Symptoms
The infection occurs primarily in children and manifests itself primarily in nocturnal itching in the anal region. This is caused by the migration of the female worms to lay eggs in the anal region. Local tickling or pain may also occur, as well as restless sleep and insomnia due to the itching, which leads to fatigue during the day. Other possible symptoms include lower abdominal discomfort, loss of appetite, weight loss, lack of concentration and irritability. However, the infestation is often asymptomatic.
Causes and course
The pinworm (formerly: Oxyuris vermicularis) is a worm from the group of nematodes (threadworms). It is between 2-5 mm (males) or 9-12 mm (females) long and lives in the human large intestine. Up to several hundred worms can be found there. At night, the female worms go to the anus and lay up to 16,000 eggs, with which the host again infects itself or other people. Compared to other nematodes, the eggs of the pinworm do not need time to mature in the soil. Humans are the only host; there are no intermediate animal hosts. After oral ingestion of the worm eggs, the larvae hatch in the duodenum of the small intestine and mature as they migrate to the colon. The worm eggs are infectious within a few hours of excretion. The incubation period ranges from 1-4 weeks to months. Self-infection can continue almost indefinitely.
Transmission
- Anal-oral autoinfection
- Smear infection by contaminated objects or persons.
- Inhalation of eggs, for example, when shaking out bedding or clothes. When shaking out the eggs are distributed in the living space.
- Oral ingestion of worm eggs through contaminated food or drinking water.
- The larvae can also hatch on the mucosa of the anus, leading to reinfection. The larvae migrate back into the intestine.
Complications
- In girls and women: Inflammation of the vulva, vagina, uterus and fallopian tube, bleeding.
- Spread of worms to atypical sites, inflammation of the urinary tract or peritoneum. Inflammation of the appendix of the worm.
- Pain during urination, frequent urination at night, incontinence.
- Superinfections in the perianal area, eczema, skin damage, small tears in the area of the anus.
- Psychological stress, disgust (worms in the stool!).
- A problem is the high relapse rates, due to anal-oral self-infection, and infection of other family members.
Risk factors
Affected are mainly children. Risk factors are contact with infected people (eg, family) and the consumption of raw vegetables. Pinworms occur in all social classes.
Diagnosis
Diagnosis can be made microscopically by detecting worm eggs on a swab of perianal skin taken in the morning with an adhesive strip. This should be done before showering and defecation. If the test is negative, it should be repeated on the following 2 days. Sometimes the adult worms can be detected in the stool or on the toilet paper. They are thread-like, yellowish-white with a sharply pointed end. Eggs are less commonly detected in the stool (5-15%). Adult worms are also often detected during colonoscopy. Possible differential diagnoses include infections of the rectum, anal eczema, anal fistulas, hemorrhoids, thrush, and infections with other nematodes.
Nonpharmacologic measures
Hygiene measures are important. Hands should be washed well regularly, especially after defecation and before eating, shower regularly, do not bite nails, do not suck thumbs. Cut fingernails short and clean with a brush. Change underwear, bed linen and towels frequently and wash well. Do not scratch the anus, as this transfers the worm eggs directly to the hand.
Drug treatment
Anthelmintics (anthelmintics) are used for drug treatment. Close contacts (family, group members) should always be treated if possible. Contraindications must be observed (e.g., pregnancy). In case of chronic recurrent infestation, it is suggested to repeat the treatment every 28 days, for 3-6 months.Mebendazole (Vermox) is considered the drug of choice in the literature and is available over the counter. Dosage for children over 1 year of age and adults, regardless of body weight: 100 mg (1 tablet) as a single dose. The dose should be repeated after 2 weeks. Mebendazole should not be used during pregnancy, according to the professional information. Pyrantel (Cobantril) is approved for use from 6 months of age and is also available over the counter. It is also administered as a single dose. The dosage is based on body weight. Pyrantel should be taken during or after a meal. The intake should be repeated after 2-3 weeks. No clinical data are available on use in pregnant women. Pyrvinium (Pyrcon, Molevac) is no longer available in many countries; it is commercially available in Germany. It is administered as a suspension or in the form of dragées. Albendazole (Zentel) is approved for use from 1 year of age and is taken as a single dose. It should not be taken during pregnancy (contraindicated!) and is available only by prescription. Ivermectin (Stromectol, France, USA) is mentioned in some publication as a way to treat urogenital tract complications because it distributes into the tissues. Ivermectin can also be used as an alternative therapeutic agent, but it is not approved or commercially available in many countries. It is available only by prescription from a physician. Antipruritic agents can be used for symptomatic treatment of itching, such as an ointment containing menthol or camphor, as used for hemorrhoids.
Cf.
Worms, nematodes, antihelminthics: mebendazole, pyrantel, albendazole, ivermectin, treatment of itching, hemorrhoids.
