In Spain, hookworm infection was first recognised as a miners’ disease at the beginning of the 20th century, leading to the adoption of legislative and public health measures. From 1924, surface foci were also detected in some highly productive agricultural lands, and specific health campaigns were developed in Murcia to match the successful intervention in mines. Hookworm was explained in terms of the geographical and human environment and largely attributed to poor working and living conditions. New rural foci were detected after the Civil War (1936-39), but this time the health administration did not intervene, due to economic shortages or because of the leading role taken by the Institute for Colonial Medicine in this field. Understanding of the disease changed, with a new emphasis on its impact on reproduction, and medical explanations pointed to the negative moral conditions of peasants rather than social issues.