Brief overview
- Symptoms: The symptoms depend on the type and number of threadworms and the location of the parasites in the body. Not every infection with threadworms leads to symptoms.
- Causes: Infection occurs in various ways and depends on the type of worm. Infection occurs, for example, through contact with contaminated food or objects. Other threadworms are transmitted by insects, for example, or penetrate the human body through the skin.
- Treatment: Special anthelmintics are used against threadworms. These have a paralyzing or killing effect on the parasites.
- Prevention: Hygiene measures (e.g. regular hand washing, heating raw meat) help to prevent infection. Direct skin contact with the ground (e.g. walking barefoot) should be avoided, especially in tropical regions. It is also advisable to have pets regularly dewormed by a vet.
- Risk factors: Poor hygiene (including food and drinking water hygiene) can lead to infection with threadworms. Other risk factors include walking barefoot or biting nails.
- Prognosis: An infestation with threadworms usually has a good prognosis and can be treated with medication.
Symptoms
Not every infestation with threadworms causes symptoms. This depends, among other things, on the number of parasites ingested. The type of symptoms depends on which nematodes are responsible for the infection and where the animals are located in the human body. An infestation with nematodes is sometimes even dangerous for humans, for example if the infection leads to life-threatening complications.
Infestation with roundworms: symptoms
The migration of roundworms through the human body leads to various symptoms. If the parasites remain in the intestines, this causes, among other things, unclear intestinal complaints with abdominal pain, nausea, vomiting, diarrhea and weight loss. Lung infestations, on the other hand, tend to trigger allergic reactions such as coughing and a slight fever.
Infestation with pinworms: symptoms
An infection with these threadworms typically causes itching in the anus at night because the females lay their eggs in this region. The nocturnal itching may be accompanied by sleep disturbances.
Infestation with whipworms: symptoms
- Abdominal pain
- Indigestion
- Weight loss
- Bloody diarrhea (diarrhea)
The nematodes also restrict the absorption of nutrients in the intestine, which can lead to a lack of nutrients and stunted growth (in children). Severe courses of the disease that remain untreated may lead to life-threatening complications in children.
Infestation with trichinae: symptoms
Experts estimate that symptoms only occur when 100 to 300 Trichinella are ingested. The stage that the parasites are currently in is also decisive for the symptoms. The type of trichinella and the strength of the human immune system also play a role and influence the severity of the disease.
A few days after infection, diarrhea (diarrhea) and abdominal pain are possible if the intestines are heavily infested with Trichinella. Patients develop a high fever (around 40 degrees Celsius), chills, severe muscle pain and swelling (edema) around the eyes. They may suffer from cardiac arrhythmia.
Other possible symptoms are
- Skin rash,
- Bleeding under the nails,
- conjunctivitis,
- headaches,
- insomnia,
- difficulty swallowing,
- dry cough,
- punctiform bleeding of the skin and mucous membranes (petechiae) and
Infestation with hookworms: symptoms
Where the larvae of these threadworms have penetrated the skin, itching and reddening of the skin develop. The larvae migrate to the lungs via the bloodstream or lymphatic system, where they cause shortness of breath and coughing, for example.
By coughing up the larvae enter the larynx and are swallowed. The parasites develop into sexually mature threadworms in the small intestine, where they survive for years. They cause symptoms such as upper abdominal pain, bloating, flatulence, constipation, diarrhea or weight loss.
Infestation with filariae: Symptoms
The symptoms caused by these nematodes depend on the type of parasite and the disease it causes (such as loa loa filariasis, onchocerciasis, etc.). Possible symptoms are for example
- Swelling and inflammation of the lymph vessels and nodes,
- fever attacks,
- massive swelling of the legs, genitals or other parts of the body (elephantiasis),
- itching,
- skin nodules or
- eye disorders.
Routes of infection and risk factors
Threadworms find their way into the human body in different ways:
Food contaminated with nematode eggs
Salad and raw vegetables may also be a source of infection if they have come into contact with contaminated faeces (e.g. during faecal fertilization) – infected people and animals excrete the threadworm eggs in their stool.
Contaminated objects
With pinworms, infection also occurs in other ways:
The females living in the human intestinal lumen (the cavity inside the intestinal loops) lay their eggs at the anus. This makes patients itch and causes them to scratch. This is how the pinworm eggs get onto the fingers and under the nails. If hygiene is poor, they may not only be transferred to food but also to objects (such as door handles), from where they can be picked up by other people.
Other routes of infection
For some genera of threadworms, there are other possible routes of infection: for example, they enter the human body in larval form through the skin (such as hookworms), are ingested by fleas living in water or are transmitted by insects (such as filariae).
Treatment
Anthelmintics are usually well tolerated if used for a short period of time. The longer the medication is taken, the more likely it is that side effects such as abdominal pain, nausea and diarrhea will occur.
Patients may be given other medication in addition to the anthelmintics. In the case of trichinellosis, for example, it may be necessary to administer antipyretics, analgesics and anti-inflammatory corticosteroids.
In the case of a threadworm infection, careful hygiene should also be observed (such as frequent hand washing). Further measures are recommended for pinworms, such as wearing tight underpants (to make it more difficult to scratch at night), clipping fingernails and boiling underwear and bed linen, towels, washcloths, etc. This helps to prevent the spread of the infection. This helps to prevent the spread of threadworms.
Preventing threadworms
To avoid infection with threadworms or other parasitic worms, hygiene (e.g. food and drinking water hygiene) and frequent hand washing should be observed. This applies in particular before eating, after using the toilet, contact with pets and gardening. Children should be reminded not to scratch their bottoms.
