Brisbane's Courier-Mail online reports that Debbie Brown has been admitted to Rockhampton Hospital to begin a five-day intravenous course of ribavirin, a drug normally used in the treatment of hepatitis.
Brown, a mother of two, was sprayed with blood and mucus from a horse who died on Saturday at J4S Equine Nursery, at Cawarall, near Rockhampton.
Testing later confirmed the horse died from Hendra.
The unproven treatment has been offered to four people considered most at risk of contracting the infection.
Just six people are known to have been infected with Hendra since the virus was isolated in 1994. Of those, three died, the most recent being Brisbane veterinarian Ben Cunneen 11 months ago.
Doctors believe the treatment stands the best chance of working if it is commenced before the disease, which has an incubation of five to 15 days, develops.
Thirteen people have been tested for the virus following Saturday's confirmed case, but testing as such an early stage is considered unreliable, given the incubation period.
Test results on more than 30 horses from the property are due back early this evening (NZ time).