How common is toxoplasmosis in domestic cats

Toxoplasmosis

Toxoplasmosis is an infectious disease caused by the parasite Toxoplasma gondii. The main hosts of toxoplasma are cats. Infected cats excrete the pathogens with their faeces. People can get infected from raw meat and vegetables, but also from gardening and cleaning the litter box.

Short version:

  • Toxoplasmosis is most often transmitted to humans through cat feces or undercooked meat.
  • The infection is symptom-free in many people.
  • Hygiene measures reduce the risk of infection.
  • Therapy is not necessary in healthy people as the disease heals spontaneously.
  • If an infection is suspected in pregnant women, a doctor must be consulted.

How does toxoplasmosis become infected?

Toxoplasmosis is a worldwide common zoonosis, i.e. a disease that can be transmitted from animals to humans.

The causative agent of toxoplasmosis is Toxoplasma gondii, a unicellular parasite whose main host is the cat. Infected cats excrete toxoplasma eggs with their feces. These can be absorbed by humans in different ways:

soil

The toxoplasma eggs end up in the soil or in sand boxes via the cat's feces. They are very resistant to external influences and can remain infectious in moist soil for several years. Humans can become infected through dirt and smear infections with contaminated soil - as in gardening.

Cats

The cat is the ultimate host of Toxoplasma gondii. This means that the parasite reaches its sexually mature form in the cat's organism. The finished toxoplasma eggs are excreted with the cat's feces. Cats infected for the first time, mostly young animals, can excrete up to a million oocysts per gram of feces. Cleaning the litter box is therefore a possible source of infection for toxoplasmosis.

flesh

The uptake of the toxoplasm system via meat and meat products is the most common source of infection. Toxoplasmas can also be ingested by farm animals through the soil, where they form tissue cysts in the muscles, in the brain and in the retina of the eye.

Toxoplasmas could, inter alia. detected in pigs, sheep, goats, poultry and cattle, with lamb and pork being the main sources of infection in humans. When eating raw or undercooked meat, the parasites are absorbed in the gastrointestinal tract and spread throughout the body via the blood.

Transmission from mother to child

Another way of transmission is that from the mother to the unborn child. The parasite reaches the embryo via the placenta, and infection is possible from the seventh week of pregnancy. Basically: Infections at the beginning of pregnancy lead to serious damage, the later the infection occurs, the smaller the extent of the changes.

Toxoplasmosis of pregnancy is feared because it can lead to blindness, physical and mental disabilities or the death of the unborn child.

Nowadays, testing for toxoplasmosis is an integral part of the mother-child pass examination and is carried out routinely. A blood test is the only way to diagnose an acute infection in the mother, as the disease is symptom-free in 90% of cases. The earlier an acute infection is detected, the lower the risk of serious consequences for the child.

About 0.2% of all pregnant women become infected for the first time during pregnancy. The initial examination usually takes place up to the 9th week of pregnancy.

Studies show that around a third of all women had contact with the pathogen before the start of pregnancy. You have antibodies in your blood that make it very unlikely that you will be infected again during pregnancy.

Pregnant women who have not yet had contact with Toxoplasma are checked for toxoplasmosis-specific antibodies as part of regular blood tests (every eight to ten weeks until the birth). These analyzes are usually carried out in a laboratory.

What are the symptoms of toxoplasmosis?

The signs of toxoplasmosis vary. The disease often goes without symptoms and goes unnoticed, sometimes the following flu-like symptoms occur:

  • light fever
  • Exhaustion
  • Swollen lymph nodes

It usually takes two to three weeks for the disease to become noticeable.

Course and incubation period of toxoplasmosis

The incubation period is two to three weeks. Toxoplasmosis has four different forms:

1. Toxoplasmosis in healthy children and adults

In healthy children and adults, a toxoplasma infection usually goes unnoticed. Symptoms such as swollen lymph nodes in the head and neck area, as well as fever and tiredness appear after infection with Toxoplasma only in 10 to 20 percent of healthy people. After a few weeks, the infection heals without complications. This clinical presentation is the most common form of toxoplasmosis.

