Nodding disease

The emergence of "new" diseases is a complicated issue. "New" diseases often just means "new to biomedical science." Viruses like Ebola and HIV were certainly circulating in Africa in animal reservoirs for decades, and probably millenia, before they came to the attention of physicians via human infections. Hantavirus in the American southwest has likely infected many people, causing pneumonia of unknown origin, before the Four Corners outbreak led to the eventual identification of the Sin Nombre virus. Encroachment of humans into new areas can bring them into contact with novel infectious…