When is a malaria-infected mosquito an infectious mosquito?

Monday 26 June 2023, 4:30 pm
PhD student
W. Graumans ing.
prof. dr. J.T. Bousema
dr. K.A. Collins, dr. A.S. Yang

Malaria is an ancient vector-borne disease causing a severe public health burden of 247 million cases and 619.000 deaths each year. Development of tools may help to improve our understanding of pathogen transmission, and could place the goal of malaria eradication within reach. To study malaria in the laboratory this research presents optimizations for mosquito rearing and an unique portfolio of eight new malaria isolates for in vitro culture and mosquito infection. It explored factors why malaria transmission is higher when mosquitoes directly feed on the skin of malaria patients compared to indirect feeding that uses drawn blood and artificial membrane feeders. While anticoagulants present in blood collection tubes reduce parasite infectivity to mosquito, also selection of feeding system and membrane is shown essential. To allow direct blood feeding of small volumes to mosquitoes, such as those collected by finger prick, a new type of small membrane feeder was designed and produced by a 3D printing technique used for dental prostheses at Radboudumc. As the contribution of infectious mosquitoes to ongoing transmission remains poorly understood this research presents a novel artificial skin model to study malaria transmissibility by the mosquito vector. For the first time expelled parasites were quantified directly in artificial skin on which low and high infected mosquitoes blood-fed, generated with cultured parasites or from patients in Burkina Faso. Results demonstrate that a substantial proportion of mosquitoes do not expel parasites during bite, and a positive correlation between mosquito infection intensity and expelled parasites. Mosquito infection burden should therefore be considered in estimations of transmission potential. Last this research examined adherence to travel advice of a highly active traveler, James Bond, who was found poorly prepared for travel-associated health risks and particularly naïve to the threat of infectious disease. His lack of preparation should be seen as a warning to the general public for seeking travel advice prior to departure.

Wouter Graumans (1985) studied technical microbiology and graduated with honor at the Rijn IJssel College in 2005. He obtained his bachelor’s degree in molecular biology at the Hogeschool Utrecht in 2008. Since he is working on malaria at the department of Medical Microbiology of Radboudumc. He pursued a PhD in 2020 to better understand malaria transmission biology.