Паратиф: причины, симптомы, диагностика и лечение

Bacterial infection caused by one of the three types of Salmonella enterica
Paratyphoid is caused by the bacterium Salmonella enterica of the serotypes Paratyphi A, Paratyphi B, or Paratyphi C growing in the intestines and blood. Symptoms are similar to those of many other infectious diseases. While no vaccine is available specifically for paratyphoid, the typhoid vaccine may provide some benefit. It is most common in parts of Asia and rare in the developed world. Most cases are due to Paratyphi A rather than Paratyphi B or C. In 2015, paratyphoid fever resulted in about 29,200 deaths, down from 63,000 deaths in 1990. The risk of death is between 10% and 15% without treatment, while with treatment, it may be less than 1%. Diagnosis is with isolation of the agent in blood or stool and demonstration of antibodies antiBH in the Widal test. The disease responds well to chloramphenicol or co trimoxazole.

Paratyphoid C is a rare infection, generally seen in the Far East. It presents as a septicaemia with metastatic abscesses. Cholecystitis is possible in the course of the disease. Antibodies to paratyphoid C are not usually tested and the diagnosis is made with blood cultures. Chloramphenicol therapy is generally effective.

Humans and, occasionally, domestic animals are the carriers of paratyphoid fever. Members of the same family can be transient or permanent carriers. In most parts of the world, short term fecal carriers are more common than urinary carriers. The chronic urinary carrier state occurs in those who have schistosomiasis (parasitic blood fluke). Continuing to shed Salmonella Paratyphi is possible for up to one year, and during this phase, a person is considered to be a carrier. The chronic carrier state may follow acute illness, or mild or even subclinical infections. Chronic carriers are most often women who were infected in their middle age.

After ingestion, if the immune system is unable to stop the infection, the bacteria multiply and then spread to the bloodstream, after which the first signs of disease are observed in the form of fever. They penetrate further to the bone marrow, liver, and bile ducts, from which bacteria are excreted into the bowel contents. In the second phase of the disease, the bacteria penetrate the immune tissue of the small intestine, and the initial symptoms of small bowel movements begin.

Providing basic sanitation and safe drinking water and food are the keys for controlling the disease. In developed countries, enteric fever rates decreased in the past when treatment of municipal water was introduced, human feces were excluded from food production, and pasteurization of dairy products began. Evidence from a study of international travelers in Israel also indicates the vaccine may prevent a fraction of infections by the serotype A, although no trial confirms this. This cross protection by a typhoid vaccine is most likely due to O antigens shared between different S. enterica serotypes.

Factors outside the household, such as unclean food from street vendors and flooding, help distribute the disease from person to person. Because of poverty and poor hygiene and insanitary conditions, the disease is more common in less industrialized countries, principally owing to the problem of unsafe drinking water, inadequate sewage disposal, and flooding. Occasionally causing epidemics, paratyphoid fever is found in large parts of Asia, Africa, and Central and South America. Many of those infected get the disease in Asian countries. About 16 million cases occur a year, which result in about 25,000 deaths worldwide.