To most Americans, the history of the guinea worm reads something like a horror story: a three foot long worm takes up residence in your leg, and must be kept alive and slowly removed over the course of weeks. Yet until very recently, the guinea worm, named after its association to west Africa, was a real and debilitating problem. After a 20 year long campaign to eradicate the parasite, the end of the guinea worm is finally in site.
The guinea worm, or Dracunculus medinensis, is a parasitic nematode. It begins its life-cycle in freshwater as free-living larvae, where it is ingested by its intermediate host, the Cyclops copepod. The copepods are then ingested by humans who drink contaminated water, and the guinea worm is released into the stomach of its definitive host. The larvae relocate into connective tissue where they mature and eventually mate. The male dies after reproduction, however the female continues to grow up to 3 feet long. Around a year after infection, the worm burrows through the tissue of the host, moving down towards their legs or feet. In an attempt to release its eggs, the worm will reach the surface of the hosts skin and form a fluid filled blister. The blister produces a painful, burning sensation, causing the host to seek water to alleviate the pain. Once submerged, the guinea worm will emerge from the blister and vomit its larvae into the water, thus continuing its life cycle (1).
References to the guinea worm can be found throughout history, beginning with the Ebers Papyrus of 1550 B.C. It was sometimes referred to as the pharaoh’s worm, and its calcified remains have been found in the stomach of a mummy. The documented method of extraction involved slowly wrapping the worm around a stick, a process that is still in use today. If the worm is broken an inflammatory response occurs, often resulting in infection, or in ancient times, death (2).
It is also believed that the ‘fiery serpents’ described in the Bible as ‘descending on the Israelites’ (Numbers 21:6), are a reference to the burning sensation caused by guinea worms, who would have been endemic to the area. Records of the nematode are also found in the writings of Plutarch and Galen of ancient Greece, the latter of which named the parasite dracontiasis, or little dragon. Galen, however, never saw the guinea worm for himself and likely believed it to be a nerve or tissue.
Due to its prevalence at the time, many believe that the rod of Asclepius, better known as the international symbol of medicine, is a guinea worm wrapped around a stick. Its removal would have been understood as a symbol of healing (the rod of Asclepius is often mistaken for the caduceus, which has also come to represent medicine through association) (2).
In 1870, Russian scientist Fedchenko became the first to describe the guinea worm’s life cycle, and its occurrence throughout the world greatly decreased. Yet by the 1980’s, 3.5 million people a year were still being infected in parts of Africa, India, and Pakistan. Infection with guinea worm causes fever and intense pain, and victims are often unable to work for up to three months during its removal. No treatment or vaccine for guinea worm exists, making it “both a disease and cause of poverty” (1).
The Jimmy Carter Center, in concert with WHO and UNICEF, began a campaign to eradicate the disease in the late 80’s. Education programs were used to prevent its spread into water sources and portable filters for drinking water were encouraged. Due to the campaign’s success the guinea worm is likely to be eliminated, with only 22 cases reported in 2015. If pushed to extinction, the guinea worm will join smallpox as only the second human disease to be globally eradicated (3).