Revisiting the Great Irish Famine: a prototype of pathogen-driven humanitarian crises and One Health insights

The Great Irish Famine (1845–1852), triggered by the potato blight pathogen Phytophthora infestans, remains one of the most devastating examples of a plant disease reshaping human history. Once misclassified as a true fungus, P. infestans is now recognized as an oomycete, and recent genomic and pangenome studies have traced its origin to the Andean highlands. Beyond its taxonomic and evolutionary importance, the famine provides a striking prototype of how a crop pathogen can cascade into widespread malnutrition, immunosuppression, and epidemic infectious diseases such as typhus and cholera-an early case of what is now conceptualized as One Health. Modern research has further demonstrated the long-term biological and developmental consequences of famine exposure, including transgenerational health effects and epigenetic scarring. At the same time, socio-political analyses have revealed how colonial policy, economic ideology, and structural neglect amplified the crisis. These interdisciplinary perspectives underscore the Irish Famine not only as a humanitarian disaster of the nineteenth century but also as a framework for understanding contemporary risks. In an era of accelerating climate change and globalization, the Irish Famine offers vital lessons for food security, global health, and crisis governance. Advances in biotechnology-including CRISPR-mediated breeding of resistant potato varieties-and genomic surveillance of plant pathogens directly draw from the legacy of this tragedy. By revisiting the Great Irish Famine through molecular, medical, and ethical lenses, this review highlights its enduring relevance as a prototype for pathogen-driven humanitarian crises and as a source of One Health lessons for the future.