Symptoms | Human parasites

Symptoms

Parasites can infest almost any region of the body. They can appear in the bloodstream, settle in the muscles or attack organs. Even the brain can be affected.

Often the symptoms are not directly associated with a parasite infestation because they are very unspecific. The symptoms usually appear some time after the parasite infestation. Depending on where the parasite has settled, a wide variety of symptoms can occur.

Inflammation can occur in the organs, which can even become chronic and lead to an overreaction of the immune system, which can damage the organ. Since the parasites feed on humans, the affected person usually suffers from a lack of nutrients. In addition, parasites excrete toxic metabolic products that can put a strain on the digestive or immune system.

  • Intestinal infestation: If the intestine is infested with worms, for example, this often leads to flatulence, constipation or diarrhoea.
  • Skin infestation: here it often comes to redness and itching
  • Respiratory infection: possible symptoms are coughing or shortness of breath
  • Urinary tract infection: incontinence can occur here
  • CNS-infection: here seizures or disturbances of consciousness can occur

Diagnosis

Since most parasites attack the intestines, the diagnosis is often made by a stool sample. As a rule, a stool sample is examined if parasitic infestation is suspected. This must be carried out over several days to obtain a meaningful result. But parasites can also be diagnosed by a blood test.Here, special antibodies against the parasites can be detected in case of infestation. In the case of lice (head lice or crabs), which are also parasites, the diagnosis can usually be made as a gaze diagnosis (see: Red spots on the scalp).

Where can parasites occur in the body?

Parasites can settle in very different places in the body. The affected region varies with the genus of the parasite. If parasites are infested, they can often be detected in the stool or blood.

Among many others, they can be found, for example :

  • In the intestine
  • Under the skin
  • In the brain
  • In the chair
  • In blood

Parasites that settle in the intestine are mainly worms (intestinal flukes, tapeworms, nematodes, roundworms, pinworms, etc.). Almost every second person harbors parasites in the intestine, but often this infestation goes unnoticed because it does not cause any symptoms. Parasites can easily enter the intestines through contaminated food or drinking water.

Especially through raw meat they are often transmitted. But also through insects, pets or other people (for example through sexual intercourse) parasites can get into the intestine. Parasites that enter the human body through the skin can reach the intestines via the bloodstream and settle there.

Some parasites can penetrate the wall of the colon and enter the bloodstream. This enables them to spread throughout the body. In the intestine, parasite infestation mainly leads to symptoms such as flatulence, constipation or diarrhoea.

In order to be able to detect parasites in the intestine, a stool examination is usually performed. Often, however, no parasites can be detected despite parasite infestation, as these are hidden in the mucus layer of the intestine or in so-called diverticula (bulges) and thus do not enter the stool. The stool should be examined on several days to obtain a meaningful result.

In addition, a blood test can determine whether antibodies against certain parasites have been formed. If a person is infested with parasites, it is important to pay strict attention to hygiene. Especially thorough hand washing after going to the toilet and after playing with pets should be observed.

Pets should also be regularly checked for parasites. Worms in the intestines can be treated with anti-worm products. An intestinal cleansing program often helps against the parasites in the intestine.

This not only cleanses the intestines but also strengthens the immune system and reduces the risk of a new parasite attack. Parasites can infest various parts of the body. These include the eyes.

One of them is the threadworm Onchorcerca volvulus, which occurs in Africa and some countries in South America. It is transmitted by black flies that can be found in water, which is why the disease is called river blindness. After infection, the parasites migrate through the connective tissue of the skin to the eye.

Often, those affected remain symptom-free for more than a year. The first signs are then more often itching, which increases and finally develops into dermatitis, i.e. an inflammation of the skin. The death of the individual parasites in the skin causes an inflammatory reaction.

Once in the eye, the nematode causes keratitis with subsequent scarring. In addition, the eye nerve is attacked and the nerve fibers die off. All in all, these changes lead to blindness of the affected person.

According to statistics, this is the second most common infection-related cause of blindness in the world. The parasite can be easily eliminated with the help of medication, but the infestation is often only noticed at a late stage, for example when vision is already deteriorating and irreversible damage has occurred. The nose can also be affected by parasites.

