Cryptosporidium is a protozoal infection affecting the small intestine and occasionally the respiratory tract of cats.
Infection occurs via the fecal-oral route via contaminated water, food, objects or during grooming.
Symptoms don’t always show in healthy cats, in those who are immunocompromised or kittens, diarrhea, loss of appetite, low-grade fever and dehydration can develop.
There are no effective medications to kill the parasite, treatment is based on supportive care such as fluid therapy and nutritional support.
Cryptosporidiosis (or crypto) is the name of a protozoal infection affecting the small intestine and sometimes the respiratory tract of affected hosts. It is caused by single-celled parasites of the genus Cryptosporidium which infects a wide variety of vertebrates including cats, dogs, humans, horses, and livestock.
There are up to 50 sub-species of Cryptosporidium with have their preferred hosts. While cats (and humans) can be infected with sub-species normally found in other animals, infection tends to be less severe. The natural hosts of the sub-species have been included in bold font.
Cryptosporidium felis – Cats and occasionally humans (rare)
Cryptosporidium canis – Dogs and occasionally humans (rare)
Cryptosporidium (along with Giardia) are both well known protozoal infections which are common causes of waterborne disease.
It is estimated that up to 15% of cats in the United States have been infected with Cryptosporidium at some point in their lives. Cats from shelters have a higher rate of infection due to often crowded conditions.
Nonsporulated (non-infective) oocysts are pass in the feces of an infected host.
Most oocysts are thick walled and are infective when they are passed out of the body in the feces, according to the CDC, it may also be possible that oocysts pass out of the body by respiratory secretions . Each oocyst contains 4 sporozoites in each of 2 sporocysts. The zoites invade the intestinal cells and develop to the schizont stage. The schizonts release more zoites which invade new cells and give rise to the next generation of schizonts. There are 3 generations of schizonts. Zoites released from the last generation of schizonts invade cells and form gametocytes. The male gametocyte releases gametes which fuse with the female gametocytes and form oocysts.
A small number of oocysts are thin walled, and remain within the body which cause re-infection.
Infection occurs via the fecal-oral route. Once the oocysts have become infective in the environment they infect their next host in a number of ways.
Drinking contaminated water. This is usually from untreated water supplies such as lakes, dams etc., but occasionally the water supply can become contaminated.
Eating contaminated food. This may have occurred during preparation (unwashed hands, contaminated food preparation area), or during slaughter or infected prey.
Exposure to objects (fomites) which have been contaminated with oocysts such as food bowls, litter trays.
Ingesting oocysts from the coat during self or mutual grooming.
Healthy adults are often asymptomatic. Kittens under six months and immunocompromised cats are typically symptomatic. Symptoms can vary depending on the sub-species.
The most common symptom of cryptosporidiosis is watery diarrhea, other symptoms may include:
Diagnosing cryptosporidium can be difficult due to the small size of the oocysts.
Sent to a specialist laboratory for testing. The oocysts of Cryptosporidium are detected using the acid-fast stain technique, which stains the oocysts red. To increase the chance of an accurate diagnosis, several stool samples may be required.
To look for the presence of antibodies to Cryptosporidium, however, all this will show is that the cat has had exposure to the organism at some point in his life, but not if it is current.
Enzyme-linked immunofluorescent antibody (ELISA)
A stool sample added to a petri dish which contains cryptosporidium antigen. If the stool sample contains antibodies to Cryptosporidium, these will bind together with the antigen in the dish.
Can reveal the organism as well as damage to the lining of the intestines caused by the organism and the cat’s own immune response.
There are no effective medications to treat cryptosporidiosis in cats. A cat with a healthy immune system will rid themselves of the parasite in time.
Some veterinarians may prescribe antiprotozoal drugs to treat immunocompromised cats. These may include Tylosin, Paromomycin, Clindamycin, Azithromycin, and Fenbendazole.
Supportive care may be necessary. This may include nutritional support and IV fluids and electrolytes to treat dehydration and anti-diarrheal medications.
Can I catch cryptosporidiosis from my cat?
It is possible, yes although it would seem to be reasonably uncommon. As we have already mentioned, most strains of Cryptosporidium are host specific. Drinking contaminated water makes up the majority of human infections. C. parvum is responsible for most cases in humans, or C. hominis, which is specific to humans.
As with cats, a healthy immune system usually fights off the disease relatively quickly, however, it can have devastating effects on the immunocompromised, it is important to keep infected cats away from immunocompromised people.
It is always safer to assume that a cat infected with Cryptosporidium could potentially infect other pets and humans and take the appropriate safety precautions.
There is no foolproof way of preventing cryptosporidiosis, however, there are ways to reduce your cat’s exposure to the parasite.
Always make sure food preparation surfaces are clean when preparing food for you or your cat.
Wash your hands before preparing food for your cat.
How can I reduce the chances of catching cryptosporidiosis from my cat?
Scoop litter trays daily and empty once a week. Place solids in a plastic bag and dispose of in the outside garbage. Wear rubber gloves when handling litter trays.
Clean and disinfect the floor with a 10% solution of bleach.
Always wash your hands after touching your cat.
Never let immunocompromised people clean out litter trays.
Keep litter trays well away from food preparation areas.