The first case of swine flu, a 14-year-old US citizen born in Detroit, has been reported in Bulgaria's second-biggest city of Plovdiv. The teenager arrived in the city on June 23 to visit his Bulgarian grandmother, Dnevnik daily has reported.

Three days after arrival, the youth was struck by high fever, which later escalated to 39C. "The patient displayed symptoms which are typical for the H1N1 strain," doctor Eli Kuncheva was quoted as saying. The case has not been officially confirmed by the Healthcare Ministry, however.

The youngster was first accepted in the emergency ward of Sveti Georgi hospital, but was subsequently transferred to the ward for contagious diseases, where he is currently in isolation and under quarantine. Tests conducted on June 28 confirmed the suspicions that the teenager had the H1N1 flu strain.

Reportedly, he is in stable condition, as he was immediately subjected to Tamiflu medication. The three other people with whom the youth had contacts with - his grandmother, uncle and aunt - have also been examined.

The teenager is the ninth reported case of a patient treated for the H1N1 virus. The first case was reported on June 1 and was a Bulgarian citizen who flew from New York, via Amsterdam, arriving at Sofia International Airport on May 27.

No fatalities have been reported in Bulgaria, while World Health Organization statistics showed 263 people have lost their lives to the H1N1 flu strain so far.