The Top Contagious Cat Infections Explained


Cats can get a variety of infectious diseases from other cats. These feline infectious diseases spread through direct contact, shared items like food bowls, or through the environment. Some of the most common feline infectious diseases that can spread between cats include:

  • Feline panleukopenia
  • Feline immunodeficiency virus (FIV)
  • Feline leukemia virus (FeLV)
  • Feline calicivirus
  • Feline viral rhinotracheitis
  • Ringworm
  • Feline chlamydiosis

While prevalence varies, studies show some feline viruses like FIV may infect up to 30% of free-roaming cats in certain areas (Stojanovic et al. 2011). Even common feline viruses like feline calicivirus infect most cats at some point. However, the risk is much higher for unvaccinated outdoor cats in multi-cat households.

These infectious diseases spread through infected saliva, respiratory secretions, urine, or feces. Shared litter boxes, food bowls, and close contact facilitate disease transmission between cats. Kittens and cats with weakened immune systems are most vulnerable to developing full-blown infections.

Feline Panleukopenia

Feline panleukopenia is caused by a highly contagious parvovirus that can spread rapidly between cats ( The virus attacks and destroys white blood cells, leaving cats extremely vulnerable to secondary infections. Feline panleukopenia most severely affects unvaccinated kittens under 5 months old.

Symptoms include high fever, lethargy, vomiting, severe diarrhea, and rapid dehydration and weight loss. There is no specific treatment beyond supportive care such as fluids, electrolytes, anti-nausea medication, and antibiotics for secondary infections. The mortality rate can be over 90% in untreated cases, but early and aggressive treatment and nursing care can significantly improve survival chances.

Vaccination is key to preventing outbreaks of this devastating disease. All kittens should receive a series of vaccines starting around 6-8 weeks of age, with boosters every 2-4 weeks until 16-20 weeks old. Adult cats need regular vaccine boosters as well. Isolating sick cats, proper disinfection, and good hygiene practices also limit transmission.

Feline Immunodeficiency Virus

Feline immunodeficiency virus (FIV) is a lifelong viral infection that progressively attacks the immune system of cats. FIV is species-specific and cannot be spread to humans or other non-feline species. The virus is transmitted primarily through bite wounds, and commonly causes disease due to chronic immune activation and dysfunction1.

Once infected, most cats develop flu-like symptoms that resolve within a few weeks. However, FIV never leaves the body and progressively weakens the immune system over months or years. This leads to an increased susceptibility to secondary, opportunistic infections. There is currently no cure for FIV, but infected cats can live normal lifespans if given appropriate care and monitoring2.

Preventing FIV relies heavily on keeping cats indoors and avoiding exposure to unknown cats who may carry the virus. Early testing and diagnosis can help manage FIV infections. Though incurable, properly cared for FIV-positive cats can live many healthy years before the virus impacts their quality of life3.

Feline Leukemia Virus

The Feline Leukemia Virus (FeLV) is a retrovirus that attacks and replicates in the cat’s bone marrow and lymphoid tissues that make up the immune system. This results in immunosuppression and can lead to diseases like anemia, immunodeficiency diseases, and leukemia in infected cats.

FeLV is spread from cat to cat primarily through saliva and nasal secretions. The main means of transmission are from bites, mutual grooming, and sharing food bowls and litter trays. It can also spread from an infected mother cat to her kittens either before birth or while nursing.

All cats should be tested for FeLV. The most common test is an ELISA test that detects antigens produced by the virus in the bloodstream. There is no treatment for FeLV, but supportive care like antibiotics, fluids, and vitamins can help support the cat’s health. Prevention is key through testing and keeping FeLV negative cats separate from infected cats.


Feline Calicivirus

Feline calicivirus (FCV) is a common upper respiratory infection in cats that causes oral ulceration and upper respiratory tract disease. It is extremely contagious and spreads through saliva and nasal and ocular secretions. FCV has been found in up to 90% of cat households unless there is strict isolation (Feline Calicivirus – an overview).

FCV often causes relatively mild symptoms, including sneezing, nasal discharge, conjunctivitis, and fever. However, it can also lead to severe oral ulceration and pneumonia. The virus damages the epithelium of the upper respiratory tract, causing ulceration that allows secondary bacterial infections. There is a high rate of mutation with FCV, leading to variable strains and clinical manifestations (Long-term analysis of feline calicivirus prevalence and viral …).

