Vivotif^® is a live attenuated vaccine for oral administration against typhoid fever. It is the only oral vaccine indicated for use against Salmonella typhi, the most prevalent of the typhoid fever-causing bacteria. The vaccine is indicated for adults and children over the age of five and has an excellent track record for safety, having been on the market for more than 20 years. It is currently licensed in 44 countries, including the United States. Recent results suggest that Vivotif^® may be unique in also protecting against S. paratyphi, a similar but milder variant of typhoid.

Typhoid fever is a debilitating and life-threatening illness caused by the bacteria S. typhi. Paratyphoid fever, a similar but generally milder disease, is caused by any of three serotypes of S. paratyphi, A, B and C.

Approximately 16 million people develop typhoid fever each year, with approximately 4% of cases resulting in death. If left untreated, typhoid fever persists for three weeks to a month. Death occurs in between 10% and 30% of untreated cases.

Incidence is highest among children between 5 and 19 years of age in virtually all endemic areas.

Typhoid fever is common in most parts of the world except in industrialized regions such as the United States, Canada, western Europe, Australia, and Japan, where the advent of proper sanitary facilities has virtually eliminated the disease. Most cases reported in industrialized countries have been contracted by travelers to endemic regions such as Africa, Asia (except Japan) and Latin America. As such, people traveling to these regions should consider precautions against the disease.

Typhoid fever is transmitted by fecal contamination of food or water, or by person-to-person contact. The disease is most commonly transmitted as a result of poor hygiene habits and public sanitation conditions. A person may become an asymptomatic carrier of typhoid, suffering no symptoms but still being capable of infecting others. According to the Centers for Disease Control and Prevention (CDC), approximately 5% of people who contract typhoid continue to carry the disease after they recover.

Symptoms of typhoid fever include fever, stomach pains, weight loss, loss of appetite, delirium, severe diarrhea (in children) and constipation (in adults). Persons with typhoid fever usually have a sustained fever as high as 39° to 40° C. In some cases, patients have a rash of flat, rose-colored spots.

Classically, there are two phases of the disease’s progression following a usual incubation period of 7-14 days:

• 1st phase: the patient's temperature gradually rises to 40ºC, with bouts of sweating, loss of appetite, coughing and headache. Constipation and skin symptoms may be the clearest symptoms, while children often vomit and have diarrhea. This phase lasts about a week, with the patient demonstrating increasing listlessness and clouding of consciousness.
• 2nd phase: in the second to third week of the disease, symptoms of intestinal infection develop, the fever remains very high and the pulse becomes weak and rapid. In the third week constipation is replaced by severe pea-soup-like diarrhea. The feces may also contain blood. Only in the fourth or fifth week does the fever drop and the general condition slowly improve.

The case-fatality rate of up to 20% can be reduced to less than 1% with appropriate antibiotic therapy. On average, antibiotic treatment for typhoid fever consists of approximately 60 tablets taken over approximately 18 days. As the trend towards antibiotic resistance continues, the widespread use of effective vaccination programs, and the vaccination of risk groups in general, is becoming paramount in the control of typhoid fever. Clearly, strict attention should be given to food and water precautions while traveling in endemic countries.

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