|Common Name(s)||Typhoid Fever|
|Scientific Name(s)||Salmonella enterica typhi bacteria|
|Physical Attributes||Gram negative, bacilli with flagella for movement; facultatively anaerobic|
|Mode(s) of Transmission||Contaminated food and drink, sewage leaks, direct contact with infected|
|Likely BW Form(s)||Aerosol; food and water contamination|
|Pathology||Fever as high as 103° to 104° F (39° to 40° C), stomach pains, headache, chills, malaise, or loss of appetite, sometimes flat, rose-colored spots; untreated the disease continues for 3-4 weeks|
|Vector/Dormant Form||Asymptomatic human carrier|
|Incubation Period||Usually 1-3 weeks|
|Fatality||Untreated: 12%-30%; with treatment: ~1%|
|Treatment||Antibiotics, most commonly ampicillin, trimethoprim-sulfamethoxazole, and ciprofloxacin|
Typhoid fever is an illness caused by the bacterium Salmonella Typhi found in contaminated food and water. As of 2005, typhoid fever remained common in the developing world, where it affects about 21.5 million persons each year. About 400 cases a year were reported in the United States, 75% of these were acquired while traveling internationally.
Salmonella typhi lives only in humans. Typically the incubation period ranges from 1 week to 3 weeks. Persons with typhoid fever carry the bacteria in their bloodstream and intestinal tract. In addition, a small number of carriers recover from typhoid fever but continue to carry the bacteria. Both ill persons and carriers shed Salmonella Typhi in their feces.
Persons with typhoid fever experience an insidious onset characterized by fever (sustained, as high as 103° to 104° F; 39° to 40° C), headache, constipation, malaise, chills, and myalgia with few clinical features that reliably distinguish it from a variety of other infectious diseases. They may suffer from loss of appetite, and in some cases patients have a rash of flat, rose-colored spots. Diarrhea is uncommon, and vomiting is not usually severe. Confusion, delirium, intestinal perforation, and death may occur in severe cases. The etiologic agent may be recovered from the bloodstream or bone marrow, and occasionally from the stool or urine.
Three types of vaccines are available in the United States. Ty21a (Vivotif Berna, Swiss Serum and Vaccine Institute) is an oral live attenuated vaccine. 4 doses are required and in each dose, one capsule is ingested. 2 days are necessary between the doses, and the vaccination process requires 2 weeks to complete. The minimum age for vaccination is 6 years. A booster shot is needed every 5 years. The ViCPS (Typhim Vi, Pasteur Merieux) vaccine is an injection given once. The minimum age for vaccination is 2 years old. A booster shot is needed every 2 years. A third vaccine is a parenteral heat-phenol-inactivated vaccine that has been widely used for many years (Typhoid Vaccine, manufactured by Wyeth- Ayerst). The vaccine consists of 2 injections no more than 4 weeks apart. The minimum age for vaccination is 6 months. Possible adverse reactions for the parenteral heat-inactivated vaccine include fever, swelling and headache. A fourth acetone-inactivated parenteral vaccine is only available to the armed forces.
Three commonly prescribed antibiotics to treat Typhoid Fever are ampicillin, trimethoprim-sulfamethoxazole, and ciprofloxacin. Persons given antibiotics usually begin to feel better within 2 to 3 days, and deaths rarely occur. However, persons who do not get treatment may continue to have fever for weeks or months, and as many as 20% may die from complications of the infection.
The Salmonella Typhi bacteria has become increasing resistance to available antimicrobial agents, including fluoroquinolones, which may foretell dramatic increases in case-fatality rates. Epidemics and high endemic disease rates have occurred in the Central Asian Republics, the Indian subcontinent, and across Asia and the Pacific Islands.
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