Supernatural beliefs encode knowledge about malaria but inhibit uptake of biomedical interventions among Siberut Mentawai

To what extent do supernatural beliefs encode medical and ecological knowledge? Here, we investigate the similarity between biomedical understandings of malaria and the spirit illness kisei (contact with spirits) through interviews with Mentawai individuals in southern Siberut, Indonesia ( n = 90). We find that kisei is the most culturally salient explanation for general fever and, contrary to some other mystically caused illnesses (e.g., moralistic punishment), is often said to occur outside the victim's control. Kisei encodes several features of the scientific understanding of malaria, including symptom profiles (fever, headache, chills) and ecological risk factors (going to the forest, doing outdoor activities at night). Although individuals endorsed supernatural and natural explanations of fever, they reported a strong preference for traditional healing practices (e.g., shamans, herbal treatments) over biomedical clinics for treating kisei , suggesting that its salience inhibits the uptake of new biomedical interventions. Our research demonstrates how traditional ecological knowledge can be embodied in apparently non-naturalistic explanations of illness.