Rare, Nearly Extinct Parasite May Have Resurfaced in Vietnam, Doctors Say

Rare, Nearly Extinct Parasite May Have Resurfaced in Vietnam, Doctors Say
A person's foot being infested by the guinea worm, date unknown. (Photo: National Museum of Health and Medicine)

Doctors in Vietnam this week say that they’ve made a mysterious and — if accurate — alarming discovery: A local resident has been infested with the nearly extinct Guinea worm. But Guinea worm experts are still trying to confirm whether this case is the genuine article, and if so, how the worm managed to reach a country thousands of kilometres away from its only known remaining refuge in parts of Africa.

The Guinea worm, formally known as Dracunculus medinensis, is an ancient parasite possibly referenced as far back as the Bible and named after the Africa region where European explorers in the 17th century first reported seeing it. It’s a nematode that explicitly relies on people as part of its cringe-inducing life cycle.

The worm usually infects people through drinking water contaminated with tiny freshwater crustaceans that have eaten worm larvae. When these first hosts die, the worms break free and penetrate into the abdomen from the intestinal wall, where they grow up into full-fledged adults and get to mating.

When the mama worm (which are much longer than male worms and can extend up to 2.5 feet or 80 centimeters in length) is ready to deliver her progeny, she migrates to just below the surface of the skin, usually along our legs and feet. Then she very painfully breaks through the skin, causing a tremendous burning sensation that makes its hosts desperate to cool off at the nearest water source. As soon that happens, the mother squirts out her clutch of larvae into the water, where the very disturbing cycle starts again. From infestation to being a worm baby surrogate, the process can take a year’s time. But it can still take several painful weeks after for the original worm — or worms — to be removed, which can leave people at risk for other infections and disabled for months.

As recently as the 1980s, the Guinea worm was commonly found in tropical and subtropical areas of Africa and Asia, and infected millions of people in Africa alone annually. But a decades-long eradication program has steadily beat back the worm to only a handful of countries and cases in Africa every year. Though these eradication efforts have taken a stumble as of late, with the discovery that the worm can also routinely infect dogs as well as humans, the worm is still expected to be wiped off the face of the Earth by 2030. Which makes the potential case in Vietnam all the more baffling and concerning.

On Sunday, in an article translated into English, the Saigon Giai Phong Online reported that doctors at the National Hospital for Tropical Diseases in Hanoi came across a young man with abscesses on his legs and later his arms. After the man was hospitalized, doctors removed “five rare intestinal worms” from his hands. The outlet cited one of these doctors, who identified the man’s worms as Dracunculus medinensis, measuring around 1 to 2 feet long (30 to 60 centimeters). The doctor also noted that such worms had never been found in Vietnam.

According to Adam Weiss, director of the Guinea Worm Eradication Program at the Carter Centre, a human rights organisation founded by former U.S. president Jimmy Carter, it’s not impossible that this man’s case could truly be Guinea worm. Both his program and the World Health Organisation are currently trying to get in touch with the doctors at the National Hospital for Tropical Diseases, which hopefully still has samples of the worm preserved for examination. But it’s just as possible that this may be a simple case of mistaken identity.

“When you consider all of the world’s diseases, there are so many other things that this could be. And if you don’t have the level of specificity that we would require, it can be hard to corroborate,” Weiss told Gizmodo over the phone. “That doesn’t mean that this is Guinea worm.”

For instance, there are other species of Dracunculus plaguing the world, though no other species are thought to regularly infect people. Many other unrelated human parasites could resemble the long white appearance of the mature female Guinea worm, at least at first glance.

One thing that doesn’t rule out Guinea worm is how the man may have gotten infested in the first place. He reportedly ate lots of raw fish and crabs. And while the worm is usually spread through contaminated drinking water, there is evidence that larvae can survive temporarily in freshwater fish long enough to infect people who eat the contaminated aquatic animals. The article doesn’t state whether the fish regularly eaten by the man lived in fresh- or saltwater, though.

If outside experts can examine the worms for themselves, then looking under the microscope should reveal key body parts that would confirm if it is Guinea worm, Weiss said. Certain preservation methods might make a physical examination less useful, since they often dry out the worm, but you could still then test their DNA. And if they do appear to be Guinea worms, then a genetic analysis would help figure out whether its lineage traces back to the worms currently living in Africa.

So far, efforts to contact the National Hospital for Tropical Diseases by Gizmodo have been unsuccessful. But Dieudonné Sankara, who leads WHO’s eradication and elimination team at the Department of Control of Neglected Tropical Diseases, told Gizmodo via email that they are well aware of the situation and looking into it.

“Because there are other types of parasites that can mimic Dracunculiasis, further investigations are being carried out to confirm whether this is a true guinea worm disease,” he said. “If this turns out to be a true guinea worm disease, then additional research and epidemiological investigations will have to be conducted to understand the full extent and how it got to Vietnam.”

If the Guinea worm has somehow ended up in Vietnam, it’s very unlikely that only one person would be unlucky enough to have been infected by it. So the possibility of its existence in Vietnam is definitely one that has to be investigated seriously, since it could have serious implications for eradication efforts. But for now, it’s still too early to add Guinea worms to the list of awful things making a comeback in 2020.