Giardia lamblia: symptoms and therapy

Infection with Giardia lamblia (giardiasis) is an intestinal disease caused by microscopic parasites spread throughout the world, which occurs mainly in areas with poor hygiene and contaminated water sources.


What is a parasite?

Parasite is the general term for a living being that lives at the expense of another organism.

A parasite can drain energy from the host or even use it as protection without contributing to its well-being.
Human parasites include germs (fungi, bacteria, viruses and protozoa) and worms.

What is Giardia?

Giardia intestinal – also known as Giardia lamblia or Giardia duodenalis – is a single-celled parasite.
Giardia can infect the intestine and cause giardiasis, i.e. become an intestinal infection (gastroenteritis).

Giardia lamblia is found in two forms:

  • An active form, a so-called trophozoite
  • An inactive form, a so-called cyst

The active trophozoite attaches itself to the small intestine wall with an adhesive disc and, according to conventional medicine, causes giardiasis in about 20-30% of infected persons.
The trophozoite cannot survive outside the body for long.
The inactive cyst can survive outside the body for a long time.
After ingestion, acid and enzymes in the stomach cause the cyst to open, which releases a trophozoite.
Ten swallowed cysts are enough to trigger an infection.

In the small intestine, the giardia attaches to the intestinal wall, multiplies and leads to the following consequences:

  • Damage to the intestinal villi in the mucous membrane (inner wall)
  • Inhibition of the absorption of nutrients, resulting in fermentation
  • Reducing digestive enzymes produced by the intestinal lining, including lactase, which is used to digest lactose

The trophozoites produce cysts that can get into the stool and infect other people.

Transmission occurs by the oral-fecal route, i.e.:

  • About disease carriers such as flies that settle on infected feces
  • Due to lack of hand washing after using the toilet or due to contact with feces (for example, when changing diapers)
  • Sexual activities involving oral contact with faeces

It is unclear whether domestic or wild mammals can infect humans.

Is infection with Giardia dangerous?

As a rule, the infection with Giardia is not dangerous, but if the diarrhoea lasts longer than two weeks, dehydration can occur.

How does giardiasis spread?

Giardia is not transmitted through the blood, but can spread by:

  • Drinking water contaminated with Giardia. In a swimming pool, a person with diarrhea can contaminate all the water. Swallowing even a small amount of water from the pool that has been contaminated with germs can cause infection.
  • Eat something that came into contact with the feces of an infected person or animal.
  • Oral contact with surfaces or objects contaminated with feces of an infected person (for example, loungers, picnic tables, toiletries).

Symptoms of giardiasis

The period between the first contact and the appearance of symptoms is 7-20 days. In some cases, there are no symptoms.

What are the signs and symptoms of giardiasis?
In most cases, infection with Giardia lamblia is asymptomatic, some authors speak of 70%, while others assume 90%.

When symptoms occur, they may include:

  • Mild fever
  • Flatulence
  • Dehydration – in extreme cases
  • Abdominal cramps
  • Stomach ache
  • Loss of appetite
  • Indisposition
  • Nausea and vomiting
  • Watery, sometimes foul-smelling diarrhea
  • The stool may eventually be fat because giardia hinders fat absorption, but does not contain blood or mucus.
  • Watery diarrhea can alternate with constipation
  • Weight loss

Most patients get better within a few weeks, some recover after six months, and others take even longer.
Medication can contribute to faster recovery.

In some cases, chronic giardiasis may develop, the symptoms are:

  • Fullness
  • Diarrhea-like stool
  • Foul-smelling stool and flatulence

Complications of giardiasis

Diarrhea can lead to significant dehydration, especially in children and infants. It is important to drink plenty of fluids, preferably water.

Diagnosis of giardiasis

For diagnosis, an antigen test for Giardia and the search for cysts in the stool is performed.
Since cysts of Giardia are excreted through the stool, different samples must be taken discontinuously (3 stool samples on different days).
Trophozoites are found in the juice of the small intestine, but to find them, an endoscopy is required, which is an expensive and time-consuming examination.

Giardiasis – therapy and medication

Children and adults who have asymptomatic Giardia infection do not need treatment if they do not spread the parasites.
When symptoms occur, they usually improve over the course of a few weeks.
If the signs and symptoms are severe or the infection persists, medications such as:

  1. Metronidazole (Flagyl). Metronidazole is the most widely used antibiotic in giardia infection. The side effects may include nausea and a metallic taste in the mouth. During treatment with this drug, one should not drink alcohol.
  2. Tinidazole (Tindamax). Tinidazole acts like metronidazole and has the same side effects, but can be given in a single dose.
  3. Nitazoxanide (Alinia). This medication comes in liquid form, making it easier for children to take. Side effects may include nausea, bloating and yellowing of the eyes.

These drugs should not be taken during pregnancy because of potential harm to the unborn child. If mild symptoms occur, the doctor may decide to wait until after the third month of pregnancy with therapy.
If therapy is required, the most suitable therapy option should be discussed with the doctor.

Natural remedies for giardiasis and nutrition

According to naturopathy, bacteria, viruses, fungi and parasites multiply on dead or in decaying tissue, but they cannot feed on living tissue.
To combat Giardia, intestinal rot caused by protein foods must be avoided.
A diet based on natural, raw and vegetable foods in the right combination does not cause intestinal rot, because they are digested quickly.
In this environment, Giardia does not reproduce, but is excreted through bowel movements.

According to Shelton’s hygiene theory, drugs are of no use, on the contrary, they aggravate the situation, while the disease is cured in a few days by a few days of fasting (if the patient has no contraindications to this) and under the guidance of experienced therapists.

Garlic is a food with various beneficial properties, including the ability to counteract many intestinal parasite species, such as ascarids, giardia, trypanosomes, plasmodia and leishmanias.

Hydrastis is a useful plant against mucosal infections.
This plant contains berberine, a substance that acts against Giardia.

Prevention of Giardia infection

To prevent a Giardia infection, it is necessary to maintain good hygiene.

Advice for good hygiene:

  • Wash hands with soap and water before eating and after using the toilet, and also educate the children to wash their hands.
  • Wash hands with soap and water after changing diapers.
  • Dispose of diapers properly and wash clothes that have been contaminated.
  • If possible, do not swallow water when swimming.

Pre-treat drinking water accordingly during a trip or excursion. Possibilities for this are:

  • Boil drinking water for at least 10 minutes.
  • Add 5 drops of an iodine tincture to a liter of water (wait 30 minutes before use).
  • Iodine is much more effective at killing giardia than chlorine-based treatments.
  • Use a high-quality water filter.
  • When cooking, pay attention to the correct preparation of food.

Recovery times – prognosis

In healthy people, symptoms last for about 2-6 weeks.

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