The Dutch public health watchdog says at least one elderly patient has died and more than 500 people have been sickened in a major salmonella outbreak caused by tainted salmon.

The National Institute for Public Health and the Environment said in a statement Saturday tests have confirmed one death and another fatality is under investigation. Both victims were aged over 80.

The institute announced earlier this month that the outbreak had been traced to a Dutch company called Foppen and ordered its products pulled off shelves at stores across the Netherlands.

It now says the number of people sickened by tainted salmon before the recall has risen to at least 550.

CostCo Wholesale Corp., which sells Foppen products in the United States, also recalled salmon products.