International Travel Raises Risk of Typhoid

Aug. 26 -- TUESDAY, Aug. 25 (HealthDay News) -- International travel is the most common cause of infection with an antimicrobial-resistant strain of typhoid fever among patients in the United States, a new study finds.

About 300 cases of typhoid fever are reported in the United States each year, and the majority of these cases are associated with foreign travel, especially to India, Pakistan and Bangladesh. Over the last 20 years, the emergence of Salmonella serotype Typhi strains resistant to antimicrobial drugs has complicated the treatment of patients in the United States, according to researchers at the U.S. Centers for Disease Control and Prevention.

The CDC team studied data on 1,902 people, median age 22, treated for typhoid fever in the United States between 1999 and 2006, and examined the test results of 2,016 Salmonella Typhi samples submitted to the CDC for analysis.

The researchers found that 1,295 (73 percent) of the patients were hospitalized and three (0.2 percent) died. They also found that 1,439 (79 percent) of the patients had traveled overseas within 30 days before they became ill, and only 58 of the travelers (5 percent) had received typhoid vaccine.

Three countries accounted for more than two-thirds of all travel-associated cases of typhoid fever -- India (47 percent), Pakistan (10 percent) and Bangladesh (10 percent).

The study appears in the Aug. 26 issue of the Journal of the American Medical Association.

The researchers also found that "272 [13 percent] of 2,016 isolates tested were resistant to ampicillin, chloramphenicol and trimethoprim-sulfamethoxazole [multidrug-resistant S. Typhi]; 758 [38 percent] were resistant to nalidixic acid [nalidixic acid-resistant S. Typhi [NARST]], and 734 NARST isolates [97 percent] had decreased susceptibility to ciprofloxacin. The proportion of NARST increased from 19 percent in 1999 to 54 percent in 2006," Dr. Michael F. Lynch, of the CDC, and colleagues wrote in a news release from the journal.