Infected cats shed the virus in saliva and respiratory secretions for up to 6 weeks, even after clinical recovery. The virus can survive in the environment for several weeks. These factors make FCV highly contagious between cats in the same household or shelter environment. FCV is generally an upper respiratory infection but can occasionally cause lameness.

Feline Viral Rhinotracheitis

Feline viral rhinotracheitis is a highly contagious respiratory infection caused by feline herpesvirus type 1 (FHV-1) that affects cats. The virus targets the upper respiratory tract, including the nose, throat, trachea, and sinuses.

FHV-1 is extremely contagious and spreads easily between cats through direct contact or airborne droplets from sneezing and coughing. The virus can survive in the environment for several weeks. Cats most at risk are those under 1 year of age, especially kittens 2-4 months old. Kittens experience more severe symptoms than adult cats.

Common clinical signs include sneezing, nasal discharge, conjunctivitis, fever, lethargy, loss of appetite, and ulcers on the tongue, mouth, and nose. In some cases, pneumonia may develop. Most cats recover within 2-4 weeks, but FHV-1 establishes lifelong latent infection. During periods of stress or immunosuppression, the virus can reactivate and cause recurrent infections (VCA Hospitals).


Ringworm is a highly contagious fungal infection that cats can transmit to each other through direct contact (source). The medical name for ringworm is dermatophytosis, and it is caused by three types of fungi – Microsporum canis, Microsporum gypseum, and Trichophyton mentagrophytes (source). Ringworm often presents itself as circular, red, raised lesions with a scaly edge and hair loss. It can appear anywhere on a cat’s body including the head, legs, and tail.

To treat ringworm in cats, most veterinarians will prescribe an oral antifungal medication like itraconazole or terbinafine. Topical antifungal medications like miconazole may also be prescribed. For mild cases of ringworm, an antifungal shampoo containing chlorhexidine, miconazole, or ketoconazole can be effective. Environmental decontamination is an important part of treatment, which involves thoroughly cleaning and disinfecting any bedding, toys, food bowls, etc. that the infected cat had contact with. Ringworm can persist in environments for up to 18 months if proper cleaning is not done.

Feline Chlamydiosis

Feline chlamydiosis is a bacterial infection caused by Chlamydophila felis that can spread between cats. It often causes respiratory issues like conjunctivitis, rhinitis, and pneumonia. Infected cats may have eye discharge, sneezing, coughing, and fever. Kittens are especially susceptible.

Chlamydiosis is diagnosed through tests like conjunctival and pharyngeal swabs, immunofluorescence assays, and PCR. It can be treated with antibiotics like azithromycin, though the infection can persist. Keeping infected cats separate from other cats is important to prevent spreading chlamydiosis. Vaccines may help reduce infection risk.



There are several ways cat owners can help prevent the spread of infectious diseases between cats:

Vaccination is one of the best defenses against many feline infectious diseases. Core vaccines that all cats should receive include panleukopenia virus, herpesvirus, calicivirus, and rabies. Vaccines are also available for feline leukemia virus and other diseases. Following vaccination schedules and guidelines provided by a veterinarian is crucial.

Proper hygiene and sanitation can limit transmission opportunities. Litter boxes should be cleaned daily and food and water bowls washed regularly. Any toys, bedding, or surfaces should be disinfected frequently. New cats should be kept separate until properly vetted and vaccinated.

Limiting contact with infected or unknown cats can reduce exposure. Keeping cats indoors, avoiding shared outdoor spaces used by strays or ferals, and preventing contact with sick cats helps stop disease spread. Catteries and shelters should isolate incoming cats until health status is determined.

Regular veterinary wellness exams allow early detection and treatment of infectious diseases in cats. Annual testing and preventative care is recommended. Consulting a vet can ensure the best disease prevention plan for each cat.


There are many infectious diseases that cats can transmit between one another. The most common and concerning are feline panleukopenia, feline immunodeficiency virus, feline leukemia virus, feline calicivirus, feline viral rhinotracheitis, ringworm, feline chlamydiosis. All of these diseases can spread rapidly between cats in close contact and some can be fatal if left untreated.

To prevent the spread of disease, cat owners should keep their cats up to date on vaccines, practice good hygiene, isolate new cats before introducing them, and take cats showing any signs of illness to the veterinarian right away. Routine veterinary care is crucial for catching diseases early and stopping contagions.

While feline infectious diseases can be scary, the good news is that most are preventable and treatable with proper medical care. By staying informed and working closely with a veterinarian, cat owners can help protect the health of their furry friends.

Scroll to Top