2. Toxoplasmosis in immunocompromised people

People with a weakened immune system can develop life-threatening meningitis as a result of an initial infection or reactivation of an infection that has previously gone unnoticed. This clinical presentation is most common in patients with HIV infection or in transplant patients.

3. Congenital toxoplasmosis

If women contract a toxoplasma infection for the first time during pregnancy, the parasites can infect the unborn child via the placenta in about half of the cases. Congenital toxoplasmosis occurs in one in every thousand live births. Infections in early pregnancy can damage almost all organs, especially the brain.

Miscarriages occur in rare cases. Depending on the time of infection and the severity of the disease, children are born with hydrocephalus (water head), microcephaly (reduction in size of the head), inflammation of the retina or calcium deposits in the brain.

In half of the cases, the children show no signs of illness at birth; they can still develop developmental disorders, hearing damage or eye changes even after years.

4. Ocular toxoplasmosis

In this form of toxoplasmosis - as a late consequence of congenital toxoplasmosis - inflammation of the eye retina occurs. The clinical picture ranges from minimal visual impairment to complete blindness and generally only manifests itself in the second to third decade of life.

How can you protect yourself from toxoplasmosis?

Preventing an infection with Toxoplasma is particularly important for pregnant women and immunocompromised people who have never had contact with the pathogen. Important measures here include:

  • General hygiene measures
  • Wash your hands after gardening, field work or earthworks and after visiting sand playgrounds
  • Handling cats: Cleaning the litter box should be done by someone else. If this is not possible, wearing disposable gloves is essential. Keeping the litter box moist prevents the toxoplasma eggs from spreading through the air. The cat must not be fed raw meat, should not go outside and not hunt if possible. Wash hands after close contact with the cat to avoid smear infections. If the general hygiene measures are observed, the cat does not have to be given away.
  • Avoiding raw and insufficiently heated meat: For safety reasons, beef tartar, meat or tea sausage and raw ham should be avoided. The consumption of well-smoked sausages is harmless. When preparing meat dishes, pork and lamb in particular should be heated to over 66 ° C for several minutes, as the cysts in the meat are viable for three weeks at a storage temperature of +4 degrees Celsius. Commercial meat processing with curing, smoking, boiling and freezing to minus 21 degrees Celsius kills the parasites. Raw vegetables and fruits growing close to the ground should be washed thoroughly before consumption.
  • Good kitchen hygiene: If you use the same kitchen utensils for meat, lettuce and vegetables when cooking, toxoplasmosis pathogens can get from meat to other foods. Chopping boards and knives, but also work surfaces and hands, must therefore be cleaned well after contact with meat.

How is toxoplasmosis treated?

In healthy people, treatment of uncomplicated toxoplasmosis is not necessary because spontaneous healing usually occurs after a few weeks. Concomitant illnesses such as fever and joint pain are treated symptomatically.

A diagnosis of toxoplasmosis infection as early as possible during pregnancy is of great importance. It is important to protect the unborn child from infection. If an acute initial infection is diagnosed, antibiotic therapy is initiated from the 16th week of pregnancy. It is designed to reduce the risk of transmission to the fetus by half and only end at birth. Even if an infection is suspected, therapy is started as a precaution.

If the infection of a pregnant woman is confirmed, an amniotic fluid test follows to clarify the infection status of the fetus. If the child's findings are positive, the child will be treated from birth to the end of the first year of life.

+++ More on the topic: Toxoplasmosis in pregnancy +++

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Authors:
Mag. (FH) Silvia Hecher, MSc
Medical review:
Astrid Leitner (2016)
Editorial editing:
Dr. med. Matthias Thalhammer, Thomas Auinger, Astrid Leitner (2016)

Status of medical information:
swell

Patient information of the Golden Cross Vienna (online, last accessed: 08.08.2016)
Robert Koch Institute: www.rki.de
Austrian Agency for Health and Food Safety: www.ages.at
 

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