OTTAWA -- CHEO and Ottawa Public Health have declared a chickenpox outbreak at the children's hospital after cases of the virus were confirmed onsite. 

In a statement on its website, CHEO says, "a child contracted chickenpox in the community and was admitted to CHEO for other reasons, then developed a rash."

"Two other children were subsequently infected."

CHEO says all safety precautions are in place, adding, "the cases are contained and the risk of transmission is extremely low."

Families whose children may have been exposed to the chickenpox have been notified of the situation.

According to the Ottawa Public Health website, chickenpox is caused by the varicella-zoster virus. It is a very common childhood infection that can also affect adults.

The health unit says, "Chickenpox usually begins with a fever, followed in one or two days by a rash. The rash appears on the chest, back or stomach and spreads to other body areas. It usually starts with spots that soon become fluid-filled blisters. New spots appear over the next two to three days."

The chickenpox virus can spread from person to person through the air, in saliva, or through direct contact with the fluid in a chickenpox blister. Chickenpox develops 10 to 21 days after a person has been exposed to the virus.

Ottawa Public Health says the best way to protect yourself and your family from chickenpox is by receiving the chickenpox vaccine. The vaccine is recommended for healthy children ages 12 months to 12 years of age.

In a message its website, CHEO tells parents that, "Most importantly, vaccines work. Please vaccinate your child for all preventable childhood infectious diseases."