This article is part of HuffPosts Project Zero campaign, a yearlong series on neglected tropical diseases and efforts to fight them.

Imagine that you wake some mornings to find youre so weak you can barely rise from your bed. Sometimes there are aches in your joints, too, or pounding in your head. Sometimes your stomach is in knots.

These symptoms have been coming and going for months, and you know somethings wrong. It usually takes hours to travel to the nearest medical clinic, but you dont feel strong enough to go. Luckily, a group of health workers arrives in your village they call over a megaphone, asking people to come for checkups. You stagger to the big tree near the market where the health workers have set up their equipment in the shade. They say they need to run some tests, and they draw blood from your fingertip.

Later, they run more tests and push a three-inch needle into your spine the pain is excruciating. You try not to scream.

The tests reveal there is a parasite lurking in your blood and inside your brain. (You were infected when a fly bit you. It happened so long ago, you dont remember when.) You have a disease called sleeping sickness , the health workers inform you. But youre very lucky, they say, because they have medicine that can treat it. If you hadnt discovered this in time and many people dont the disease would have progressed until you began hallucinating, then slipped into a coma and died.