Pet-owners are being warned they could be at risk of catching pneumonia after an elderly man who may have caught the illness from his birds, sold them on.
Infected parrots may be being bought and sold
It is thought the man, who has not been named, contracted psittacosis - a respiratory disease - from parrots he kept at his Berkshire home.
The birds were sold before they could be tested to see if they were infected.
Council health bosses are now trying to trace the buyer or anyone else the birds may have been sold on to.
John Parfitt, head of public protection services at West Berkshire Council, said: "It is probable that one or all of these birds may be carrying the infection.
"If they are, they pose a risk of infection to bird handlers and this includes cleaning out the birdcage."
Eleven parrots and six canaries were bought from the owner on 7 June.
The council has declined to name the specific area in Berkshire where the birds were sold, saying they want to protect the owner's medical confidentiality.
It is urging anyone who has been in contact with birds and is concerned about their health to consult their GP.