Dangerous of cat related diseases

Dangerous of cat related diseases
Zoonoses (also called zoonotic diseases) are diseases that can be passed from animals to man. Most diseases are species specific. Humans don't catch cat flu despite urban legends to the contrary. Most zoonotic diseases can be avoided through good hygiene - disinfecting areas which have become contaminated, washing hands after handling contaminated items (including cats) and wearing rubber gloves to prevent infectious matter entering skin wounds. The majority of diseases pose no threat to humans and can be treated by your doctor. A few are more dangerous to those with poor immune systems and a very small minority are unquestionably dangerous e.g. rabies.

There are very few diseases of the cat that are zoonotic (transmissible from cat to human). It is fairly rare to pick up a disease from a cat. It is recommended that you take your cat to the vet for a thorough check up before your baby is born. Keeping your cat indoors and away from roaming cats is your safest way to keep your cat disease and parasite free.

Common examples of zoonoses are toxoplasmosis (a protozoan), psittacosis (virus) and ringworm (fungus). Toxoplasmosis is a protozoan which can be spread from cats and a wide variety of other sources to humans. A pregnant woman who contracts toxoplasmosis risks having a baby with congenital defects. Psittacosis is an upper respiratory infection usually caught from cage birds e.g. parrots. It is a chlamydial infection of birds which can cause pneumonia in humans. Although easily cured in healthy adults, it is dangerous to the very young, very elderly and to those with a poor immune system. Psittacosis also causes chlamydial eye and respiratory infections in cats. Ringworm is a fungal skin disease which for most people is more irritating than dangerous, though it can cause scarring (due to constant scratching) and may be of concern to individuals with poor immune systems.

This a short and simple owner's guide to common zoonoses. A web-search will provide in-depth information on any of these infections. If you have any concerns, your veterinarian and your doctor will be able to provide information. Remember - zoonoses are only newsworthy because dangerous ones are so rare! Many pet owners have probably had zoonotic illnesses without even noticing the symptoms.


Bacteria are usually secondary infectious agents that follow viral or mycobacterial infections. Bacteria may be present in diarrhoea which is an effective means of cross-infection (solid stools buried in litter are less infectious). Common zoonotic bacteria include species of campylobacter, streptococcus and staphylococci; these generally respond to antibiotic.

However, some cat breeders now routinely dose their cats on antibiotics in an attempt to reduce disease in the cattery. This is leading to an increase in antibiotic-resistant strains of bacteria. The problems of resistant bacteria have already been encountered in the livestock/poultry industry, caused by too many animals in too little space and routine dosing with 'preventative' antibiotics.

  • Feline conjunctivitis can be caused by a variety of conditions including bacterial or viral infections; conjunctivitis caused by a foreign body may lead to a secondary bacterial infection. Since some of these germs can also infect humans, it is wise to observe basic hygiene precautions when handling cats with conjunctivitis. Most cases are easily treated in both cats and humans by eye drops and eye ointments - often containing the same active ingredients!

  • Persistent streptococcal infections in cats can cause tonsilitis and pharyngitis in the owners.

  • Pasteurella is possibly the most common bacterial zoonosis, carried in the mouths of up to 75% of cats. Cat bite wounds should be always be cleaned carefully with antiseptic or antibiotic cleansers and an antibiotic ointment applied. Any sign of wound inflammation, persistent swelling or fever should be referred to the doctor as it may require oral antibiotics. Most healthy adults will recover without treatment; but you may not wish to risk your health.

  • Salmonella bacteria is more common in the faeces of cats fed raw meat or those that catch wild birds. Infection follows a faecal-oral route (you clean the litter tray and scratch your lip without first washing your hands).

Cat Scratch Disease

Cat Scratch Disease is caused by the bacteria Bartonella henselae (formerly called Rochalimaea henselae). Despite its British common name, it does not usually cause fever. The bacteria is carried by cat fleas. Cat Scratch Disease causes systemic illness and lymph node lesions and can be very serious in individuals with poor immune response. Antibiotic therapy usually cures the disease without complications in healthy young adults. Clearing the bacteria from infected cats requires long term antibiotic treatment, however, and cats may be continuously or intermittently infected indefinitely. Studies in the United States suggest 20-40% of cats carry the disease. The figures will be different in other countries due to different cat-keeping habits.

