Typhoid fever in the U.S. is acquired primarily through international travel by unvaccinated travelers. There is currently no typhoid vaccine licensed in the U.S. for use in children <2 years old.
We reviewed Salmonella enterica serotype Typhi infections reported to CDC and antimicrobial resistance (AMR) data on Typhi isolates in CDC’s National Antimicrobial Resistance Monitoring System from 1999 through 2015.
5,131 cases of typhoid fever were diagnosed and 5,004 Typhi isolates tested for antimicrobial susceptibility. Among 1,992 pediatric typhoid fever patients, 1,616 (81%) had traveled internationally within 30 days of illness onset, 1,544 (81%) of 1,906 were hospitalized (median duration 6 days; range 0–50), and none died. Forty percent (799) were less than 6 years old; 12% were <2 years old. Based on age and travel destination, 1,435 (83%) of 1,722 of pediatric patients were vaccine-eligible; only 68 (5%) of 1,361 were known to be vaccinated. Of 2,003 isolates tested for antimicrobial susceptibility, 1,216 (61%) were fluoroquinolone-nonsusceptible, of which 272 (22%) were also resistant to ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole (multidrug-resistant [MDR]). All were susceptible to ceftriaxone and azithromycin. MDR and fluoroquinolone-nonsusceptible isolates were more common in children than adults (16% vs. 9%, P<0.001, and 61% vs. 54%, P<0.001, respectively). Fluoroquinolone nonsusceptibility was more common among travel-associated than domestically-acquired cases (70% vs. 17%, P<0.001).
Approximately 95% of currently vaccine-eligible pediatric travelers were unvaccinated, and antimicrobial-resistant infections were common. New public health strategies are needed to improve coverage with currently licensed vaccines. Introduction of an effective pre-travel typhoid vaccine for children <2 years old could reduce disease burden and prevent drug-resistant infections.
Click here to read the article, published in Clinical Infectious Diseases.