WASHINGTON (AP) — Mosquitoes harbor gut bacteria just like people do — and the bugs inside the bugs may hold a key to fighting malaria.

Today, bed nets and insecticides are the chief means of preventing malaria, which sickens about 200 million people around the world and kills 400,000 a year, mostly children in Africa. But what if scientists instead could hatch malaria-resistant mosquitoes?

Johns Hopkins University researchers reported Thursday that beneficial bacteria living inside a mosquito's gut can help do just that — two somewhat accidental discoveries that, if they pan out, might one da...