This post is the 4th in a series highlighting the WHO’s list of 17 Neglected Tropical Diseases (now technically 18 as mycetoma was added to the list at the 69th World Health Assembly in May 2016). To read the previous posts in this series click here.
Guinea worm (dracunculiasis) has the potential to be the second human disease ever eradicated, the first being that not-so-familiar old scourge smallpox. Guinea worm disease is caused by the parasitic worm Dracunculus medinensis. While the disease is rarely fatal, it does seriously debilitate infected persons because once the worm painfully erupts from the skin it needs to be slowly extracted from the person. In addition, the person can suffer from an allergic reaction to the worm or additional bacterial infection at the eruption site.
The life cycle of Guinea worm makes it relatively easy and simple to prevent, making it a promising candidate for eradication. The larvae live inside water fleas in fresh water, people drink the fresh water and infected water fleas thereby becoming infected with the parasite, the larvae survives the onslaught of the stomach and then migrate around the body while turning into worms, then the worm erupts from the skin and the eruption is painful and fiery so the person puts the affected area into water for relief, where the worm releases a bunch of larvae to perpetuate the cycle.
So how do we break this transmission cycle? The Carter Center has developed an extensive and successful Guinea worm eradication campaign involving simple water filters for people to use and education to prevent people from putting affected areas with erupted worms into fresh water.
There are only a few areas of the world that still have some cases of Guinea worm. During the mid-1980s about 3.5 million cases of Guinea worm occurred in 21 countries around the world, most of which were in Africa. In 2015 there were only 22 cases worldwide, the lowest number of cases ever. To be declared free of Guinea worm, a country needs to have 0 instances of transmission and maintained active surveillance for 3 years afterwards. Guinea worm takes about 10-14 months from time of larval ingestion to worm eruption so it requires a long surveillance period to ensure there are no additional infected folks who are still carrying the worms. Even though there are relatively simple and easy ways to prevent Guinea worm, some areas haven’t been able to successfully interrupt transmission. That’s usually due to those areas being remote, inaccessible rural areas, due to instability in the country, and more recently due to dogs being recognized as carriers/transmitters of Guinea worm.
Even with the challenges to eradication facing the remaining locations which still have transmission, Guinea worm has real potential to be the second human disease ever eradicated. Just think, we may soon be celebrating the eradication of Guinea worm from our planet. Guinea worm will then become public health folklore like smallpox has become, a dreaded disease that affected our parents and grandparents which is now only written about in history books.