Updated: March 11, 2005
Typhoid fever is a serious disease caused by the bacterium called Salmonella enterica serotype Typhi (S. Typhi).
The infection is spread from person-to-person by the fecal-oral route. That means that people get typhoid from food or water contaminated with the feces of infected people.
Typhoid symptoms include high fever, weakness, stomach pains, headache, loss of appetite, and sometimes a rash. Infection can spread to many other places in the body (such as bones) and can cause rupture of the intestine. It kills up to 30% of people who get it, if they are not treated.
Some people who become infected with S. Typhi become chronic carriers—they have no symptoms but have S. Typhi in their feces. Chronic carriers can spread S. Typhi to other people especially when handling food.
Antibiotic therapy reduces deaths and complications caused by typhoid fever. However, in recent years S. Typhi has acquired resistance to many of the antibiotics most widely available for its treatment. Typhoid vaccine can reduce the risk of illness in those who are exposed to S. Typhi.
According to the World Health Organization, 16 million people get typhoid every year around the world and about 600,000 die from the disease.
Typhoid is not common in the United States. Although 356 cases of typhoid fever were reported in the US in 2003, most of these infections are acquired during travel to other parts of the world or by contact with someone who is a carrier—either someone who has recently traveled or is a chronic carrier of S.Typhi.
Product: Vivotif Berna® (Live-attenuated Oral Vaccine)
Manufacturer: Berna Biotech, Ltd
Year licensed: 1989
Product: TYPHIM Vi ® (Capsular Polysaccharide Vaccine)
Manufacturer: Aventis Pasteur, SA
Year licensed: 1994
During the past 15 years, the two typhoid vaccines licensed in the US have been widely used globally. These vaccines have largely replaced the old heat-phenol inactivated whole-cell vaccine in many countries, including the US.
Who should receive the vaccine?
Typhoid fever is rare in the United States, so routine typhoid vaccination is not recommended. However, the following people should receive the vaccine:
Who should not receive the Polysaccharide Typhoid Vaccine (Shot)?
Who should not receive the live attenuated Typhoid Vaccine (Oral)?
The oral typhoid vaccine can be administered to children 6 years of age or older and adults. They should take 1 capsule every other day for a total of 4 capsules. The last dose should be taken at least 1 week before travel to allow the vaccine time to work. A booster dose is needed every 5 years for people who remain at risk.
The polysaccharide typhoid vaccine can be administered to children older than 2 years of age. One shot is enough to provide protection. It should be given at least 1 week before travel to allow the vaccine time to work. A booster dose is needed every 2 years for people who remain at risk for exposure.
The efficacy of the two licensed vaccines ranges from 50% to 80%.
The oral vaccine has shown a protective efficacy of 62% for at least seven years after the last dose. The inactivated vaccine for its part, showed a 55% efficacy in a recent study in South Africa three years after immunization of children 5 to 16 years of age.
The two typhoid vaccines licensed in the US have few adverse reactions. Most reactions that do occur are mild.
Reactions to the oral typhoid vaccine include fever or headache (5%), abdominal discomfort, nausea, vomiting, or rash (rare). Reactions to the inactivated vaccine include fever (1%); headache (3%); and redness or swelling at the site of the injection (7%).
The Vaccine Adverse Event Reporting System (VAERS) received 1,482 US adverse event reports after typhoid vaccination during the period of 1 July 1990 through 31 June 2002. A total of 321 of these reports involved the polysaccharide vaccine, 345 involved the oral vaccine, 707 involved whole-cell vaccine (which is no longer available in the US), and 109 did not identify the vaccine type.
Although causal relationships for specific conditions cannot be established from VAERS data, an analysis of these reports identified some unanticipated conditions that may be related to the vaccines: influenza-like syndromes and anaphylaxis (hypersensitivity to the vaccine) after receipt of the oral vaccine and other serious allergic events after receipt of the polysaccharide vaccine. However, VAERS reports do not indicate any unexpected serious side effects that compromise these vaccines’ use for travelers’ prevention of typhoid fever.