roundworms

Roundworms: description

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

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

Ascariasis is one of the world’s most common worm infections. Experts estimate that about 760 million to 1.4 billion people are infected with this worm. Especially in East Asia, Africa and Latin America many cases are recorded. A low standard of living in slums and rural areas favors the proliferation of roundworms. Children in these areas are even up to 90 percent infected. In developed countries, however, it is usually less than one percent. Since the fifties, the numbers in Central Europe have decreased significantly.

Lifestyle of roundworms

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

Then they continue along the bloodstream via the right heart into the lungs. At the age of about one week, they break through the vascular system and settle in the alveoli. There they skin one or two times 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 into the stomach and finally into the small intestine. Here, the roundworms mature into adult, sexually-transmitted parasites. The first eggs produce these roundworms when they have spent about two to three months in their host. Overall, they are about 18 months old.

Roundworms: symptoms

Roundworms wander through various regions of the human body during their development. If roundworms start to evoke symptoms, they usually reveal the currently populated organ. One distinguishes a pulmonary ascariasis in the lung from an intestinal ascariasis in the intestine. During the first days of roundworms in the stomach, intestine, blood and liver, the immune cells of the body are activated. In this disease stage, roundworms usually do not produce any signs of disease.

Roundworms in the lungs

Arrived in the lungs, the defense reactions can increase significantly. The lungs produce more mucus. The bronchi can become irritated and narrow (bronchospasm). Sufferers often suffer from a dry cough and may breathe less well. They feel a pressure sensation behind the sternum. It can also come to asthma-like attacks. Often, these symptoms are accompanied by elevated temperatures or mild fever. Occasionally, allergic reactions such as skin rashes (urticaria) or facial swelling (angioedema) occur. Within a week or two, these symptoms usually return to normal. In contrast, roundworms in children sometimes lead to life-threatening pneumonia.

Roundworms in the gut

The adult roundworms preferably remain in the upper small intestine (jejunum). The symptoms usually depend on the number of worms. Single roundworms often cause no discomfort or occasionally mild abdominal pain. Unspecific complaints such as nausea or vomiting are possible. Living around the 100 roundworms in the small intestine, they can clog the intestine (ileus). Affected suffer from the strongest partly colicky abdominal pain and have to vomit. The belly is bloated thick and tender. If the intestinal wall is poorly perfused, it can tear or become inflamed. A bowel perforation is life threatening and must be operated on immediately.

Roundworms in children often cause symptoms earlier because of the smaller intestine. The worms also prevent food from being properly digested. Some sufferers develop a protein deficiency. If roundworms get into the stomach, sufferers have to vomit. Roundworms in the large intestine are excreted in the stool.

Roundworms in the bile ducts

If roundworms enter the bile ducts, they can trigger a so-called biliary ascariasis there. They clog the bile ducts and prevent the bile from draining from the liver. An inflammation of the biliary tract (cholangitis) or encapsulated inflammatory foci in the liver (abscesses) are the result. The most violent attacks of pain in the right upper abdomen attack those affected out of nowhere. Often they have to vomit bilious and develop a fever. If the bile does not drain for a longer period of time, the skin and the white of the eye may turn yellowish (icterus). If the liver is inflamed, symptoms of hepatitis exist. If roundworms infect the pancreas, symptoms of pancreatitis occur.

In rarer cases roundworms can also migrate into the paranasal sinuses, the middle ear, the eyes or the female genital and cause most different symptoms. They often emerge from the various orifices or cause bumps.

Roundworms: causes and risk factors

Roundworms occur especially in poor hygienic conditions. A high population density and moist soils favor their reproduction. Humans become infected by picking up eggs in their mouths. In adults, eggs usually enter the body through contaminated food. If vegetables, fruit or other natural products are fertilized with faeces or sewage, roundworm eggs can adhere to the food. Uncooked vegetables or raw lettuce are therefore just as contaminated drinking water common sources of infection for roundworms. In the case of children, the eggs often reach the mouth while playing on the floor, in the dust or with contaminated toys.

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

Roundworms: examinations and diagnosis

If there is a suspicion of a roundworm infestation, one tries the worms themselves to prove their eggs or their larvae in the body. If the worms already colonize the intestine, one can identify their typical round-oval eggs from a stool sample under the microscope. If adult worms are completely excreted or vomited with the stool, the diagnosis of ascariasis can also be made. In some cases roundworms are discovered by chance during a gastroscopy or colonoscopy. Even in an ultrasound examination or X-ray examination with contrast agent, roundworms can be visualized.

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

Roundworms: treatment

The anti-worm agents albendazole and mebendazole can kill the roundworms in the body even with a single dose. In pregnancy, these drugs may damage the embryo and should not be used. Comparable preparations such as piperazine, ivermectin and pyrantel are also effective against adult roundworms. However, the larvae are not killed by any of the drugs mentioned. No healing therapy is possible in the initial stage of the disease.

Pronounced allergic reactions can be treated with cortisone preparations. A bowel obstruction by roundworms always represents an emergency and must be treated surgically. If roundworms clog the bile ducts, they are widely spread by medication. Concomitant treatment with anti-worm drugs usually leads to healing. It is rarely necessary to remove the worms with an endoscope or a surgical operation.

Roundworms: Disease course and prognosis

The disease course 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. Some worms are not noticed at all. If the worms multiply quickly and live in large numbers in the body, usually more severe symptoms and more frequent complications occur. An intestinal obstruction or a lung infection can be fatal. Especially children are at risk from these complications.

Although one can cure a simple ascariasis by administering a single drug, around 20,000 people worldwide die from roundworms each year. Man and worm will continue to exist together as long as the hygienic conditions do not improve and human manure is used as fertilizer. By thoroughly cleaning and boiling down potentially contaminated food, drinking water or toys, you can roundworms keep away.