What causes pinworms

Worm diseases

Worm diseases(Helmet pants): Diseases of the gastrointestinal tract and other organs such as the lungs, liver and brain caused by worm infestation. Some of the main worms that attack humans are Tapeworms (Cestodes), Roundworms (Nematodes) and Flukes (Trematodes). Many worm diseases can be treated well with wormers. In the case of dog tapeworms or flukes, the prognosis depends on how severely infected organs have been destroyed. Those who become infected with fox tapeworm are often dependent on lifelong therapy.

Leading complaints

  • Often only vague complaints, e.g. B. Pressure in the upper abdomen or slight abdominal pain
  • Itching and skin changes in the anal area
  • Visible excretion of worms or worm parts in the stool
  • Weight loss, paleness and weakness (anemia)
  • Jaundice, dry cough, shortness of breath (dog or fox tapeworm)
  • Fever, headache, abdominal pain and blood in the stool or urine after trips to Africa and Asia (schistosomes).

When to the doctor

In the next few days if

  • Worms or parts of worms can be seen in the stool
  • previously unknown itching occurs in the anal region
  • unspecific abdominal pain has existed for a long time
  • the conjunctiva turn yellowish
  • Returning travelers develop a fever or inexplicable general symptoms
  • Blood occurs in stool or urine.

The illness

Worm diseases are common worldwide. Most of the time, the infection occurs through the consumption of infectious raw or undercooked meat or unwashed vegetables, lettuce or fruit contaminated with faeces. The preferred infected organs and the reproduction cycles differ from worm species to worm species.

Roundworms (pinworms, roundworms and trichinae)

To the Roundworms (Nematodes) include, inter alia. the Pinworms (Oxyuren, Enterobius vermicularis), which are also widespread in our latitudes. Children of kindergarten or elementary school age in particular become infected through contaminated food, toys or laundry. The worms, which are around 12 mm long, settle in the lower area of ​​the small intestine, in the large intestine and in the appendix. At night, the females crawl out of the anal opening and lay their eggs around the anus. This leads to severe itching at the anus. The infected person scratches himself, touches various things with the contaminated hands and thus helps the pinworms to spread further.

The eggs of Roundworms (Ascaris lumbricoides) are mostly ingested with contaminated vegetables and end up in the small intestine of humans. The roundworm larvae hatch in the intestine, pass through the intestinal wall into the blood and via the bloodstream to the liver and lungs. From there the larvae migrate to the larynx, are swallowed and thus reach the small intestine again. Now they have completed their migration and are growing into mature worms up to 40 cm long. Those affected often suffer from a slight fever, cough and other flu-like or asthma-like symptoms while they are moving through the lungs. The worm infestation of the intestine causes abdominal pain; the worms can form clusters in the intestine and thus cause a mechanical intestinal obstruction. In some cases, migrating worms block the bile duct, causing jaundice or biliary colic.

Trichinae (Trichinella spiralis): Trichinella attack domestic pigs and wild boars and are ingested by humans when they consume raw pork. The trichinosis caused by them has become very rare in Germany because of the meat inspection required by law. However, it is still widespread in Eastern Europe and North America. The worm infestation in the intestines causes watery diarrhea, nausea, vomiting and a slight fever. If the larvae attack the muscles, muscle pain, water retention in the tissue and, later, possibly persistent rheumatic complaints occur. Danger to life exists when trichinae reach the heart and z. B. cause myocarditis. If larvae encapsulate themselves in the brain, neurological complaints also occur.

Beef and pork tapeworm

Humans become infected mainly through raw or insufficiently cooked meat with the Finns (young form = larva of the tapeworm) from Beef tapeworm (Taenia saginata) and Pork tapeworm (Taenia solium). The Finns grow in the intestine into a mature tapeworm, which consists of a head, a neck and the tapeworm limbs (proglottids) formed from them. Individual tapeworm limbs are excreted with the stool. Most people experience very little discomfort when they have tapeworm disease. Particularly noticeable are loss of appetite alternating with cravings and weight loss despite regular eating. Tapeworm limbs rarely migrate into the appendix or pancreatic duct; where they can cause acute appendicitis or pancreatitis.

If a person ingests the tapeworm eggs (not the Finns) of the pork tapeworm - which is also possible through self-infection - larvae (cysticerks) develop in the human body. These migrate from the intestine via the blood vessels to muscles and organs (cysticercosis). When the eyes are affected, there is a risk of blindness, and seizures when entering the central nervous system. If the infestation remains limited to the muscles, those affected complain of muscle pain. Larvae lying superficially in the skin or muscles can often be felt as small lumps.

Dog and fox tapeworm (echinococcosis)

Echinococcosis are among the most dangerous worm diseases. Infection occurs through contact with infected foxes, dogs, or cats. Infection from the consumption of unwashed blueberries or wild strawberries, which are often contaminated with fox excretions due to their low growth, is also conceivable. From the eggs ingested, larvae develop in the intestine, which migrate via the blood vessels mainly to the liver and, more rarely, to the lungs and other organs. The incubation period can last from weeks to years.

  • Dog tapeworm (Echinococcus granulosus): The dog tapeworm forms a large cyst in the liver in which numerous new larvae develop. Symptoms such as upper abdominal pain often only occur when the cyst is very large and mechanically displaces other organs or tissue in the abdominal cavity. If the cyst presses on the biliary tract, there is a risk of obstructive jaundice. If the cyst bursts, the flushed larvae can lead to a potentially fatal allergic shock. The lungs are also often affected by cysts, resulting in shortness of breath and a dry cough, sometimes with bloody sputum. However, the disease often heals on its own.
  • Fox tapeworm (Echinococcus multilocularis): The fox tapeworm infestation is one of the most severe worm diseases in our climatic zone and the most severe liver disease of all. The fox tapeworm forms several small cysts in the liver that grow tumor-like into surrounding tissues and organs and destroy them. The liver is primarily affected, but the lungs, heart, spleen, and brain are also often affected. Damage to these organs can usually not be prevented, even if treatment is given in good time.


