What causes pseudotuberculosis in children: causes, pathogenesis
Last reviewed: 20.11.2021
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Causes of pseudotuberculosis
The causative agent of pseudotuberculosis is a gram-negative rod in the culture located in the form of long chains, it does not form a spore, it has a capsule. A distinctive feature of the causative agent is the ability to grow at low temperatures (1-4 ° C), the optimum growth temperature is 22-28 ° C. On the surface antigen, 8 serovars are distinguished, each of which can cause disease in humans, but serovars 1 and 3 are more common. It possesses high invasive qualities, due to which it is able to penetrate natural barriers of humans and animals and contains endotoxin. It is suggested that endotoxin is represented by a soluble fraction of O-antigen. The possibility of exotoxin formation has been proved.
Pathogenesis of pseudotuberculosis
The causative agent with infected food or water penetrates the mouth (infection phase) and, breaking the gastric barrier, enters the small intestine, where it enters the enterocytes or intracellular spaces of the intestinal wall ( enteral phase). From the intestine microorganisms penetrate into the regional mesenteric lymph nodes and cause lymphadenitis (phase of regional infection). Massive entry of the pathogen and its toxins from the primary localization into the blood leads to the emergence of a phase of generalization of the infection (bacteremia and toxemia). It corresponds to the appearance of clinical symptoms of the disease. Further progression of the process is associated with the fixation of the pathogen by the cells of the reticuloendothelial system, mainly in the liver and spleen. In essence, this is the parenchymal phase.
Epidemiology of pseudotuberculosis
Extraintestinal yersiniosis (pseudotuberculosis) is registered in virtually all administrative territories of our country. The disease is classified as a group of zoonotic infections. Wild and domestic animals serve as a source of infection. The causative agent was found in 60 species of mammals and in 29 species of birds. The main reservoir of infection is the mouse rodent. They infect with food products, in which, during storage in refrigerators and vegetable stores, reproduction and mass accumulation of the pathogen occur. It is assumed that its reservoirs can be not only rodents and other animals, but also soil where the microorganism is able to reproduce and persist for a long time. It is isolated from water, air, forage, root crops, vegetables, milk. Dairy products, containers, kitchen utensils, etc.
The role of man as a source of infection remains unproven. Infection occurs alimentary in the use of infected foods (salads, vinaigrettes, fruits, dairy products, water, etc.), not subjected to heat treatment. Epidemic outbreaks of different intensity arise as a result of the spread of the pathogen by the food and water ways, and sporadic cases also occur.
Both children and adults are susceptible to pseudotuberculosis. Children under 6 months practically do not get sick, at the age of 7 months to 1 year they rarely get sick, which can be explained by the peculiarities of their nutrition.
Diseases recorded throughout the year, the maximum is in February-March, which is explained by the wider consumption of vegetables and fruits coming from vegetable stores. Infectivity is moderate - 8-20 per 1000 children's population.