'Sushi parasites' have increased 283-fold in past 40 years - Science Daily
'Sushi parasites' have increased 283-fold in past 40 years - Science Daily |
| 'Sushi parasites' have increased 283-fold in past 40 years - Science Daily Posted: 19 Mar 2020 12:00 AM PDT The next time you eat sashimi, nigiri or other forms of raw fish, consider doing a quick check for worms. A new study led by the University of Washington finds dramatic increases in the abundance of a worm that can be transmitted to humans who eat raw or undercooked seafood. Its 283-fold increase in abundance since the 1970s could have implications for the health of humans and marine mammals, which both can inadvertently eat the worm. Thousands of papers have looked at the abundance of this parasitic worm, known as Anisakis or "herring worm," in particular places and at particular times. But this is the first study to combine the results of those papers to investigate how the global abundance of these worms has changed through time. The findings were published March 19 in the journal Global Change Biology. "This study harnesses the power of many studies together to show a global picture of change over a nearly four-decade period," said corresponding author Chelsea Wood, an assistant professor in the UW School of Aquatic and Fishery Sciences. "It's interesting because it shows how risks to both humans and marine mammals are changing over time. That's important to know from a public health standpoint, and for understanding what's going on with marine mammal populations that aren't thriving." Despite their name, herring worms can be found in a variety of marine fish and squid species. When people eat live herring worms, the parasite can invade the intestinal wall and cause symptoms that mimic those of food poisoning, such as nausea, vomiting and diarrhea. In most cases, the worm dies after a few days and the symptoms disappear. This disease, called anisakiasis or anisakidosis, is rarely diagnosed because most people assume they merely suffered a bad case of food poisoning, Wood explained. After the worms hatch in the ocean, they first infect small crustaceans, such as bottom-dwelling shrimp or copepods. When small fish eat the infected crustaceans, the worms then transfer to their bodies, and this continues as larger fish eat smaller infected fish. Humans and marine mammals become infected when they eat a fish that contains worms. The worms can't reproduce or live for more than a few days in a human's intestine, but they can persist and reproduce in marine mammals. Seafood processors and sushi chefs are well-practiced at spotting the worms in fish and picking them out before they reach customers in grocery stores, seafood markets or sushi bars, Wood explained. The worms can be up to 2 centimeters in length, or about the size of a U.S. 5-cent nickel. "At every stage of seafood processing and sushi preparation, people are good at finding worms and removing them from fish," Wood said. Some worms can make it past these screening steps. Still, Wood -- who studies a range of marine parasites -- said she enjoys eating sushi regularly. For sushi consumers who remain concerned about these worms, she recommends cutting each piece in half and looking for worms before eating it. For the analysis, the study's authors searched the published literature archived online for all mentions of Anisakis worms, as well as another parasitic worm called Pseudoterranova, or "cod worm." They whittled down the studies based on set criteria, ultimately keeping only those studies that presented estimates of the abundance of each worm in fish at a given point in time. While Anisakis worms increased 283-fold over the study period of 1978 to 2015, Pseudoterranova worms did not change in abundance. Although the health risks of these marine worms are fairly low for humans, scientists think they may be having a big impact on marine mammals such as dolphins, whales and seals. The worms actually reproduce in the intestines of these animals and are released into the ocean via the marine mammals' feces. While scientists don't yet know the physiological impacts of these parasites on marine mammals, the parasites can live in the mammals' bodies for years, which could have detrimental effects, Wood said. "One of the important implications of this study is that now we know there is this massive, rising health risk to marine mammals," Wood said. "It's not often considered that parasites might be the reason that some marine mammal populations are failing to bounce back. I hope this study encourages people to look at intestinal parasites as a potential cap on the population growth of endangered and threatened marine mammals." The authors aren't sure what caused the large increase of Anisakis worms over the past several decades, but climate change, more nutrients from fertilizers and runoff, and an increase in marine mammal populations over the same period could all be potential reasons, they said. Marine mammals have been protected under the Marine Mammal Protection Act since 1972, which has allowed many populations of seals, sea lions, whales and dolphins to grow. Because the worms reproduce inside marine mammals -- and their rise occurred over the same time period as the mammals' increase -- this is the most plausible hypothesis, Wood said. "It's possible that the recovery of some marine mammal populations has allowed recovery of their Anisakis parasites." Wood said. "So, the increase in parasitic worms actually could be a good thing, a sign that the ecosystem is doing well. But, ironically, if one marine mammal population increases in response to protection and its Anisakis parasites profit from that increase, it could put other, more vulnearble marine mammal populations at risk of increased infection, and that could make it even more difficult for these endangered populations to recover."  |
