A boil, or “furuncle,” is a type of abscess around hair follicles. Both boils and abscesses are characterized by a large accumulation of pus and dead cells under the skin that eventually rupture or must be drained, typically by a medical professional. Although boils are typically the result of a bacterial or fungal infection, the Guinea worm and the worm-like botfly larvae can sometimes be the culprits.
The Guinea worm is a parasitic roundworm that can grow up to about 3 feet in length. The worm larvae infect small water fleas; when you consume flea-contaminated water, the worm larvae travel to the intestines, where they mature and mate. The males and many of the females then die off. But the surviving females make their way to the surface of the skin, usually in the legs and sometimes arms. There, they form boils. When the infected area is placed in cool water, the full-grown female Guinea worm bursts through the boil or blister, ejecting her larvae into the water. The Guinea worm is prevalent in parts of Africa.
The only way to get rid of a Guinea worm is to snag it when it bursts from the sore and wind it around something, like a stick. The worm must be slowly wound out of the sore, usually over a period of weeks to months. The pain during this period of extraction is immense and may be partly, if not fully, debilitating.
Unless you are visiting, or live in, certain parts of Africa, primarily Sudan, you are not likely ever to encounter the Guinea worm. If you are visiting an African country make sure to drink only bottled water. Those infected with the worm should never enter lakes or rivers where the worm can release its larvae and infect others.
The botfly is a large, hairy fly that lives in parts of South and Central America. Female botflies tackle mosquitoes or other small insects and deposit their larvae on them. When an infected mosquito bites you, some of the botfly larvae may drop onto your skin and enter either through the mosquito bite or by boring their own holes. The larva then matures under the skin for around six weeks, feeding off you and creating a red sore that may look like a boil or abscess. This sore is actually called a “warble.” (A boil or abscess is enclosed, eventually bursting open with pus, but a warble always has a hole in it for the larva to breathe.)
Treatment involves suffocating the larva living under your skin. The most common method involves rubbing a layer of petroleum jelly over the sore. The larva will emerge from the sore searching for air. You must then grasp the maggot with some sort of tweezers and pull it from the wound. This can be very painful, as botfly larvae have spikes along their bodies to keep them anchored inside the wound.
The best way to avoid botfly parasitism is to use mosquito repellent and net off the entranceways to your living quarters when visiting South or Central America, especially jungle areas where botflies are most prevalent.