TY - JOUR
T1 - Lassa fever outbreaks, mathematical models, and disease parameters
T2 - a systematic review and meta-analysis
AU - Doohan, Patrick
AU - Jorgensen, David
AU - Naidoo, Tristan M.
AU - McCain, Kelly
AU - Hicks, Joseph T.
AU - McCabe, Ruth
AU - Bhatia, Sangeeta
AU - Charniga, Kelly
AU - Cuomo-Dannenburg, Gina
AU - Hamlet, Arran
AU - Nash, Rebecca K.
AU - Nikitin, Dariya
AU - Rawson, Thomas
AU - Sheppard, Richard J.
AU - Unwin, H. Juliette T.
AU - van Elsland, Sabine
AU - Cori, Anne
AU - Morgenstern, Christian
AU - Imai-Eaton, Natsuko
AU - Morris, Aaron
AU - Forna, Alpha
AU - Dighe, Amy
AU - Vicco, Anna
AU - Hartner, Anna Maria
AU - Lambert, Ben
AU - Cracknell Daniels, Bethan
AU - Whittaker, Charlie
AU - Santoni, Cosmo
AU - Geismar, Cyril
AU - Dee, Dominic
AU - Knock, Ed
AU - Unwin, Ettie
AU - Thompson, Hayley
AU - Dorigatti, Ilaria
AU - Routledge, Isobel
AU - Wardle, Jack
AU - Skarp, Janetta
AU - Hicks, Joseph
AU - Parchani, Kanchan
AU - Fraser, Keith
AU - Drake, Kieran
AU - Geidelberg, Lily
AU - Cattarino, Lorenzo
AU - Kusumgar, Mantra
AU - Kont, Mara
AU - Baguelin, Marc
AU - Guzman, Pablo Perez
AU - Lietar, Paul
AU - Christen, Paula
AU - Nash, Rebecca
AU - Fitzjohn, Rich
AU - Sheppard, Richard
AU - Johnson, Rob
AU - Leuba, Sequoia
AU - Ruybal-Pesantez, Shazia
AU - Radhakrishnan, Sreejith
AU - Naidoo, Tristan
AU - Cucunuba Perez, Zulma
N1 - Publisher Copyright:
© 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license
PY - 2024/12
Y1 - 2024/12
N2 - Background: Understanding the epidemiological parameters and transmission dynamics of Lassa fever, a significant public health threat in west Africa caused by the rodent-borne Lassa virus, is crucial for informing evidence-based interventions and outbreak response strategies. Therefore, our study aimed to collate and enhance understanding of the key epidemiological parameters of Lassa fever. Methods: We conducted a systematic review, searching PubMed and Web of Science for peer-reviewed studies published from database inception up to June 13, 2024, to compile and analyse key epidemiological parameters, mathematical models, and outbreaks of Lassa fever. English-language, peer-reviewed, original research articles were included if they reported on Lassa fever outbreak sizes, transmission models, viral evolution, transmission, natural history, severity, seroprevalence, or risk factors. Non-peer-reviewed literature was excluded. Data were extracted by two independent individuals from published literature, focusing on seroprevalence, transmissibility, epidemiological delays, and disease severity. We performed a meta-analysis to calculate pooled estimates of case-fatality ratios (CFRs) and the delay from symptom onset to hospital admission. This study is registered with PROSPERO (identifier number CRD42023393345). Findings: The database search returned 5614 potentially relevant studies, and a further 16 studies were identified from backward citation chaining. After de-duplication and exclusion, 193 publications met our inclusion criteria and provided 440 relevant parameter estimates in total. Although Lassa virus is endemic in west Africa, the spatiotemporal coverage of general-population seroprevalence estimates (ranging from 2·6% [6/232] to 58·2% [103/177]) was poor, highlighting the spatial uncertainty in Lassa fever risk. Similarly, only four basic reproduction number estimates (ranging from 1·13 to 1·40) were available. We estimated a pooled total random effect CFR of 33·5% (95% CI 25·8–42·2, I2=95%) and found potential variation in severity by geographical regions typically associated with specific Lassa virus lineages. We estimated a pooled total random effect mean symptom-onset-to-hospital-admission delay of 8·19 days (95% CI 7·31–9·06, I2=93%), but other epidemiological delays were poorly characterised in the existing literature. Interpretation: Our findings highlight the absence of empirical Lassa fever parameter estimates despite its high burden in west Africa. Improved surveillance approaches to capture mild cases in humans and to further cover rodent populations are needed to better understand Lassa fever transmission dynamics. Addressing these gaps is essential for developing accurate mathematical models and informing evidence-based interventions to mitigate the effect of Lassa fever on public health in endemic regions. Funding: UK Medical Research Council, National Institute for Health and Care Research, Academy of Medical Sciences, Wellcome, UK Department for Business, Energy, and Industrial Strategy, British Heart Foundation, Diabetes UK, Schmidt Foundation, Community Jameel, Royal Society, and Imperial College London. Translation: For the French translation of the abstract see Supplementary Materials section.
