Paratif

Paratyphoid fever is an acute infectious disease similar in etiology, epidemiology, pathogenesis, morphology and clinical picture to typhoid fever. Paratyphoid fever is classified as A, B and C.

ICD-10 code

A01. Typhoid and paratyphoid.

Epidemiology of paratyphoid fever

Paratyphoid fever accounts for about 10-12% of all typhoid-paratyphoid diseases. For a long time, paratyphoid A and B were described as a mild variant of typhoid fever, lacking a clear clinical picture. At the same time, they were often limited to data on their differentiation from typhoid fever.

Paratyphoid A and B are typical intestinal infections, anthroponoses, found everywhere. Before the First World War, paratyphoid B was more common in our country, now both diseases are quite common. Paratyphoid C as an independent disease is rarely registered, usually in people with immunodeficiency states.

The main source and reservoir of infection is a patient or a carrier of bacteria, releasing pathogens with feces, urine and saliva. A patient with paratyphoid fever begins to release the pathogen into the environment with feces and urine from the first days of the disease, but the greatest intensity of bacterial excretion is reached in the 2nd-3rd week of the disease. After suffering paratyphoid fever, acute (up to 3 months) or chronic (over 6 months) bacterial carriage may develop. Chronic carriers are 5-7% of people who have suffered paratyphoid fever. There is no reliable data on human infection with paratyphoid A and B from animals.

As the incidence of paratyphoid fever decreases, the role of carriers as sources of infection increases compared to patients. They become especially dangerous if they work in food production facilities, trade, public catering, in medical and children's institutions, in the water supply system.

The mechanism of transmission of the causative agents of paratyphoid A, B, C is fecal-oral. The factors of infection transmission are food products, water, household items infected by patients or carriers of bacteria, as well as flies. There are both sporadic cases and epidemic outbreaks.

If the sanitary maintenance of wells or other open water bodies is violated, they are easily polluted, including by wastewater. Waterborne epidemics of paratyphoid fever can also occur in the event of a faulty water supply when connecting technical water supply, more often encountered with paratyphoid A.

The food route of spreading paratyphoid fever, especially paratyphoid B, is primarily associated with the consumption of infected dairy products, as well as products that have not been heat-treated after preparation: salads, jellied meat, ice cream, creams. Food outbreaks of paratyphoid A are less common than those of paratyphoid B.

Infection by contact and household means is possible from chronic carriers of the bacteria, less often from sick people when sanitary conditions are violated.

If increased paratyphoid fever incidence is observed in populated areas, then its seasonality is usually observed, associated primarily with infection through water, poorly washed berries, fruits, vegetables. With a low level of paratyphoid fever incidence, its seasonal rise is smoothed out or absent altogether.

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What causes paratyphoid fever?

Paratyphoid bacteria are an independent species of microbes of the genus Salmonella, the causative agent of:

• paratyphoid A - S. paratyphi A;
• paratyphoid B - S. schotmuelleri;
• paratyphoid C - S. hirschfeldii.

In shape, size, tinctorial properties they do not differ from typhoid fever; biochemically more active, especially S. schotmuelleri, which is consistent with lower pathogenicity for humans. They have somatic (O-antigen) and flagellar (H-antigen) antigens. Paratyphoid pathogens are well preserved in the external environment, including drinking water, milk, butter, cheese, bread, are relatively resistant to physical and chemical factors, and are preserved for a long time at low temperatures (in ice for several months). They die instantly when boiled.

Recently, there has been a need to differentiate the causative agent of paratyphoid B from S. java, which is classified as a salmonella of group B and has the same antigenic structure as S. schotmuelleri, but differs from it in biochemical properties. S. java is often isolated from animals, causing food poisoning in humans, which is mistaken for paratyphoid B.

Pathogenesis of paratyphoid

The pathogenesis of paratyphoid A, B. C and typhoid fever does not have any fundamental differences.

In paratyphoid fever, the large intestine is affected more often than in typhoid fever, and destructive processes in the intestinal lymphatic apparatus are expressed to a lesser extent.

Symptoms of paratyphoid fever

Paratyphoid fever A is usually characterized by typhoid (50-60% of patients) or catarrhal (20-25%) forms. Unlike typhoid fever, paratyphoid fever A often occurs in a moderate form and in the initial period is manifested by facial hyperemia, scleral injection, cough, runny nose. These symptoms of paratyphoid fever make the initial period of paratyphoid fever A similar to ARVI. The rash appears on the 4th-7th day of the disease in 50-60% of patients. Along with the typical roseola rash, maculopapular elements resembling measles exanthema can be found. Some patients have petechial elements. The rash is more abundant than with typhoid fever. There is no characteristic type of fever with paratyphoid fever A, but remittent fever is still more common. Relapses and complications are rare.

In paratyphoid B, the gastrointestinal form is most common (60-65% of patients), less common are typhoid (10-12%) and catarrhal (10-12%) forms. Distinctive symptoms of paratyphoid B are signs of gastroenteritis, which occur in the first days of the disease. Later, fever and exanthema are added, represented by roseola, which are much more abundant and elevated than in typhoid fever. The temperature is often undulating, with a large daily amplitude. The severity of paratyphoid B can vary - from latent and abortive to very severe forms, but in general it is easier than paratyphoid A and typhoid fever. After suffering paratyphoid B, persistent immunity is formed, relapses occur infrequently - in 1-2% of patients. Rarely, such formidable complications as intestinal perforation (0.2%) and intestinal bleeding (0.4-2% of patients) can occur. Non-specific complications also occur: bronchopneumonia, cholecystitis, cystitis, mumps, etc.

Symptoms of paratyphoid C are characterized by intoxication, muscle pain, yellowing of the skin, and fever.

Diagnosis of paratyphoid

Diagnosis of paratyphoid fever involves bacteriological examination of feces, blood, urine, vomit and gastric lavage, as well as detection of antibodies to salmonella in RIGA, Vi-agglutination reaction with typical serums and/or linear RA (Widal reaction). Monodiagnostics for specific pathogens are used as antigens. It is recommended to start studies from the 7th day (time of antibody titer increase).

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What is the prognosis for paratyphoid fever?

Paratyphoid fever has a favorable prognosis if treated promptly and adequately. Treatment of paratyphoid fever, preventive measures, medical examination, recommendations for discharge - see " Typhoid fever ".