Toxoplasmosis - Treatment and Prevention

Most effective in the acute phase of the disease: patients with latent chronic acquired toxoplasmosis do not require treatment. The effectiveness of etiotropic drugs in chronic toxoplasmosis is low, since chemotherapy drugs and antibiotics have virtually no effect on endozoites located in tissue cysts. Treatment of toxoplasmosis is indicated only in the case of exacerbation of the process and in case of miscarriage (treatment is carried out outside the period of pregnancy).

Pyrimethamine in combination with sulfonamides or antibiotics is used as an etiotropic drug for toxoplasmosis. The duration of the treatment cycle is 7 days. Usually 2-3 cycles are carried out with 10-day breaks between them. It is possible to use co-trimoxazole, one tablet twice a day for 10 days. Two cycles are carried out with an interval of 10 days. At the same time, calcium folinate is prescribed at 2-10 mg per day or brewer's yeast at 5-10 tablets per day. It is necessary to monitor the hemogram (suppression of bone marrow hematopoiesis is possible) and general urine analysis in dynamics.

Treatment regimen for acquired toxoplasmosis

	Daily doses
Preparation	1-3 days of the course		4-7th day of the course
	Adults, mg	Children	Adults, mg	Children
Pyrimethamine (once daily)	75	2 mg/kg	25	1 mg/kg
Sulfadiazine (four times a day)	2000	100 mg/kg	2000	25 mg/kg
Calcium folinate	-	1 mg	2-10	1 mg

Pregnant women are treated with spiramycin (accumulates in the placenta and does not penetrate the fetus). It is prescribed at 3 million units three times a day for 2-3 weeks.

Treatment of toxoplasmosis in children is carried out with the same drugs as treatment of adults: pyrimethamine 1 mg/kg per day in two doses in combination with short-acting sulfonamides 0.1 g/kg per day in 3-4 doses. Treatment of toxoplasmosis is carried out in cycles: pyrimethamine is taken for 5 days, and the sulfonamide drug is taken 2 days longer - 7 days. Three cycles are carried out with breaks between them of 7-14 days. Additionally, calcium folinate is prescribed 1-5 mg once every 3 days during the entire course of treatment to eliminate the side effects of antifolates (pyrimethamine, sulfonamides). The same course of treatment according to indications (for example, chronic form of the disease, immunodeficiency state, exacerbation of chorioretinitis) is repeated after 1-2 months.

Macrolides, which are less toxic, are second in effectiveness. Spiramycin is prescribed at 150,000 U/kg per day in 2 doses for 10 days, roxithromycin - 5-8 mg/kg per day, azithromycin - 5 mg/kg per day for 7-10 days. In case of exacerbation of chronic toxoplasmosis, one course of etiotropic treatment for 7-10 days is usually sufficient.

Pathogenetic treatment of toxoplasmosis is carried out depending on the nature of the organ pathology. If necessary, immunocorrective drugs, vitamins, and desensitizing drugs are prescribed.

Patients with toxoplasmosis and HIV infection are prescribed the same drugs as other patients: pyrimethamine - 200 mg on the first day in combination with sulfadiazine (1 g four times a day), clindamycin (0.6 g six times a day) or spiramycin (3 million IU three times a day). At the same time, patients take calcium folinate 10-50 mg per day. The course of treatment is at least 4 weeks, then secondary prophylaxis is prescribed to prevent relapses: pyrimethamine 50 mg per day and sulfadiazine 0.5 g four times a day. Due to the complexity of diagnosis and the severity of cerebral toxoplasmosis, treatment is prescribed even if the disease is suspected. Improvement within 2-4 weeks of treatment with a high degree of probability indicates the presence of toxoplasmosis.

Etiotropic treatment of toxoplasmosis is assessed by clinical signs: improvement of the patient's general condition, disappearance of lymphadenitis; lesser severity of hepatosplenic syndrome, signs of encephalitis, eye damage; absence of relapses of the disease for 12 months or more. The results of serological studies are not used to assess the effectiveness of etiotropic treatment, since the titers of specific antibodies do not correlate with the nature of the clinical course of the disease.

Prognosis for toxoplasmosis

Acquired toxoplasmosis has a favorable prognosis, since the latent form without clinical manifestations predominates. Septic forms observed in AIDS patients and in patients with immunodeficiency of other etiologies are severe and can end in death.

Clinical examination

Patients with acute acquired and recurrent chronic toxoplasmosis, as well as HIV-infected patients seropositive to toxoplasma antigens, require dispensary observation. The scope and duration of dispensary observation depend on the clinical form of toxoplasmosis and the nature of the disease. In case of congenital toxoplasmosis in children, depending on residual phenomena, the issue of dispensary observation is decided jointly with neurologists, ophthalmologists and other doctors. Some patients require lifelong dispensary observation (with eye damage when etiotropic treatment is ineffective, HIV-infected patients seropositive to toxoplasma antigens).

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How to prevent toxoplasmosis?

Theoretically, the most radical way to prevent human toxoplasmosis is elimination (Latin Eliminare - exclusion, removal) and reliable sanitation (Latin Sanacio - treatment) of the parasite's final host, i.e. the cat. In this sense, toxoplasmosis prevention is similar in content to rabies prevention. There is no doubt that the complete extermination of stray cats and effective veterinary supervision of domestic cats is a guarantee, if not of complete recovery of synanthropic foci of toxoplasmosis, then in any case of reducing the incidence of the population in them by tens and thousands of times. And what is especially important, such measures will simultaneously serve as a reliable guarantee of preventing cases of congenital toxoplasmosis. Unfortunately, not a single experience of radical prevention of toxoplasmosis has yet been undertaken in any country. Moreover, to date, all recommendations for the prevention of toxoplasmosis are based on the tacit recognition of the impossibility of effectively influencing the final host of the parasite - the cat.

Taking into account the above, it seems to us quite timely to begin developing a system of active preventive anti-toxoplasmosis measures and to organize testing of its effectiveness in strictly controlled epidemiological experiments. We are talking about the sensitivity of various stages of the parasite to external factors, including chemical reagents. Oocysts are the most resistant to the effects of environmental factors. The resistance of tachyzoites and tissue cysts is extremely low; they die even under the influence of tap water. That is why it is necessary to insist on such a simple measure as washing hands after contact with raw meat. A temperature of 100 °C is absolutely intolerable for tissue cysts. Freezing meat at -20 °C also guarantees the death of cysts.

Specific prevention of toxoplasmosis

The main measures to prevent congenital toxoplasmosis are timely examination of women of childbearing age and pregnant women in antenatal clinics. Primary and secondary prevention of toxoplasmosis is performed in HIV-infected patients. The goal of primary prevention is to prevent infection with T. gondii or the development of toxoplasma encephalitis in individuals with a latent form of the disease. In HIV-infected individuals with a positive serological reaction to toxoplasmosis, chemoprophylaxis with etiotropic drugs is performed. The goal of secondary prevention or maintenance treatment is to prevent relapses of toxoplasma encephalitis in AIDS patients.

Non-specific prophylaxis of toxoplasmosis

Prevention of toxoplasmosis consists of careful heat treatment of meat products and milk; compliance with personal hygiene rules, especially in risk groups (veterinarians, meat processing plant workers, hunters, etc.); preventing contamination of children's sandboxes with cat excrement.