Typhoid Fever in Travelers: Who Should Be Targeted for Prevention? Steinberg EB, Bishop R, Haber P, Dempsey AF, Hoekstra RM, Nelson JM, Ackers M, Calugar A, and Mintz ED. Clinical Infectious Diseases 2004;39:186-191
Explanatory note: Typhoid fever is rare in the United States, so routine typhoid vaccination is not recommended. However, travelers to parts travel of the world where typhoid fever is common should receive the vaccine prior to travel. Risk of acquiring typhoid fever is greater for travelers to the Indian subcontinent, Latin America, Asia, and Africa who may have prolonged exposure to contaminated food and drink.
Three vaccines against typhoid were available in the United States during the period of this study (between 1994 and 1999): an oral live-attenuated vaccine (Ty21a; Vivotif Berna); a parenteral heat-inactivated vaccine (Typhoid vaccine); and, after December 1994, a capsular polysaccharide vaccine (Typhim Vi) given by injection. In 2000, the heat-inactivated typhoid vaccine was discontinued in the US; the other two vaccines are still in use.
In the US, who should be vaccinated against typhoid fever?
Researchers reviewed data from all laboratory-confirmed cases of typhoid fever reported to the CDC’s National Typhoid Fever Surveillance System from 1994 through 1999.
They also estimated the risk of adverse reactions, by reviewing all reports to the Vaccine Adverse Event Reporting System (VAERS) for persons who received a typhoid vaccination in the US between 1994 and 1999.
Additionally, the researchers reviewed data provided by the 3 vaccine manufacturers to estimate the number of persons immunized during those years.
From 1994 through 1999, 1,393 laboratory-confirmed cases of typhoid infection were reported in the United States—of which 1,027 (74%) were associated with foreign travel.
These travelers visited a total of 64 countries. Among 940 travelers who visited a single country, 53% acquired typhoid fever in the Indian subcontinent, 17% in Mexico and Central America, 7% in the Caribbean, 3% in Africa, and 4% in other regions.
Only 36 of the infected travelers (4%) reported having received a typhoid vaccination at any point during the 5 years preceding travel.
Even short-term travel was associated with a risk of typhoid fever. For 626 travelers who traveled to a single country and reported their duration of stay, 5% stayed at least 1 week, 16% stayed at least 2 weeks, 27% stayed at least 3 weeks, 37% stayed at least 4 weeks, 54% stayed at least 5 weeks, and 60% stayed at least 6 weeks.
The study also found that 688 adverse events had been reported to VAERS following a dose of typhoid vaccine, given alone or in combination with other vaccines, from 1994 through 1999. The most commonly reported symptoms were fever (28%), headache (18%), chills (16%), nausea (15%), and hypersensitivity at the injection site (12%); 10% with more than 1 adverse event following typhoid vaccination alone were reportedly hospitalized, 2 persons had a disability, and none died. The majority of reports were associated with the now discontinued whole cell vaccine.
The researchers calculated that about 5.6 million doses of typhoid vaccine were administered during that 6 year period of time.
The results of this study suggest that vaccination against typhoid fever for persons planning short-term travel to high-risk areas, such as the Indian subcontinent, should be considered.
Vaccination against typhoid fever and careful attention to hygiene and to the types of foods and drinks that are eaten while abroad remain the best ways that travelers can lower their risks of developing typhoid fever.