TORONTO -- Ten former Ontario health ministers representing three political parties urged the provincial government Thursday to reverse its cuts to public-health funding.

"Public health helps Ontarians stay healthy, so they don't need to go to the doctor, or a hospital, saving time and money," the former politicians wrote in an open letter to Health Minister Christine Elliott.

"If the government wants to end hallway medicine, as you have pledged, one of the best ways to do that is to actually invest more, not less, in public health."

The Progressive Conservative government is lowering its share of public health spending as it works to eliminate an $11.7-billion deficit, requiring municipalities to contribute millions more to their health budgets than anticipated. The changes are retroactive and take effect after municipalities have already passed this year's budgets.

By 2021-2022, the provincial cut is expected to be $200 million annually.

The former ministers, including six Liberals, three New Democrats and one Progressive Conservative who served for five years under premier Bill Davis implored Elliott in their open letter to stop what they call "drastic" cuts.

They cite the 2003 SARS epidemic, which killed 44 people in Toronto, as evidence of the "devastating impact of failing to invest in public health."

"Traditionally, ministers of health have avoided commenting on the policies of their successors," they write in the letter. "Health has been seen as a non-partisan issue -- something we all support. This attack on public health has prompted us to break our silence."

The province is also working on consolidating Ontario's 35 public health units into 10, which the agencies say could affect the delivery of programs and lead to layoffs.

Elliott took to Twitter to defend the government's moves.

"In 2017, the Auditor General reported that public health units were poorly co-ordinated, duplicating work and not delivering consistent service," she wrote. "Instead of resorting to scare tactics, we can all deliver public health more efficiently while protecting and improving vital programs."

Ontario's public health units co-ordinate services including vaccination programs, infectious disease outbreak investigations, and restaurant inspections.