[1] Diagnosis may be based on symptoms and confirmed by either culturing the bacteria or detecting the bacterial DNA in the blood, stool, or bone marrow.

Infection is characterized by a sustained fever, headache, abdominal pain, malaise, anorexia, a nonproductive cough (in early stage of illness), a relative bradycardia (slow heart rate), and hepatosplenomegaly (an enlargement of the liver and spleen).

About 30% of people with light skin colour who are infected develop rosy spots on the central body.

Nonspecific symptoms such as chills, sweating, headache, loss of appetite, cough, weakness, sore throat, dizziness, and muscle pains are frequently present before the onset of fever.

[citation needed] They are usually spread by eating or drinking food or water contaminated with the feces of an infected person.

[citation needed] Salmonella Paratyphi B strains causing paratyphoid fever do not ferment dextrorotatory tartrate.

[citation needed] Continuing to shed Salmonella Paratyphi is possible for up to one year, and during this phase, a person is considered to be a carrier.

[citation needed] 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.

[citation needed] Providing basic sanitation and safe drinking water and food are the keys for controlling the disease.

This would include careful handwashing after defecation and sexual contact, before preparing or eating food, and especially the sanitary disposal of feces.

[4] 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.

[14] 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.

[15] 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.

[13] 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.

[17] Occasionally causing epidemics, paratyphoid fever is found in large parts of Asia, Africa, and Central and South America.