Cat Scratch Disease was first described in 1950 and aroused considerable interest for the next twenty years, with hundreds of case reports in medical literature. Early attempts to identify the causal agent failed and the diagnosis was made on clinical criteria such as lymphadenopathy and a history of animal contact, positive skin test results, negative laboratory findings for other causes of lymphadenopathy and/or characteristic histopathology of lymph node biopsy. In healthy humans, Cat Scratch Disease is usually a benign self-limiting infection and is usually diagnosed too late for any action to be taken (i.e. the body already has it under control by the time a doctor takes samples).

There are at least eight species of Bartonella of which four (B. bacilliformis; B. elizabetbae; B. henselae and B. quintana) are known to cause disease in humans. B. henselae is thought to be the cause of Cat Scratch Disease although French studies also implicate B. quintana. Bartonella is a successful parasite of a wide range of mammals in that it usually causes no ill effects to its host. It is only when they get into the wrong host (e.g. humans) that disease is seen. Cats are unlikely to be the only source of infection. Other small mammals carry Bartonella, but humans are more likely to interact with cats than with other carriers so the cat is generally blamed. In up to 10% of cases there is no recognised cat contact.


Tuberculosis - Mycobacterium tuberculosis and related tuberculosis-causing mycobacteria can infect cats and be transmitted to humans. It is particularly dangerous to humans with poor immune systems e.g. with HIV. Since there is no fully effective treatment in cats, euthanasia is recommended to reduce the risk to humans. It is, however, a rare disease in cats.

Most viruses are extremely species specific. Feline Immunodeficiency Virus, Feline Infectious Peritonitis, and Feline Leukaemia Virus can not cause illness in people. A cat can not catch a human common cold, although there is indication that canine coronavirus infection may potentiate FIP in cats and human influenza can infect cats. As well as rabies, there are a few feline viral infections which can cause illness in humans. At the end of this section there is a specific note about feline coronaviruses to clear up the misunderstanding which arose when some newspapers mistakenly attributed the SARS coronavirus to cats (felids) instead of to civets (viverrids).

Rotaviruses cause diarrhoea in a number of species; the infection is usually transient and remedied with diarrhoea treatments. Rotaviruses can cross species and though affected cats are not considered infectious to humans, rubber gloves should be worn when clearing up diarrhoea and the affected area (litter trays, floors, carpets etc) disinfected as a precaution.


Rabies is a viral infection spread through saliva e.g. via biting or by saliva entering an open wound. It attacks the central nervous system causing a variety of symptoms (including behaviour changes) and is almost always fatal. Documented cases of human recovery are extremely rare. Carriers do exist but are uncommon. Rabies vaccines are available for cats and for humans, but post-exposure treatment is also required. Oral vaccines may be given to wildlife to limit the spread of rabies in the mammal population. An infected animal which has bitten a human is destroyed and presented for necropsy to confirm whether it was infected by rabies. Rabid cats generally exhibit the passive form or the disease and rarely become furious biters (the classical image of the disease) hence cat to human transmission is not common.

Feline Leukaemia (FeLV)

The idea of an infectious agent being the cause of a childhood leukaemia led researchers to wonder whether acute lymphoblastic leukaemia in children was caused by FeLV through close contact between children and cats. They had several reasons for suspicion. Firstly, FeLV is spread "horizontally" i.e. from cat to cat through close contact and interaction. Secondly FeLV can infect and multiply in cells from other species in laboratory conditions - in the laboratory, FeLV was able to multiply within human bone marrow cells. Thirdly there have been reported clusters of cancers or leukaemia in human patients and simultaneously in their pets.

FeLV is found in large quantities in saliva, blood and urine of infected cats. It is contagious among cats living in close contact or crowded conditions. It is spread from cat to cat through licking, scratching and biting. Cats may also lick, scratch or bite humans, exposing humans to the virus. Can the virus multiply in human tissue or cause outside of laboratory conditions?

