Rubella is no longer viewed as a major health risk in Canada or the U.S., health officials say.
Rubella, commonly known as German measles, was a relatively common childhood illness until 1969.
Since then, a comprehensive vaccination program in both countries has prevented cases of the viral infection.
Dr. Theresa Tam of the Public Health Agency of Canada said maintaining a robust vaccination program is key to protecting those who may be exposed to the virus while travelling outside the country.
Most children in Canada and the U.S. are vaccinated against rubella by age two.
On Monday, Dr. Julie Gerberding, director of the Centers for Disease Control, announced the U.S. had eliminated the disease.
The nine cases that occurred in the U.S. in 2004 are all thought to have been imported, she told an immunization conference in Washington.
The WHO's Pan-American Health Organization aims to eliminate rubella from the New World by 2010.
Rubella causes mild illness in children. In pregnant women, the virus can trigger miscarriages, stillbirths and birth defects such as heart diseases, cataracts and deafness.