In late 1991 and early 1992, a rare neurological condition affecting vision and the peripheral nervous system first emerged in Cuba's Pinar del Río province, primarily affecting adult males from tobacco-growing areas who experienced bilateral visual deficits, color vision problems, and subacute photophobia. The outbreak progressively escalated from 472 cases across 5 provinces by December 1992 to an exponential increase in early 1993 that spread to all Cuban provinces, ultimately reaching 45,584 cases by June 1993—a prevalence rate of 418.7 per 100,000 inhabitants. Initially suspected to have a toxic cause, the outbreak prompted international scientific collaboration for investigation. Research ultimately concluded that the epidemic resulted from nutritional deficiency directly linked to the severe economic crisis Cuba experienced following the collapse of the Soviet Union.

ENRIQUE BELDARRAÍN CHAPLE is a Professor and Researcher of Merit at the Medical University of Havana, and member of the Cuban Academy of Sciences. Trained as a medical epidemiologist, his main focus of work is the historical studies on epidemics in Cuba and public health. He has 98 scientific publications including books, book chapters and articles. He has been guest lecturer and professor at universities in Europe, the USA, Canada and Latin America. He is currently a visiting professor at the Justus Liebig University Giessen in Germany, as part of the GLACIER Project (German Latin- American Center for Infection and Epidemiology Research) funded by the German Federal Foreign Office through the DAAD-programme Global Centres for Health and Pandemic Prevention.