Toxoplasmosis: symptoms in humans, treatment, prognosis, prevention

general information

Toxoplasmosis Is an infection caused by a single-celled protozoan parasite toxoplasma. Usually, the infection does not cause any symptoms, although some people have swollen lymph nodes. the temperature rises, a feeling of general malaise develops, sometimes a sore throat or blurred vision and Pain in the eyes. In people with weakened immune systems due to AIDS or another medical condition, toxoplasmosis can reactivate, usually affecting the brain. A reactivated infection can cause weakness, confusion, seizures, or coma, or spread throughout the body. Babies who are infected before birth (called a congenital infection) may have birth defects, loss of vision, seizures, mental retardation, and other abnormalities.

• A person becomes infected by getting the eggs of the parasite from an infected object into the mouth or through contaminated food.

• In most cases, the infection is asymptomatic or with mild symptoms.
• Women who become infected during pregnancy can transmit the parasite to the fetus, sometimes causing miscarriage, stillbirth, or serious problems in the newborn.
• Usually, severe symptoms only occur in people with weakened immune systems and are caused by inflammation of the brain (encephalitis), resulting in muscle weakness on one side of the body, confusion or coma.
• Other organs are less likely to be affected in people with weakened immune systems.
• Typically, a doctor makes a diagnosis with a blood test that detects the presence of antibodies to the parasite.
• Cooking and freezing meat and washing your hands thoroughly after handling raw meat, contact with soil, and cleaning the litter box will help prevent the spread of infection.
• Most healthy people do not require treatment, but adults with symptoms and an infected newborn are often given pyrimethamine in combination with sulfadiazine and leucovorin.

Toxoplasma distributed throughout the world where cats live. The parasite infects a large number of animals as well as humans. The disease is common in Russia, although only a few people experience symptoms. Severe infection usually only develops in the fetus and in people with a disorder that weakens the immune system (such as AIDS or cancer) or taking drugs that suppress the immune system (immunosuppressants), especially those used to suppress organ transplant rejection.

Do you know that…

The parasite that causes toxoplasmosis can only lay eggs in the intestines of cats.

Although the parasite can grow in the tissues of many animals, it only lays eggs (oocysts) in the cells of the lining of the intestines of cats. Eggs are excreted in cat feces and can cause infection 1–5 days after that. Eggs in the soil can cause infection for several months. Wild birds, rodents, deer, and many domestic animals (especially pigs and sheep) can ingest eggs in food or soil contaminated with cat feces. Parasites are released from the eggs in a form called tachyzoites. Tachyzoites spread through animal tissues and eventually form cysts.

Pathogen transmission

Toxoplasmosis can develop in several ways:

• Eating food, water, or other substances (such as soil) contaminated with cat feces containing eggs Toxoplasma.
• Eating meat that contains cysts Toxoplasma.
• The fetus can become infected from an infected mother.
• In rare cases due to blood transfusions or organ transplants that contain parasites.

Eggs Toxoplasma can enter the stomach of a person when he touches his mouth or is engaged in cooking or eating food without washing your hands after contact with contaminated litter, soil, or other objects. Cysts can enter the human body by eating raw or undercooked meat (most often pork or lamb) from infected animals.

Rarely, the parasite is transmitted through blood transfusions or organ transplants from an infected person.

Toxoplasmosis during pregnancy

A woman who becomes infected during pregnancy can transmit Toxoplasma gondii through the placenta to the fetus. The infection is more severe if the fetus is infected early in the pregnancy. The result can be fetal growth retardation, premature birth, miscarriage, stillbirth, or birth defects in the newborn. Congenital toxoplasmosis can later cause vision problems, seizures, and mental retardation.

If a woman was infected before pregnancy, then the parasite can enter the fetus only if the mother's immune system is weakened (for example, due to HIV infection in a woman), which leads to the reactivation of the infection.

Toxoplasmosis in people with weakened immune systems

People with a weakened immune system, such as patients with AIDSohm or cancer, as well as people taking medications to suppress the rejection of a transplanted organ. If infection has occurred at any time in the past, then the development of a disease that weakens the immune system, or taking drugs that suppress it (immunosuppressants) may cause reactivation infections.

