The Alberta government rejected expert advice to expand public reporting of measles to include probable cases, despite the measure being supported by local and provincial public health officials, documents obtained by The Globe and Mail show.

Since the outbreak began in Alberta last spring, only confirmed cases of measles have been publicly reported. New data provided through a Freedom of Information request show at least 450 probable cases of measles have also been identified in the province, bringing the total to nearly 2,500.

These numbers provide a more accurate portrayal of a crisis that has gripped Alberta, one of the two provinces at the centre of a countrywide outbreak that lost Canada its long-held measles elimination status last month. The new data show Alberta, not Ontario as previously understood, has the highest case count of any province, despite having a much smaller population. Ontario publicly reports probable cases.