Giardiasis

Fabian Dupont is a freelance writer in the medical department. The human medicine specialist is already doing scientific work in Belgium, Spain, Rwanda, the USA, Great Britain, South Africa, New Zealand and Switzerland, among others. The focus of his doctoral thesis was tropical neurology, but his special interest is international public health and the comprehensible communication of medical facts.

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Giardiasis (Lamblia disease) is a diarrheal disease that is triggered by single-cell intestinal parasites. In some regions, up to a third of the population is infected with the parasite. It can cause irregular bowel movements or prolonged diarrhea. It can also be dangerous for children, people with previous illnesses and immunocompromised. Read everything you need to know about giardiasis here!

ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. A07

Giardiasis: description

Like malaria, giardiasis is triggered by so-called protozoa. These are single cells with a real nucleus. In the case of giardiasis, these small pathogens come from the group of giardia (lamblia). They are transmitted fecal-orally. This means that they are transmitted through food or drinking water that is contaminated with traces of an infected person's stool. This often happens when preparing food through "dirty hands" or contaminated drinking water.

Giardiasis is widespread worldwide, but is particularly common in southern countries. Depending on the hygienic conditions of the general population, up to a third of the population is infected.

More than 3,400 cases of giradiasis were reported in Germany in 2018. Especially those who return to travel bring the parasites with them from their vacation, especially from southern vacation regions such as India, Turkey, Egypt or other African countries.

Life cycle: giardiasis

The pathogens of giardiasis - the giardia (lamblia) - have a very simple life cycle:

The adult parasites (trophozoites) live in the furrows in the wall of the small intestine of infected people. As a rule, they do not leave the mucous membrane, so that the infection remains limited to the intestines. However, the Giardia change the surface of the intestine, which disrupts the absorption of nutrients and can cause deficiency symptoms as a result.

The pathogens can reproduce asexually by simply dividing and thus producing offspring. Some adult pathogens migrate along the intestines and turn into cysts (inactive stage): They surround themselves with a protective covering, with which they - if they are excreted in the stool - can survive in the outside world for a while until they enter the body another human being. For example, the cysts in (drinking) water can remain infectious for up to three months.

If the cysts are ingested by a person through food or drinking water, the cysts in the intestine develop again into fully grown trophozoites - the cycle begins again.

As mentioned, the giradia usually settle in the wall of the small intestine. In people with previous damage to the intestine or a weak immune system, however, they can break through the intestinal wall and cause "problems" in various other parts of the body (e.g. pancreatitis = pancreatitis).

Giardiasis: symptoms

Many people infected with Giradia show no symptoms at all, so they never see a doctor or receive treatment. However, if symptoms do occur, the recurring, weeks-long diarrhea is usually the main problem. Unexplained abdominal pain and bloating are other common symptoms of giardiasis.

Overall, the following symptoms are mainly possible with a Giardia infection:

Nausea and vomiting
colicky stomach pain
moderate, often frothy-watery diarrhea, possibly with blood
Flatulence
Edema, i.e. water retention in the tissue (in protracted cases of illness)
Malnutrition (in severe cases, because too few nutrients can then be absorbed through the intestine)
Inflammation of the pancreas or bile ducts (in the case of massive infestation or in people with weakened immune systems)

Since many people have no symptoms and therefore the disease is not recognized and treated, those affected represent a potential source of infection for others for a long time.

Giardiasis: causes and risk factors

The cause of giardiasis is infection with the unicellular organism Giardia intestinalis. Some sources call the parasite by its old name Giardia lamblia.

In addition to humans, the parasite also infects other mammals. Beavers, cats and dogs represent an important reservoir. A reservoir is the term used to describe animals that are home to the pathogen in nature and thus ensure the pathogen's survival, even if all people were treated efficiently.

Since the parasite is particularly transmitted through contaminated drinking water or food, one of the main risk factors is poor food hygiene. These prevail in many developing countries, so that there are around 200 million new infections worldwide each year. But there is also a risk of infection in southern and eastern Europe. The parasite is even native to Germany or the USA and infection is possible.

Some travelers get infected with Giardia in risk regions. Even weeks after returning home, the long-lasting, relatively mild diarrhea that is typical for giardiasis can occur.

Children are more likely to be affected by the infectious disease than adults. Infants who are breastfed are almost never infected. There is an increased risk of infection for those children who attend a day care facility (kindergarten, crèche). The likelihood of infection decreases with puberty.

Giardiasis examinations and diagnosis

Giardiasis pathogens can often be detected in (fresh) stool. Usually an immunological test for surface molecules of Giardia intestinalis. More rarely, the single-cell organisms are searched for using a microscope. As a rule, three stool samples, which have to be given at different times, are necessary for a reliable diagnosis.This increases the likelihood of actually recognizing an infection with giardiasis.

If the diagnosis of giardiasis in the stool is not successful, an intestinal biopsy may be necessary: the doctor takes a sample of the small intestinal mucosa. The pathogen can be detected in almost all infected people.

Giardiasis: treatment

Giardiasis can be treated with certain antibiotics and anti-worm drugs, although the pathogen is still a worm. Nevertheless, these two substances disrupt the parasite's metabolism and lead to its death. The doctor usually prescribes the antibiotic metronidazole or albendazole.

If the person concerned has lost a lot of fluid as a result of diarrhea, he is given special electrolyte solutions as a replacement.

Giardia infection should be treated even if there are no symptoms. The infected excrete the pathogen with the stool and thus represent a source of infection for others.

Course of the disease and prognosis

Giardiasis is a harmless but common parasite infection. Many patients are unaware of their illness. This is why it is so difficult to fight the parasite efficiently.

In patients with previous illnesses such as immunodeficiency or cystic fibrosis, where the intestinal barrier does not provide adequate protection, there is a risk that the Giardia will penetrate further into the body and make the person seriously ill. However, this is the exception. As a rule, there are no serious complaints. Giardiasis that has existed for a long time and has not been (adequately) treated can lead to deficiency symptoms because the absorption of nutrients in the affected intestine is disturbed.

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