However, there is no evidence of disease and the result was picked up as part of a standard animal monitoring programme.
Australia has filed a report with the World Organisation for Animal Health in respect of the single positive test result, which occurred among a herd of 24 sentinel cattle.
Dr Jill Mortier, who sent the report, said it is believed the infected vectors are periodically blown to Australia by monsoonal winds.
The positive result was confirmed by a second laboratory.
Dr Mortier reported that bluetongue serotypes 1,3,9, 15, 16, 20, 21 and 23 had previously been isolated in Northern Australia cattle. This was the first time serotype 7 had been isolated.
The positive result was on a farm near Humpty Doo.
Bluetongue is a disease of sheep and cattle The midges that spread it can also carry the closely related African horse sickness.
Bluetongue is present in many countries worldwide, with various strains having been present in the Mediterranean area for some time. In 2006, a new strain, bluetongue serotype 8, began to circulate in northern European countries such as Germany, Belgium, Luxembourg, Holland, and France. In 2007, it appeared for the first time in Britain, in East Anglia.
African horse sickness has spread north from Africa and has caused horse deaths in several European countries. It has a high fatality rate and is considered a major disease threat to northern European horses, which have never been exposed to it.