The parasite from the genus Leishmania attacks the mucous membranes of the nose, but also of the mouth or throat, causing the infectious disease leishmaniasis. Ulcers can develop and the affected patients report increased nosebleeds and difficult nasal breathing. Inflammatory processes can damage the nasal septum, which is why drug therapy is necessary.

Another parasite, Naegleria fowleri, in turn uses the nose as an entrance to the brain, where it can cause immense damage. Both types of parasite occur mainly in warm and humid regions of Africa or America.The liver is a popular organ for various parasites. Parasitoses of the liver usually occur after staying in tropical areas.

Schistosomes, for example, live in water and can bore through the skin to reach their host. In the body, they first lay eggs in the veins of the intestine, which are then washed into the liver via the portal vein, where they cause liver damage. The liver fluke Fasciola hepatica in turn enters the body via the oral route.

Once the larvae colonize the liver, they develop into flukes up to 3 cm in size. These can lead to hepatitis, liver cirrhosis and inflammation of the pancreas. The lungworm Paragonimus westermani is mainly spread in Southeast Asia and, as the name suggests, it attacks the lungs.

It finds its way into humans via freshwater crabs and crustaceans, which is why the consumption of raw shellfish carries a certain risk and can lead to infestation. After the worms have reached the duodenum, they penetrate the intestinal wall and the diaphragm until they reach the lungs. There the parasites encapsulate themselves and begin to lay their eggs.

Those affected suffer from lung paragonimiasis, which causes unspecific symptoms such as chills, fever and diarrhea. As the disease progresses, blood is repeatedly expectorated. The schistosomes already mentioned in the above section can also attack the bladder, where they implant themselves in the veins.

The eggs laid there cause a strong immune response from the body. Tissue of the bladder wall is destroyed and scarred, which often causes bleeding. This is indicated by blood found in the urine of those affected.

The severe destruction of the urinary tract ultimately causes incontinence. This clinical picture is known as bladder bilharzia and is the most common parasitic disease after malaria. Some parasites enter the body through the skin by drilling into the upper layers of the skin and settling there.

This is the case with scabies, for example. This disease is caused by mites digging tunnels in the skin. Soft, thin and moist skin areas are mainly affected, such as the spaces between the fingers or the genital area (see: Eczema in the genital area).

Itching is very severe and usually occurs at night. Mites can be transmitted through body contact or through the laundry. Mites are treated by applying special creams.

There are also so-called house dust mites. Some people are allergic to these mites. These mites in bed do not cause a skin rash, unlike the mites that cause scabies.

Also the so-called “skin mole” settles under the skin of humans. These are larvae of the hookworm, which can be transmitted to humans by dogs or cats. Humans are not suitable hosts for the larvae.

Nevertheless, they dig corridors under the human skin, causing severe itching and redness. Sometimes they also blister on the skin. The larvae can be killed by applying certain creams.

When infested with fly maggots, the blowflies lay their eggs on the mucous membranes or in wound secretions. The larvae hatch from the eggs and penetrate the skin. Painful knots appear under the skin.

Via the bloodstream, parasites can also penetrate into the brain. More than half of all people have antibodies against the parasite Toxoplasma gondii (toxoplasmosis), which are caused by previous contact with the toxoplasmosis pathogen. The parasite can be transmitted to humans via cat feces or raw meat.

Toxoplasma gondii influences the hormone production of dopamine in the brain. This has effects on human movements and behaviour. The infestation is noticeable by long-lasting flu-like symptoms.

It is being discussed whether the pathogen possibly plays a role in diseases such as schizophrenia, Parkinson’s or ADHD. If a patient complains of symptoms such as diarrhea, constipation or flatulence and no cause is initially found, the stool can be examined for parasites. The infestation of the intestine by intestinal parasites can be the cause of these unspecific complaints.

In order to obtain a meaningful result, the stool is examined on several days, as some worms cannot be directly detected in the initial phase.If parasites are found in the stool, appropriate therapy must be initiated to combat the intestinal parasites (often worms). Various drugs are suitable for this purpose. In addition, intestinal rehabilitation is one way to restore the normal healthy intestinal flora.

If the parasites are in the bloodstream, antibodies against the parasites can usually be found in the blood test. This is carried out if no parasites can be found in the stool sample when a parasite infestation is suspected. In addition, if malaria is suspected, a blood test for parasites must be carried out. If the parasites are in the bloodstream, they can reach almost any organ of the human body and cause damage there.