Bacterium found to kill malaria in mosquitoes

Researchers at the Johns Hopkins Bloomberg School of Public Health have identified a bacterium in field-caught mosquitoes that, when present, stops the development of Plasmodium falciparum, the parasite that causes malaria in humans. According to the study, the Enterobacter bacterium is part of the naturally occurring microbial flora of the mosquito's gut and kills the parasite by producing reactive oxygen species (or free radical molecules). The study is published in the May 13 edition of Science.

"We've previously shown that the mosquito's midgut bacteria can activate its immune system and thereby indirectly limit the development of the malaria parasite. In this study we show that certain bacteria can directly block the malaria parasite's development through the production of free radicals that are detrimental to Plasmodium in the mosquito gut," said George Dimopoulos, PhD, senior author of the study and associate professor at theW. Harry Feinstone Department of Molecular Microbiology and Immunology, and the Johns Hopkins Malaria Research Institute.

Malaria mosquitoes accurately find their way to smelly feet

Malaria mosquitoes utilize CO₂ from exhaled air to localize humans from afar. In the vicinity of their preferred host, they alter their course towards the human feet. Researcher Remco Suer discovered how female malaria mosquitoes use foot odors in the last meters to guide them to their favoured biting place. Suer, who is defending his doctoral thesis May 9 at Wageningen University, part of Wageningen UR, sees possibilities to disrupt the host seeking behaviour of the malaria mosquito.

African malaria mosquitoes, Anopheles gambiae, use their olfactory organs, two antennae, two mouthparts (maxillary palps) and the proboscis, to search for their hosts to obtain a bloodmeal. From a distance of several tens of meters mosquitoes detect CO₂ which forms part of exhaled air by humans. However, a malaria mosquito does not follow the CO₂ trail to its source, the mouth, but at a certain point close to the source is diverted toward the feet, which is the preferred biting place for this mosquito species.