Comparative Epidemiology of Salmonella enterica Serovers Paratyphi A and Typhi Causing Enteric Fever, Bangladesh, 2018-2020.

Enteric fever remains a public health challenge. We analyzed data from a cluster-randomized Vi-tetanus toxoid conjugate vaccine trial to compare the epidemiology between Salmonella enterica serovars Paratyphi A, which causes paratyphoid fever, and Typhi, which causes typhoid fever. The overall incidence rate of paratyphoid fever was 27 (95% CI 23-32)/100,000 person-years (PY) and of typhoid fever was 216 (95% CI 198-236)/100,000 PY. We observed the highest incidence for both diseases in children 2-4 years of age: 72 (95% CI 41-117)/100,000 PY for paratyphoid and 887 (95% CI 715-1,088)/100,000 PY for typhoid. Lack of private toilets and safe drinking water were associated with both diseases. Prevalence of multidrug resistance was significantly higher in Salmonella Typhi (20.2%) than in Salmonella Paratyphi A (0.8%) (p<0.001). Our data suggest that integrated control measures targeting water, sanitation, and hygiene measures and bivalent vaccine targeting both pathogens are promising strategies to control both diseases.