AB - Background: Understanding the epidemiological parameters and transmission dynamics of Lassa fever, a significant public health threat in west Africa caused by the rodent-borne Lassa virus, is crucial for informing evidence-based interventions and outbreak response strategies. Therefore, our study aimed to collate and enhance understanding of the key epidemiological parameters of Lassa fever. Methods: We conducted a systematic review, searching PubMed and Web of Science for peer-reviewed studies published from database inception up to June 13, 2024, to compile and analyse key epidemiological parameters, mathematical models, and outbreaks of Lassa fever. English-language, peer-reviewed, original research articles were included if they reported on Lassa fever outbreak sizes, transmission models, viral evolution, transmission, natural history, severity, seroprevalence, or risk factors. Non-peer-reviewed literature was excluded. Data were extracted by two independent individuals from published literature, focusing on seroprevalence, transmissibility, epidemiological delays, and disease severity. We performed a meta-analysis to calculate pooled estimates of case-fatality ratios (CFRs) and the delay from symptom onset to hospital admission. This study is registered with PROSPERO (identifier number CRD42023393345). Findings: The database search returned 5614 potentially relevant studies, and a further 16 studies were identified from backward citation chaining. After de-duplication and exclusion, 193 publications met our inclusion criteria and provided 440 relevant parameter estimates in total. Although Lassa virus is endemic in west Africa, the spatiotemporal coverage of general-population seroprevalence estimates (ranging from 2·6% [6/232] to 58·2% [103/177]) was poor, highlighting the spatial uncertainty in Lassa fever risk. Similarly, only four basic reproduction number estimates (ranging from 1·13 to 1·40) were available. We estimated a pooled total random effect CFR of 33·5% (95% CI 25·8–42·2, I2=95%) and found potential variation in severity by geographical regions typically associated with specific Lassa virus lineages. We estimated a pooled total random effect mean symptom-onset-to-hospital-admission delay of 8·19 days (95% CI 7·31–9·06, I2=93%), but other epidemiological delays were poorly characterised in the existing literature. Interpretation: Our findings highlight the absence of empirical Lassa fever parameter estimates despite its high burden in west Africa. Improved surveillance approaches to capture mild cases in humans and to further cover rodent populations are needed to better understand Lassa fever transmission dynamics. Addressing these gaps is essential for developing accurate mathematical models and informing evidence-based interventions to mitigate the effect of Lassa fever on public health in endemic regions. Funding: UK Medical Research Council, National Institute for Health and Care Research, Academy of Medical Sciences, Wellcome, UK Department for Business, Energy, and Industrial Strategy, British Heart Foundation, Diabetes UK, Schmidt Foundation, Community Jameel, Royal Society, and Imperial College London. Translation: For the French translation of the abstract see Supplementary Materials section.
UR - http://www.scopus.com/inward/record.url?scp=85209560560&partnerID=8YFLogxK
U2 - 10.1016/S2214-109X(24)00379-6
DO - 10.1016/S2214-109X(24)00379-6
M3 - Article
C2 - 39577970
AN - SCOPUS:85209560560
SN - 2572-116X
VL - 12
SP - e1962-e1972
JO - The Lancet Global Health
JF - The Lancet Global Health
IS - 12
ER -