Last-come, best served? Mosquito biting order and Plasmodium transmission

A pervasive characteristic of parasite infections is their tendency to be overdispersed. Understanding the mechanisms underlying this overdispersed distribution is of key importance as it may impact the transmission dynamics of the pathogen. Although multiple factors ranging from environmental stochasticity to inter-individual heterogeneity may explain parasite overdispersion, parasite infection is also overdispersed in an inbred host population maintained under laboratory conditions, suggesting that other mechanisms are at play. Here, we show that the aggregated distribution of malaria parasites within mosquito vectors is partially explained by a temporal heterogeneity in parasite infectivity triggered by the bites of mosquitoes. Parasite transmission tripled between the mosquito's first and last blood feed in a period of only 3 h. Surprisingly, the increase in transmission is not associated with an increase in parasite investment in production of the transmissible stage. Overall, we highlight that Plasmodium is capable of responding to the bites of mosquitoes to increase its own transmission at a much faster pace than initially thought and that this is partly responsible for overdispersed distribution of infection. We discuss the underlying mechanisms as well as the broader implications of this plastic response for the epidemiology of malaria.

Taming the Boys for Global Good: Contraceptive Strategy to Stop Malaria Transmission

Transmission of human malaria parasites (Plasmodium spp.) by Anopheles mosquitoes is a continuous process that presents a formidable challenge for effective control of the disease. Infectious gametocytes continue to circulate in humans for up to four weeks after antimalarial drug treatment, permitting prolonged transmission to mosquitoes even after clinical cure. Almost all reported malaria cases are transmitted to humans by mosquitoes, and therefore decreasing the rate of Plasmodium transmission from humans to mosquitoes with novel transmission-blocking remedies would be an important complement to other interventions in reducing malaria incidence.

Male-Specific Protein Disulphide Isomerase Function is Essential for Plasmodium Transmission and a Vulnerable Target for Intervention

Inhibiting transmission of Plasmodium is an essential strategy in malaria eradication, and the biological process of gamete fusion during fertilization is a proven target for this approach. Lack of knowledge of the mechanisms underlying fertilization have been a hindrance in the development of transmission-blocking interventions. Here we describe a protein disulphide isomerase essential for malarial transmission (PDI-Trans/PBANKA_0820300) to the mosquito. We show that PDI-Trans activity is male-specific, surface-expressed, essential for fertilization/transmission, and exhibits disulphide isomerase activity which is up-regulated post-gamete activation. We demonstrate that PDI-Trans is a viable anti-malarial drug and vaccine target blocking malarial transmission with the use of PDI inhibitor bacitracin (98.21%/92.48% reduction in intensity/prevalence), and anti-PDI-Trans antibodies (66.22%/33.16% reduction in intensity/prevalence). To our knowledge, these results provide the first evidence that PDI function is essential for malarial transmission, and emphasize the potential of anti-PDI agents to act as anti-malarials, facilitating the future development of novel transmission-blocking interventions.

Control of Malaria by Blocking Transmission of Plasmodium

Malaria is a major global health problem with the greatest burden in sub-Saharan Africa (sSA). Unfortunately, Nigeria accounts for 25 percent of the world’s malaria burden and it accounts for more deaths than HIV/AIDS. The causative agent of malaria is plasmodium species. This paper reviews the current approaches to inhibiting plasmodium transmission, and the phyto active compound currently in use in the sSA (particularly in Nigeria) with the goal to ameliorate the high incidence of malaria and to correlating it with recent progress and scientific understanding. Using search engines, several databases including Google scholar, Pub Med, Academic Resource Index, Scopus, etcetera, were utilized to source for relevant publications and literatures. The complex life cycle of the Plasmodium species (causative agent of malaria) gives room for measures that can disrupt its completion. Several methods are currently being tested and experimented on to disrupt the parasite transmission. The disruption of a cell surface transport protein, Feline Leukemia Virus subgroup C Receptor (FLVCR) that pumps heme out of the cell; Gene silencing-techniques used to reduce the levels of FLVCR in the mosquito gut; Prevention of the interaction between the plasmodium TRAP and the Anopheles Saglin protein, which aid the malaria parasite invasion of the mosquito salivary gland; Prevention of the Interaction of Surface Enolase and Plasminogen of Mammalian Blood, disrupting an important role in ookinete invasion of the mosquito midgut; the use of Plants with antimicrobial peptides(cyclotide), that possess structural similarities to SM1 peptide, an inhibitor of plasmodium TRAP-saglin binding;and Use of Phyto-Active Compounds to Block Plasmodium Transmission. These approaches are novel methods in the control and transmission of plasmodium species/malaria. Chemically, phytochemicals with structural similarities to artemisinin, (asesquiteterpene lactone containing an unusual peroxide bridge) is thought of to be present in certain plants with antimalarial and other medicinal value.