Zoonotic diseases are diseases which can be passed from animals to humans. In the case of this article, we are concentrating on bacterial infections only.
People most at risk from zoonoses are the young and elderly and people with a compromised immune system such as those with HIV, chemotherapy patients, and organ recipients. Pregnant women should also be careful as some infections can harm the unborn child. Many diseases are passed from cat to cat via fleas, which enforces the important of proper flea control!!
Cat bites are to be taken seriously. Cat mouths (as are human mouths) are teeming with bacteria, due to the nature of 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. S/he will probably give you a course of antibiotics. It is important you make sure you're up to date with your Tetanus shot.
Before you panic, many of these infections are rare. If you take proper precautions you will greatly reduce the chances of picking up an infection from your cat.
Streptococci are gram-positive bacteria. It is often a cause of death in kittens and puppies. It 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.
Epizootic is most often seen in large cat 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 which have become resistant to antibiotics.
Pasteurella is a gram-negative bacteria. Pasteurella multocida found in the mouths of approximately 75-80% of all cats. Cats with tartar build up and gingival disease have a higher rate of infection than cats with clean teeth.
It is believed that Pasteurella is the most common disease passed from cat to human. Humans are usually infected via bites or scratches. Symptoms are usually a swelling and local infection around the wound, which may lead to an abscess. More serious systemic symptoms can include sinusitis, pneumonia and brain abscess.
Treatment is generally a course of 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 mammal, 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.
In humans, salmonella can cause severe intestinal problems, although salmonella infection from cats is not very common. One study in north-central Colorado showed less than 1% of cats carried the Salmonella bacteria. Treatment is generally dependent on the severity of symptoms. Symptoms of infection are gastroenteritis, with vomiting, diarrhoea and fever. Due to the over use 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 are used to treat salmonellosis.
Cat Scratch Disease (Cat Scratch Fever, Bartonellosis)
As the name suggests, Cat Scratch Disease is most often associated with cat scratches (although cat bites and licks can often lead to CSD too). It is 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 is found 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. It can be transmitted from cat to cat by fleas.
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.
Bacillary angiomatosis is a "syndrome" that is most often seen 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. Antibiotic treatment has been shown to cure the infection.
12-29% of veterinarians have shown 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 apparent at all.
Campylobacter jejuni (campylobacteriosis)
Campylobacter jejuni is a gram negative bacterium which 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 is 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. This includes thoroughly washing chopping boards and utensils which have been used to prepare raw meat.
Cats can become infected with campylobacter, which can then be passed onto their human owners via cat faeces.
Symptoms include 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 may 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.
(see Cat Scratch Disease)
Leptospira Infection (leptospirosis)
Leptospira (also known as also known as canicola fever, hemorrhagic jaundice, infectious jaundice, mud fever, spirochetal jaundice, swamp fever, swineherd's disease, caver's flu or sewerman's flu) is a gram-negative bacteria. Leptospirosis can infect many species of wild and domestic animal although leptospirosis infection in cats is very rare. It has been shown that cats have tested positive for exposure to leptospira but typically don't go on to display symptoms of illness. This is possibly 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 Weils disease. Symptoms of Weils disease include jaundice, severe headache, and vomiting, bloodshot eyes. This may progress on to liver and kidney failure. Treatment is a course of one of the following antibiotics: penicillin, streptomycin, tetracycline, and erythromycin.
Plague (Yersinia pestis) Infection
The plague is caused by a gram-negative bacteria known as 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, infection can also occur in cats from eating rodents (including rats and squirrels) infected with Y. pestis. Cats can pass it onto humans via two ways. Either 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 bubonic plague is the most common form of plague and is almost always caused by a bite from an infected flea. The bubonic form affects the lymph system. Symptoms usually appear within 3 - 7 days of being bitten 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 spreads to the lungs. This form of plague is passed from person to person. Symptoms appear within 2 - 3 days and include 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. It is usually contracted the same way bubonic plague is. Bubonic and pneumonic plague can also lead to septicemic plague. It is rarely contagious. Symptoms include fever, chills, abdominal pain, vomiting, exhaustion, bleeding under the skin.
Streptomycin is the antibiotic of choice. Gentamicin is used when streptomycin is not available. Tetracyclines and chloramphenicol are also effective.
Plague is an extremely dangerous disease and medical attention should be sought immediately if you suspect you or your pet have been exposed.