Venice’s Hidden Time Capsule: Lazzaretto Vecchio as a 300-Year Molecular Archive of Epidemic Pathogens

Background: Lazzaretto Vecchio (old Lazaret), founded in 1423 in the Venetian lagoon, is the world’s earliest permanent quarantine hospital. For nearly three centuries, it served as the primary containment and burial site for both residents and travelers, who died under suspicion of infectious disease. Historical records describe tens of thousands of deaths during major Venetian plague epidemics and mandated burial on the quarantine islands. Yet, the small artificial island could physically accommodate only a fraction of the recorded deaths. Most epidemic victims appear absent from the official burial grounds, exposing a striking discrepancy between the material record and historical narratives of early epidemic containment. Hypothesis: Lazzaretto Vecchio was not a comprehensive burial ground for Venice’s epidemic dead, but a demographic and evolutionary filter. We evaluate three hypotheses: (H1) Venetian Plague House: quarantine burials are dominated by residents, and residents account for most total deaths. (H2a) Ellis Island Effect: burials predominantly represent travelers intercepted at the maritime frontier. (H2b) Secret Republic Fire: peak urban deaths were rapidly removed through undocumented emergency disposal, leaving little archaeological trace. H1 is mutually exclusive with either H2a or H2b. H2a and H2b are complementary, together describing a dual-regime containment system in which Lazzaretto Vecchio functioned differently under normal (H2a) versus crisis conditions (H2b). Methods Feasibility: Approximately 1,200 individuals are sampled for analysis. Ancient DNA, pathogen screening, stable isotopes, proteomics, radiocarbon dating, and stratigraphic modeling will reconstruct demographic composition, geographic origin, kinship structure, and pathogen dynamics. Hypotheses Testing: If H1 is correct, then remains should primarily reflect Venice’s general population, adults and children in family groups. If H2a is correct, then remains should consist largely of unaccompanied adults of diverse geographic origin, with pathogen genomes showing stalling, extinction, or limited transmission. If H2b is correct, then radiocarbon and stratigraphic gaps will mark epidemic peaks absent from burial layers, indicating crisis mortality managed through off-record disposal. Conclusions: Lazzaretto Vecchio offers an archaeological testbed for a dual-regime epidemic system, routine quarantine mortality coupled with hidden surge disposal, and a hypothesis-driven model for how governance, logistics, and containment infrastructure may shape pathogen evolution and resilience.