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. 2023 Sep 1;15(5):608-610.
doi: 10.1093/inthealth/ihac076.

Lassa fever cases suffer from severe underreporting based on reported fatalities

David Simons  1   2
Affiliations

Lassa fever cases suffer from severe underreporting based on reported fatalities

David Simons. Int Health. .

Abstract

Background: Lassa fever is a viral haemorrhagic fever endemic to eight West African countries. Symptomatic disease is expected to occur in 20% of those infected and transmission typically occurs from viral spillover from rodent hosts. The combination of limited access to diagnostics and healthcare means the true burden of this disease is unknown.

Methods: The case fatality rate among confirmed, probable and possible cases of Lassa fever in endemic regions is expected to be ≈15%. Here, annual reported cases and deaths have been used to estimate the case fatality rate, using three subsets of available data, to understand the scale of underreporting of severe human cases.

Results: The literature review produced 38 records of cases and fatalities, comprising 5230 reported cases and 1482 reported deaths in seven countries. The estimated case fatality rate ranges from 16.5 to 25.6% (standard deviation 11.5-32.2). The expected number of severe cases between 2012 and 2022 is 8995, with current reported numbers 58% of what is expected.

Conclusion: This analysis highlights current uncertainty and systemic underreporting of the morbidity and mortality burden of Lassa fever in its endemic region and must be considered when discussing the epidemiology of this neglected tropical disease.

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Conflict of interest statement

None declared.

Figures

Figure 1.
Figure 1.
(A) CFR of Lassa fever following development of symptomatic disease and presenting to healthcare using three data sources for estimation. Method 1 uses all reported cases and deaths where the CFR is not equal to 0% or 100%. Method 2 uses all reported cases and deaths provided by NCDC data prior to 2021 where the CFR is not equal to 0% or 100%. Method 3 uses all reported cases and deaths from Edo and Ondo states from 2017 to 2021. The black line represents the weighted mean CFR. (B) The difference between reported cases and expected cases derived from the number of reported deaths divided by the CFR (note that the y-axis scale varies by country).
See this image and copyright information in PMC

References

    1. Balogun OO, Akande OW, Hamer DH. Lassa fever: an evolving emergency in West Africa. Am J Trop Med Hyg. 2021;104(2):466–73. 10.4269/ajtmh.20-0487. - DOI - PMC - PubMed
    1. Redding DW, Gibb R, Dan-Nwafor CCet al. . Geographical drivers and climate-linked dynamics of Lassa fever in Nigeria. Nat Commun. 2021;12(1):5759. 10.1038/s41467-021-25910-y. - DOI - PMC - PubMed
    1. Duvignaud A, Jaspard M, Etafo ICet al. . Lassa fever outcomes and prognostic factors in Nigeria (LASCOPE): a prospective cohort study. Lancet Glob Health. 2021;9(4):e469–78. 10.1016/S2214-109X(20)30518-0. - DOI - PMC - PubMed
    1. Shaffer JG, Grant DS, Schieffelin JSet al. . Lassa fever in post-conflict Sierra Leone. PLoS Negl Trop Dis. 2014;8(3):e2748. 10.1371/journal.pntd.0002748. - DOI - PMC - PubMed
    1. Strampe J, Asogun DA, Speranza Eet al. . Factors associated with progression to death in patients with Lassa fever in Nigeria: an observational study. Lancet Infect Dis. 2021;21(6):876–86. 10.1016/S1473-3099(20)30737-4. - DOI - PMC - PubMed

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