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Roundworms: description

Roundworms belong to the group of roundworms (Nematoda). They are distributed worldwide and can also occur in Germany. Male roundworms grow up to 25 centimeters, female even up to 40 centimeters long. Roundworms are parasites. They live in another living organism, their host. Although roundworms can usually feed in several organisms, they only reproduce in their ultimate host.

A type of roundworm prefers humans, pigs, dogs or other living beings. They are usually named after this main host. Anisalkis marina, for example, mainly affects marine animals and Toxocara canis affects dogs (canis means dog). If roundworms occur in humans, it is almost always Ascaris lumbricoides. For him, humans are both main and final hosts. A worm disease with Ascaris is also known as ascariasis. Other roundworms can also attack and harm humans, even if they do not reproduce in them. The following table shows which roundworms occur in humans and animals.

Ascariasis is one of the most common worm infections in the world. Experts estimate that around 760 million to 1.4 billion people are infected with this worm. Many cases are recorded, especially in East Asia, Africa and Latin America. A low standard of living in slums and rural regions favors the spread of roundworms. In children in these areas, up to 90 percent are infected. In industrialized countries, on the other hand, it is usually less than one percent. The numbers in Central Europe have been falling significantly since the 1950s.

Way of life of roundworms

The sexually mature roundworms live in the small intestine. They are as thick as a pencil and colored pink-yellow. The female roundworms produce around 200,000 eggs a day, which are excreted in human stool. The eggs ripen best in a warm and humid environment of around 30 degrees. The eggs must first mature outside the body before they are infectious. Therefore, direct infection from person to person is also excluded. If the eggs are ingested by contaminated food after two to six weeks, the larvae can hatch in the small intestine and infect their host. To do this, they pierce the wall of the small intestine and enter the liver via the veins.

They then travel further along the bloodstream via the right heart to the lungs. At around a week old, they break through the vascular system and settle in the alveoli. There they shed their skin once or twice and crawl up the bronchi and trachea into the pharynx. There they irritate the mucous membrane and trigger a swallowing reflex. The host swallows the young roundworms and transports them through the esophagus to the stomach and finally back to the small intestine. Here the roundworms mature into adult, sexually capable parasites. These roundworms produce the first eggs when they have spent around two to three months in their host. They live to be around 18 months in total.

Roundworms: symptoms

Roundworms migrate through different regions in the human body during their development. If roundworms cause symptoms, these usually reveal the organ that has just been colonized. A distinction is made between pulmonary ascariasis in the lungs and intestinal ascariasis in the intestine. During the first few days of roundworms in the stomach, intestines, blood and liver, the body's defense cells are activated. At this stage of the disease, however, the roundworms usually do not cause any symptoms.

Roundworms in the lungs

Once in the lungs, the defense reactions can increase significantly. The lungs make more mucus. The bronchi can become irritated and narrow (bronchospasm). Those affected often suffer from a dry cough and have difficulty breathing. You feel a feeling of pressure behind your sternum. Asthma-like attacks can also occur. These symptoms are often accompanied by high temperatures or a slight fever. Occasionally, allergic reactions such as skin rashes (urticaria) or facial swelling (angioedema) occur. These symptoms usually subside within one to two weeks. Roundworms in children, on the other hand, sometimes lead to life-threatening pneumonia.

Roundworms in the intestine

The adult roundworms prefer to stay in the upper small intestine (jejunum). The symptoms mostly depend on the number of worms. Individual roundworms often cause no symptoms at all or only occasionally cause slight abdominal pain. Unspecific complaints such as nausea or vomiting are possible. If around 100 roundworms live in the small intestine, they can block the intestines (ileus). Those affected suffer from severe, sometimes colicky, abdominal pain and vomit. The abdomen is bloated and painful on pressure. If the blood supply to the intestinal wall is poor, it can tear or become inflamed. An intestinal perforation is life-threatening and must be operated on immediately.

Roundworms in children often cause symptoms earlier because of their smaller intestines. The worms also prevent food from being properly digested. Some people develop a protein deficiency. If roundworms get into the stomach, those affected vomit. Roundworms in the colon are excreted in the stool.

