Toxoplasmosis is a disease caused by Toxoplasma gondii. Although it infects a lot of people around the world, most of them are infected with little or no symptoms. In immunocompromised people and pregnant women, toxoplasmosis is a dangerous disease that causes many serious complications. How to treat toxoplasmosis?

Toxoplasmosisis a parasitic disease caused by the intracellular protozoan Toxoplasma gondii. There arethree types of Toxoplasma gondii- types I, II and III, which differ, among others, in the ability to cause disease in humans and animals. People are most often infected by type II. The parasite that causes toxoplasmosis has a very complex life cycle and occurs in various developmental forms - tachyzoite, bradyzoite, tissue cyst, oocyst.

Toxoplasmosis - life cycle

After eating, for example, undercooked meat or contaminated food, Toxoplasma gondii cysts enter the stomach. There, under the influence of gastric juice, the outer cyst wall surrounding the bradyzoites is broken down.

Then, in the small intestine, bradyzoites transform into mobile tachyzoites and actively enter the intestinal epithelium, from where they will spread throughout the body.

Tachyzoites are the rapidly growing forms of Toxoplasma gondii and can penetrate every cell in the body, including cells of the immune system. Although the parasite has the potential to grow in any tissue and organ, it has the highest affinity for nerve and muscle tissue, including the heart muscle.

With the onset of the immune response, tachyzoites are suppressed and eventually transformed into slowly multiplying forms of the so-called parasite. bradyzoites. They form a thick envelope around each other, thus transforming into tissue cysts, which remain dormant in people with an efficiently functioning immune system.

Additionally, they are surrounded by connective tissue and saturated with calcium s alts. In this form, they can remain in the tissues for life. In immunocompromised people, bradyzoites can be reactivated from the tissue cysts and transformed back into rapidly dividing tachyzoites.

  • The ultimate hostfor Toxoplasma gondii are animals from the felidae family, e.g. a domestic cat.
  • Intermediate host there are other mammals (including humans) and some species of birds.

The incubation period of toxoplasmosis is from 2 weeks to 2 months in the case of the acquired form. It is worth knowing thatan infected person does not infect others through contact .

Toxoplasmosis - pathways of infection

A person can become infected with Toxoplasma gondii via:

  • consumption of cysts found in undercooked or raw meat and its products (mainly pork, sheep and goat meat)
  • eating unpasteurized milk and products made from it
  • ingestion of oocysts with contaminated food (vegetables, fruits) and water
  • transfer of oocysts to the oral mucosa with contaminated hands
  • mother infected to fetus via placenta (congenital toxoplasmosis)
  • organ transplant
  • transfusion of blood or blood products

Toxoplasmosis - occurrence

Toxoplasmosis is one of the most common parasitic infections and zoonoses. In Europe, toxoplasmosis is mainly associated with eating raw or undercooked meat.

In Central America, it results from the large number of homeless cats and the climate favorable to the survival of Toxoplasma gondii in the environment. Toxoplasmosis is much less common in colder regions of the world and where the climate is hot and dry.

In Poland, about 60% of people have antibodies against Toxoplasma gondii .

Toxoplasmosis - symptoms

Symptoms of toxoplasmosis will depend on the normal function of the immune system and the way we become infected -acquired or congenital toxoplasmosis .

In many people with a properly functioning immune system, acquired toxoplasmosis is asymptomatic (85% of cases).

However, if symptoms of toxoplasmosis occur, they are nonspecific and poorly expressed:

  • fever,
  • enlarged lymph nodes,
  • headache,
  • pharyngitis,
  • muscle pain,
  • rash,
  • liver enlargement,
  • and spleen enlargement.

Gastrointestinal symptoms such as abdominal pain, vomiting and diarrhea may also occur due to Toxoplasma gondii involvement of the mesenteric lymph nodes.

Toxoplasmosis acquired in immunocompromised people, e.g. with AIDS or cancer, usually occurs as cerebral toxoplasmosis, which is characterized by neurological symptoms, and their severity depends on the area of ​​the brain involved and the number of lesions.

Symptoms may includefever, seizures, headache, visual disturbances, mood changes, cognitive impairment, involuntary movements.

In addition, people with lowered immunity develop extra-cerebral toxoplasmosis, usually manifesting as pneumonia and chorioretinitis.

Toxoplasmosis - clinical forms

Nodal form

The most common form in people with a properly functioning immune system. There is mainly an enlargement of the cervical lymph nodes and the appearance of flu-like symptoms:

  • muscle pains,
  • headache,
  • pharyngitis
  • and feeling weak.

Eye form

It occurs more often in immunocompromised people. It takes the form of inflammation of the retina and choroid. Other symptoms of ocular toxoplasmosis are:

  • visual disturbance,
  • tearing,
  • photophobia,
  • scotomas and eye pain.

Generalized form

Symptoms range from one to several internal organs (e.g. myocarditis and pneumonia) or the central nervous system (e.g. encephalitis or meningitis).

Toxoplasmosis in pregnancy

Due to severe complications of fetal toxoplasmosis, pregnant women who are seronegative (lacking antibodies to Toxoplasma gondii) are a special risk group. In Poland, they are about 50% pregnant.

In contrast to acquired toxoplasmosis, congenital toxoplasmosis is the result of primary infection with Toxoplasma gondii during pregnancy. The tachyzoite parasite crosses the placenta (so-called vertical transmission) and infects the fetus.

It is also worth noting that the degree of tachyzoite transmission through the placenta to the fetus depends on the duration of pregnancy.

