More than 200 million people get malaria each year.

And about half a million die—mostly in Africa,many of them children.

And those staggering numbers are an improvement.

Malaria deaths have been cut in half since 2000.

In many places,a remarkably simple tool has led the fight:bed nets treated with a mild insecticide that stop mosquitoes from biting people in their sleep.

Both people and mosquitoes are pawns in the malaria transmission cycle.

If an infected person gets bitten by a mosquito, the parasite gets picked up along within the blood meal.

That mosquito can then transfer the parasite to the next person it bites.

Bed nets help stop mosquitoes from easy attacks on motionless sleepers.

But now some mosquitoes seem to be giving up the night shift.