Cats and Toxoplasmosis

Toxoplasmosis is the name of one of the diseases (collectively known as zoonoses) that can be transmitted from animals to humans. It probably attracts the most publicity of all zoonoses in the popular press, and cats are frequently blamed for passing on the disease, whereas many of these articles tend to over-dramatise the dangers. However, although it's true that it is possible to pick up this disease from your cat (although it's not as common as we are sometimes led to believe), it's something that can be largely avoided with rigorous cleaning routines and common sense in and around the home.Toxoplasmosis is the result of infection with Toxoplasma gondii (T gondii), a parasite that can affect most mammals, although cats (wild and domestic) are the definitive hosts. Research has suggested that around 50% of all cats are infected with the parasite at some point during their lives, but in most cases it does not have a serious or life-threatening effect. Most affected cats contract toxoplasmosis by eating meat containing the T gondii cysts, which can be found in raw on undercooked meat, or more commonly in cats that go outside, in catching and eating wildlife such as mice and voles. Ofcourse, you cannot control what your cat catches and eats when he is outside, but if you feed him fresh food, always make sure that it is thoroughly cooked as you would with cooked meat for human consumption. Undercooked chicken, for example, is just as bad for cats as it is for people. After a cat has been infected for the first time, it will shed high volumes of eggs (known as oocysts) in its faeces, though probably only for a period of about fourteen days, after which the cat's immune system will stop producing them altogether. Other animals, including humans, can be secondary hosts of T gondii, and whereas they can become infected, the difference is that they themselves do not produce the eggs. The eggs passed in a cat's faeces go through a transformation known as sporulation, lasting for up to five days, and it is after this time that they can infect humans if accidentally ingested. Although cats are frequently cited as the root cause of the disease, the most common cause of toxoplasmosis in humans is eating undercooked meat that has acted as a host to the eggs. Those most at risk from toxoplasmosis are pregnant women, as the disease can affect the unborn foetus, particularly during months two to nine of the pregnancy when the foetus could be lost or could ultimately suffer birth defects. Other groups at high risk from this disease include babies and young children, the elderly, and those with a known reduced immune system such as those receiving treatment for cancer or on immunosuppressive treatment, or anyone with acquired immunodeficiency syndrome (AIDS), when the effects of the disease could be very serious. However, despite cats not necessarily being the main culprits where this disease is concerned, it is nevertheless very good practice to wear protective gloves when dealing with your cat's litter tray, and also to wash your hands with an anti-bacterial soap immediately you have finished and certainly before touching your face or preparing food. It is important to wash litter trays thoroughly every couple of days at the very least (although soiled litter should be removed at least twice a day), or more often if they need it, completely changing the litter and replacing it with fresh litter. Pregnant women are always advised by GPs not to deal with cat litter trays at all during the period of their pregnancy because of the high risk. Other considerations to be aware of include keeping small children away from litter trays, and also making sure that outside sandpits are covered over when not in use so that they are not used as impromptu litter trays by your cat or those belonging to your neighbours. For this reason children should wash their hands whenever they come in from the garden, as soil or even grass could be contaminated by T gondii. People in low-risk groups when it comes to toxoplasmosis will rarely show any serious signs of infection other than mild flu-like symptoms, although there is a strong possibility of passing it on to those in high-risk groups if high standards of personal hygiene are not observed, particularly with regard to washing hands after handling litter trays and going to the toilet. Cats infected with T gondii don't often display any signs of disease, although there are similar risks with pregnant cats as there are with pregnant humans. Very occasionally symptoms of general poor health might be seen, including fever, lethargy, loss of appetite and weight loss, although it would probably need a blood test to pinpoint this specifically to toxoplasmosis. More rarely, a cat might suffer from pneumonia, eye problems, liver disease or neurological symptoms, though this is not common if he is otherwise healthy and not suffering from any condition that could lower his immunity to disease. Despite the bad 'press' that cats often get regarding the transmission of toxoplasmosis, you are not likely to contract the disease from a cat, provided that you take proper precautions and always wash your hands when dealing with litter trays, or anywhere else that a cat may have defecated especially in the case of young children. For the same reason, it's always a wise precaution to wear gloves when gardening, and to wash your hands as soon as you've finished. Research has indicated that you won't pick it up from stroking a cat, as the oocysts are not found on the coat. You are far more likely to pick up the disease from poor kitchen hygiene (such as not washing fresh fruit and vegetables or keeping kitchen surfaces clean) or from eating undercooked meat, particularly when you are having summer BBQs.