, Emami et al . 2017, Pathak et al . 2022), accelerate parasite growth and shorten the extrinsic incubation period (Brackney et al .…”

“…2021, Shaw et al . 2021, Pathak et al . 2022), thereby enhancing the transmission potential of malaria-infected mosquitoes.…”