Our disease ontology provides information on infectious diseases, disease synonyms, transmission pathways, disease agents, affected populations and disease properties. Diseases have been grouped into syndromic disease categories, such that programmers can look through relevant categories, as well as at specific diseases. Organisms, linked to both agents and populations, are structured hierarchically, to provide multiple levels of organism resolution. In addition, both disease transmission and relevant disease properties are available to search. Disease properties include tags like 'notifiable diseases' and 'economic importance' to flag particular disease characteristics that may be of interest, but are not captured elsewhere.