Reactivation of the infection usually causes symptoms. Initial infection is often asymptomatic. Most often, when reactivated, the infection affects the brain, although it may also involve the eyes or spread throughout the body (dissemination).

In people with weakened immune systems, toxoplasmosis is very severe and can lead to death if left untreated.

Signs and symptoms

People with healthy immune systems usually show few or no symptoms of toxoplasmosis and recover completely. About 10–20% of these people have enlarged but painless lymph nodes. Some of these people also have periodic fever, mild malaise, muscle aches and sometimes a sore throat. Symptoms resolve on their own, usually within a few weeks.

- Congenital toxoplasmosis.

Babies with congenital toxoplasmosis may be seriously ill and die before or shortly after birth, or they may have birth defects or other symptoms. Some children don't get sick at all. Other children look healthy at first, but they develop symptoms (such as epilepsy, mental retardation, and chorioretinitis) after a few months or even years.

Typical symptoms in newborns may include the following:

• infection of the lining of the back of the eyeball and retina (chorioretinitis);
• enlargement of the spleen and liver;
• jaundice;
• rash;
• easy bruising;
• seizures (epilepsy);
• large head caused by accumulation of fluid in the brain (hydrocephalus);
• small head (microcephaly);
• mental retardation.

Chorioretinitis can cause blurred vision, eye pain, sensitivity to light (photophobia) and blindness.

- Symptoms in people with weakened immune systems.

Symptoms of toxoplasmosis in people with weakened immune systems depend on the location of the infection, namely:

• Toxoplasmosis of the brain (encephalitis): Symptoms such as weakness on one side of the body, speech problems, vision problems, headache, disorientation, seizures and coma.
• Toxoplasmosis that has spread throughout the body (acute disseminated toxoplasmosis): Rash, fever, chills, labored breathing and fatigue.

In some people (usually with a severely weakened immune system), toxoplasmosis causes inflammation of the lungs (pneumonitis), heart (myocarditis), or, less commonly, the liver (hepatitis). The damaged organ may not function properly (organ failure). If untreated, these types of toxoplasmosis are usually fatal.

Affected populations

Up to half of the world's population is infected with toxoplasmosis. In the United States of America, 23 percent of the population are native speakers, in Russia about 20 percent, and in some parts of the world the share of speakers reaches 95 percent.

The global annual incidence of congenital toxoplasmosis is estimated at 190,100 cases. High levels of the disease have been reported in South America, some Middle Eastern countries, and low-income countries. In this regard, this nosology is referred to the group of neglected diseases.

Diagnostics

Diagnostics include:

• A blood test to detect antibodies against the parasite.
• In case of possible brain damage - computed or magnetic resonance imaging followed by a spinal tap (lumbar puncture).
• Tissue from the brain or other affected organs is examined under a microscope and checked for DNA from the parasite.

Typically, the diagnosis of toxoplasmosis is based on a blood test that detects the presence of antibodies to the parasite. (Antibodies are proteins produced by the immune system to protect the body from attacks, including from parasites). A blood test can be used to diagnose a new infection.

These blood tests can be done in people with weakened immune systems who do not have symptoms of toxoplasmosis. The purpose of the analysis is to identify a previous infection, the reactivation of which may occur in the event of a further weakening of the immune system. However, if the immune system is compromised by AIDS, blood tests may indicate no infection when it is actually present (false negative results).

Sometimes tests to identify the genetic material of the parasite (DNA) are also performed on blood samples, tissues taken by a biopsy, or cerebrospinal fluid (the fluid that surrounds the brain and spinal cord), obtained with a spinal cord puncture.

For complaints of vision problems, an eye exam is performed for lesions characteristic of toxoplasmosis and blood tests are done to detect antibodies to the parasite.

To check for an infection in the fetus, your doctor may take a sample of the surrounding fluid (amniotic fluid) for analysis (a procedure called amniocentesis). This fluid is tested for antibodies to the parasite and for the genetic material of the parasite. Because it is difficult to diagnose toxoplasmosis during pregnancy, in a fetus or newborn, doctors often consult with an expert.

In case of suspicion of toxoplasmosis of the brain, computed tomography (CT) or magnetic resonance imaging is performed imaging (MRI) of the brain, usually followed by a lumbar puncture to obtain a sample of the spinal cord liquids. Rarely, a sample of infected brain tissue is taken and examined under a microscope to determine the presence of parasites and test for the genetic material (DNA) of the parasites.

