The latest LSTM Seminar saw a presentation on ‘exploiting Vector, Pathogen and Host interactions’ by Dr James Logan, Senior Lecturer at the London School of Hygiene and Tropical Medicine (LSHTM) and Director of ARCTEC, the Arthropod Control Product Test Centre.
His presentation outlined the various projects with which his Group is involved with to improve the understanding of vector behaviour towards the host, how they are affected by differences in host attractiveness as well as mosquito behaviour itself.
Dr Logan presented a number of studies that have looked into the protective efficacy of unformulated mixture of human-derived repellents and DEET against An. Gambiae and whether there is a genetic influence into host attractiveness by researching odour similarity of twins which ultimately might form the basis for the development of a new repellent
The inclusion of the pathogen whilst studying host – vector interactions creates a whole new dynamic as parasites and other pathogens may manipulate their host to increase transmission whereas the vector themselves respond differently to infected hosts. Dr Logan is part of an international consortium, led by Wageningen University, researching whether host attractiveness increases when experimentally or naturally infected with the pathogen and how the various Plasmodium stages effect the host attractiveness: i.e. does the human odour profile change with the stages of infection.
Field tests demonstrate that mosquitoes infected with Plasmodium falciparum are more likely to have fed on multiple hosts leading to partial blood feeding as they are significantly less attracted to human odour. Dr Logan’s research group managed to artificially infect Anopheles gambiae mosquitoes with P. falciparum enabling them to study the effect of infection and partial blood feeding on vector behaviour. It showed that responses of infected and uninfected mosquitoes are significantly different to attractive host compounds. Spin offs of the main study are looking at whether infection with P. falciparum affect the mosquito response to repellents and the role of human skin odorants and microflora in the attraction of both malaria infected and uninfected mosquitoes.
Dr Logan’s work shows that the influence of the parasite significantly influences the vector-host interactions both on the human host attractiveness as well as on the olfactory responses of mosquitoes. Increased understanding of this interaction provides useful information for the development of malaria control tools such as repellents; attractants and potentially a novel diagnostic for malaria based on host odour.