Routine suspected typhoid notification rates in Sierra Leone exceed African blood-culture surveillance estimates, 2019–2025

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. 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. 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). 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.

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Journal
BMC Infectious Diseases
Published
2026-08-28
DOI
https://doi.org/10.1186/s12879-026-14325-z
Primary Topic
Salmonella and Campylobacter epidemiology
Type
article
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article

Routine suspected typhoid notification rates in Sierra Leone exceed African blood-culture surveillance estimates, 2019–2025

Lucy Namulemo, Foday Sahr, Eric Nzirakaindi Ikoona, Mohamed Alex Vandi et al.
BMC Infectious Diseases
Salmonella and Campylobacter epidemiology
article

Routine suspected typhoid notification rates in Sierra Leone exceed African blood-culture surveillance estimates, 2019–2025

Lucy Namulemo, Foday Sahr, Eric Nzirakaindi Ikoona, Mohamed Alex Vandi, Bridget Magoba, Mary Magdalene Sinnah
article en

Abstract

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. 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. 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). 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.

BMC Infectious Diseases
Public Health Agency (GB), Training Programs in Epidemiology and Public Health Interventions Network (US)
Good health and well-being
Openalex Percentile: Top 13%
Salmonella and Campylobacter epidemiology
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