A parasite is defined as an organism that lives in or on another organism and gets its food from its host or at the host’s expense. While many people think parasites occur only in developing countries with poor sanitation, the increase in international travel and transportation of food across borders increases the chances of somebody getting a parasite from their food, regardless of where they live.
Diagnosing a parasitic infection is not always straightforward. Doctors use the term “pseudoparasite” to describe something that resembles a parasite but isn’t. Yeast cells, for example, can look like cysts of the protozoan Giardia. In 2011, a doctor treated a man who feared he had hookworms. An examination of his stool sample showed the “worms” were really bean sprouts.
Rope worms may be an example of a pseudoparasite. As described here https://microbeformulas.com/blogs/microbe-formulas/rope-worm-parasite-or-mucoid-plaque, rope worms are rope-like strands that appear in a person’s stool after they have undergone a cleansing regimen like a parasite cleanse or colonic. There is actually a debate as to whether they are actual parasitic worms or simply a type of debris from the intestines called “mucoid plaque” that may be produced when the intestines are trying to ward off a parasitic or bacterial infection.
Other intestinal parasites, however, are undeniably real — and dangerous. Here are seven such parasites that might find their way into your food.
The pork tapeworm, known by the scientific name Taenia solium, is among the largest tapeworms to affect humans. It can grow to be ten meters or nearly 33 feet long. People get the worms by eating uncooked pork contaminated by the worm’s eggs or larval cysts. Ingesting cysts “only” results in malnutrition, for the cysts soon become adult worms that live in the host’s intestines and eat their food. Eggs, by contrast, hatch into larvae that spread throughout the body and form cysts and thus cause a condition called cysticercosis. Symptoms vary depending on the part of the body affected. Cysts that develop in the central nervous system can cause epilepsy, and neurological cysticercosis is believed to be a common cause of epilepsy in some parts of the world.
Entamoeba histolytica is a protozoan that affects the digestive tract and causes amebic dysentery, which can be life-threatening. Its symptoms include severe abdominal pain and bloody diarrhea. If the parasite leaves the intestines and spreads to other organs like the liver, it can cause severe problems like abscesses on the affected organ. E. histolytica is believed to infect 50 million people throughout the world and kill over 55,000 people every year. People get amebic dysentery by ingesting, food, water, or soil contaminated by the feces of someone infected with the parasite.
Ascaris is a genus of nematodes, and they are the largest of the intestinal roundworms that affect humans. Adults can be up to 35 cm or nearly 14 inches long. The most common species in humans is A. lumbricoides or the human roundworm, which might infect as many as 1.2 billion people. The parasite lives in the intestines, and infected people pass the eggs out with their feces. People can thus get the eggs by ingesting contaminated dirt or fruits and vegetables that have not been washed, peeled, or cooked. People infected with Ascaris usually show no or mild symptoms. Heavy infestations, however, can cause intestinal blockage and impair the growth of children.
Toxoplasma gondii is a protozoan parasite that can infect almost any mammal. It also occurs in many countries and is one of the most common parasites infecting humans. It may infect ten to eighty percent of the population in any given area. Domestic cats and other small felines are the definitive hosts of T. gondii. They get the parasite by eating other animals that carry it and pass the eggs out with their feces. Humans can get it by ingesting contaminated soil, eating improperly prepared food, or handling cat feces. While the parasite is dormant in most people, it can multiply extensively in people with weakened immune systems like HIV/AIDS patients. Such patients may develop symptoms like seizures, lung disease, confusion, blurred vision, and headache. If a pregnant woman is infected, her child may be born with birth defects.
Echinococcus multilocularis is a small tapeworm that is native to Europe and North America – and that is becoming more common. About a million people are believed to be infected with it. The tapeworm typically infects dogs, foxes, cats, and some rodents, but can also infect livestock like cattle or goats. People get it by drinking contaminated water, ingesting contaminated soil or food, or by handling infected animals. E. multilocularis can cause a disease called alveolar echinococcus, which usually develops in the liver. Over several years, a lesion resembling a tumor will develop and cause symptoms like weight loss, malaise, abdominal pain, and signs of liver failure. The parasites can also spread to other parts of the body. Untreated alveolar echinococcus can eventually kill.
Echinococcus granulosis is a cousin of E. multilocularis that is between three and seven millimeters long. It also infects about a million people worldwide, and it is also often transmitted by dogs. Livestock like sheep can carry the tapeworm. People get it by eating contaminated food, ingesting contaminated soil, handling dog feces, or through extensive contact with infected animals. E. granulosis causes a disease called cystic echinococcus, hydatid disease, or hydatidosis. The tapeworm’s larvae will form a fluid-filled sac called a hydatid cyst. While the cysts can develop anywhere in the body, they are most common in the liver or lungs. Symptoms will vary depending on the cyst’s location. If it’s in the lungs, for example, the symptoms can include shortness of breath, chronic coughing, and chest pain. A cyst in the liver can cause nausea, vomiting, and abdominal pain.
Trypanosoma cruzi is a protozoan parasite transmitted by triatomine beetles, which are also known as “kissing bugs,” for their habit of biting the faces of sleeping humans to drink their blood. The beetle will then defecate on the person and thus give them some parasites. In 2013, researchers found that people could also get infected by eating food contaminated by the beetles’ feces. A person infected with T. cruzi will gradually develop a condition called Chagas’ disease that eventually damages the heart and intestines. While the early symptoms are mild, Chagas’ disease can become fatal. Some scholars believe that Chagas’ disease caused the health problems that plagued Charles Darwin throughout much of his adult life.
Intestinal parasites are something to take seriously. While they can generally be treated, the treatments can take time. Preventing infection is simpler and involves careful food preparation and handling of animals and their wastes.