Filtering guinea worms in Sudan

The guinea worm or Dracunculus (Latin for little dragon) is thought to have existed since ancient times. To this day, treatment involves wrapping the worm around a stick. This ancient parasitic infection is nearing extinction, with only Sudan standing as a major obstacle to the disease's disappearance in the coming years.

Humans acquire the infestation by drinking water infected with guinea worm larvas. The larvas penetrate the upper gastrointestinal tract and remain in the peritoneal space for up to three months. The female worm bores holes through the body and makes its way to the surface; holes may be anywhere on the body but they are usually on the legs and feet. At this stage millions of eggs, embryos, and first stage larvas occupy most of the worm's body cavity. A blister forms on the skin of the host at the anterior end of the worm and erupts. The female worm then protrudes its anterior end from the ulcer and releases first stage larvas into the water. Upon emergence the Dracunculus medinensis parasite can be up to a metre long.

Immersing the affected skin into water provides some relief from the pain the infestation causes. The temperature change causes the blister to …