Coccidia in Cats: Understanding the Parasite and Its Impact
Coccidia are microscopic, single-celled parasites (protozoa) that target the intestinal tract of cats. The most common culprits in feline infections are Isospora felis and Isospora rivolta, both of which are host-specific—meaning they only infect cats and not other animals or humans. Other less common species include Hammondia, Besnoitia, Toxoplasma, Sarcocystis, and Cryptosporidium.
Life Cycle and Transmission
Coccidia live within the cells lining a cat's intestine. They reproduce by forming oocysts—immature forms that exit the body through feces. These oocysts aren't immediately infectious; they require several hours to days (typically 7–10 days) in the environment to mature. Once mature (sporulated), they're highly resistant to environmental conditions and many disinfectants, surviving for months or even over a year on surfaces like soil or litter boxes.
- Cats become infected by ingesting these infectious oocysts from contaminated feces, water, food, litter boxes, or soil.
- Kittens often pick up coccidia from their mother's feces or contaminated environments.
- Eating prey such as mice or rats can also introduce certain coccidia species.
Direct contact isn't required for transmission—oocysts can be tracked around on fur and paws and ingested during grooming sessions.
Symptoms of Coccidiosis
The primary symptom of coccidiosis, the disease caused by coccidia infection, is diarrhea. This can range from watery to mucousy to bloody. Other possible signs include:
- Dehydration
- Weight loss
- Lethargy
- Abdominal pain
- Anorexia (loss of appetite)
- Vomiting
- Crying during defecation
Kittens are especially vulnerable; severe cases may lead to anemia or even death. Symptoms typically appear 3–11 days after ingesting infectious oocysts and often worsen with stress (like weaning or crowded living conditions). Many adult cats show no symptoms but can still shed oocysts and infect others.
Diagnosis of Coccidiosis
A veterinarian diagnoses coccidiosis by examining a fresh stool sample under a microscope using a fecal flotation test. Oocysts are tiny and sometimes hard to spot if few are present or shedding is intermittent. In ambiguous cases, PCR testing may help confirm infection. Diagnosis also considers the cat's history, symptoms, and ruling out other causes of diarrhea (such as bacterial or viral infections).
Treatment Options
Treatment usually involves oral medication. The most common drug is sulfadimethoxine (Albon), which doesn't kill oocysts directly but stops them from reproducing so the immune system can clear the infection. Treatment lasts 5–21 days depending on response. Alternatives like ponazuril, toltrazuril, or trimethoprim-sulfonamide combinations may be used if needed.
- Supportive care: fluids for dehydration, probiotics, dietary changes, anti-nausea medication.
- Severely ill kittens might need hospitalization with IV fluids.
It's crucial to complete all prescribed medication—even if symptoms improve early—to prevent relapse or ongoing environmental contamination.
Environmental Management & Prevention
Coccidia oocysts resist most household disinfectants. Effective cleaning includes:
- Daily removal of feces from litter boxes and living areas.
- Cleaning surfaces with diluted chlorine bleach (one cup bleach per gallon water) or steam cleaning for high-heat disinfection.
- Bedding, bowls, cages should be cleaned regularly.
Shelters and catteries should isolate litters when possible and use gloves between handling groups. Preventive deworming in kittens helps limit outbreaks. At home:
- Quarantine new/sick cats until tested clear.
- No raw meat feeding; control rodents indoors.
Kittens recover best with prompt treatment; those facing concurrent illness or stress are at greater risk for complications.
Zoonotic Risk & Human Safety
The common coccidia species found in cats don't infect humans or other animals. However, rare types like Toxoplasma gondii and Cryptosporidium can affect people—especially pregnant women and immunocompromised individuals—so good hygiene matters: wash hands after cleaning litter boxes, remove feces promptly, avoid feeding raw meat to cats.
No Vaccine Available
No vaccine exists for feline coccidia yet; prevention relies on hygiene practices and routine veterinary care.
