What is Toxoplasmosis?
Toxoplasmosis is a parasitic disease characterized by damage to the nervous system, eyes, skeletal muscles and heart muscles, as well as an increase in lymph nodes, liver and spleen. Prone to chronic course.
The prevalence of toxoplasmosis in the world is incredibly high, mainly due to African countries, as well as Latin and South America, in which the infection rate of the population reaches 90%. Rates in Europe and North America are lower – 25-50% of the population.
Causes of Toxoplasmosis
The causative agent of toxoplasmosis, Toxoplasma gondii, belongs to the protozoa type (Protozoa), the class of sporozoans (Sporozoa), the coccidia order (Coccidia). Toxoplasmas are mobile and have the form of an arc, arches or resemble an orange slice. There are also oval and rounded shapes. The type of movement in Toxoplasma sliding.
Pathogenesis during Toxoplasmosis
The life cycle of Toxoplasma includes the stages of sexual and asexual reproduction. Toxoplasmosis is common in many countries. A person becomes infected from domestic animals, most often from cats, which are the ultimate owner of the parasite. In their body, sexual reproduction of the pathogen occurs. Sick animals with toxoplasmosis produce parasites with urine, saliva, and milk. Man is an intermediate owner. Infection occurs by alimentary (most often), drip, through damaged skin and mucous membranes, transmissible (by arthropod bite) by. Perhaps intrauterine infection when the parasite penetrates from the mother to the fetus through the placenta. Toxoplasma infected from 50 to 80% of the adult population.
Ways to Toxoplasmosis
Infection occurs when eating meat products and eggs that have not undergone sufficient heat treatment. The possibility of infection if the pathogen enters the mucous membranes and damaged skin, transmissive, etc., is not excluded. There is also an intrauterine infection.
Factors that can contribute to the parasite in the body and increase the risk of toxoplasmosis:
- Touching with dirty hands to the mouth after contact with the ground, after cleaning the cat litter, or any other contact with the cat excrement.
- Eat raw or undercooked meat, especially pork, lamb or venison.
- Touch the mouth after contact with raw or uncooked / stewed meat.
- Organ transplantation or blood transfusion (very rarely).
- If a woman is pregnant and she has become infected with toxoplasmosis, the infection can be transmitted from her to the child, which can lead to serious consequences.
In humans, toxoplasma multiplies in the intestine, spread by lymphogenous and hematogenous. The phase of lymphogenous drift (lymph nodes are enlarged and inflamed) is replaced by hematogenous dissimination. The stage of finding the parasite in the blood is short (several days). Once in the internal organs, Toxoplasma causes inflammation in them. The nervous system, the retina, the liver, and the myocardium are particularly often affected. In these organs, toxoplasmas are intracellular and extracellular. Clusters of parasites are called pseudocysts. Toxoplasma can form cysts in tissues, causing a state of latent infection. The parasite is activated when conditions are unfavorable to the microorganism and its immunological reactivity decreases. In the pathogenesis of the toxoplasmosis of the nervous system, focal inflammatory phenomena (necrotizing encephalitis), dyscirculatory disorders associated with vasculitis, and obstruction of the cerebrospinal fluid, leading to hydrocephalus and microcephaly, are important.
The most gross morphological changes in the nervous system are observed in children. At macroscopic examination revealed expansion of the ventricles with periventricular zone of necrosis. Scars are found, replacing areas of necrosis, obliteration of the interventricular opening and lateral aperture of the IV ventricle. Hydrocephalus can be expressed, leading to thinning and deformation of the substance of the hemispheres.
Morphological manifestations of toxoplasmosis of the brain in adults are diverse. Microscopic examination is most characteristic of miliary granulomas scattered throughout the brain and spinal cord, consisting of large epithelioid cells, lymphocytes, monocytes, and sometimes eosinophils. Granulomas contain numerous parasites, surrounded by a zone of edema with necrotic foci caused by vasculitis. Typical for toxoplasmosis is the calcification of small foci. In the presence of toxoplasm seroproductive leptomeningitis occurs in the subarachnoid space.
Most infected have no clinical manifestations of the disease. In some patients, sluggish chronic forms are observed and extremely rarely acute, with a severe course of the disease. With intrauterine infection in the first months of pregnancy, miscarriage and fetal death often occur. The possibility of fetal deformities and the birth of children with developmental defects is not excluded. If the infection occurred in late pregnancy, a child is born with generalized toxoplasmosis.