Roundworms in the biliary tract

If roundworms get into the biliary tract, they can trigger what is known as biliary ascariasis there. They clog the biliary tract and prevent the bile from draining out of the liver. Inflammation of the biliary tract (cholangitis) or encapsulated inflammation centers in the liver (abscesses) are the result. The most violent pain attacks in the right upper abdomen attack those affected as if out of nowhere. They often vomit biliously and develop a fever. If the bile does not drain for a long time, the skin and the whites of the eyes can turn yellow (jaundice). If the liver becomes inflamed, there are signs of hepatitis. If roundworms infect the pancreas, symptoms of pancreatitis occur.

In rarer cases, roundworms can also migrate into the sinuses, the middle ear, the eyes or the female genitals and cause a wide variety of symptoms. Often they peep out of the various body orifices or cause bumps.

Roundworms: causes and risk factors

Roundworms mainly occur in poor hygienic conditions. A high population density and moist soils favor their reproduction. People become infected by ingesting the eggs in their mouth. In adults, eggs mostly enter the body through contaminated food. If vegetables, fruit or other natural products are fertilized with faeces or sewage, roundworm eggs can stick to the food. Uncooked vegetables or raw lettuce, like contaminated drinking water, are therefore frequent sources of infection for roundworms. In children, eggs often end up in their mouths while they are playing on the floor, in the dust or with contaminated toys.

The eggs are very resilient and can survive for years in warm, moist soil. Only high temperatures over 40 degrees, direct sunlight or extreme drought can destroy the eggs. In areas with seasonal drought, people only become infected at certain times of the year. Once roundworms have reached the human intestines, they can crawl into practically every tiny opening.

Roundworms: examinations and diagnosis

If roundworms are suspected, attempts are made to detect the worms themselves, their eggs or their larvae in the body. If the worms already colonize the intestines, their typical round-oval eggs can be identified from a stool sample under the microscope. If adult worms are completely excreted in the stool or vomited, a diagnosis of ascariasis can also be made. In some cases, roundworms are discovered accidentally during a gastroscopy or colonoscopy. Roundworms can also be made visible in an ultrasound or X-ray examination with a contrast agent.

In the first few days after an infection, however, it is more difficult to detect roundworms. Certain immune cells (eosinophils) can increasingly be found in the blood or saliva. However, they do not yet prove a roundworm infection. Occasionally, larvae can be found in saliva or gastric juice. If this proof is not successful, one must wait until the roundworms have reached the gastrointestinal tract.

Roundworms: treatment

The anti-worm drugs albendazole and mebendazole can kill the roundworms in the body even with a single dose. If you are pregnant, these active ingredients can damage the embryo and should not be used. Similar preparations such as piperazine, ivermectin and pyrantel are also effective against adult roundworms. The larvae, however, are not killed by any of the drugs mentioned. Curative therapy is not possible in the initial stage of the disease.

Pronounced allergic reactions can be treated with cortisone preparations. A bowel obstruction caused by roundworms is always an emergency and must be treated surgically. If roundworms clog the biliary tract, drugs are used to widen them. Simultaneous treatment with anti-worm drugs usually leads to a cure. It is rarely necessary to remove the worms with an endoscope or surgical operation.

Roundworms: disease course and prognosis

The course of the disease in worm diseases is determined by the life cycle of the worms. They develop in different parts of the body and can cause a variety of symptoms. Individual worms are sometimes not noticed at all. If the worms multiply quickly and live in large numbers in the body, they usually experience more severe symptoms and more frequent complications. A bowel obstruction or lung involvement can be fatal. Children in particular are at risk from these complications.

Although simple ascariasis can be cured with a single dose of medication, roundworms kill around 20,000 people worldwide each year. Humans and worms will continue to co-exist as long as sanitary conditions do not improve and human feces are used as fertilizer. By thoroughly cleaning and boiling potentially contaminated food, drinking water or toys, you can Roundworms keep away.

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