Toxoplasmosis

In 1984 Toxoplasmosis hit the headlines because a British athlete came down with this disease and the good name of the cat was called into question as being the cause! While most of what has been said about toxoplasmosis has been informative and accurate, a lot has been alarmist and inaccurate. Here are some commonly-asked questions and some straightforward answers.

What is toxoplasmosis?
Toxoplasmosis is an infection which is caused by a tiny type of germ called a protozoan, too small to be seen without a microscope.It can affect not only humans but all sorts of animals and birds as well, including farm animals and cats.

How do people catch it?
Although it is an infection, toxoplasmosis doesn't spread from person to person like a cold or 'flu. The germ has to enter the digestive tract through your mouth, for example, on fingers or food in order to infect you. The germ can be present in:
*  Raw or undercooked meat (any type).
*  Cat faeces and the soil contaminated by cat faeces.
*  Unpasteurised goat's milk and dairy products made from goat's milk. .
*  Vegetables, salad or fruit where the soil has not been properly washed off.


Effects of toxoplasmosis

Most people who catch it do not have any ill effects at all, although they can suffer 'flu-like symptoms or swollen glands which wear off in a week or two. About half the population in the UK have had toxoplasmosis without even knowing! But there are two groups of people for whom toxoplasmosis may be serious:
*  People whose body defences are weak, for example, some cancer patients on strong anti-cancer drugs and people with AIDS (the germ can affect the brain and heart of such people with serious consequences).
*  Pregnant women; the mother is not usually ill but if she has the germ, it has a four in ten chance of infecting the unborn baby via her bloodstream:If that does happen, most infected babies will be born perfectly normal, but about one in ten may have damage to the brain or eyes, or both. This is known as "congenital toxoplasmosis".

How do cats catch it?
Although the toxoplasma germ can affect all sorts of animals, cats are the only animal in which the germ can change into a special form which allows it to reproduce.  The usual way for a cat to pick up toxoplasma is when, as a kitten, it goes on its first hunting venture and eats a bird or rodent which has the germ in its tissues. The germ reproduces in the cat's intestine and forms millions of microscopic egg cysts which are excreted in the cat's faeces for about two weeks.If the cat uses the garden as well as, or instead of, a litter tray, the egg cysts enter the soil and can survive there for years, especially if it's damp. This is how farm animals can pick up the germ. It passes from their intestines to their muscles, and often tissues, and that's why humans can catch it from raw or undercooked meat or, in the case of goats, their unpasteurised milk. Like farm animals, humans can also get it from soil if they don't wash their hands after gardening, or they eat raw vegetables, salad or fruit where the soil has not been completely washed away.  

ls it safe to handle cats?
Should pregnant women, people with AIDS or those receiving cancer treatment handle cats? When considering this question it is important to remember that the cat most likely to be shedding toxoplasma cysts in its faeces is the young kitten on its first hunting venture, and even then only for a couple of weeks. After that it is extremely unlikely to pose any threat unless it becomes ill with a serious disease such as feline leukaemia virus (FeLV) or feline immunodeficiency virus (FlV). Even then, unless it has diarrhoea and is incontinent, the chance of the cysts being transmitted to a human handler is unlikely given the cat's fastidious cleaning habits.

So, the adult cat that has been sharing  your home for years and who is healthy can safely be kept by pregnant women or people whose immune defences are weakened. Provided the basic rules of personal and kitchen hygiene are observed and the advice given is taken, pregnant women and people with AIDS or cancer, or other serious illnesses should have no fear of cats. There is evidence that animals, especially cats, have a soothing and relaxing effect on their owners and there is no better time to relax than in pregnancy!

Are there tests and is there treatment for the disease ?
The answer to both is yes! However, it can be very difficult to diagnose toxoplasmosis in a pregnant woman, her unborn baby and in seriously ill people for a number of complicated reasons. There are several drugs which can kill the germ and which have improved the outlook for toxoplasmosis both in pregnancy and in people with impaired immune systems although we don't yet have a guaranteed cure.If you are worried, you must consult your GP or hospital doctor.

How to avoid getting it
This advice is particularly important for women who are, or are intending to become, pregnant and for people whose body defences are impaired.
* If you are a meat eater, only eat meat which is well cooked (brown right through); avoid any raw meat dishes (like steak tartare) or underdone (pink or bloody) meat. This applies to any meat. Remember, some types of cured continental sausage contain raw meat.
*  Keep surfaces on which raw meat has been prepared
scrupulously clean. If possible, keep a separate chopping board for raw meat. Always wash your hands with soap and water after handling raw meat.
*  Keep raw meat separate from cooked meat in the fridge.
*  Avoid unpasteurised goat's milk (in fact it is a good idea for pregnant women and people whose body defences are impaired to avoid all unpasteurised milk).
*  Wash your hands after gardening (even if you have been wearing gloves) with soap and water. Never eat with soil-covered hands and fingers.
*  Wash soil-covered vegetables and salad carefully until they are quite clean, and clean up any soil from kitchen surfaces afterwards.
*  If your cat uses a litter tray, remove any faeces at least once a day. Wash your hands with soap and water immediately afterwards.
*  Avoid cuddling, or allowing on to work surfaces, cats which are ill especially if they have diarrhoea or are incontinent.



It is possible (though not proven) that pregnant women who assist with lambing when there is an outbreak of toxoplasmosis in the flock, are at risk of catching the infection from the placenta of an aborted lamb. So, if at all practical, this should be avoided.


** We are grateful to Dr Susan Hall UB, BS, MSc, FRCP, FFPHM for her help in producing this leaflet.**