Lesson of the Week: Katayama fever: an acute manifestation of schistosomiasis

Schistosomiasis is prevalent throughout sub-Saharan Africa and parts of south east Asia. It is contracted through contact with any fresh (but not salt) water that harbours the intermediate snail host. Katayama fever is a manifestation of acute schistosomiasis. Typical features include fever, an urticarial rash, enlarged liver and spleen, and bronchospasm. The precise pathogenesis of Katayama fever is unknown, but it is thought to be an immune complex phenomenon, initiated by eggs laid by maturing schistosomes. Typically, symptoms occur four to six weeks after infection. Diagnosis is on clinical grounds as there is no definitive serological or immunological test. Conventional antibody titres may take three months or more to become positive.1 As a result, the diagnosis is often missed, occasionally with disastrous results, such as schistosomal myelopathy, which may result in permanent neurological damage.2