Moonlight causes blindness If so, how

Parasite Infection Blindness

SEND DATE Sun, 11/21/10 | 5:03 pm | The first

Tobias' left eye is practically blind from birth and his right eye is also in danger of going blind: clear scars have formed on the retina, of all things in the area of ​​sharpest vision. About two years ago, the now 14-year-old came to the Berlin Charité eye clinic, when the vision of his "good" eye was just 20 percent. Charité expert Uwe Pleyer found antibodies against Toxoplasma gondii, a tiny, unicellular parasite that is widespread and generally considered harmless, in the boy's eye water.

But apparently this is only partially true: "Toxoplasmosis is the most common cause of infectious retinal inflammation," says Pleyer. The disease known as uveitis often leads to blindness. After identifying the parasite as the cause, the ophthalmologist started Tobias' long-term treatment with antibiotics and anti-inflammatories. With success: In the meantime, Tobias' right eye is back at over 80 percent.

The parasite is permanently embedded

Tobias Augenlicht is not finally saved, because the drugs can only control the disease, not cure it. Once in the body, the Toxoplasma pathogens can no longer be completely eliminated.

The immune system normally ensures that the aggressive pathogens that occur in an acute infection are quickly encapsulated in cysts. In this form, which is considered harmless, the pathogens remain in the body for life. It is estimated that one third of all people carry the cysts in their bodies. They are only reactivated if there is a weak immune system, for example in HIV patients or organ transplants.

But even with Tobias, antibiotics have to keep the pathogens in check. The drugs do what the immune system normally does: They stop the pathogens from multiplying and thus ensure that they are re-encapsulated in cysts.

Danger to life for the unborn child

The reason that Tobias' immune system cannot control the pathogens is that he was infected before he was born. "In the case of patients who become infected during pregnancy in the womb, there is an apparently very strong, nerve-oriented infection that affects both the nervous system and the eye as part of the nervous system," explains Pleyer.

The pathogen, which is harmless to most people, becomes a threat to the unborn child if the mother becomes infected with it for the first time during pregnancy. This happens to about six out of 1,000 women. Even if the mother does not notice the infection, it can be transmitted to the fetus.

It was the same with Tobias, who was still lucky: The consequences could have been even more dramatic: The Toxoplasma pathogens can even kill the fetus or lead to severe disabilities. But even if nothing is noticeable at birth, as with Tobias, there are still consequences years later: "Up to 80 percent of those infected in the womb later suffer from eye problems," says Uwe Pleyer.

Every year around 1,000 children in Germany are infected with Toxoplasma before they are born, estimates Uwe Groß, head of the National Consultative Laboratory for Toxoplasmosis at the University of Göttingen. "60 to 100 of them show clinical symptoms at birth, another 500 develop late complications."

Health insurance companies do not pay for the blood test

There are no exact figures, because a blood test for antibodies against Toxoplasma is not part of the usual prenatal care in Germany. A general toxoplasma screening such as in France and Austria does not take place in this country. The maternity guidelines only provide for a blood test if there is “justified suspicion”. Consequence: The statutory health insurances do not pay for the test, it is usually offered by gynecologists as a privately financed "individual health service" (IGeL) for around 20 euros.

Experts recommend a blood test for Toxoplasma antibodies if possible before or as early as possible during pregnancy. For about a third of all women, it gives the all-clear: they have already been infected with the toxoplasmosis pathogen and have formed antibodies. You are no longer at risk of acute infection, and neither is your baby.

Without antibodies, there is danger

But most women are negative, so they don't have antibodies in their blood yet. If you first encounter Toxoplasma during pregnancy, your child would be in danger. A possible infection must be discovered as early as possible so that the gynecologist can treat mother and child quickly.

The chances of success of a treatment have not yet been scientifically proven; Without an untreated control group, the effect of the treatment can hardly be demonstrated. But such an attempt is unthinkable for ethical reasons. Uwe Groß, however, is convinced "that a significant advantage can be demonstrated with timely and adequate therapy". He is based on 700 cases of pregnant women with an acute infection, which he examined retrospectively.

Ingrid Reiter-Owona from the Institute for Medical Parasitology at the University of Bonn estimates that if there is no therapy, transmission to the child occurs in every second case. One thing is certain: the therapy can only be successful if it starts on time. An acute infection must therefore be recognized as early as possible. To do this, the blood test must be repeated regularly. But gynecologists don't have a uniform line here. Some test twice, some three times, others not at all.

High number of unreported cases for damage caused by Toxoplasma

Many experts recommend at least one examination per trimester of pregnancy. "It would be safer to repeat the test every month," says Reiter-Owona. But only a minority of women even get tested, with a decreasing tendency. Acute infections during pregnancy are therefore only recognized in exceptional cases and much of the damage caused by Toxoplasma in children is not attributed to the parasite.

Pregnant women should definitely take certain precautionary measures to protect themselves. This includes strict hygiene in the household. Vegetables and lettuce should always be washed thoroughly. The Toxoplasma pathogens lie dormant in many places in the soil, where they get through the faeces of infected cats. Gloves when gardening and thorough hand washing therefore also reduce the risk of infection.

No raw meat during pregnancy

But the most important thing is to avoid raw meat. Mettwurst and salami are taboo, steaks should always be cooked through, because permanent stages in tissue cysts only die off within one to two minutes at a temperature of over 67 ° C.

Tobias mother knew nothing of any of this: Her gynecologist didn't even point out the risk of toxoplasmosis. Your son will therefore have to live with the consequences of the parasite infection for life.

Author: Güven Purtul (NDR)

Status: 07/21/2015 2:13 p.m.