Giardia Lamblia is a single-celled parasite, which settles in the cat’s intestines. The parasite also occurs in other species of mammals, such as humans.

It is transmitted via the fecal-oral route. This means that an animal defecates the cysts and that another animal, or human, infects itself with it through ingestion through the mouth. Often Giardia infections, in healthy animals, go without symptoms but periodically excrete the infectious cysts. However, in cats with less resistance, it does lead to disease symptoms. Young cats and cats with reduced resistance, for example, due to illness or stress, can get diarrhea from Giardia. Especially cats who stay in a shelter or guesthouse, or who come from a farm can easily become infected with Giardia. Giardia gives thin stools or mucky remarkably smelly diarrhea. Diarrhea may contain mucus and blood. You also often see that the cats are nauseous and vomit easily, but usually, they retain their appetite.

Giardia comes in two forms.

  1. The parasite stage = trophozoite.
    It shows itself as a tiny multicellular whip creature, which can only be seen with a microscope at high magnification. Reproduction takes place by bifurcation, and therefore the multiplication can be quite explosive. From each trophozoite, a cyst is formed.
  2. Cyst or also called an oocyte.This is a highly infectious stage. After excretion in the stool, the cyst is contagious under cold and humid conditions for weeks or even months.

The incubation time, the time between ingestion, and the onset of the disease is 5-16 days. The excretion of infectious cysts starts 7 days after ingestion and takes place intermittently for 4-5 weeks. This contagious period may be much longer if the animal re-infects itself. Nowadays, Giardia can be detected using a directly viable SNAP or ELISA test. This test is more reliable and sensitive than the previous microscopic method. Using the snap test antigens are identified, so both living and dead or disintegrated trophozoites or cysts are seen.

As therapy Metronidazole (e.g. Metrazol) or Fenbendazol (e.g. Panacur) can be given. Some Giardia strains are not sensitive to Metronidazole, but to Fenbendazole and vice versa. The cat can re-infect itself with oocysts, which have ended up in the coat. This can happen if diarrhea (containing the oocysts) sticks to the coat and is being licked. It is advised to wash the cat on the 3rd and 5th days. After the start of the treatment to prevent this. If stools are attached to the hair, this should be washed out immediately.

All the animals in the family should be treated. Good hygiene is essential. Clean and disinfect the environment where the animal lives and wash your hands after contact with the animal. Sometimes diarrhea continues even though the Giardia has been adequately controlled. Then the diarrhea is treated with hypoallergenic food and digestive enzymes (e.g., Tryplase or Pancrex).

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