| What is a parasite cleanse, and does it work? - Medical News Today Posted: 16 Oct 2019 12:00 AM PDT  A parasite cleanse is any diet, supplement, or other detox product that is intended to eliminate parasites from the body without using prescription medications. Many companies go so far as to recommend these cleanses for just about anyone, without a doctor ever diagnosing them with a parasitic infection. Many natural plants and compounds may help the body clear out parasites. However, in cases where a person does not have a parasite, they will do very little. In this article, learn more about parasite cleanses and what the evidence says about whether they are effective. There is a myth in some natural health circles that argues that the vast majority of people have parasites, and, therefore, need parasite cleanses. This presumption is untrue. However, well-known parasitic infections such as malaria are a global epidemic. Malaria alone kills over 660,000 people each year, according to the Centers for Disease Control and Prevention (CDC). Most of these deaths are young children in sub-Saharan Africa. Many parasitic infections are also possible in the United States. The CDC calls these neglected parasitic infections and include several statistics for their occurrence in the U.S.:
However, some manufacturers of parasite cleanses and other detox products may inflate these numbers. Many makers of parasite cleanse products will go so far as to say everyone should do a parasite cleanse once or twice a year, with or without evidence of them having a parasite. In reality, the only people who need treatment for parasites are the people who have parasitic infections. Anyone who is concerned they have a parasitic infection should speak to a doctor. There is little research on whether commercial parasite cleanses are useful. Many of the people who try these products likely do not have a parasitic infection. However, some parasite cleansers may be effective for people who do have an infection. For example, wormwood is the main ingredient in many parasite cleansing products, and it contains powerful antioxidants and other helpful compounds. A recent study in the Journal of Helminthology showed that wormwood reduced dwarf tapeworm levels in a similar way as a leading antiparasitic medication in animal studies. These results are promising, but the researchers call for more tests before recommending wormwood as a treatment. Another 2018 study in humans found that wormwood could treat schistosomiasis, which occurs in people with a type of parasitic worms, as effectively as the standard medical treatment. In the study, 800 participants with schistosomiasis received either the standard medical treatment (praziquantel) or one of two types of wormwood tea. Those who received the wormwood tea cleared the infection faster and experienced fewer side effects than those who took standard medication. Plants often have natural defense compounds built into them that work to protect the plant from infections, as well as ward off bugs and other invaders. Many plants and herbs contain compounds that may have an antiparasitic effect in laboratory testing and other studies. Therefore, manufacturers of parasite cleanses claim that many plants may kill parasites in the body as well, including: Many natural sources have similar effects to standard medications for parasites and show promise as antiparasitic tools. However, it may be difficult to tell if they are effective when many people using at-home parasite cleanses do not have any underlying infection. Countless anecdotes appear online about people's experiences with parasite cleansing diets and how much better they feel afterward. While people may feel better, the effects may have more to do with the general tips of a cleansing or detoxing diet. Cleansing diets or programs will often require a person eats a supportive diet while taking the product. This diet may include avoiding greasy, processed foods and eating natural, whole foods. Some parasite cleansing diets ask the person to avoid specific types of foods, such as gluten, dairy, or pork. Diets may also include the use of anti-inflammatory herbs and spices, such as garlic, turmeric, and ginger. These dietary changes alone may be enough to cause a noticeable change in a person's body, as they are moving to a cleaner and more healthful diet. The ingredients in the detox product tend to be very high in antioxidants, and many can easily cause a reaction in the digestive system. People often mistake these effects for what they call "parasitic die-off." After a round of these herbs, some diets will suggest adding supplements to restore the digestive system, such as prebiotics and probiotics. Some research suggests that probiotics may also help reduce the risk of parasitic infections or help treat them. Many parasite cleanse diets may make a person feel better simply by eliminating processed and greasy foods and introducing healthful probiotics and antioxidants. However, some cleanses ask a person to consume only one type of food for a prolonged period. Common symptoms of a parasitic infection include: However, many of these symptoms appear with other digestive health issues. Anyone experiencing these symptoms should see a doctor for a full diagnosis. In some cases, parasites clear up on their own, especially in a person with a healthy immune system. If the parasite causes concerning symptoms or may cause complications, doctors will likely order an antiparasitic medication that kills the parasite. Some people choose natural methods to clear their body of a parasite. Certain ingredients in these products may show promise in clearing parasites. The authors of a 2013 study note that many natural products show promise as antiparasitic treatments. However, there is not enough research to suggest them as cures yet. While individual ingredients may work in laboratory studies, there is little proof that commercial cleansing products kill parasites. A person can have a parasitic infection, even if they do not experience symptoms. However, there is no evidence to show that people self-diagnosing and using parasite cleanses benefit from these products if no parasite is present. The methods behind many cleansing programs typically involve the person switching to a whole foods diet, eating supportive herbs, and improving their digestive health. The switch to a more healthful diet overall may produce many of the positive effects people note when taking parasite cleanses. Anyone concerned about parasites or the possibility that they have a parasitic infection should see a doctor.  |
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