Cats

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TOXOPLASMOSIS

Toxoplasmosis is a disease caused by a protozoa (a complex celled organism) called Toxoplasmia gondii. It can be transmitted to humans and can cause disease.

Symptoms

Toxoplasmia has a two-part life cycle. The cat is the primary host. When the cat ingests the organism it reproduces in the cat's gut and large numbers of oocytes (eggs) are shed. The cat does develop immunity to the organism subsequent to exposure.

Kittens are most at risk when they first start to hunt or they are fed raw meat for the first time. They often have foul smelling diarrhoea and are unwell though this is rarely a fatal disease. Immunity develops over a week and the kitten recovers. Cats can intermittently shed oocytes when they are older particularly if they are unwell from another cause.

The second part of the life cycle involves all warm-blooded animals. This includes humans. The oocyte must be outside the cat for at least 24 hours before it is active (however it remains infective for years). If it is then ingested it will travel across the intestinal lining to other parts of the body. It then becomes inactive unless the cat eats the animal to restart the life cycle. The animal does develop immunity to the oocytes so that further ingested oocytes don't get into the body.

When a pregnant, previously unexposed, animal eats an oocyte it can travel to the placenta and the baby. In humans it can cause congenital defects such as blindness and deafness as well as abortion and stillbirths. It is therefore extremely important to avoid this infection when pregnant.

There is also another form of disease which can occur. This form is seen in both cats and humans. Some conditions prevent the body from taking effective action against the organism and allow it to multiple. HIV, chemotherapy for cancer or post-transplant drug therapy to prevent rejection are the commonest causes in man. FIV and FeLV are the common causes in the cat. Inflammation of the heart, lungs, brain and eyes have all been reported. This form of the disease does not need recent exposure.

Prevention in the cat

It must be assumed that the average outdoor cat has already been in contact with Toxoplasmia. Young kittens are most at risk of the disease. To avoid infection kittens should not be fed any fresh raw meat. Cooking the meat thoroughly or freezing it for 2 weeks will kill the organism.

Prevention in humans

It is extremely important that women who have not been infected prior to pregnancy do not become infected while they are with child. If you have cats and are concerned about toxoplamosis it is important to talk to your doctor and your veterinarian. Your doctor may run a toxoplasma titre that will tell you if you have already been in contact with the organism. As some estimates put the figure at 50 % of the population this is actually very likely.

A positive result to Toxoplasmia indicates past exposure not an active infection. If a woman's test result is negative, and she has cats, she must taken precautions not to catch Toxoplasmosis while pregnant.

To put into perspective one of our staff member's recently decided to start a family. As she is constantly working with cats, and has one of her own, she wished to know if she had been exposed. She was very relieved when her results came back positive.

It is unlikely that you will catch Toxoplasmosis directly from your cat as it the faeces that is the source of this disease. It is also important to note that the organism can be caught from ingesting poorly cooked meat. In countries where raw meats are ingested positive Toxoplasma titres are more common. During pregnancy is not the ideal time to purchase a new kitten however.

To avoid contact with Toxoplasma the following are recommended:

• Avoid raw or uncooked meat.
• Always wear gloves when gardening.
• Clean the cat litter tray DAILY with very hot water. If you are pregnant this is a job for someone else in the household.
• Dispose of the faeces in the trash not the garden.
• Cover sand pits as cats love to use them for their toilet and young children tend to eat dirt.

Treatment

Kittens with diarrhoea can be treated with anti-protozoal compounds to limit the severity of the symptoms. Immunity does develop quickly and some kittens may not need any treatment.

Cats with other forms of the disease may be very sick and need to be given varying treatment depending on the site in the body that is infected. This is usually not an easy disease to treat in this form, partly because it is not easily diagnosed. Veterinarians can run a Toxoplasmia titre on a cat but it only indicates past exposure not that the cat is actively infected. We would not treat a cat unless it is showing signs there is a disease process occurring.

Cats make wonderful pets, however from time to time there is bad press regarding the diseases we can catch from our cats. It is important to take precautions especially when you are pregnant. Against this remember stroking a cat decreases blood pressure and heart rate. People who own pets on average live longer and go to the doctor less. Just be sensible.

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