Toxoplasmosis – symptoms, diagnosis, treatment. Prevention of toxoplasmosis

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Toxoplasmosis is a common parasitic infectious disease that occurs all over the world. Approx. 50% of people have positive antibodies that testify to having experienced toxoplasmosis. The main danger of the disease results from the possibility of congenital infections during pregnancy and the reactivation of the disease in people with reduced immunity.

Toxoplasmosis – causes

Toxoplasmosis is caused by a protozoan Toxoplasma gondiiwhose ultimate host is felids. Parasites multiply in the cat’s intestinal epithelium and are then excreted in the faeces in the form of weather-resistant oocysts. Oocysts are infectious to animals, birds and humans. After ingestion of these infectious forms, the parasite multiplies inside the cells of organs and tissues of our body, but most often it locates in the muscles, central nervous system and the eye.

The invasion results in a local inflammatory reaction and the possibility of the formation of cysts that persist for life – without causing symptoms. In favorable situations, e.g. in AIDS or during immunosuppressive treatment, the activation of spore forms and recurrence of the disease can occur, and cysts are contagious if raw or undercooked meat of infected animals is eaten.

Also read: Why are zoonotic viruses dangerous to humans? Scientists explain

When is there a risk of contracting toxoplasmosis?

Due to the prevalence of the parasite in cats and the possibility of infecting other animals: sheep, pigs or poultry, infection can occur through:

1. consumption of oocysts after contact with cat excrements, e.g. when cleaning litter boxes or while playing in the sandbox,
2. consumption of oocysts with unwashed vegetables or fruit (strawberries, wild strawberries) contaminated with contaminated cat faeces or by transmission of oocysts by flies or cockroaches,
3. consumption of cysts in raw or semi-raw meat of infected pigs, sheep or poultry,
4. blood transfusion
5. graft,
6. work with contaminated material (e.g. patient’s blood) in the laboratory.

There are also two specific situations of infestation with the parasite:

1. infecting the fetus by passing parasites through the placenta,
2. infection of the transplant result of an organ containing parasites.

Toxoplasmosis – symptoms

Depending on the period and method of infection, we distinguish acquired toxoplasmosis and congenital toxoplasmosis.

Symptoms of acquired toxoplasmosis

Most infected people are unaware that they have had toxoplasmosis, as the disease is usually asymptomatic.

In other cases, toxoplasmosis can take the form of:

1. nodal – enlarged lymph nodes, especially in the neck area; sometimes there may also be fever, general malaise, headaches or muscle aches
2. ocular – rarely as a result of primary infection; it usually takes the form of inflammation of the retina and the choroid of the eye; runs with periods of remission and exacerbation; the end result can be a significant reduction in visual acuity
3. generalized – it mainly affects people with a significant decrease in immunity – changes in the lungs, liver or heart muscle are observed
4. cerebral – the effect of reactivating the infection in people with a decrease in immunity (e.g. in the course of AIDS) – takes the form of encephalitis and meningitis

Symptoms of congenital toxoplasmosis

Toxoplasmosis is a very serious problem, because infecting a child during pregnancy may result in birth defects and late consequences of the infection. Fortunately, the classic symptoms of congenital toxoplasmosis occur in less than 30% of infected children. The risk of developing symptoms of the disease is greatest in the first trimester of pregnancy. Infection in the third trimester of pregnancy is asymptomatic in most cases.

It should also be emphasized that the infection of the fetus occurs only in the case of the so-called primary infection, i.e. the pregnant woman has not had toxoplasmosis before. The measure of this state is the lack of IgG antibodies against Toxoplasma gondii in a woman.

The classic symptoms of congenital toxoplasmosis are:

1. the so-called Sabin-Pinkerton triad: chorioretinitis; intracranial calcifications; hydrocephalus or microcephaly
2. enlargement of the liver and spleen
3. hemorrhagic diathesis
4. jaundice
5. nystagmus
6. mental retardation, epilepsy, speech disorders

Find out more: Echinococcosis, toxoplasmosis, scabies. What else can we get infected from dogs and cats?

Toxoplasmosis – diagnostic tests

The diagnosis of toxoplasmosis is based primarily on serological tests, that is, the determination of the titre of antibodies in the direction of Toxoplasma gondii in the class of IgM, IgG and IgA. IgM antibodies appear in the case of a recent illness and disappear after some time – their presence indicates an active disease. IgG antibodies appear as a result of infection and most often their presence in the blood serum occurs until the end of life.

