Intestinal parasites

Intestinal parasites

A parasite is an organism that attaches itself to a “host” and causes harm as a result. The parasite uses the host as a source of nutrition, weakening it. The word parasite is derived from para-sitos; para means “beside” and sitos means “food”. It can be translated as “sitting at the table and eating along” (even though you were not invited). It describes organisms that live at the expense of the host. Worms and single-celled organisms (protozoa) are both parasites.

Causes

Single-celled parasites may be present in the intestine. These parasites, known as protozoa, are on average only hundredths of a millimeter in size; they cannot be seen with the naked eye. Protozoa often do little more than take up food and bacteria from the intestine, and you may notice very little. There are many harmless protozoa. However, symptoms can arise when intestinal parasites attach to the mucous membrane and cause inflammatory reactions. Irritation and swelling of the intestinal lining can cause abdominal distension, pain and diarrhea. Fatigue also commonly occurs. Protozoa that affect the small intestine cause loss of nutrients and can therefore lead to loss of appetite, weight loss or anemia. The most common intestinal protozoa are:

• Dientamoeba fragilis
• Blastocystis hominis
• Giardia lamblia
• Cryptosporidium spp.
• Entamoeba histolytica

Worms are larger and can be seen. However, they are not common in the Netherlands.

Testing for intestinal protozoa

The chance of a positive test increases when stool samples are collected on two different days. It is important to collect the sample during a period when symptoms are present and the stool is mushy. The tubes into which the stool is placed contain a liquid that prevents DNA from breaking down.

When there is an infection, several people are often infected, so the partner and other household members are also tested. This can help prevent reinfection within a household.

Giardia lamblia

G. lamblia infects the small intestine; an infection mainly causes abdominal pain and diarrhea. One function of the small intestine is to absorb nutrients. An infection with this parasite therefore has more consequences than an infection in the large intestine. In healthy people, the villi in the small intestine absorb nutrients, but when these villi are damaged, absorption is reduced. Not only food but also minerals such as iron can be lost as a result. Iron deficiency causes fatigue due to anemia.

Cryptosporidium spp.

Cryptosporidium is a parasite that invades the cells of the small intestine. In the Netherlands, this parasite is responsible for 2 to 3% of acute cases of diarrhea. It is also found in approximately 1% of people with mild gastrointestinal complaints.

The condition mainly occurs among young people. People with a weakened immune system and people with AIDS can develop severe diarrhea as a result of infection.

Blastocystis hominis

The parasite Blastocystis can be present in large numbers in the large intestine. Recent publications have shown that Blastocystis hominis is not always harmless. The most typical complaint caused by this intestinal parasite is a severely bloated abdomen and flatulence. Infection with this parasite can also cause abdominal pain, chronic skin rashes and flatulence. It appears that 70% of people with itching of previously unknown cause are infected with Blastocystis hominis.

Dientamoeba fragilis

Dientamoeba fragilis is 7–12 µm in size, does not form cysts and causes symptoms in half of infected people. Children often experience abdominal pain.

Entamoeba diapar

When Entamoeba is found, it is usually the harmless dispar form. Infection with this parasite is very uncommon in the Netherlands. Infection can only be acquired in tropical regions where this parasite occurs. E. histolytica occurs only in the tropics. After a visit to tropical regions and in cases of severe gastrointestinal complaints and diarrhea, the test can be requested through the hospital’s tropical medicine department.

Risk factors

You can acquire an infection through the toilet or through contact with people who carry parasites. The group at greatest risk of infection is children attending daycare. Because of close contact, children are infected with intestinal parasites more often than children who grow up at home.
When one person is infected, several people within the household are often infected as well. In the event of an infection, it is therefore important to test all household members. All infected people can then preferably be treated at the same time.

Testing and diagnosis

The only way to detect the presence of protozoa is to analyze the stool using a microscope or DNA analysis. To test for worms, the stool can be examined for the presence of worm eggs.

Prevention

Intestinal parasites are transmitted through contact with stool. However, not everyone becomes infected. Because most parasites can survive outside the body for an extended period, good hygiene is important. First of all, hands should be washed after using the toilet. The advice is to wash your hands after using the toilet, dry them with a paper towel, and use that towel to turn off the faucet and open the door. The only way to prevent the spread of harmful organisms is to wash your hands while also keeping the faucets and toilet door handle thoroughly clean.

Treatment

If intestinal parasites are detected, it is advisable to test the partner and other household members as well. If they are infected, they should also be treated. It is important to treat all household members at the same time.

Intestinal parasites are treated with conventional medicines. Treatment should always be prescribed by a doctor. In combination with medication, a low-starch diet can be followed and anti-inflammatory products can be used.

A follow-up test should be performed 7 days after the course of treatment. Hygiene measures should also be taken to prevent reinfection.

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