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. Pathophysiology
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. Diagnosis
Prevention
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. In addition, children and adults should be carefully educated about personal hygiene. This would include careful handwashing after defecation and sexual contact, before preparing or eating food, and especially the sanitary disposal of feces. Food handlers should be educated in personal hygiene prior to handling food or utensils and equipment. Infected individuals should be advised to avoid food preparation.
Sexually active people should be educated about the risks of sexual practices that permit fecal-oral contact.Those who travel to countries with poor sanitation should receive a live attenuated typhoid vaccine—Ty21a (Vivotif), which, in addition to the protection against typhoid fever,  may provide some protection against paratyphoid fever caused by the S. enterica serotypes A and B. In particular, a reanalysis of data from a trial conducted in Chile showed the Ty21a vaccine was 49% effective (95% CI: 8–73%) in preventing paratyphoid fever caused by the serotype B. 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.Exclusion from work and social activities should be considered for symptomatic, and asymptomatic people who are food handlers, healthcare/daycare staff who are involved in patient care and/or child care, children attending unsanitary daycare centers, and older children who are unable to implement good standards of personal hygiene. The exclusion applies until two consecutive stool specimens are taken from the infected patient and are reported negative. Treatments
Control requires treatment of antibiotics and vaccines prescribed by a doctor. Major control treatments for paratyphoid fever include ciprofloxacin for 10 days, ceftriaxone/cefotaxime for 14 days, or aziththromycin. Prognosis
Those diagnosed with Type A of the bacterial strain rarely die from it except in rare cases of severe intestinal complications.