The large difference in antibody titers between the two studies may indicate disease reactivation. Additionally, these antibodies have the ability to pass across the placenta into the blood of the fetus. On the other hand, IgA antibodies are helpful in the diagnosis of toxoplasmosis in the newborn.

Testing against toxoplasmosis should be done before pregnancy, so we recommend the pregnancy preparation – blood tests for the expectant mother, which you can find at Medonet Market.

In addition to serological tests, the diagnosis of toxoplasmosis also uses:

1. genetic tests (PCR) that allow to detect the genetic material of the parasite in amniotic, cerebrospinal or eyeball fluids
2. histopathological examinations biological tests
3. imaging tests: ultrasound, computed tomography, magnetic resonance imaging – helpful in the assessment of pathological changes characteristic of toxoplasmosis

Toxoplasmosis – diagnosis

Correct interpretation of tests is very important in the diagnosis of toxoplasmosis in pregnant women, because it translates into the risk of fetal infection and prompt treatment during pregnancy.

A reliable diagnosis of acquired toxoplasmosis is when the negative antibody result changes towards T. gondii for a positive result between two consecutive tests. In pregnant women, both tests must be performed after pregnancy.

Acquired toxoplasmosis may be diagnosed when:

1. there is a seroconversion (change from negative to positive) in a pregnant woman when one of the tests was done before pregnancy
2. there is a significant increase in the titer of IgG antibodies to high values ​​between tests performed with an interval of 3 weeks
3. high levels of IgG antibodies with low avidity are found (avidity test allows to determine how long the antibodies were formed, and so the result: high avidity indicates a long history of infection; low avidity indicates a recent infection (<20 weeks))
4. there are specific IgM and IgG antibodies and clinical signs of infection
5. high titer of specific IgG, the presence of IgM and the presence of changes at the fundus are found
6. there are positive genetic results or a characteristic picture in the examination of histopathological lymph nodes or other tissues

Congenital toxoplasmosis is diagnosed when:

1. the isolation (culture) of the parasite is positive from the amniotic fluid, blood or tissues of the fetus or infant up to 6 months of age or the parasite is found in the tissues based on histological examinations
2. DNA of the parasite is detected in the amniotic fluid
3. IgG antibodies towards T. gondii during the first year of life with or without clinical symptoms (antibodies obtained from the mother during pregnancy should disappear after approx. 3 months)
4. specific antibodies in the IgM or IgA class up to 6 months of age are detected in the infant’s blood serum
5. in an infant are detected changes characteristic of congenital toxoplasmosis born to a woman who underwent toxoplasmosis during pregnancy

Find out more: Toxoplasmosis in pregnancy – causes, tests, prevention [EXPLAINED]

Toxoplasmosis – treatment

In the treatment of toxoplasmosis, chemotherapeutic agents such as pyrimethamine, sulfonamides or spiramycin are used.

Treatment should be used in: pregnant women, people with immunosuppression, infants, people with active ocular toxoplasmosis and people with a prolonged or severe course of the disease. In the case of pregnant women, spiramycin is an acceptable drug – other drugs have a strong teratogenic effect.

Also check: Other medications that contain spiramycin

Toxoplasmosis — prevention

The basic principles of the prevention of toxoplasmosis are:

1. not eating raw or semi-raw meat
2. not drinking unprepared water from an unknown source
3. washing vegetables and fruits
4. protecting food products against flies or cockroaches
5. securing sandboxes against cat access
6. washing hands after contact with cats or litter boxes; steaming cat litter boxes and feeding cats with ready-made food

Prevention of congenital toxoplasmosis is primarily based on the proper care of the pregnant woman and it is recommended to:

