Conditions and syndromes that can result in deafblindness



Toxoplasmosis is caused by a parasite called toxoplasma gondii. It forms cysts (hard-walled miscroscopic forms) which are passed in the faeces of its primary or main host, the cat.

In Britain, cats contaminate gardens and vegetables in their wanderings and even though they bury their faeces you can still come into contact with them, resulting in your eating the cystic form of toxoplasmosis. The infection is very likely to be contracted by children playing in sandpits, which is one reason why sandpits are supposed to be given new sand and sterilised each year.

Toxoplasmosis can affect almost all animals, including humans, but most animals carry it in their bodies.  In pet-owning countries, humans can catch it from changing cat litter trays, gardening without gloves (in earth, cats' faeces may remain infected for 14 months), and even by eating unwashed garden vegetables. Cats alone are not the only reason for the incidence of this condition. Undercooked meat and the increasing consumption of unpasteurised goat's milk are two other potential causes. In France, the eating of raw or rare meat is considered a major cause of the spread of infection.

Luckily the infection that can result is usually very mild. It can be a glandular-like illness or produce symptoms of a mild flu. However, in a pregnant woman the infection, although not a risk to her, can cause congenic abnormality in the unborn child in up to 40% of infections. Of these, ten per cent are likely to be seriously affected.

If the disease is caught in early pregnancy it is less likely to cross the placenta to the foetus but, if it does, the effects are more serious. If the pregnant woman catches the infection later, it is more likey to cross the placentra but the effects on the foetus are less severe.

In France and Belgium the problem is considered to be so great that women are routinely screened as they are for rubella in Britain.

Babies that are born with toxoplasmosis (usually when infected between the third and sixth month) may develop severe symptoms. These include hydrocephalus, calcification in the brain and chorioretinitis (damage to the retina). Epilepsy and deafness can also result. Most worrying in this regard is that eye disease may not develop until the late teens.

The Public Health Laboratory in Swansea, UK, estimated in 1988 a rate of infection of two per 1,000 pregnant women. If the French figures of 40% passing infection to their babies is the same in the United Kingdom, it could mean that about 480 babies a year are affected in the UK.

Most adults recover spontaneously from toxoplasmosis without any treatment at all, although it is possible to treat the condition using sulpha drugs. Eye treatment of toxoplasma infections is more complicated, and pregnant women must be given a different drug since the usual one is too toxic. No treatment manages to eradicate all cysts. This means that an infection which may appear to have been cured can be reactivated.

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