Feline Fever. The Most Contagious Cat Disease Explained


Contagious diseases in cats are illnesses that can spread from one cat to another. Understanding feline contagious diseases is important for cat owners and veterinarians to help prevent outbreaks and properly treat affected cats. In this article, we will examine some of the most contagious cat diseases, looking at their causes, symptoms, transmission, prevention, diagnosis, and treatment options.

We will specifically focus on viral diseases like feline panleukopenia, feline immunodeficiency virus, feline leukemia virus, and feline infectious peritonitis. Bacterial and fungal contagious cat diseases like ringworm and feline calicivirus will also be covered. By the end, you will have a comprehensive overview of the most contagious feline diseases.

Being informed about these highly transmittable cat illnesses allows owners to safeguard the health of their pets. It also arms veterinarians with the knowledge to rapidly identify and treat outbreaks in their feline patients before they spread further.

Feline Panleukopenia

Feline panleukopenia (FPV) is a highly contagious viral disease caused by the feline parvovirus that affects cats. It is sometimes referred to as “cat plague” due to its severity. FPV attacks and destroys white blood cells, leaving the cat vulnerable to secondary infections. It has a mortality rate of 10-50%, especially in unvaccinated kittens under 5 months old.

Symptoms of FPV include fever, lethargy, loss of appetite, vomiting, severe diarrhea (often bloody), and rapid dehydration. The incubation period ranges from 2-10 days. The virus can survive in the environment for up to a year under optimal conditions.

FPV spreads through direct contact with infected cats or contact with contaminated feces, litter, food bowls, etc. It can also be tracked indoors on shoes and clothing. Thorough disinfection of the environment is necessary to prevent spread.

Prevention involves vaccinating susceptible cats and isolating or euthanizing sick cats. There is no specific treatment beyond supportive care such as fluids, antibiotics for secondary infections, anti-nausea medication, and nutritional support. FPV vaccination is considered a core vaccine for cats.

Feline Immunodeficiency Virus (FIV)

Feline immunodeficiency virus (FIV) is a lentivirus that causes an immunodeficiency disease in cats similar to human immunodeficiency virus (HIV) in humans. According to the Cornell Feline Health Center, FIV attacks and weakens the immune system so infected cats are more prone to other infections 1.

The most common symptoms of FIV include poor coat condition, chronic dental disease, infections of the skin, urinary bladder and upper respiratory tract. Other symptoms can include weight loss, swollen lymph nodes, diarrhea, eye discharge, poor appetite, and a fever 2.

FIV is spread through bite wounds, mainly by aggressive male cats. It can also spread from an infected mother cat to her kittens. FIV is not spread through sharing food bowls, grooming, sneezing or other casual contact 1.

There is no cure for FIV, but infected cats can live long healthy lives with proper care. Prevention includes neutering cats, especially males, to reduce fighting and potential spreading. Keeping cats indoors also reduces exposure risk. There is a vaccine available, but its efficacy is debated 2.

Feline Leukemia

Feline leukemia virus (FeLV) is a contagious retrovirus that infects cats. It is typically spread through saliva and nasal secretions between cats in close contact. An infected cat can spread FeLV to other cats through actions like grooming, sharing food bowls, and bite wounds from fighting. Kittens can also contract it from their mother in utero or while nursing.

The symptoms of feline leukemia can take months or years to develop. Common signs include lethargy, weight loss, poor coat condition, fever, diarrhea, enlarged lymph nodes, anemia, and a decreased ability to fight infection. Diagnosis involves a blood test to detect the presence of the virus. There is no cure for feline leukemia, but supportive care can help manage symptoms.

To prevent transmission, cats should be tested before entering a multi-cat household. Vaccination provides some protection, but primarily prevents development of disease rather than infection. Keeping cats indoors reduces their exposure. Routine testing, separating positive cats, and proper disinfection of items like food bowls and litter boxes can also limit spread. Unfortunately, FeLV is extremely contagious and challenging to control in environments like shelters and feral cat colonies.

Feline Infectious Peritonitis

Feline infectious peritonitis (FIP) is a viral disease caused by a feline coronavirus (FCoV). Most strains of FCoV are benign, but some can mutate into a virulent form that causes FIP. While FIP primarily affects cats under 2 years old, cats of any age can develop it. There is no cure, and it is ultimately fatal in cats who develop the disease.

According to research published in Viruses, FIP occurs when a benign FCoV mutates and is able to replicate within macrophages (a type of white blood cell). This mutated virus spreads systemically throughout the cat’s body and causes immune-mediated vasculitis – inflammation of blood vessels. The most common symptoms of FIP include persistent fever, weight loss, lethargy, diarrhea, vomiting, loss of appetite, jaundice, and abdominal or chest effusions (buildup of fluid in cavities).

FIP is not typically contagious from cat to cat. Most cats are exposed to benign FCoV at some point in their life, often as kittens. FIP develops when a cat’s immune system cannot effectively fight off the mutated form of the virus. According to Cornell University College of Veterinary Medicine, while FCoV is spread through feces, direct contact with an infected cat is unlikely to transmit FIP specifically. However, Cornell recommends isolating FIP-infected cats from other household cats as some research shows spread is possible.

There is no vaccine that can prevent FIP. But maintaining a clean litter box, eliminating exposure to possibly infected feces, reducing stress, and supporting immune health may reduce risk according to Mar Vista Animal Medical Center. Supportive care to manage symptoms is the main treatment for cats diagnosed with FIP.


