What is Giardiasis?

Giardia lamblia is a protozoan (single celled organism) parasite which is found in the small intestine of vertebrates including mammals. Infection with Giardia lamblia causes giardiasis.

Giardia causes severe diarrhoea, dehydration & stomach cramps.

How do cats become infected with Giardia?

The most likely transmission in cats is direct animal to animal (fecal-oral route). Cats can also become infected by drinking water containing the infective cysts. Once inside the intestine the cyst opens releasing two trophozoites.

There are two stages to the life cycle. Trophozoites are the active motile (swimming) form & it is in this stage that lives in the intestines feeding & reproducing. The trophozoites have flagella, which are long hair like structures which enables toe protozoa to move around. During the feeding stage, the parasite replicates in the small intestine by binary fission (this is the asexual reproductive process where one cell divides into two cells.

The trophozoites move towards the colon where they produce a cyst wall. The trophozoite within the cyst divides once, and this mature cyst now contains two trophozoites. This cyst is carried away by the passing fecal stream & leaves the body. [1] These cysts are extremely hardly and can survive for long periods in water.

What are the symptoms of Giardia in cats?

The parasite has a one to two week incubation period. Most cats are asymptomatic, although they may keep passing on cysts for months or years. Clinical signs are most likely to be seen in younger animals from multi-cat households/environments.

If large numbers of trophozoites develop the cat will develop symptoms which include;

Fecal flotation (zinc sulfate solution) may be used to detect cysts. Cysts may not be present in the stool of a cat with diarrhoea. Fecal smears may detect the  active trophozoites. These are more likely to be seen moving around in watery stools & cysts are more commonly found in firm stools. A negative sample doesn't necessarily rule out giardiasis. Three stool samples should be studied over a period of 7 - 10 days before a definite diagnosis is made.

ELIZA is another method of testing for giardiasis. This may either be performed in your veterinarian's office of sent off to a laboratory for testing.

How is giardiasis treated?

Your veterinarian will prescribe whichever drug they feel is best to treat giardiasis in your cat.

Can I catch giardiasis from my cat?

This answer is still not entirely known so it is safe to err on the side of caution & presume it is possible to catch giardiasis from cats & practice strict hygene.

References:

[1] The Cornell Book of Cats (page 311).