The warning from public health leaders comes as ministers prepare to unveil the biggest public health strategy to date, targeting smoking, obesity and sexual health.
A massive NHS shake-up in 2002 saw health authorities in England scrapped - to be replaced by larger strategic health authorities. At the same time public health budgets and commissioning switched to primary care trusts.
But the policy has meant public health consultants are often struggling alone to deliver a challenging agenda with too few resources.
Retired Bristol senior lecturer in epidemiology and public health medicine Sir Alexander Macara said he had never seen public health in such an unhealthy state. 'It is potentially disastrous,' he said.
He said when he started work in Bristol more than 40 years ago, there were 28 public health consultants. Now there are just five or six serving a larger population.
BMA public health committee chairman Peter Tiplady warned: 'It is not possible to deliver public health on the cheap.'
The BMA's public health committee is planning to use the launch of the white paper on public health in England, due next month, to highlight the problems they face.