Reasoning
The outbreak record is dominated by cases sharing a common exposure - injections at Yambuku Mission Hospital via reused needles - or onward contact with such cases, i.e. amplification of a single index infection. That the epidemic collapsed once the hospital closed (with the needle-reuse practice removed) shows the venue amplified rather than originated the pathogen. The index case, however, acquired the virus elsewhere from an unidentified reservoir, and no serosurvey or contact tracing in the record captures that upstream spillover (the search for a link to the Sudan outbreak failed; the disease was new to the region). Therefore the geographic and institutional centre of the recognized cluster - a hospital - is set by the amplification and ascertainment process, not by the location of the animal-to-human jump. This furnishes a concrete precedent that a novel pathogen’s first internationally recognized cluster can centre on a high-throughput venue bearing no relation to the true spillover site, with that spillover left permanently unresolved by the outbreak data.
Validity verdict
status: approved; reason_if_not_false: checked. Premises: the case series is dominated by a shared needle-injection exposure plus onward contact (amplification of one index infection); the epidemic collapsed once the venue’s needle-reuse practice was removed; the index/reservoir exposure was never captured. Load-bearing step: the hospital’s centrality is an artifact of where transmission was amplified and recorded, not where spillover occurred. Traced directly — the collapse-on-venue-closure is a near-experimental manipulation showing the venue amplified rather than originated the pathogen, and an amplifier by definition is downstream of the index’s (elsewhere) acquisition. No undercutting defeater survives that leaves the premises intact (the venue is demonstrably not the spillover site given collapse on closure). The “concrete precedent” generalization is a correctly qualified existence claim, not a universal. Approved, checked.