Standard treatments

Treatment includes:

• Pyrimethamine and sulfadiazine, clindamycin, or atovacon plus leucovorin.
• For eye infections, drugs that are effective against toxoplasmosis, plus a corticosteroid.

Most infected individuals who are asymptomatic and with healthy immunity do not need treatment.

Individuals with symptoms of toxoplasmosis may be treated with pyrimethamine, sulfadiazine, and leucovorin. Leucovorin is intended to protect against decreased blood cell production in the bone marrow, which is a side effect of pyrimethamine. If pyrimethamine is not available, trimethoprim-sulfamethoxazole can be used. If the patient is unable to take sulfadiazine, clindamycin or atovaquone is used instead.

With a healthy immune system, treatment usually continues for several weeks.

Patients with AIDS and other diseases that weaken the immune system are prescribed the same drugs, but they are treated for longer (usually at least 6 weeks). Relapses are frequent, and there are several long-term maintenance options available until the immune system improves.

In AIDS patients, toxoplasmosis tends to relapse, so taking drugs against toxoplasmosis continues until the immune system improves (as evidenced by an increase in the number of CD4 cells) and resolution of symptoms. The physician must ensure that the most effective antiretroviral drugs are being used.

People with an eye infection may be given pyrimethamine in combination with sulfadiazine (or clindamycin) and leucovorin. To reduce inflammation, prednisone or another corticosteroid hormone is usually given at the same time.

Women who contract toxoplasmosis during pregnancy should consult a doctor who specializes in toxoplasmosis during pregnancy. The selection of drugs is a complex process and depends on the time of infection of the pregnant woman (i.e. the trimester of pregnancy), as well as on the infection of the fetus. Pyrimethamine can cause birth defects and is not prescribed during the 1st trimester of pregnancy. Spiramycin (an antibiotic) can be given during the 1st trimester to prevent the transmission of toxoplasmosis from a woman to a fetus.

Newborns infected before delivery are usually given pyrimethamine, sulfadiazine, and leucovorin for up to one year after birth.

Forecast

Immunocompetent patients have an excellent prognosis, and lymphadenopathy and other symptoms usually resolve within a few weeks after infection.

Toxoplasmosis in immunocompromised patients often recurs if treatment is stopped. Suppressive therapy and restoration of immunity significantly reduce the risk of infection recurrence.

Individuals with congenital toxoplasmosis can experience multiple complications, including mental retardation, seizures, deafness, and blindness. Treatment can prevent symptomatic and asymptomatic children with congenital toxoplasmosis from developing adverse events. Children with congenital toxoplasmosis usually have a good prognosis and by the fourth year of life are on average identical in development to uninfected children.

Toxoplasmic encephalitis and brain abscess can lead to permanent neurological complications, depending on the site of the lesion and the degree of local damage and inflammation. The basal ganglia appear to be predominantly involved. People with CNS toxoplasmosis may experience seizure disorder or focal neurologic deficits.

Prophylaxis

Pregnant women should avoid contact with cats. If contact is unavoidable, pregnant women should, at a minimum, avoid cleaning cat litter or wear gloves during cleaning.

Meat must be thoroughly cooked to a temperature of 74–77 ° C. Hands should be thoroughly washed after handling raw meat, soil, or cleaning cat litter.

Potential organ donors should be tested to prevent the spread of the parasite through organ transplants.

Trimethoprim-sulfamethoxazole (an antibiotic) can be used to prevent the reactivation of toxoplasmosis in AIDS patients or people with a weakened immune system for any other reason. If the person cannot take this drug, it can be replaced with pyrimethamine (an antiprotozoal) in combination with sulfadiazine or clindamycin (antibiotics). Other options are atovaquone (antiprotozoal) with or without pyrimethamine, or dapsone in combination with pyrimethamine. Because pyrimethamine can decrease the production of blood cells in the bone marrow, leucovorin (also known as folinic acid) is given along with it to prevent this side effect.

People with AIDS are also prescribed antiretroviral drugs to help strengthen the immune system and reduce the risk of toxoplasmosis reactivation.