Plant-based foods should be carefully cleaned before consumption. This is especially true if you eat them raw (salad, vegetables, fruit). Always heat meat well (to over 80 degrees Celsius). Deep-freezing (at minus 25 degrees Celsius and for at least 20 days) also kills the Trichinella larvae.
When traveling (especially in regions with poor hygiene conditions), the advice when eating is: “Cook it, peel it or forget it!” Especially in tropical regions, it is also important to avoid walking barefoot and other direct skin contact with the ground.
These tips can often prevent threadworms from entering the body!
Description of nematodes
Nematodes are the parasites that most commonly infest humans. They are mainly found in tropical developing countries. However, some representatives also live in Europe – which is why it is also possible to contract this type of worm disease in this country.
What are nematodes?
Nematodes are elongated, thread-like worms that can reach a length of a few millimetres to one meter – and therefore resemble threads of different lengths. They move forward in a meandering manner.
The development cycle of the parasites runs from the egg through several larval stages to adult male and female worms. Well-known parasitic representatives of the nematodes are roundworms, pinworms, whipworms, trichinella, hookworms and filariae.
Roundworms
Infection with roundworms is the most common worm disease in humans. You can read how an infestation with these threadworms is detected and treated in the article on roundworms.
Pinworms
An infection with the pinworm Oxyuris vermicularis (Enterobius vermicularis) is known as oxyuriasis (enterobiasis) and mainly affects children – even in Germany. You can read more about these threadworms in the article Pinworms.
Whipworms
Whipworms belong to the species Trichuris trichiura. Tropical and subtropical areas are the main distribution area for these threadworms, which are around five centimetres long. Humans and animals (monkeys, pigs, etc.) are possible host organisms, but humans are the main host. Children in particular are infected with whipworms.
Trichinella
Various members of the genus Trichinella lead to infection (trichinellosis) in humans. The larvae of this form of nematode that infect humans are known as trichinella.
Trichinellosis occurs worldwide, but is now rare in Germany due to the legally prescribed meat inspection.
Hookworms
Hookworms that infest humans are Ancylostoma duodenale and Necator americanus. These blood-sucking threadworms, which are around one centimeter long, are widespread worldwide, especially in warm regions with poor hygienic conditions. They owe their name to their hook-shaped curved front end.
Filariae
These tropical threadworms are transmitted by insects and cause different forms of filariasis depending on the species. You can find out more about this in the article Filariasis.
Examinations and diagnosis
It is advisable to consult a family doctor or pediatrician if you discover worms or worm parts in your stool and/or have been suffering from unspecific abdominal pain for a long time. The same applies if a previously unknown itchy anus occurs repeatedly. Threadworms may be the cause of such symptoms. To clarify this, the doctor will first ask the patient to describe their symptoms in detail and ask questions such as:
- When does the anal itching occur?
- Have you been traveling recently?
- Has anyone around you recently suffered from a worm infestation?
- Intestinal obstruction (ileus): Roundworms may form “balls” in the intestine
- Appendicitis (inflammation of the appendix)
- Inflammation of the liver (hepatitis)
- Cramps
- shock
An infestation with pinworms can lead to appendicitis, especially in children. In women, the infection may lead to inflammation of the reproductive organs (ovaries, uterus, vagina). In addition, severe cases may lead to intestinal perforation (intestinal perforation).
Whipworms sometimes penetrate the intestinal mucosa, causing bleeding and anemia. If the worm infestation is very severe, possible consequences include
- Inflammation of the large intestine (colitis)
- Rarely appendicitis (inflammation of the appendix)
- Anemia
Trichinella infestation can also lead to dangerous and sometimes even life-threatening complications. These include
- Inflammation of the heart muscle (myocarditis)
- Inflammation of the brain (encephalitis)
- pneumonia
- Blood poisoning (sepsis)
- Circulatory failure
- Hypofunction of the adrenal glands (adrenal insufficiency)
- Psychotic states
- Coma and seizures
Stool sample shows threadworm infestation
In order to detect threadworms such as roundworms, pinworms, whipworms or hookworms, a stool sample from the patient is examined for eggs and larvae of the parasites. In the case of a heavy infestation, live worms can sometimes be seen in the stool with the naked eye.
Lung X-ray for roundworms
If the larvae of roundworms are currently migrating through the lungs, this can sometimes be recognized on an X-ray of the chest by cloud-like “shadows” (light spots).
Adhesive strip method for pinworms
If pinworms are suspected, the adhesive strip method is often used for clarification: A piece of transparent adhesive tape is stuck to the skin of the anal region, then peeled off and examined under a microscope to see if any worm eggs or worms can be detected. For a reliable diagnosis, it is best to make such a preparation on three consecutive days, as these threadworms do not lay eggs every day.
Antibody test and muscle biopsy for trichinellosis
In the case of trichinellosis, a sample of muscle tissue (from the biceps, pectoral muscle or deltoid muscle) is sometimes taken and examined for the parasites. This is because the larvae of these nematodes migrate into the skeletal muscles (especially in muscles with a good blood supply) and destroy muscle fibers.
Laboratory values
In the case of a threadworm infection (or another parasitic infection), the number of certain immune cells in the blood (eosinophil granulocytes) is increased. The increase in this subgroup of white blood cells is known as eosinophilia.
Other blood changes often occur, such as an increase in creatine kinase in trichinellosis. In this nematode infection, a urine sample is also examined for changes, for example an increased excretion of protein (proteinuria) as a result of kidney involvement.
Course of the disease and prognosis
A threadworm infestation has a good prognosis: the infection can generally be treated with medication without any problems.