Feline Zoonoses – Bacterial Infections

What is feline zoonoses?

Zoonotic diseases are spread from animals to people and a number of bacterial, viral and parasitic infections can be passed from cats to
people. This article looks at bacterial infections people can catch from cats.

  • Streptococcosis
  • Pasteurellosis
  • Salmonellosis
  • Bartonella henselae (cat scratch disease)
  • Campylobacteriosis
  • Leptospirosis
  • Yersinia pestis (plague)

Prevention: In most cases, the risk of zoonosis is small if measures are taken to prevent transmission. That includes frequent hand washing, veterinary check-ups and infection control in the event of a disease outbreak.


Zoonotic diseases are diseases that can spread from animals to humans. In the case of this article, we are concentrating on bacterial infections only.

Very young infants, the elderly and people who are immunocompromised are at increased risk. Pregnant women should also be careful as some infections can harm the unborn child.

Cat bites are to be taken seriously. Cat mouths (as are human mouths) are teeming with bacteria, due to the nature of a cat’s teeth, when it bites you, bacteria are injected under the skin. If you are bitten by a cat, it is important that you go to your doctor who can prescribe antibiotics.

Most of these infections are rare and if you take proper precautions you will greatly reduce the chances of picking up a zoonotic disease.


Streptococci are gram-positive bacteria and infection can lead to death in kittens and puppies. Infection is rarely passed on from cats to humans. The most common strain of streptococcus in felines is S. canis. There are three forms of streptococcal infections in cats.

1) Epizootic

2) Neonatal

3) Localised

Epizootic is most often seen in large cat colonies.

Neonatal is most often seen in catteries. S canis can be found in the vagina of approximately 50% of queens. The rate of infections is higher in queens under 2 years of age. S canis is a cause of neonatal mortality.

Localised is most often seen can be isolated either by itself or as a part of a “mixed” bacterial infection from infections such as abscesses, pyometra, mastitis etc.


Penicillin is the antibiotic of choice in treating streptococci infections. Due to the overuse of antibiotics, there are some strains of streptococcus that have become resistant.


Pasteurella is a gram-negative bacteria that is a part of the oral flora in cats. Cats with tartar build-up and gingival disease have a higher rate of infection than cats with clean teeth.

Pasteurella is the most common disease to spread from cat to human which most frequently occurs via bites.


Swelling and local infection around the wound may lead to an abscess. More serious systemic symptoms can include sinusitis, pneumonia and brain abscess.


Antibiotics, usually penicillin, tetracycline or cephalosporin.


Most commonly known as a cause of food poisoning, there are almost 2,000 serotypes of the genus Salmonella. They live in the intestinal tracts of many species of mammals, birds, amphibians, and reptiles. Salmonella appears to be uncommon in cats, the rate of infection is higher in stressed cats, such as ones living in overcrowded conditions. Salmonella is shed orally, conjunctively and in the faeces. It can grow on food and can survive on objects for long periods of time. Cats often become infected from catching prey.


Salmonella can cause severe intestinal problems. One study in north-central Colorado showed less than 1% of cats carried the Salmonella bacteria.

Symptoms of infection are gastroenteritis, vomiting, diarrhea, and fever.


  • Treatment depends on the severity of symptoms. Due to the overuse of antibiotics, there are some strains of Salmonella that are now resistant, so some doctors may avoid the use of antibiotics in minor cases in both humans and felines. Chloramphenicol and trimethoprim-sulfonamides can treat salmonellosis.

Cat scratch disease

Caused by a recently discovered gram-negative bacterium called Bartonella henselae and is found worldwide. Cats are the main reservoir of CSD although puncture wounds and scratches from dogs, thorns, splinters and even fish bones have been implicated in a few cases too. It occurs in approximately 30%-41% of all clinically healthy cats. Although the bacterium is relatively common in cats, it is quite uncommon to catch CSD, which indicates that it’s quite difficult to catch. Fleas can transmit the infection from cat to cat.


Typical CSD

Usually, the first sign is a “lesion” which appears 1-2 weeks after the initial scratch. Lymphadenopathy…swollen lymph nodes (especially those in the armpits) and sometimes abscess 1-3 weeks after the scratch, headache, joint pain, lethargy, loss of appetite and flu-like symptoms lasting several weeks. 75-80% of cases are people under 20 years of age. In healthy people, CSD usually resolves itself, treatment is not necessary.

