A strain of bird flu discovered in February in British Columbia, in western Canada, is more virulent than had first been thought, according to the Canadian Food Inspection Agency.

Although the strain was found to be more potent, the agency said it was still not considered a danger to humans, reported Agence France Presse.

“The risk to human health remains low. This is not the same virus which currently exists in Asia,” the agency was quoted by AFP as saying. 

In February an outbreak of bird flu was discovered at a farm east of Vancouver, leading to the cull of around 16,000 chickens. It was believed to be a low pathogenic strain of the disease, but now officials have said tests have found both low and high pathogenic forms of the H7N3 strain of the virus. High pathogenic strains are more contagious and have a higher fatality rate amongst infected birds than low pathogenic strains.

“The presence of both forms of the virus on the same premises is not unheard of but is rare,” the agency said. 

In response to the discovery, Japan re-imposed its total ban on live birds, chicken and other poultry meat from Canada. The Japanese agriculture ministry had recently eased the ban, allowing imports from other parts of Canada except British Columbia, but has now re-imposed the original ban, reported Kyodo News.