Feline Immunodeficiency Virus (FIV, Feline AIDS)

A comparison between FIV and HIV shows that the two viruses differ virologicallv, pathologically, and epidemiologically. Although there is no evidence that FIV can infect or cause disease in humans, from a public health perspective it is often recommended that immunosuppressed people should have limited contact with infected cats. However, the risks are considered extremely small and for most patients, the benefits of feline companionship greatly outweighs any risk.

Chlamydia and Psittacosis

Chlamydia causes conjunctivitis in cats and, less commonly, respiratory symptoms. In humans it can cause pneumonia; however human infection (psittacosis) is generally from parrots and cage birds. There are only isolated cases of chlamydia being spread from cat to human.


Feline Cowpox is an uncommon virus which causes skin lesions in cats. There is no vaccine and treatment involves antibiotics to treat secondary bacterial infections. Cats are the source of about half of all human cowpox virus infections. Cat to human transmission can be prevented by basic hygiene precautions. Human infection is often limited to a single lesion on the hand or face (after touching it with an infected hand). Widespread infection and severe disease can develop in individuals with poor immune systems or pre-existing skin disease. Human cowpox can cause systemic illness with ‘flu-like symptoms, which may require hospitalization. Occasional human deaths have also been reported, but these are extremely rare. Smallpox vaccination may only provide partial protection. Those handling infected cats should wear gloves and take care not to allow infected material into wounds or the eyes. Young children, the elderly and those with a existing skin condition or with poor immune systems should avoid contact with the cat until its scabs have completely healed. The poxvirus is extremely hardy, and may remain infectious in dry material kept cool for several months or even years. It is susceptible to most disinfectants.


This section is included because of media confusion over the cat's role in SARS and headlines such as "SARS triggered by cat eating" which fail to distinguish between civet cats and true cats.

There are cat-specific coronaviruses, but these are not linked to SARS or to other zoonoses. True feline coronaviruses (FCoV) are Feline Infectious Peritonitis viruses (FIPV) and Feline Enteric coronaviruses (FECV). Although these two coronaviruses are closely related, FIPV causes a fatal disease in cats while FECV usually only causes milder, short-term enteritis ("tummy upset"). Neither is known to cause disease in humans.

Asian Bird Flu & Feline H5N1

The occurrence of H5N1 in domestic cats is due to eating raw chicken, proximity to infected farms, through contact with infected bird carcasses or through close contact with cats already infected. All the affected domestic cats had a high degree of exposure to the virus. Almost all cases of H5N1 in humans are traceable to infected chickens or infected wildfowl. Although cats are susceptible to the virus, they have not been found to pose a danger to humans. Thai pet owners took immediate precautions, switching meals from cooked chicken to beef. Owners were advised not to let their cats eat dead chicken carcasses, dead birds, or any dead animals found in infected areas. Cat lovers who feed the strays and semi-feral cats around temples were asked not to feed raw chicken. This aims to prevent H5N1 from jumping to other cats and reduces the risk of mutation.

By April 2006, there are still no known cases of bird flu transmitted from cats to humans. However, it is recommended that cats be kept indoors (and dogs be kept on the leash) in areas where H5N1 is confirmed.


Feline strains of coccidia and giardia do not appear to be infectious to humans. Giardia cause diarrhoea in cats and normal precautions should be followed when cleaning up; normally cats and humans are infected by the same source (contaminated water) not by each other.

Media attention is sometimes focussed on Toxoplasmosis, a type of coccidia that can cause birth defects in unborn babies. Toxoplasmosis, a disease of cats and other mammalian species, is caused by the protozoan parasite Toxoplasma gondii. Protozoa are single-celled animals and though infection with Toxoplasma is fairly common, actual disease caused by the parasite is relatively rare.

Ensure your cat is regularly de-flead and de-wormed. Make sure the products you use on your cat are safe to use around the baby. If you are worried about your cat scratching your baby, (which is highly unlikely) you can regularly trim your cat's claws.

