Two Spanish poultry workers have tested positive for the bird flu virus, the first known case of human infection in Spain and the second in Europe since 2003, the World Health Organization said on Thursday, Reuters reported.

The poultry outbreak was confirmed by authorities on September 20, and to date there has been no evidence of human-to-human transmission linked to the event, WHO said.

Influenza A (H5N1) infections in two workers – men aged 19 and 27 – were detected in September and October, probably through contact with infected poultry or contaminated environment at a farm in Guadalajara, in central Spain.

Both men showed no symptoms and were isolated until they tested negative. After the poultry outbreak, all farm workers and their close contacts were tested.

Avian influenza infections in humans can range from asymptomatic infections or mild upper respiratory tract infections to rapid progression to severe pneumonia and even death.

From 2003 to October 21, 2022, there were 868 human cases worldwide, including two cases in Spain, and 456 deaths in 21 countries, according to the WHO.

In total, three human cases have been reported in Europe so far: one in the UK in 2021 and two in Spain in 2022.

The notification of these two cases does not change WHO’s current recommendations for public health measures and influenza surveillance, the organization said.