|Classification and external resources|
- This about the disease paratyphoid fever. See typhus for an unrelated disease with a similar name. Typhoid fever is a related disease but is caused by a different bacterium.
Paratyphoid fever is an enteric illness caused by one of the following three serotypes of Salmonella enterica subspecies enterica: S. Paratyphi A, S. Paratyphi B and S. Paratyphi A. Like S. Typhi they are transmitted by means of contaminated water or food.
Factors outside the household like unclean food from street vendors and flooding help distribute the disease from person to person. Because of poverty and poor hygiene and sanitary 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, Central and South America. Many of those infected get the disease in Asian countries. There are about 16 million cases a year, which result in about 25,000 deaths worldwide.
Salmonella Typhi can specifically only attack humans, so the infection nearly always comes from contact with another human, either an ill person or a healthy carrier of the bacterium. The bacterium is passed on with water and foods and can withstand both drying and refrigeration, although keeping food refrigerated minimizes the production of the bacterium significantly.
Paratyphoid fever is caused by any of three strains of Salmonella paratyphoid: S. Paratyphi A; S. schottmuelleri (also called S. Paratyphi B); or S. hirschfeldii (also called S. Paratyphi C). It starts when the bacterium S. Paratyphi A, B or C is passed from another person due to bad hygiene such as not washing one's hands after using the restroom. Eventually the bacterium passes down to the bowel, then penetrates the intestinal mucosa (lining) to the underlying tissue.
If the immune system is unable to stop the infection here, the bacterium will multiply and then spread to the bloodstream, after which the first signs of disease are observed in the form of fever. The bacterium penetrates 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 bacterium penetrates the immune tissue of the small intestine, and the initial symptoms of small-bowel movements begin.
Paratyphoid fever resembles Typhoid Fever but presents with a more abrupt onset, milder symptoms and a shorter course. Infection is characterized by a sustained fever, headache, abdominal pain, malaise, anorexia, a non productive cough (in early stage of illness), a relative Bradycardia (slow heart rate), and Hepatosplenomegaly (an enlargement of the liver or spleen). Approximately 30% of Caucasians will develop rosy spots on the central body. In adults, constipation is more common than diarrhea.
Only 20% to 40% of people will initially have abdominal pain. Nonspecific symptoms such as chills, diaphoresis (perspiration), headache, anorexia, cough, weakness, sore throat, dizziness, and muscle pains are frequently present before the onset of fever. Some very rare symptoms are psychosis (mental disorder), confusion and seizures.
Those diagnosed with Type A of the bacteria strain rarely die from it save in rare cases of severe intestinal complications. With proper testing and diagnosis, the mortality rate falls to less than 1%. Antibiotics such as Azithromycin are particularly effective in treating the bacteria.
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 Schistosoma (parasitic blood fluke).
It is possible to continue to shed Salmonella Paratyphi 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, mild or even sub clinical infections. Chronic carriers are most often women who were infected in their middle age.
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.
Control requires treatment of antibiotics and vaccines prescribed by a doctor. Major control treatments for Paratyphoid fever include Ciprofloxacin for ten days or Ceftriaone/Cefotaxime for 14 days or Aziththromycin.
Paratyphoid B is more frequent in Europe. It can present as a typhoid like illness, as a severe gastroenteritis or with features of both. Herpes labialis, rare in true typhoid fever, is frequently seen in Para B.
Diagnosis is with isolation of the agent in blood or stool and demonstration of antibodies anti BH in the Widal test.
Antibodies to para C are not usually tested and the diagnosis is made with blood cultures.
Chloramphenicol therapy is generally effective.
Providing basic sanitation, safe drinking water and food is the key for controlling the disease. In developed countries enteric fever rates decreased in the past when treatment of municipal water was introduces, human faces 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 hand washing 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, and may provide some protection against paratyphoid fever caused by the S. enterica serotypes A and B. In particular an re-analysis of data from a trial conducted in Chile showed that the Ty21a vaccine was 49% effective (95% CI: 8–73%) in preventing paratyphoid fever caused by the serotype B. There is also evidence from a study of international travelers in Israel indicating that the vaccine may prevent a fraction of infections by the serotype A, however no trial confirms this. This cross-protection by a typhoid vaccine is most likely due to O antigenes shared between different S. enterica serotypes.
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