Neglected tropical diseases (NTDs) are threatening diseases that afflict some of the world’s poorest populations. People infected by an NTD like Guinea worm disease are often plagued by parasites — but they may not even realize it until the parasite decides it’s time to come out.
Tiny water fleas that are undetectable in water to the naked eye carry larvae of the Guinea worm parasite (Dracunculus medinensis). When someone drinks contaminated water, the parasite can make its way into the body.
As the parasite migrates through the human body’s subcutaneous tissue, it can cause severe joint pain. The larvae matures as it travels through the stomach, penetrating the digestive tract, burrowing itself in the intestinal tract, and beginning to reproduce. It takes about a year for the larvae to grow into a full-sized adult.
Full adults measure up to 1 metre in length and have the width of “a cooked spaghetti noodle.” This makes it the largest parasitic worm that affects humans.
After having released its larvae, the adult worm remains in the body for a year or so. Then, the worm is ready to emerge. At this time, the person infected will notice swelling that rapidly turns into a blister with severe itching or burning in the area where the worm will eventually emerge — 90% of the time, worms come out through the legs and feet, according to the Centers for Disease Control and Prevention.
It can take many days or even weeks to pull out the worm, as it must be done slowly to prevent the worm from resisting or retreating back into the body. Many people are unable to move the affected body part and some try to relieve the pain by submerging the infected area in a water source.
Unfortunately, this perpetuates the Guinea worm life cycle. Adult female worms carry about 3 million larvae embryos that are then released into the water source in which it's been submerged. These are eaten by water fleas, which continue to transmit worms to humans.
There is no drug or preventative vaccine for Guinea worm disease. The best way to prevent it is to filter drinking water from unsafe sources or to only drink water from protected sources that are free from contamination, like boreholes or hand-dug wells.
The Carter Center, which is committed to eradicating this disease, works with health ministries to deliver health education and alter people's behaviors on the ground. It teaches people how to filter their water and explain how to halt transmission of the emerging worms in water sources.
Guinea worm cases were only reported in Angola, Chad, and South Sudan in 2018, with only 28 cases in total, thanks to international efforts to eradicate this disease, according to the Carter Center.
While the world is closer than ever to eradicating the disease, unexpected cases remind us that we must remain vigilant.
In 2018, there was a confirmed case with an 8-year-old girl in Angola, a country that had never seen Guinea worm disease before.
“Measures are being put up to strengthen surveillance, reporting and investigation of all suspicious cases through the country’s Integrated Disease Surveillance and Response,” Dr. Nzuzi Katondi, field officer for the World Health Organization country office in Angola said. “Intelligence and alerts are being reported and rumours are being followed up and investigated.”
In recent years, many countries have been successful in eliminating the disease and have been declared free of transmission — important milestones in the fight for global health and the elimination of NTDs around the world.
"What You Don’t Know About X" is a new series focusing on neglected tropical diseases (NTDs). NTDs are a cluster of parasitic and bacterial diseases. While you may have heard of a few of them, it’s likely you know very little about their actual effects or why they are so often overlooked. This series looks to shed light on these devastating — and preventable — diseases.