Protozoan Infection in Cats

Protozoa are a type of microscopic, single-celled organism. Some of these tiny animals can live on their own, but many are parasites. While some don’t cause any harm for their hosts, others can cause serious illness. Cats that are hosts to harmful, parasitic protozoa may contract a protozoan infection. The type of infection, as well as the symptoms and treatment, will vary based on the type of protozoa present.

There are several different types of protozoa, and they can affect your cat in different ways. Many protozoan infections will affect the digestive system. While many cats won’t show any signs of infection, you should seek immediate veterinary attention if you notice any of the following symptoms:

• Severe diarrhea
• Weight loss
• Loss of appetite
• Difficulty defecating
• Dehydration
• Vomiting
• Mucus or oocysts present in feces

Some cats can become infected by protozoa that can also infect people. These protozoa will cause abnormalities in the feces and may spread to humans. If you notice anything unusual in your cat’s feces, dispose of it immediately and wash your hands carefully to prevent the infection from spreading.

Types

It is possible that cats can be infected by more than one type of protozoa at a time. There are three main types of protozoan infection in cats:

Amebiasis

This type of protozoan infection primarily affects the large intestine, causing inflammation and diarrhea. Amebiasis may also affect the liver and pancreas. Cats are exposed to this protozoan by eating or drinking contaminated food or water. This condition can also affect humans.

Coccidiosis

Cats develop this condition after consuming infected feces or prey animals. This infection usually affects kittens or weak animals, and they may not show any symptoms at all. Symptoms are most likely to appear if the cat is living in an unsanitary environment. In many cases, the infection clears up by itself.

Giardiasis

Giardiasis is prevalent in many species of animal worldwide. This condition will affect the small intestine and causes oocysts (protozoa offspring or “eggs”) to appear in the feces. Cats contract the disease through feces-to-mouth transmission. 

Several more types of protozoan infection exist, and many present the same or similar clinical signs. Your vet will be able to determine the type of protozoan infection upon diagnosis.

Protozoan infections occur when a cat comes into contact with a protozoan parasite. This can happen by ingesting contaminated food or water, coming into contact with infected cats (or, in some cases, humans), or ingesting the feces of affected animals.

Your vet will first perform a general physical exam to assess the cat’s overall health and symptoms. They will likely ask you if your cat has had any recent contact with other animals, particularly if they have been in an animal shelter or similar environment. Be sure to inform the vet of the extent and duration of your cat’s symptoms.

Because there are so many different types of protozoan infection, the best way for your vet to reach a definitive diagnosis is by examining the fecal matter. The vet may do this using a microscope or through fecal flotation. This process will involve mixing the fecal matter with a solution that will cause the parasites to float to the surface. The vet will then collect the parasites and place them on a slide to examine.

In some cases, particularly with the coccidiosis infection, illness may clear up on its own. However, it’s unwise to delay treatment based on this fact, as some protozoan infections have a high chance of recurrence and may become life-threatening.

It’s also important to note that, while your cat may test positive for protozoan infection, it may not be the cause of diarrhea. Your vet will be able to assess this during diagnosis, and then will start the appropriate course of treatment. Treatment may not resolve diarrhea if there is another cause apart from the infection.

Amebiasis is generally treated with an antibiotic regimen. Coccidiosis may not require any treatment, but if the animal is particularly ill or if the condition has recurred, treatment may involve any type of drug that is successful in fighting off protozoan infection. Giardiasis is usually treated in the same way, though treatment is not always effective and recurrence rate is high. In certain countries, a vaccine may be administered to prevent recurrence of Giardiasis. 

Dietary changes may also be recommended for many cases of protozoan infection. Your vet will discuss treatment options with you based on your cat’s specific needs.

Always follow your vet’s treatment instructions carefully. If your cat has been placed on an antibiotic regimen, it is imperative that you continue to administer the medication for the entire recommended duration of treatment. Failure to do so could result in aggressive recurrence.

It may be a good idea to regularly monitor your cat’s feces for signs of reinfection or ineffective treatment. Always dispose of infected feces and sanitize your hands afterward. Consult your vet immediately if symptoms do not resolve, as this may be a sign that another condition is causing diarrhea or abnormalities in the feces.

Certain protozoan infections are more likely to occur in unsanitary environments. Following an infection, you’ll need to disinfect all possible contaminated areas to prevent recurrence or spread to humans. It is important that you clean out your cat’s litter box regularly, particularly if you live in a multi-cat household. Always provide fresh, clean water as well.

Your vet will schedule at least one follow-up appointment for most cases of protozoan infection. They will perform fecal tests to ensure that there are no infectious parasites present in the feces.