1. perform a test for toxoplasmosis, preferably before the planned pregnancy – to find out about the serological status (presence or absence of specific antibodies)
2. in seronegative women (who have not had toxoplasmosis before – negative IgG antibody result) should be tested at least three times during pregnancy: at the beginning of pregnancy, around 20-24 weeks of pregnancy and around 38 weeks of pregnancy
3. women who are seronegative should strictly follow the main principles of the prevention of toxoplasmosis and should avoid contact with cats; clean the cat’s litter box daily or several times a day if the cat is an outgoing animal as the parasite becomes invasive and infectious 1 to 5 days after excretion with cat faeces.
4. use disposable gloves when cleaning the cat’s litter box; avoid contact with unknown or wild cats and do not take new cats home,
5. in the case of gardening and during any contact with soil or sand, gloves should be used because it may be contaminated with cat faeces containing sporocysts Toxoplasma gondiiand after work, you cannot forget to wash your hands thoroughly,
6. you should thoroughly wash the kitchen equipment (dishes, knives, cutting boards) that was used to prepare raw meat, seafood, unwashed fruit and vegetables after each use; it is also worth allocating some kitchen equipment such as knives or boards only to work with raw meat,
7. freeze the meat for a few days before cooking as this will reduce the possibility of contamination.

Toxoplasmosis – the risk of infection from the cat

Infected cats may shed oocysts Toxoplasma gondii. Then, the protozoan is excreted with the faeces and becomes a source of infection. Interestingly, however, despite the high number of infected cats, oocysts are rarely found in their faeces (this is observed only in 0,8-1% of the population). However, it should be remembered that oocysts Toxoplasma gondiithat end up in sand or earth, they can survive there for up to 2 years. It seems that the most dangerous are wild cats that kill in sandboxes or home gardens, not cats kept in houses.

It is worth adding that the oocyst itself becomes dangerous to humans only with time, that is, from 1 to 5 days after excretion, and feline faeces, which are fresh, are not yet dangerous. To avoid contamination, our cat’s litter should be changed daily and the litter box should be thoroughly disinfected.

In addition, you should know that a cat that is seropositive, that is, one that has previously had contact with a protozoan and developed antibodies, is not dangerous as it no longer carries oocysts. When it comes to safety, the same applies to seronegative cats, i.e. those that have not been infected and have never gone outside, so they cannot hunt sick animals (birds and rodents), are not fed raw meat and are at the same time. the only cats in the house, then they do not pose a threat.

See also: Toxoplasmosis – is a cat an enemy of a pregnant woman?

What to do to check if our cat is infectious with toxoplasmosis?

In order to check whether the cat is infectious, take a cat stool sample to the laboratory where it will be checked for the presence of oocysts. Toxoplasma gondii. Sometimes immunobiological tests are also performed (specific antibodies or antigens are searched for).

However, it should be added that the high level of antibodies, which indicates a recent infection, is inconclusive. More specifically, it could mean a cat that infects, that is, is in the process of being sick and sheds oocysts into the environment, but it may well mean a cat that has encysted parasites in its organs but is not spreading the disease. If we are dealing with the second case, it is to get infected with bacteria Toxoplasma gondiiyou would have to eat the flesh of such a cat.

For cats that shed oysters, they should be hospitalized until they stop shedding them in their faeces, which usually takes about 2 weeks.

Toxoplasmosis and AIDS

In AIDS, patients who are treated with immunosuppressants, or in those with other immunodeficiencies, toxoplasma can be caused by acquired primary infection as well as by recurrence of latent infection.

Complications related to the disease may end up in blindness, eye infection, brain infection, brain abscess, hepatitis, pneumonia, or other systemic diseases. Brain toxoplasmosis in people with AIDS is most often caused by the reactivation of a chronic infection.

Toxoplasmosis – prognosis

As for the prognosis for acquired toxoplasmosis, in people with normal immunity, it is quite good. As for immunocompromised people or children with congenital toxoplasmosis, the prognosis is uncertain. It should be mentioned that in the case of congenital toxoplasmosis, the mortality rate is as high as 10%.

Toxoplasma and climate change

According to research, climate change affects the occurrence, survival and growth of bacteria T. gondii. Bacteria Toxoplasma gondii, have been identified in the Arctic, a place that was once too cold for the bacteria to survive. Higher temperatures increase survival time T. gondii.

Increased snow melting and rainfall can increase the number of Toxoplasma gondii oocysts that are transported across the river. In addition, it has been noted that changes in bird, rodent and insect populations and migration patterns may influence the distribution of T. gondii due to their role as vectors. It has also been suggested that urbanization and natural environmental degradation affect the transmission of T. gondii and increase the risk of infection.

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