Schistosomes (Schistosoma haematobium, mansoni or japonicum): The flukes belonging to the trematodes occur mainly in Africa, South America and Asia. In the meantime, more and more long-distance travelers are bringing schistosomes home with them as a souvenir.

The larvae of the worms develop in freshwater snails and penetrate humans through the skin, e.g. B. when bathing in rivers and lakes or when wading through puddles. In humans, they reach the liver, mature there and then migrate to the intestines or bladder. This is where the worms lay their eggs, which then get back into the water through stool and urine. Eggs that remain in the body lead to inflammation, whereby the symptoms depend on the respective organ involvement.

The actual symptoms do not appear until weeks to months later, e.g. B. fever, fatigue, headache, cough, and abdominal pain. This is due to an allergic reaction to the worms and their eggs. The disease often goes away on its own, but severe courses involving the brain and heart are also possible.

Diagnostic assurance

If the doctor finds worm eggs during a microscopic examination of the stool, an infection is proven. Tapeworm links from beef and pork tapeworms can be seen in the stool with the naked eye. The eggs of roundworms can be detected by sticking a piece of scotch tape on the anus. The eggs sticking to the tape can then be seen under the microscope.

Dog and fox tapeworm infestations are detected in ~ 85% of cases via antibodies in the blood. The doctor can usually recognize the cysts in the liver well on ultrasound or CT.

Suspicion of acute schistosomiasis among travelers returning. About 5–12 weeks after the suspected infection, it is possible to detect the eggs of the flukes in the stool. An alternative is to test for antibodies in the blood. Differential diagnosis. Tumors, abscesses and tuberculosis of the liver can look similar to the liver cysts of dog or fox tapeworm, especially in imaging diagnostics.

CT image of the abdomen of a 41-year-old patient with a giant echinococcus cyst in the right lobe of the liver. The cyst takes up over half of the cross-section of the liver. Despite the successful surgical removal of the cyst, which weighed more than 1 kg, it did not heal, the patient had to continue taking anthelmintics and eventually died of further complications.
Georg Thieme Verlag, Stuttgart


Wormers (anthelmintics) are almost always sufficient to treat diseases Beef and pork tapeworms as well as through Roundworms to fight. They are usually well tolerated if the treatment is short. Frequently used active ingredients are

  • Pyrantel (e.g. Helmex®, also as a juice), which has a paralyzing effect on worm species, whereby the worms are excreted alive with the stool
  • Albendazole (e.g. Eskazole® in tablet form) or Mebendazole (e.g. Vermox® in tablet form), which block the nutrient absorption of the worms so that they die and are then also excreted via the intestines.
  • The longer the therapy, the more severe the side effects such as abdominal pain, nausea and diarrhea.

Therapy is difficult with Dog and fox tapeworms. In dog tapeworms, the cysts are surgically removed or the contents carefully suctioned off. Sometimes doctors also inject 95% alcohol into the cyst to destroy it. At the same time, wormers are taken.

In the case of the fox tapeworm, doctors manage to completely remove the cysts in only a quarter of the cases. Even if cysts have been surgically removed, wormer treatment is still required for another two years. If an operation is not possible, infected people often have to take high-dose wormers for life.

The acute Schistosomiasis can be combated well with wormers. In the acute form, doctors first wait and only treat symptomatically. This prevents too large a number of worms from dying off too quickly, leading to an allergic crisis. After the fever has subsided, praziquantel (e.g. Biltricide®) is administered. Organ involvement in chronic schistosomiasis is treated according to the symptoms and findings.


Roundworms, beef and pork tapeworms can easily be treated with medication and the prognosis is good after therapy.

The infection with schistosomes can also be treated well with wormers. How well any affected organs recover depends on the extent of the infection. If the bladder was involved in the disease, the later risk of bladder cancer increases.

Some doctors rightly compare dog and fox tapeworm cysts with a malignant tumor - the prognosis here depends on the destruction of the liver or lungs caused by the cysts. The fox tapeworm infestation is more dangerous than the dog tapeworm: Only a third of the patients infected with a fox tapeworm are still alive 10 years after the diagnosis.

Your pharmacy recommends


You can protect yourself against worm infections by washing your hands before every meal. Pets should be regularly dewormed by the vet (possibly even monthly for small children in the household), dog feces on the shoes should always be removed thoroughly and not carried into the house. Prevent your children from scratching their buttocks. Frequent hand washing and trimmed fingernails support these basic measures.

The warning that used to be widespread to avoid low-growing wild berries such as blueberries or wild strawberries because of possible contamination with fox tapeworm eggs is now considered obsolete.

Only eat meat from home slaughter if you are sure that the required meat inspection has been carried out.

Avoid freshwater contact when traveling to Africa, South America and Asia! Do not swim in lakes or rivers, wear high rubber boots when wading through puddles or streams, and protective clothing when working in the water.


Dr. med. Arne Schäffler, Dr. Bernadette Andre-Wallis in: Health Today, edited by Dr. med. Arne Schäffler. Trias, Stuttgart, 3rd edition (2014). Revision and update: Dr. med. Sonja Kempinski | last changed on at 11:19 am

Important note: This article has been written according to scientific standards and has been checked by medical professionals. The information communicated in this article can in no way replace professional advice in your pharmacy. The content cannot and must not be used to make independent diagnoses or to start therapy.