Source: Gizmodo
By Ed Cara
Translation: SME Technology Story
Last week, doctors in Vietnam issued a warning that many people were confused and worried about: a local Vietnamese resident was infected with the nearly extinct Guinea worm Dracunculiasis.
International Guinea worm experts are also trying to further confirm the case, and if this is true, then the question is big – how did guinea worm, which is currently only in Africa and endangered due to human control, cross the ocean to reach another country thousands of miles away?
A foot infected with Guinea worm nematodes
Guinea worm, also known as Guinea worm or Guinea worm (scientific name: Dracunculus medinensis). This ancient parasite can be traced back to biblical records and named after the African region where they were first discovered by European explorers in the 17th century. In their full life cycle, the dependence on humans can be said to be very high.
Guinea worms generally infect humans through drinking water. There are some tiny freshwater crustaceans that eat their larvae, but these larvae do not die. Once the first host dies, the nematodes will still break free. Once they enter the human body through water or animals, they penetrate from the human intestinal wall into the abdomen, where they grow into fully mature adults and begin to mate.
The habit of indigenous Africans to drink water makes it the biggest victim of the parasite
When the pregnant female (the female is much larger than the male and can reach a length of up to 80 cm) is ready to give birth, they migrate below the surface of the skin, usually the area of the legs and feet. The female then breaks through the skin, causing a huge burning sensation, causing humans to instinctively look for the nearest source of water to cool down.
Once the ruptured part is submerged in the water, the female waits for an opportunity to spray a nest of larvae into the water – and a new terrible cycle begins. It takes about a year to go from being parasitized to becoming a surrogate with a baby nematode. And even after the primordial nematode is removed, the human body has to go through painful weeks to fully recover, in the process the risk of infection of other diseases increases, and is accompanied by months of inconvenient "paralysis" time.
"The Life of Guinea Worm"
Guinea worms were widely distributed in tropical and subtropical regions of Africa and Asia as early as the 1980s, when millions of people in Africa alone were infected with Guinea worms each year. However, after decades of eradication plans, humans have repelled the parasitic disease to the few countries and regions that currently exist in Africa, and the number of cases per year has been contained.
Although recently the nematode has been discovered to infect not only humans, but also cats and dogs, plans to eradicate the virus have suffered some setbacks. But it is expected that by 2030, Guinea worms will still disappear from the earth. This also makes the case in Vietnam even more confusing and worrying.
On Sunday, The Saigon Giai Phong Online reported that doctors at the National Hospital for Tropical Diseases in Hanoi met a young man with swelling in his legs and arms. After the man was admitted to the hospital, doctors removed "five rare intestinal parasites" from his hand.
The media quoted one of the doctors, who confirmed that the worm in the man's body was Dracunculus Medinensis (the scientific name of guinea worm), which was about 30 to 60 centimeters long. The doctor also noted that the parasite has never been found in Vietnam.
Adam Weiss, head of the Guinea worm eradication program at the Carter Center, a human rights group founded by former U.S. President Jimmy Carter, said the man's case may indeed have been caused by Guinea worm.
Adam Weiss, who treats guinea worm disease in Ghana, the parasitic disease in the region has been eradicated
Both his team and the World Health Organization are currently trying to get in touch with doctors at Vietnam's National Hospital for Tropical Diseases, hoping that there are still preserved parasite samples there for examination. But of course, there is also the possibility of miscalculation in this case.
"Given that there are so many diseases with similar symptoms in the world, there are still many undetermined possibilities for this matter." If the sample does not have the specificity we require, it is difficult to determine. "At least so far, that doesn't mean guinea worms are really in Vietnam." ”
While there are many other types of nematodes in the world, they do not usually infect humans. However, there are also many human parasites with a long white appearance similar to that of mature female Guinea worms, which at first glance can easily make unprofessional doctors misjudge.
There are also records of parasitic diseases in ancient paintings
Another key piece of information is that the report says the man ate a lot of sashimi and crab. Although Guinea Dracunculia is generally transmitted through contaminated drinking water, its larvae can also survive in freshwater fish long enough to infect people who eat contaminated aquatic animals. (However, the report did not indicate whether the fish the man ate lived in fresh or salt water.)
If his team of experts can examine the parasites themselves, weiss says, then a microscope can uncover key body parts of the parasites to confirm whether they are guinea worms. However, some erroneous preservation methods may reduce the effect of physical examination, because the nematode will dry out, but we can still detect its DNA. If they are indeed Guinea worms, genetic analysis will help figure out whether its ancestry can be traced back to the nematodes currently living in Africa.
Guinea worm nematodes is one of the largest known nematodes
Dieudonné Sankara, who leads the eradication team in WHO's Neglected Tropical Diseases Control Unit, told us via email that they were already well aware of the situation and were in the process of further investigation. "Since there are other types of parasites that can mimic guinea worm disease, further investigation confirmation is needed," he said.
If it is confirmed to be a true guinea worm disease, then more research and epidemiological investigations will have to be carried out to fully understand its transmission path and range of influence. ”
If guinea-worm disease does somehow "land" in Vietnam, the odds that only one person will unfortunately be infected are slim. Therefore, the question of its presence in Viet Nam must be carefully studied, which will also have a terrible impact on the global eradication plan for the disease.
But for now, it may be too early to add Guinean dracunculiasis to the list of scary things to do in 2020.