A—Vectors of Disease-causing Organisms

The wasting disease of dogs known as heartworm or canine filariasis, caused by the nematode Dirofilaria immitis, is absent from New Zealand. In order to guard against its importation, together with that of other causal organisms of canine diseases, dogs may only be brought into this country under rigid quarantine regulations. Among the vectors of D. immitis are Aëdes aegypti and Culex fatigans (Del Rosario, 1936), also Pulex irritans (Summers, 1943). As has already been indicated, living examples of all these species were collected from aircraft which had come from or passed through Fiji, where heartworm is very prevalent (Laird, 1951). Any of these species, should they succeed in escaping from aircraft at Whenuapai in the infective state, might bite dogs in this area and so infect them with D. immitis. Heartworm thrives in both warm and temperate climates, and there is a decided possibility that it could become endemic at least in the northern parts of the North Island, locally bred C. fatigans and P. irritans serving to spread the disease.

Aëdes aegypti, Culex fatigans, and Stomoxys calcitrans are all known vectors of the virus which causes fowl-pox, and the first-named species may also transmit equine encephalomyelitis. Here again, there is a possibility that epidemics of these diseases might be originated in the farmlands adjacent to New Zealand airports, following the introduction of infective insects.