A bug that nips malaria in the bud

13 May 2011
Johns Hopkins researchers have identified a bug that nips malaria in the bud by halting the development of the parasite, plasmodium falciparum, that causes it.

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 (free radical molecules).

Worldwide, malaria afflicts more than 225 million people and kills nearly 800,000, many of whom are children living in Africa, the journal Science reports.

"We've previously shown that the mosquito's midgut bacteria can activate its immune system and thereby indirectly limit the development of the malarial parasite," said George Dimopoulos, senior study author and associate professor at the Johns Hopkins Malaria Research Institute.

"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 Dimopoulos, who has specialised in molecular microbiology and Immunology.

"We are particularly excited about this discovery...and we may also use this knowledge to develop novel methods to stop the spread of malaria," said Dimopoulos, according to a Johns Hopkins statement.

"One biocontrol strategy may, for example, rely on the exposure of mosquitoes in the field to this natural bacterium, resulting in resistance to the malaria parasite."

The researchers isolated the enterobacter bacterium from the midgut of Anopheles mosquitoes collected near the Johns Hopkins Institute in southern Zambia.

About 25 percent of collected mosquitoes had the specific enterobacter strain. Lab studies showed the bug halted the growth of plasmodium up to 99 percent, both in the mosquito gut and in a test tube culture of the human malaria parasite. Higher doses of bacteria had a greater impact on plasmodium growth.