Correct answer: Dracunculus medinensis (or Guinea worm) infection. This occurs after drinking water containing crustaceans infected with Dracunculus medinensis. It is characterized bij a chronic ulcer from which the worm protrudes. When the worm has penetrated the skin, it can be removed by carefully rolling it around for example a pencil. Since it can be a few feet long, it can take weeks or months to remove the entire worm, for it is important to not break the worm by wanting to get rid of it too quickly.