Toxoplasmosis is caused by a parasite called Toxoplasma Gondii. Many animals can get Toxoplasmosis including sheep, cattle and pigs. Cats shed the parasitic cysts in their faeces and which then infect humans and other animals.
In healthy adults, Toxoplasmosis usually causes only mild symptoms. If a woman becomes infected during her pregnancy it can have devastating affects on the unborn fetus.

If you own a cat and are pregnant it is advisable to ask your doctor to do a blood test to see if you have antibodies to Toxoplasmosis, which would indicate a past exposure to the parasite. If you have been infected in the past, there is little to no risk of you passing it on to your unborn baby. If this is not possible, use rubber gloves and try to avoid inhaling any dust from litter trays, it is advisable to wear a mask. It takes between 24-48 hours for the cysts to become infective, so daily cleaning of the litter tray will almost entirely eliminate the risk of infection. It is perfectly safe for pregnant women to co-exist with their family cat as long as these precautions are taken.

It is wise to take some precautions. You can purchase a net to put over the crib so the cat can't sleep with the baby. Another good suggestion is to replace the door to the baby's nursery with a screen door. This enables the cat to see and smell the baby and not feel entirely left out, but it can't get into the bedroom.

If a cat is found close to the baby's head it's more likely due to the cat seeking some warmth. Make sure litter trays and food bowls are kept in an area the baby can't access, this is especially important when the child starts crawling. A safety gate is recommended to prevent your child getting close to the litter tray.

A large percentage of North Americans are already carriers of the disease and will never become sick. However it can be passed to the fetus by a woman who contracts it during pregnancy, and it can seriously harm the fetus because it is so fragile. In order to pass it on to the fetus the parasite enters the body orally usually by way of unclean hands that have touched infected cat feces or infected raw meat. It is therefore recommended that pregnant women avoid litter box duties if at all possible. If it's not possible then wear disposable gloves and a mask and put the feces into a sealed plastic bag before disposal. Wash hands thoroughly afterward.
It's true that toxoplasmosis is dangerous to pregnant women and can affect an unborn baby's brain and nervous system. But the disease is easily prevented. All you have to do is take a few precautions.

  •  Tell your obstetrician that you have a cat and ask her to run a toxoplasmosis antibody titer, a simple blood test that measures antibody levels for past and present infection. Previous exposure to the disease will cause a positive titer, which means you are immune and can no longer contract the disease or pass it to your unborn child.

  • Ask your husband or another family member to take care of your cat's litter box while you're pregnant. Toxoplasmosis is caused by a Toxoplasma gondii, a protozoan that a cat can pass in its feces. If you must tend to your cat's box while you're pregnant, wear rubber gloves when cleaning the litter box and wash your hands carefully when you're finished.

  • Clean the litter box daily. It takes three days for the Toxoplasma gondii's eggs to hatch and become infectious. So removing feces every day will help prevent infection.

  • If you work outdoors in soil, wear gloves, and wash your hands when you get inside.
    Signs of Toxoplasmosis are enlarged lymph nodes, rash, fever, muscle pain and fatigue. If you experience any of these symptoms ask your doctor to run a toxoplasmosis titer. If the test is positive, begin taking antibiotics immediately.

Cats acquire Toxoplasma infection by ingesting infected prey. The organisms multiply in the wall of the small intestine and produce oocysts, which are then excreted in the faeces for 2-3 weeks. Most cats shed oocysts only once after infection and are then effectively immune. Within 5 days the shed oocysts become infectious to other animals and to humans. Infectious "sporulated oocysts" are highly resistant to environmental conditions and can survive in moist shaded soil or sand for many months. Some Toxoplasma organisms migrate from the cat's intestine to muscle and brain but usually remain dormant. The same migration can also occur in humans. Congenital infection (transmission from mother to foetus) occurs in sheep, goats, and humans.

In humans, toxoplasmosis symptoms may be flu-like, in most cases there are no symptoms. Infection is more serious in individuals with poor immune response. If such people contract toxoplasmosis for the first time it can run riot in the body with the immune system unable to keep it in check. In people who have previously been infected, the dormant tissue cysts are activated. Stress can also activate dormant cysts. Activated tissue cysts can produce millions of toxoplasmas which can lodge in the heart or brain and other major organs.

