OTTAWA - Ontario has asked Ottawa for help in dealing with a dangerous outbreak of C. difficile.

The Public Health Agency of Canada says it has sent a field epidemiologist to the Niagara region to help investigate the outbreak of the deadly superbug in several hospitals there.

The deployment was in response to a request from the Ontario government, acting on behalf of the Niagara Region Public Health Department and Niagara Health System, said agency spokesman Robert Cyrenne.

There's more the federal agency could do if required.

On request, the Public Health Agency can collaborate with provincial and infection control experts to put in place prevention programs. The agency can also provide laboratory support to help with diagnosis and strain analysis.

At least four health centres in the Niagara Region and one in Guelph, Ont., have declared an outbreak after seeing the number of cases spike. Some emergency rooms in nearby towns have been closed to prevent a further spreading.

The hospital-acquired disease causes severe diarrhea in vulnerable patients who have taken antibiotics. C. difficile is typically spread in hospitals through contact with bodily fluids.

Experts say outbreaks of the contagious bug can usually be avoided if staff recognize the signs early and take measures such as hand-washing to prevent the bacteria from spreading.

Patients are usually placed in isolation.

At least 16 people -- mainly elderly -- have died in the Niagara region since the outbreak was declared May 28.

About 100 protesters took to the streets Wednesday to complain about the state of cleanliness at regional health centres.

The Ontario government has sent teams of experts to work with affected hospitals.