Toxoplasmosis
- What is toxoplasmosis?
- How is the infection acquired?
- Who is at risk?
- How common is this infection in pregnant women?
- What effects does toxoplasmosis have on babies when the infection has been acquired in pregnancy?
- If one pregnancy is affected by toxoplasmosis, are subsequent pregnancies likely to be at risk?
- What tests are available to confirm the diagnosis?
- What treatment is advised for Toxoplasmosis infection?
- Is there a vaccine available for humans?
- Is the infection common in sheep in Great Britain?
- What are the manifestations of disease in sheep?
- Is a vaccine for use in sheep available?
1. What is toxoplasmosis?
Toxoplasmosis is a zoonotic infection (an infection that can be transmitted between animals and humans) caused by the parasite Toxoplasma gondii. Infection is usually asymptomatic or mild and self-limiting. When symptoms do appear, these are most commonly persistent acute fever with enlarged lymph glands. Very rarely there may be severe infection involving the brain, muscle and eye.
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2. How is the infection acquired?
Routes of infection include direct contamination of cuts and grazes or ingestion of tissue cysts. If contact with ewes at lambing time is unavoidable, open wounds (cuts, grazes etc,) should be covered with waterproof dressings and hands should be thoroughly washed after handling animals to prevent the possibility of infection. Transmission of the organism can also occur from hand-to-mouth contact with faeces of infected cats, contaminated soil, poorly washed garden produce and ingestion of cysts in undercooked meat.
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3. Who is at risk?
Pregnant women and individuals with a depressed immune system are most at risk from infection with Toxoplasma gondii.
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4. How common is this infection in pregnant women?
In the UK, toxoplasmosis is thought to affect about 2 per thousand pregnancies. Less than half of these cases are transmitted to the unborn baby. Even when transmission occurs, the majority of babies (90-95%) have no symptoms.
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5. What effects does toxoplasmosis have on babies when the infection has been acquired in pregnancy?
Toxoplasmosis, acquired for the first time in pregnancy, may lead to infection of the foetus and this may lead to congenital malformation. Some affected babies may develop eye disease in later life.
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6. If one pregnancy is affected by toxoplasmosis, are subsequent pregnancies likely to be at risk?
No. Chronic or recurrent infection in expectant mothers is not associated with foetal infection.
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7. What tests are available to confirm the diagnosis?
Blood tests can be carried out to detect antibodies to the organism. Since these may reflect infection in the past, confirmatory tests have to be carried out to see whether the infection is recent.
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8. What treatment is advised for Toxoplasmosis infection?
Toxoplasmosis is usually a mild, self-limiting disease and does not usually require specific treatment when it occurs in normal, healthy people.
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9. Is there a vaccine available for humans?
No.
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10. Is the infection common in sheep in Great Britain?
After chlamydia ( EAE), toxoplasmosis is the second most common cause of abortion in sheep in Great Britain. The number of incidents recorded each year by Defra laboratories between 1991 and 2002 ranged from 197 to 1100 reported incidents. In 2002 it accounted for 25% of the incidents where a diagnosis of the cause of abortion was reached.
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11. What are the manifestations of disease in sheep?
Abortion, often in the last 4 weeks of pregnancy. Full term lambs may be born dead or alive but weak, often dying within the first 2 weeks of life. Mummified lambs, often one of a pair, may be seen.
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12. Is a vaccine for use in sheep available?
Yes. There is a live vaccine for use in sheep. However, it should not be handled by pregnant women or women of childbearing age, as it may interfere with normal foetal development.
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