Atypical CSD

Bacillary angiomatosis is a syndrome found in immunocompromised people. Serious skin lesions develop, patients may develop a high fever, sweats, chills, poor appetite, vomiting and weight loss. If not treated, it can lead to death. Antibiotics can treat the condition.

12-29% of veterinarians have positive skin tests and 5% of healthy people in other jobs, which indicates that while they have had the infection, symptoms have been mild it not appear at all.


Campylobacter jejuni is a gram-negative bacterium that is responsible for gastrointestinal illness. It is one of the most common causes of gastrointestinal illness in the United States. Most cases of campylobacteriosis in humans are caused by handling or consuming contaminated food. Birds are a common reservoir of this bacterium and therefore care and safety when handling and cooking raw meat should be carried out. Thoroughly wash chopping boards and utensils used to prepare raw meat.

Cats can become infected with Campylobacter, which can then be passed onto their human owners via cat feces.


Fever, abdominal cramps, watery or bloody stools and usually begin 2 – 5 days after exposure. People infected should drink plenty of fluids.


Usually, this illness will resolve itself, if not antibiotics can be prescribed. It’s important to note that any case of vomiting or diarrhea should be seen by a doctor urgently. Young children can dehydrate quickly.

Rochalimaea henselae

(see Cat Scratch Disease)


Leptospirosis (canicola fever, hemorrhagic jaundice, infectious jaundice, mud fever, spirochetal jaundice, swamp fever, swineherd’s disease, caver’s flu or sewerman’s flu) is a bacterial infection caused by the species Leptospira. Leptospirosis can infect many species of wild and domestic animals although leptospirosis infection in cats is very rare. Cats have tested positive for exposure to leptospira but remain asymptomatic. This is possible because cats have a long history of exposure to this bacteria via their long association with rats.

Infection occurs via contact with infected urine either via the skin (especially broken skin) or the mucous membranes (eyes, nose, and mouth).


The incubation period varies from 2 days to 12 days. Symptoms include flu-like symptoms, headache, nausea. The patient usually recovers after 2 – 3 weeks. However, in some cases may develop into the most severe form known as Weil’s disease. Symptoms of Weil’s disease include jaundice, severe headache, and vomiting, bloodshot eyes. This may progress on to liver and kidney failure.


Penicillin, streptomycin, tetracycline, and erythromycin are antibiotics that are effective against leptospirosis.

Plague (Yersinia pestis)

Plague is a serious and life-threatening disease caused by the gram-negative bacteria Yersinia pestis. There are three types of plague (bubonic, septicemic and pneumonic). The most common mode of infection is via a bite from the rat flea (Xenopsylla cheopis), however, the infection can also occur in cats from eating rodents (including rats and squirrels) infected with Y. pestis. Cats can pass it on to humans in two ways, bringing in infected fleas which then go on to bite the human or if the cat is infected with plague it can pass it on via a bite or scratch.

Bubonic plague (infection of the lymph glands):

The most common form of plague and is almost always due to a bite from an infected flea. The bubonic form affects the lymph system.


Symptoms usually appear within 3 – 7 days after the bite and include flu-like symptoms, extreme exhaustion, and swollen/painful lymph nodes (called buboes) closest to the bite. Bubonic plague is not contagious.

Pneumonic plague (infection of the lungs):

Pneumonic plague is the second most common form of the plague and occurs when the Y. pestis bacterium infects the lungs. It may also occur in a patient who has untreated bubonic or septicemic plague and the bacteria spread to the lungs. Respiratory secretions spread this form of plague.


Coughing, frothy/bloody sputum, fever, difficulty breathing, and shock.

Septicemic plague (infection of the blood):

Septicemic plague is the rarest form of the plague and occurs when the Y. pestis bacterium infects the blood. Bubonic and pneumonic plague can also lead to septicemic plague. It is rarely contagious.


Fever, chills, abdominal pain, vomiting, exhaustion, bleeding under the skin.


Streptomycin is the antibiotic of choice. Tetracyclines and chloramphenicol are also effective.

Take-home points

Feline zoonosis is possible in households with cats, although the incidence is low. Ways to reduce risks include keeping cats indoors so that they don’t hunt, annual veterinary health checks, parasite control and frequent hand washing.

If you do receive a bite or a scratch from a cat, clean the area with antiseptic and see your doctor.

