A health ministry official, Turan Buzgan, told the Anatolia news agency that four of the new cases of human infection are from the Black Sea provinces of Samsun, Kastamonu, and Corum. The fifth new case is in the southeastern province of Van, where the first three confirmed bird-flu deaths outside of East Asia occurred in early January.
It was unclear if the new cases involve the H5N1 strain that has already killed at least two children in Van.
Authorities say the victims probably contracted the illness after contact with sick birds.
At least 100 people are being treated at Turkish hospitals for flu-like symptoms that authorities suspect might be linked to bird flu.
Bird flu has killed at least 70 people in five Asian countries -- including Indonesia, Thailand, Vietnam, China, and Cambodia -- and Indonesia reported that local tests confirmed the death of a 39-year-old man in Jakarta in early January was due to the virus.