TORONTO - The head of an agency tracking pig health says a deadly virus that has hit swine farms in at least two provinces would be spreading more quickly if the industry hadn't acted proactively against it.

The Canadian Swine Health Board's Robert Harding says the outbreak of porcine epidemic diarrhea in the United States last May gave farms and governments a "heads up" they've used to improve biosecurity measures.

This week has seen a suspected case on Prince Edward Island along with one confirmed instance of the virus in Manitoba.

Meanwhile, Ontario on Friday added two more locations to its list of farms testing positive for PED, bringing the total to 16.

Harding says steps such as stricter cleaning of trucks are hindering the spread of the virus, and that due to there being relatively few cases "we still have an opportunity to win this battle."

The virus poses no risk to human health or safety but is highly contagious and has already killed millions of piglets in the United States.