Canine heartworm (Dirofilaria immitis) detected in red foxes (Vulpes vulpes) in urban Melbourne.

Canine heartworm (Dirofilaria immitis) was detected by antigen ELISA in 8 (6.4%) of 125 red foxes (Vulpes vulpes) captured in the Melbourne (Australia) metropolitan area. Circulating microfilariae were also detected by whole blood filtration in six of these foxes. Cursory sampling of mosquitos at two of the sites where positive foxes were captured revealed the existence of two known mosquito vectors of Dirofilaria. The existence of widespread fox populations in Melbourne, together with known mosquito vectors may offer the potential for a sylvatic cycle of canine heartworm within the urban area.