Background: In the United States, typhoid fever is rare. About 300 typhoid cases are reported to CDC annually through the National Typhoid and Paratyphoid Fever Surveillance (NTPFS) system. Most are acquired during international travel and while visiting friends and relatives. CDC recommends pre-travel vaccination of at-risk children with one of two currently available vaccines: oral (age ≥6 years) or injectable (age ≥2 years). In anticipation of licensure of new protein-conjugate typhoid vaccines that could be administered to children ≥6 months old, we characterized clinical, epidemiologic, and antimicrobial resistance data of pediatric typhoid fever cases reported to CDC.
Methods: We reviewed laboratory-confirmed Salmonella enterica serotype Typhi infections reported to NTPFS and antimicrobial resistance data on Typhi isolates in the National Antimicrobial Resistance Monitoring System (NARMS) from 1999-2015.
Results: Of 2,051 pediatric (≤18 years) cases of typhoid fever, 80% had traveled internationally within 30 days of illness onset (most frequently to South Asia [82%]), 81% were hospitalized (median duration 6 days; range 0-77 days), and none died. Eight hundred twenty-seven (40%) were <6 years old; 219 (26%) were 6 months - 2 years old. While 76% of pediatric cases were vaccine eligible (travelers ≥2 years old), only 6% were known to be vaccinated. Of 2,020 isolates tested for antimicrobial susceptibility, 1,211 (60%) had decreased susceptibility or resistance to ciprofloxacin, of which 277 (23%) were also resistant to ampicillin, chloramphenicol, and trimethoprim/sulfamethoxazole (multi-drug resistant [MDR]). None were resistant to ceftriaxone or azithromycin. MDR isolates were more likely in children than adults (16% vs 9%, p<0.05) and in travel-associated than domestically-acquired cases (16% vs 6%, p<0.05).
Conclusion: Among pediatric cases of typhoid fever, 94% of currently vaccine-eligible travelers were unvaccinated. Emphasis on current vaccine indications and an effective pre-travel typhoid vaccine for children between 6 months and 2 years old available during routine immunization visits could begin to reduce the burden of disease, and help prevent drug resistant infections, in this vulnerable age group.
M. Hughes, None
A. Bhatnagar, None
F. Medalla, None
K. Chatham-Stephens, None
G. D. Appiah, None
E. D. Mintz, None
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