Key findings
Africa CDC Final Outbreak Brief 16 for Sudan Virus Disease in Uganda (visible via cross-scope signals, Apr 20) confirms the most recent filovirus spillover event in sub-Saharan Africa has ended, providing a completed-case data point relevant to the 180-day new-filovirus-spillover hypothesis. PubMed (Apr 17, 22) published a study on Marburg virus persistence in the male reproductive tract, highlighting diagnostic and surveillance gaps for sexually transmitted Marburg chains post-outbreak. Nigeria Lassa and Burundi mystery illness hypotheses are unchanged with no new sitrep data this cycle. Connector health for this scope is the best of 7 scopes (7 green, 1 amber).
Technical analysis
Sudan VHF Uganda Final Brief: Africa CDC Outbreak Brief 16 (final) for Sudan Virus Disease in Uganda signals outbreak termination. This is directly relevant to hyp:hemorrhagic-fevers:180d:6e0656aa4d — the hypothesis that ≥1 new laboratory-confirmed filovirus spillover will occur in sub-Saharan Africa by Oct 20 2026. The Uganda Sudan VHF event counts as a qualifying filovirus spillover event that occurred within the hypothesis window, providing directional support.
Marburg persistence in male reproductive tract (PubMed Apr 17, 22): Study on diagnostic and surveillance strategies for Marburg persistence in semen post-infection. This is operationally relevant: if a new Marburg spillover occurs, current surveillance frameworks may miss sexually transmitted secondary chains. Neutral to existing hypotheses but flags a post-outbreak surveillance gap.
Nigeria Lassa / Benue State: No new NCDC weekly sitrep entered the evidence stream. The 8-confidence hypothesis on ≥800 cumulative cases by Jul 31 and 7-confidence Benue HCW death hypothesis are the highest-confidence active bets in this scope. Connector gaps (PubMed stale at 1.906 staleness ratio) are the primary limitation.
Burundi mystery illness: No etiology announcement. The 30-day resolution hypothesis (resolves May 20) and 60-day hypothesis (resolves Jun 19) are tracking; no new Africa CDC or WHO DON content this cycle regarding Burundi.
RVF Sahel cluster (hyp:hemorrhagic-fevers:180d:bb96d79141, conf 6): No WHO DON or Africa CDC alert for new RVF cluster in Senegal, Mauritania, or Mali this cycle.
Full appendix
Filovirus spillover hypothesis (hyp:hemorrhagic-fevers:180d:6e0656aa4d, conf 7): Uganda Sudan VHF Final Outbreak Brief 16 (Africa CDC, Apr 20) confirms a recent filovirus event. The hypothesis requires ≥1 new confirmed spillover between Apr 20 and Oct 20 2026. The Uganda event is recent and supports the overall pattern of regular filovirus spillover in the region. Direction: supporting. Note that the hypothesis is forward-looking from Apr 20, so whether the Uganda outbreak pre-dates or post-dates the hypothesis start matters — the final brief Apr 20 aligns with hypothesis creation date.
Nigeria Lassa >800 cases (hyp:hemorrhagic-fevers:90d:92534789b7, conf 8): No NCDC sitrep this cycle. This is the highest-confidence hypothesis in this scope. NCDC's weekly Lassa situation reports are the resolution path; not yet in evidence feed.
Benue HCW deaths ≥20 (hyp:hemorrhagic-fevers:60d:1698aed01c, conf 7): No Benue State or NCDC update. Resolves Jun 20.
Burundi mystery illness (30-day) (hyp:hemorrhagic-fevers:30d:60169b1675, conf 5): Resolves May 20. No etiology announced. Africa CDC flagged ≥5 deaths; no WHO DON bulletin yet.
Burundi mystery illness (60-day) (hyp:hemorrhagic-fevers:60d:350cca8d7a, conf 5): Resolves Jun 19. Same trajectory.
RVF Sahel (hyp:hemorrhagic-fevers:180d:bb96d79141, conf 6): No new RVF signal in Sahel this cycle.
Marburg surveillance gap: The reproductive-tract persistence paper is operationally significant for post-outbreak surveillance design. Marburg persistence in semen has been documented in survivors; this new study formalizes diagnostic strategies. Relevant if a new Marburg spillover occurs.