Using community surveillance data to differentiate between emerging and endemic amphibian diseases

We analyzed submission data from a wildlife care group during amphibian disease surveillance in Queensland, Australia. Between January 1999 and December 2004, 877 white-lipped tree frogs Litoria infrafrenata were classified according to origin, season and presenting category. At least 69% originated from urban Cairns, significantly more than from rural and remote areas. Total submissions increased during the early and late dry seasons compared with the early wet season. Frogs most commonly presented each year with injury, followed by ‘other’, sparganosis and irreversible emaciation of unknown aetiology. This is the first report of Spirometra erinacei infection in this species. A high prevalence (28%) of visible S. erinacei infection was found in emaciated frogs, but this was not statistically different from that in non-emaciated diseased frogs (25%). However, 14 emaciated specimens that were necropsied all had heavy S. erinacei infections, and the odds of visible sparganosis were statistically greater in emaciated frogs compared with injured, non-diseased frogs. We provide a detailed case definition for a new endemic disease manifesting as irreversible emaciation, for which S. erinacei may be the primary aetiological agent. The lack of significant spatial or temporal patterns in case presentation suggests that this is not a currently emerging disease. We show that community wildlife groups can play a valuable role in monitoring disease trends, particularly in urban areas, but identify a number of limitations associated with passive syndromic surveillance. We conclude that it is critical that professionals be involved in establishing syndromic case definitions, diagnostic pathology, complementary active disease surveillance, and data analysis and interpretation in all wildlife disease investigations.