Journal Article

A prospective, multi-site, cohort study to estimate incidence of infection and disease due to Lassa fever virus in West African countries (the Enable Lassa research programme)–Study protocol

Chioma Dan-Nwafor, Énagnon Junior Juvénal Prince Honvou, Christine Jacobsen, Nathalie J. Vielle, Robert F. Garry, Adebola Olayinka, Olufemi Ayodeji, Magassouba N’Faly, Mambu Momoh, Ephraim Ogbaini, Aminata Ndiaye, David A. Wohl, Anton Camacho, Robert Samuels, Jefferson Sibley, Sylvanus Okogbenin, Danny Asogun, Augustine Goba, Lansana Kanneh, John Demby Sandi, Stephan Günther, Thomas Verstraeten, Emmanuel Koffi Yovo, William A. Fischer, Benedict N. Azuogu, Chinwe Ochu, Manfred Accrombessi, Ayola Akim Adegnika, Akpénè Ruth Esperencia Deha, Jean DeMarco, Chikwe Ihekweazu, Suzanne Penfold, Donald Samuel Grant, Giuditta Annibaldis, Christian Happi, Ifedayo Adetifa, Anges Yadouleton, Sophie Duraffour, Robert Nsaibirni, Énagnon Parsifal Marie Alexandre Logbo, John S. Schieffelin, Rebecca Grais

2023

Overview

Background Lassa fever (LF), a haemorrhagic illness caused by the Lassa fever virus (LASV), is endemic in West Africa and causes 5000 fatalities every year. The true prevalence and incidence rates of LF are unknown as infections are often asymptomatic, clinical presentations are varied, and surveillance systems are not robust. The aim of the Enable Lassa research programme is to estimate the incidences of LASV infection and LF disease in five West African countries. The core protocol described here harmonises key study components, such as eligibility criteria, case definitions, outcome measures, and laboratory tests, which will maximise the comparability of data for between-country analyses. Method We are conducting a prospective cohort study in Benin, Guinea, Liberia, Nigeria (three sites), and Sierra Leone from 2020 to 2023, with 24 months of follow-up. Each site will assess the incidence of LASV infection, LF disease, or both. When both incidences are assessed the LASV cohort (nmin = 1000 per site) will be drawn from the LF cohort (nmin = 5000 per site). During recruitment participants will complete questionnaires on household composition, socioeconomic status, demographic characteristics, and LF history, and blood samples will be collected to determine IgG LASV serostatus. LF disease cohort participants will be contacted biweekly to identify acute febrile cases, from whom blood samples will be drawn to test for active LASV infection using RT-PCR. Symptom and treatment data will be abstracted from medical records of LF cases. LF survivors will be followed up after four months to assess sequelae, specifically sensorineural hearing loss. LASV infection cohort participants will be asked for a blood sample every six months to assess LASV serostatus (IgG and IgM). Discussion Data on LASV infection and LF disease incidence in West Africa from this research programme will determine the feasibility of future Phase IIb or III clinical trials for LF vaccine candidates.

• Publisher: Public Library of Science (PLoS)