Paratyphoid fever A and B are acute infectious diseases similar in clinical course to typhoid fever caused by intestinal bacteria of the genus Salmonella. The paratyph A clinic is characterized by a febrile syndrome, catarrhal phenomena, an abundant roseolous rash on the body; paratyph B proceeds with an increase in body temperature, skin rashes, signs of gastroenteritis. In order to diagnose paratyphs A and B, a bacteriological examination of feces, blood, urine, vomit, as well as serological reactions (RPH, Vidal reaction) is carried out. Treatment includes diet therapy, the appointment of antibacterial drugs (chloramphenicol), detoxification therapy.
Paratyphoid fever A and B are infections of the typhoid–paratyphoid group, occurring with a temperature reaction, intoxication syndrome, skin rashes, dyspeptic disorders of varying severity. The incidence of paratyphus in the world is 0.02 cases per 100 thousand population; in the structure of typhoid-paratyphoid diseases, they account for 10-15%. Typhoid-paratyphoid infections are characterized by a pronounced summer-autumn seasonality. Men aged 15 to 45 years are more likely to get sick. The prevalence and incidence of paratyphs A and B are higher in regions with a low level of sanitary culture of the population and unsatisfactory living conditions.
Characteristics of the pathogen
The causative agent of paratyphoid fever A is the bacterium Salmonella paratyphi, paratyphoid fever B is Salmonella schotmulleri. They are immobile, facultatively anaerobic, gram-negative, rod-shaped microorganisms similar in their morphological properties to the causative agent of typhoid fever. Pathogens of paratyphs sometimes produce gas when sown on nutrient media. Paratyphoid rods are quite stable in the external environment, can remain viable outside the body for up to a week, survive in water and soil for several months. They are able to multiply in food products, for example, in milk and cottage cheese, minced meat. Salmonella cooling is tolerated well, they die quickly when boiled. They respond well to disinfection.
The reservoir in the case of paratyph A is a person, a patient or a carrier, and for the causative agent of paratyph B – livestock, poultry. Paratyphoid fever A and B are transmitted through the fecal-oral mechanism by food, water or household means. For paratyph A, the waterway of infection is more characteristic, for B – food (especially when using dairy products). Humans and animals release the microorganism into the environment throughout the entire period of clinical manifestations and about 2-3 weeks after (convalescence). Asymptomatic bacterial transmission in paratyphs develops more often than in typhoid fever.
People have a high natural susceptibility to the disease, and type-specific immunity remains after recovery. The incidence of paratyph A is mainly observed in Southeast Asia, Africa, paratyph B has no regional foci. Both isolated cases and epidemic outbreaks are noted.
The incubation period for paratyphoid A is usually from 6 to 10 days, the onset is acute, there is a rapid increase in body temperature, runny nose. Cough. Examination reveals facial hyperemia, injections of sclera, sometimes rashes like herpes on the lips and wings of the nose. Unlike typhoid fever, fever is not so constant, is less prolonged, and often acquires an incorrect character. In the midst of the disease, chills and sweating may occur. On the 4-7 day of the disease, a rash appears, most often of a rose-like nature, but it can also be petechial or bark-like. The rash abundantly covers the skin of the abdomen, chest, limbs, differs in polymorphism of elements, and spreads extensively over the course of the disease. Usually, the course of paratyphoid A is moderate, with moderate, more short-term than typhoid intoxication. Sometimes the paratyphoid can become recurrent.
Paratyphoid fever B is characterized by an incubation period of about 5-10 days, characterized mainly by intestinal manifestations in the initial period. Against the background of an increase in temperature, abdominal pain, nausea, vomiting, diarrhea are noted. Often, the initial clinical picture resembles the symptoms of food toxicoinfection. Soon a rash similar to that of paratyphoid A joins. Otherwise, the types of paratyphs are similar in their course. Paratyphoid fever in rare cases can be severe with the development of complications, such as septicemia, inflammation of the meninges.
When people with weakened protective mechanisms of the body are affected, myocarditis, secondary pneumonia, purulent meningitis and meningoencephalitis, septicopiemia may develop. Intestinal bleeding, perforation of the intestinal wall are possible.
Preliminary diagnosis is carried out on the basis of complaints, epidemiological history and physical examination. The causative agent of paratyphs is isolated from blood, vomiting, feces, urine, bile. Specific serological diagnosis is carried out with the help of RPH (becomes positive on the 5th-6th day of the disease), is quite sensitive and specific. Vidal’s reaction is often negative or late and in low credits. A general blood test may show some leukocytopenia, more often eosinophilia.
Treatment of paratyphs includes dietary nutrition: a gentle, easily digestible diet with the exception of components that irritate the intestines. With frequent diarrhea – table No. 4, after normalization of body temperature – table No. 13, the expansion of the diet is carried out gradually. Frequent fractional drinking is recommended.
Etiotropic treatment involves the appointment of antibiotics (chloramphenicol) up to 10 days after the fever subsides. In combination with antibiotic therapy, drugs stimulating the protective properties of the body are prescribed, vaccination with typhoid-paratyphoid vaccine B, thereby enhancing immune resistance. As means of symptomatic therapy, if necessary, rehydration mixtures, cardiovascular agents are used.
Prognosis and prevention
Paratyphoid fever A and B usually have a favorable prognosis, with adequate therapy, a complete recovery occurs, vaccination is used as a prevention of the development of bacterial carrier. Deterioration of the prognosis is possible in case of complications.
General preventive measures consist in sanitary and hygienic measures aimed at monitoring the condition of water sources, sewage, harvesting, storage and transportation of food products, fly control and sanitary education. Individual prevention involves personal hygiene, washing food (vegetables, fruits, herbs), drinking water from proven sources. Employees of food industry and public catering enterprises are subject to preventive examination for the carrier and isolation of the pathogen. If the facts of the carrier are revealed, they are suspended from working with food.