The risk of fetal infection is:

  • in the first trimester 17-25%,
  • in the second trimester 25-54%,
  • and in the third trimester as much as 60-90%.

Congenital toxoplasmosis

The incidence of congenital toxoplasmosis is 1 to 2 per 1,000 births. Fetal involvement is most severe in the early stages of pregnancy and may lead to spontaneous abortion or cause serious neurological disorders in the fetus.

However, infection at a later stage, e.g. in the third trimester, is often asymptomatic. Eventually, chorioretinitis may develop later in life.

Congenital toksplasmosis affects almost exclusively fetuses of seronegative women who develop acute Toxoplasma gondii infection during pregnancy and does not occur in HIV-positive women prior to pregnancy.

The most common symptoms of congenital toxoplasma in a child are:

  • uveo-retinal inflammation,
  • hydrocephalus or microcephaly,
  • intracranial calcifications.

This is the so-calledSabin-Pinkerton triad .

In addition, other symptoms may occur, such as:

  • fever,
  • enlargement of the liver and spleen,
  • jaundice,
  • enlargement of the lymph nodes,
  • anemia,
  • mental retardation,
  • blindness,
  • epilepsy.

Acquired toxoplasmosis - diagnosis

The basis for the diagnosis of toxoplasmosis in people with a properly functioning immune system are serological tests that detect the presence of specific antibodies directed against Toxoplasma gondii. The presence of antibodies indicates an active or previous parasite infection.

  • IgM antibodies appear first after infection, i.e. after about a week, and disappear after about 4 months. However, in people with chronic toxoplasmosis, they may persist for up to 2 years.
  • IgA antibodies appear in parallel with IgM. They reach their maximum concentration after about a month and disappear after 6-9 months.
  • IgG antibodies appear after 1-2 weeks and reach the maximum concentration 2-3 months after infection. They persist throughout life. A high level of IgG antibodies together with the simultaneous appearance of IgM and / or IgA antibodies indicates an active parasite infection.

In some clinical situations, testing for specific antibodies may not be conclusive in the diagnosis of toxoplasmosis. This is the case, for example, in people with the ocular form of congenital toxoplasmosis and in children. They may not have increased levels of specific IgG antibodies. In addition, testing for specific antibodies in immunocompromised individuals may lead to false negative results.

Therefore, it is advisable to perform other laboratory tests for toxoplasmosis, such as isolation of the parasite from tissue sections, blood or other body fluids.

However, currently the most commonly used method is molecular biology methods using PCR to detect the genetic material of the parasite.

Imaging tests are also helpful in the diagnosis of toxoplasmosis, such as:

  • USG,
  • computed tomography
  • and magnetic resonance imaging.

Congenital and pregnant toxoplasmosis - diagnosis

Pregnant women who have been infected with Toxoplasma gondii prior to conception and have high levels of specific IgG antibodies are not at risk of developing fetal infections.

Win some situations, it is important to establish the time since infection of the pregnant woman. Then you mean the so-called the avidity of IgG antibodies, i.e. the binding strength of the antibody with the parasite antigen. Low avidity antibodies indicate an acute phase of toxoplasmosis.

The diagnosis of neonatal toxoplasmosis should always be done in infants of mothers who become infected with Toxoplasma gondii during pregnancy.

The diagnosis of congenital toxoplasmosis is based on the detection of the presence of the parasite (specific antibody or molecular tests):

  • in cord blood,
  • in amniotic fluid,
  • bearing
  • or your baby's body fluids.

Toxoplasmosis - diagnostic criteria

The diagnosis of acquired toxoplasmosis requires one of the following to be met:

  • seroconversion of specific IgG antibodies, i.e. change of status from negative to positive
  • significant increase in the level of specific IgG antibodies ≥ 2 times with an interval of ≥ 4 weeks
  • clinical symptoms of toxoplasmosis and detection of specific IgA / IgM antibodies and high level of specific low avidity IgG ( <20%)
  • detection of epithelial cells by histological examination of an enlarged lymph node and detection of specific IgM antibodies or increasing or high levels of specific IgG antibodies

The above criteria also apply to pregnant women.

Toxoplasmosis - treatment

People with normal immunity and acquired form of toxoplasmosis usually do not require treatment and the toxoplasmosis is self-limiting. Only patients with severe symptoms and immunocompromised patients require treatment.

Pyrimethamine is usually administered in combination with sulfonamides (sulfapyrimidine, clindamycin, rovamycin).

Toxoplasmosis - prevention

  • Avoid eating raw or semi-raw meat and its products as well as unpasteurized milk and its products, and thoroughly washing hands and kitchen utensils after handling them
  • washing fruits and vegetables thoroughly before consumption
  • use of protective gloves to work in the garden and in the field
  • use in women before planning pregnancy for toxoplasmosis tests

Toxoplasmosis in cats

House cats can be a source of Toxoplasma gondii oocysts, but remember that not every cat is infected and in fact domestic cats are not a significant risk factor for parasite infection in Poland, even though the percentage of infected cats in some regions of Poland reaches even 75% .

Infected cats shed oocysts in their faeces, howeverextremely rare. Moreover, the expelled oocysts do not become contagious a few days after their expulsion.

Cats become infected with Toxoplasma gondii, most commonly by the ingestion of oocysts or tissue cysts from raw meat. Therefore, if we want to prevent our cat from becoming infected, we should avoid feeding it raw meat and prevent it from hunting rodents and birds.

  • Toxoplasmosis: results and interpretation
  • Toxoplasmosis in pregnant women - prevention first of all!
  • What can you get infected from a cat? What diseases do cats transmit?

Category:

Infectious diseases