Queensland's racing body says more horses have contracted equine influenza (EI) in the state despite inoculations against the contagious virus.

Queensland Racing Limited (QRL) announced "several" horses in the Ipswich precinct, west of Brisbane, had returned positive results for EI.

The announcement comes after the discovery of EI in five thoroughbreds in stables adjoining Toowoomba's Clifford Park racecourse on Monday.

QRL chief operations manager Malcolm Tuttle said each horse to have contracted the virus in both precincts had received their first vaccination.

But he said QRL continued to work with the Department of Primary Industries to continue the second round of vaccinations in both precincts.

Horse flu has crippled the Queensland and NSW racing industries since its discovery at Sydney's Eastern Creek in August.

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