Congenital infection is of greatest concern in humans; especially in pregnant women who contract toxoplasmosis for the first time while they are pregnant. They may show no symptoms themselves, but the foetus may suffer birth defects including blindness and brain damage. Since most cat-owning women have already been exposed to toxoplasmosis (and hence do not become reinfected), this is uncommon which is why it causes headlines. Most infected babies are born healthy, but with dormant toxoplasmosis cysts, in later life these may lead to reduced vision and loss of sight.

Cats are not the main source of toxoplasmosis infection in humans. In industrialised nations, poorly cooked meat is a much more significant source of infection, particularly lamb and pork (in many areas of the world, approximately 10% of lamb and 25% of pork products contain Toxoplasma cysts). The vogue for 'rare cooked' meat is part of the problem. Contact with contaminated soil is a major means by which toxoplasmosis is spread - including soil of vegetables. The organism may be present in some unpasteurized dairy products, such as goat's (possibly also sheep's) milk.

Simple hygiene can prevent infection. Avoid undercooked meat and unpasteurised goats milk products. Thorough cooking (70 Centigrade/158 Fahrenheit for 15-30 minutes). Freezing to -20 Centigrade may be effective (there is some argument on this). Garden vegetables should be thoroughly washed to remove soil which may be contaminated. Chopping boards which have been used for raw meat should be washed in hot water before they are used for foods to be eaten raw or for ready-to-eat cooked foods. Other precautions are important to pregnant women (or those trying to become pregnant).

Avoid contact with potentially contaminated soil, or wear rubber gloves. Wash with soap and water afterwards. Do not touch mouth with soil-tainted fingers. Cover children's sandboxes to prevent contamination by cats.Clean out litter trays daily i.e. before oocysts can become infectious. Wear rubber gloves for this task (if pregnant, you may wish to get another family member to empty the litter trays). Preferably disinfect litter tray with boiling water. Disinfect potentially contaminated litter boxes with scalding water or with dry-heat sterilization (55°C, 131°F). Chemical disinfection does not reliably destroy oocysts. Wash hands after handling litter trays; even if you have worn gloves.Avoid rare or undercooked meat, unpasteurized dairy products and unwashed garden vegetables. Vegetables should be scrubbed and preferably not eaten raw. All food preparation areas should be kept disinfected and cat-free. Keep surfaces on which raw meat has been prepared scrupulously clean, preferably use a separate chopping board for raw meat. Disinfect these surfaces after preparation of raw meat and scrub hands thoroughly.

It is possible to test cats and humans (especially women contemplating pregnancy or already pregnant) to see whether they have antibodies. Those without antibodies are more susceptible to infection and preventative measures should be taken. Those with antibodies are unlikely to be reinfected.

Protect cats from infection (or reinfection) by preventing access to birds, rodents, uncooked meat, and unpasteurized dairy products. Food preparation areas can be infectious to cats! If pregnant (or trying) avoid handling free-roaming cats as their fur or paws may be contaminated; this also means keeping indoor-outdoor cats off of bedding, pillows etc and kitchen counters. Avoid cuddling a cat with diarrhoea or bowel incontinence or one which has an illness (FIV, FeLV) which might reactivate tissue cysts.


Feline Spongiform Encephalitis is a prion disease rather than a virus. As with human vCJD, it may be related to consumption of infected cow products although another chemical agent (producing BSE-like symptoms) has been implicated in the past. Since transmission is believed to be by eating contaminated food, an infected cat does not pose a threat to its owners. Veterinarians handling FSE-infected cats (especially post mortem) should take standard precautions to avoid tissue or fluids coming into contact with open wounds.


Certain parasites may be transferred from cat to human. Fleas are the most common and cause itchy, sometimes inflamed, spots. Some people are more prone to flea bites than others and some people react worse than others. Ticks may also attach to humans but are picked up from long grass where a gorged tick has fallen off of its former host; a tick attached to a cat stays there until it is gorged or until it is removed by the owner/veterinarian. Some feline intestinal parasites can also be transmitted to humans. Roundworm eggs infect humans, particularly children, through a faecal to oral route. Tapeworm eggs are not directly infectious to people.