A Bulgarian man has tested negative for bird flu after doctors isolated him when two of his ducks died and he began showing flu-like symptoms, health ministry officials said on Thursday.

The 32-year-old man from southern Bulgar was isolated last Saturday.

“Final results came out negative for bird flu. The man will soon be released from hospital,” said Delcho Yanev, director of the health ministry’s regional office in the town of Haskovo.

Results from tests on the two dead ducks are expected by this week but veterinarians say the ducks most probably died of hunger and thirst because the family could not afford to feed them properly for several weeks.

Bulgaria has stepped up measures to prevent the virus from spreading among domestic poultry after several cases of the H5N1 strain lethal to humans were detected in wild swans in the Danube river and Black Sea wetland areas.

It has blocked off lakes and started to shoot wild predators around the lakes to prevent them from carrying the remains of potentially infected birds. Another four people in the poor northeast Silistra region are also being treated with anti-viral drugs after they captured a wild swan and tried to cook it.

They have shown no symptoms and preliminary tests indicated they do not have bird flu but final results are due next week, said the regional office of the health ministry in Silistra.