Malaria remains a major cause of morbidity and mortality in the tropics, with Plasmodium falciparum responsible for the majority of the disease burden and P. vivax being the geographically most widely distributed cause of malaria. Gametocytes are the sexual-stage parasites that infect Anopheles mosquitoes and mediate the onward transmission of the disease. Gametocytes are poorly studied despite this crucial role, but with a recent resurgence of interest in malaria elimination, the study of gametocytes is in vogue. This review highlights the current state of knowledge with regard to the development and longevity of P. falciparum and P. vivax gametocytes in the human host and the factors influencing their distribution within endemic populations. The evidence for immune responses, antimalarial drugs, and drug resistance influencing infectiousness to mosquitoes is reviewed. We discuss how the application of molecular techniques has led to the identification of submicroscopic gametocyte carriage and to a reassessment of the human infectious reservoir. These components are drawn together to show how control measures that aim to reduce malaria transmission, such as mass drug administration and a transmission-blocking vaccine, might better be deployed.

Epidemiology and Infectivity of Plasmodium falciparum and Plasmodium vivax Gametocytes in Relation to Malaria Control and Elimination

Effects of artemisinin derivatives on malaria transmissibility

https://apps.dtic.mil/dtic/tr/fulltext/u2/a469116.pdf

The Plasmodium falciparum sexual development transcriptome: a microarray analysis using ontology-based pattern identification.

The protozoan Plasmodium falciparum has a complex life cycle in which asexual multiplication in the vertebrate host alternates with an obligate sexual reproduction in the anopheline mosquito. Apart from the apparent recombination advantages conferred by sex, P. falciparum has evolved a remarkable biology and adaptive phenotypes to insure its transmission despite the dangers of sex. This review mainly focuses on the current knowledge on commitment to sexual development, gametocytogenesis and the evolutionary significance of various aspects of gametocyte biology. It goes further than pure biology to look at the strategies used to improve successful transmission. Although gametocytes are inevitable stages for transmission and provide a potential target to fight malaria, they have received less attention than the pathogenic asexual stages. There is a need for research on gametocytes, which are a fascinating stage, responsible to a large extent for the success of P. falciparum.

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Gametocytogenesis : the puberty of Plasmodium falciparum

Protein Export Marks the Early Phase of Gametocytogenesis of the Human Malaria Parasite Plasmodium falciparum

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1 In a previous paper (Hawking et al, 1968) it has been shown that with malaria parasites exhibiting a periodic synchronous asexual cycle (eg Plasmodium knowlesi; P cynomolgie and P cathemerium), the gametocytes show a 24 or 48 hour rhythm in their development to maturity and that this maturity is short lived (6–12 hours)

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2 In the present work, exflagellation of the male gametocytes of Plasmodium falciparum was studied quantitatively in 4-hourly blood films taken from 5 infected children in Gambia, West Africa

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3 In 2 cases there was clear evidence of a 48 hour cycle in the number of exflagellations observed; in 2 cases there was a “probable” cycle present, and in 1 case there was a “possible” cycle although the evidence is not decisive

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4 It is concluded that the gametocytes of P falciparum probably resemble those of other periodic plasmodia in showing a (48 hour) rhythm of development to maturity (taking into account the well known irregularity of P falciparum)

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5 The development of gametocytes of P falciparum was also studied in Aotus monkeys The classical view was confirmed that development from the merozoite takes more than 9 days and that there is no evidence for cell division during this process

Kenneth Gammage

Papers

Evidence for cyclic development and short-lived maturity in the gametocytes of Plasmodium falciparum.