This book looks at folk illnesses in the Philippines including, as the title suggests, usog, pasma, and kulam. Rather than looking at these folk illnesses as “superstitions,” Tan explains the broader social and cultural contexts of these concepts.

Tan uses different social science perspectives to explore the deeper meanings of these illnesses, including their links to social norms, tensions, and conflicts. He emphasizes, too, that far from being static, these folk illnesses continue to evolve, influenced by western medicine as well as new images around health and illnesses that come with mass media and advertising.  Finally, he calls attention to a medical ecological perspective, looking at how our changing relationships with the natural environment also lead to modifications in the folk illnesses.