Vivotif®
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Description

Vivotif® is a live attenuated typhoid fever vaccine for oral administration. 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 over 30 countries, including in the USA. Recent results suggest that Vivotif® may be unique in also protecting against S. paratyphi, a similar but milder variant of typhoid.

About typhoid fever

Typhoid fever is a debilitating and life-threatening illness caused by the bacterium S. typhi. Enteric fever can also be caused by S. paratyphi A, B or C (paratyphoid fever).

Morbidity and mortality

21 million people are estimated to develop typhoid fever each year. 1-4% of persons with typhoid fever die. If untreated, typhoid fever persists for three weeks to one month. Death occurs in between 10% and 30% of untreated cases. At least 5 million people are believed to develop paratyphoid fever annually.

 

In most endemic areas incidence is highest among children between 5 and 19 years of age.

Geographical distribution

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 and Latin America. People traveling to these regions should consider precautions against the disease.

Transmission

Typhoid fever bacteria are 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 facilities. A person may become an asymptomatic carrier of typhoid fever bacteria, 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 fever continue to carry the bacteria after they recover.

Symptoms

Symptoms of the disease include fever, stomach pain, weight loss, loss of appetite, delirium, severe diarrhea (in children), constipation (in adults), cerebral dysfunction and intestinal perforation. 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. However, the clinical picture varies and resembles many other infectious diseases. Clinical diagnosis should be always confirmed by blood culture.

Treatment and prevention

The case-fatality rate of up to 30% can be reduced to less than 1% with appropriate antibiotic therapy. Treatment of typhoid fever usually takes 10 – 14 days and can be done with a variety of antibiotics.

As the trend towards antibiotic resistance continues, the widespread implementation vaccination programs, and the vaccination of risk groups in general might effectively control of typhoid fever. People traveling to endemic countries should get vaccinated and be cautious with local food and drinks.

 

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