Authors
Eric Nzirakaindi Ikoona, Lucy Namulemo, Bridget Magoba, Mary Magdalene Sinnah, Mohamed Alex Vandi & Foday Sahr
Background
Sierra Leone records suspected typhoid in the electronic Integrated Disease Surveillance and Response (eIDSR) system as aggregate district notifications. The records are not linked to diagnostic method or microbiological result. We compared annual notification rates from 2019 to 2025 with 535 per 100,000 person-years, the upper 95% confidence limit of the highest adjusted all-age site estimate in the Typhoid Fever Surveillance in Africa Program. The comparison assessed how routine notifications relate to the country’s underlying typhoid burden.
Methods
We analyzed 112 district-year records from all 16 health districts. Annual district and national notification rates were calculated from suspected typhoid counts and projected populations. A district-clustered Poisson generalized estimating equation (GEE) estimated annual notification rates, 95% confidence intervals, and rate ratios against that reference. Geographic analyses described district variation. A secondary negative-binomial GEE examined whether within-district changes in malaria notification rates were associated with changes in suspected typhoid notifications.
Results
eIDSR recorded 1,016,325 suspected typhoid notifications from 2019 to 2025. Annual national notification rates ranged from 1,290 per 100,000 population in 2019 to 2,054 per 100,000 in 2025. Rate ratios relative to the reference ranged from 2.41 to 3.84. Every district-clustered 95% confidence interval lay above the reference, and all seven Holm-adjusted two-sided p values were below 0.002. In 2025, district notification rates ranged from 43 to 5,116 per 100,000 population. A doubling of the within-district clinical malaria notification rate was associated with a typhoid rate ratio of 1.44 (95% CI 0.87–2.39; p = 0.14).
Conclusions
Routine suspected typhoid notification rates exceeded the reference in every study year and varied widely between districts. The pattern may reflect true transmission, diagnostic classification, care seeking, reporting, or combinations of these processes. Standardized febrile-patient screening, sentinel blood culture, and register and eIDSR review in both high- and low-notification districts are needed to determine how routine notifications relate to culture-confirmed typhoid.
Click here to read the full paper in BMC Infectious Diseases.