Ringworm is a highly contagious fungal skin infection in cats. The medical name for ringworm is dermatophytosis. Ringworm is caused by several types of fungi in the genus Microsporum and Trichophyton. These fungi live on skin cells shed from infected cats. Ringworm gets its name from the circular lesions that can form on a cat’s skin.

Ringworm fungi thrive in warm, moist environments. The spores can survive in the environment for long periods. Ringworm is spread through direct contact with an infected cat or contaminated objects like bedding. The fungi are transmitted when their spores come into contact with abraded or broken skin. Kittens and cats with weakened immune systems are most susceptible.

Symptoms include round, red bald patches that appear scaly. The edges often form blisters and become crusty. Areas around the head, paws and ears are often affected first. As the infection spreads the cat may develop multiple lesions across its body. Ringworm causes severe itching.

To prevent spreading ringworm, affected cats should be isolated. All bedding should be cleaned and disinfected daily. There are antifungal shampoos, creams and oral medications to treat ringworm. Treatment can take weeks to months to fully resolve. Environment disinfection is key as well. With appropriate treatment and precautions, ringworm can be managed and eliminated.

Feline Calicivirus

Feline calicivirus (FCV) is a highly contagious virus that causes upper respiratory infections in cats. It is one of the most common causes of respiratory disease in cats and kittens worldwide (Feline Calicivirus, 2023).

The most common symptoms of FCV include (Feline Calicivirus Infection | VCA Animal Hospitals, 2023):

  • Sneezing
  • Nasal discharge
  • Ulcers in the mouth
  • Conjunctivitis
  • Fever
  • Lethargy

FCV spreads through direct contact with infected saliva, nasal discharge, or eye discharge. It can also spread through contaminated objects like food bowls, toys, and litter boxes. The virus can survive in the environment for several weeks if conditions are favorable (Feline Calicivirus: More Than A Cold – Animal Emergency Care, 2023).

To help prevent FCV infection, keep cats up-to-date on vaccines, isolate sick cats, disinfect surfaces, wash hands between handling cats, and limit contact with infected cats. There is no specific treatment for FCV beyond supportive care, but most cats recover within 2-4 weeks (Feline Calicivirus Infection | VCA Animal Hospitals, 2023).


Rabies is a viral disease that affects the central nervous system and is fatal once clinical signs appear. The rabies virus is spread through the saliva of infected animals. Cats most commonly get infected through a bite from wildlife like bats, raccoons, skunks, and foxes. Rabies can spread between cats, but this is very rare. The rabies virus incubates from 2 weeks to 6 months before signs start (source).

The initial symptoms of rabies in cats include behavioral changes like restlessness, hiding, and irritability. As the disease progresses cats may have seizures, paralysis, loss of appetite, weakness, disorientation, and fever. Eventually the paralysis becomes severe and leads to coma and death (source).

Rabies spreads through the saliva of infected animals. A cat can be infected through a bite wound from a rabid animal. Cats with rabies can potentially spread it to other animals and people through bites or saliva, but this is rare. The virus is usually dead within 10 days of clinical signs starting (source).

Prevention involves vaccinating cats against rabies and preventing contact with wildlife. There is no cure for rabies, so any potentially exposed cat should be quarantined and observed. If a cat bites a person, the wound should be washed thoroughly and medical attention sought.

Feline Herpesvirus

Feline herpesvirus (FHV-1) is one of the most contagious viral diseases in cats. The virus targets the feline’s upper respiratory tract, causing symptoms like sneezing, eye discharge, conjunctivitis, and open sores on the nose and lips. FHV-1 spreads through direct contact with infected secretions, like nasal discharge or saliva. It can also spread through shared food bowls, water bowls, and litter boxes. The virus can survive in the environment for several weeks. Kittens are especially susceptible if their mother has an active infection at the time of birth.

There is no cure for feline herpesvirus, but the symptoms can be managed through supportive care and antiviral medication. Isolating infected cats is crucial to prevent transmission. Vaccines are available and routinely given, but they don’t provide complete immunity. Prevention involves limiting exposure of kittens to infected cats, quarantining new cats before introducing them into the household, and maintaining a clean home environment.





In summary, the most contagious cat diseases are feline panleukopenia and feline calicivirus. Feline panleukopenia is a highly contagious viral disease that can cause severe illness and death in cats if left untreated. The feline panleukopenia virus is very resilient and can survive for months to years in the environment. Feline calicivirus is another very contagious viral disease that causes upper respiratory infections in cats. It spreads easily through direct contact and contaminated surfaces.

To prevent contagious diseases in cats, it is important to vaccinate kittens and cats according to veterinary guidelines. Kittens should receive a series of vaccines starting around 6-8 weeks of age, with boosters every 3-4 weeks until 16 weeks of age. Adult cats need boosters every 1-3 years depending on risk factors and lifestyle. Keeping cats indoors and away from strays can also reduce disease exposure. Proper hygiene and sanitation are essential, including disinfecting food/water bowls, litter boxes, and other surfaces regularly.

While contagious diseases in cats can be concerning, following veterinary recommendations for preventive care and being alert to signs of illness can help keep cats healthy. Consult a veterinarian promptly if a cat exhibits symptoms like fever, lethargy, vomiting, diarrhea, breathing issues, or discharge from nose/eyes.

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