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Last update
21 Oct 2026 · 22:28 UTC
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Lassa fever outbreaks — tracked episodes and clusters

Each tracked episode as a citable page — with its own epidemic curve, timeline, and map.

  • 2026 Nigeria Lassa fever season

    Active
    Jan 4, 2026 – OngoingNigeriaLineage II

    Nigeria's 2026 Lassa fever season, the country's annual dry-season epidemic driven by the Natal multimammate mouse (Mastomys natalensis). Confirmed cases climbed through a peak spanning epi weeks 6 to 12 (February and March) and tapered into the rainy-season tail, but the season is running well ahead of 2025: 1,138 confirmed cases and 268 deaths by epi week 40, against 924 and 172 at the same point a year earlier, with the case fatality rate rising from 18.6% to 23.6%. Eighty-eight percent of cases come from Ondo, Bauchi, Taraba, Edo and Benue States, and 54 healthcare workers have been infected. NCDC coordinates the response through a multi-sectoral Technical Working Group and publishes weekly situation reports.

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