Typhoid Fever: A Reduction and a Resurgence

Several population-based studies have recently published data on the incidence of typhoid fever. 1 – 4 These studies redress gaps in our knowledge of disease burden in speci fi c locations and contribute to improved estimates of the global burden of typhoid fever. 5 These data are increasingly important to decision-makers in typhoid-endemic countries as they consider implementing typhoid conjugate vaccine (TCV) programs and apply for GAVI funding. 6 Although typhoid incidence estimates are informative, we should be cautious in generalizing their fi ndings beyond the period during which data were collected. Typhoid incidence is dynamic, with increases following the introduction of new strains with increased antimicrobial resistance, 7,8 and reductions following the introduction of disease control interventions. 9 Long-term incidence data from single-sites is rare, but can provide crucial insights into how various factors in fl uence rates of typhoid fever. 10 This is why the study by Ng ’ eno et al., published in a recent issue of the American Journal of Tropical Medicine and Hygiene , is so relevant. 11 Ng ’ eno et al. provide a decade of typhoid incidence data from the informal Kenyan settlement of Kibera. The authors report crude incidence rates ranging from 144 to 233 per 100,000 person-years of observation (pyo) between 2010 and 2012. This was followed by a decline in typhoid incidence from 2013 to 2017. Cases rebounded in the fi nal two years of surveillance, reaching 130 per 100,000 pyo in 2019. The authors