Immunoepidemiology helps to unravel the mysteries of dengue haemorrhagic fever.

It is now nearly 20 years since a strong correlation was noted in Thailand between secondary immune responses and severe dengue syndromes. It is currently thought that 'enhancing' antibodies, in an individual undergoing a second infection with a different serotype of dengue virus, promotes viral replication in monocytes which then become the targets of an immune elimination response (possibly T-cell mediated). The monocytes then release various chemical mediators which produce the symptoms of shock and haemorrhage seen in dengue haemorrhagic fever (DHF). Much new knowledge has been gained in recent years especially from immunoepidemiological and immunological studies, and these were discussed at a recent meeting.