These statistics compare to the 1,000 to 3,000 cases reported annually in the United States. Since August 1991, there have been no cases of paralytic poliomyelitis in the Western Hemisphere. However, because of the persistence of poliomyelitis in many developing countries and the resurgence of paralytic polio in the parts of the former Soviet Union, the risk of importation of wild polio into Canada by immigrants, refugees, and travellers continues. However, the number of reported cases in U.S. and Canada increased in the past decade. Mumps Mumps is a common childhood disease caused by mumps virus.
Mumps is more severe in older children and adults.
Meningoencephalitis occurs commonly in mumps, and before vaccination became routine, was the commonest cause of aspetic meningitis. Epididymo-orchitis is the most common nonsalivary manifestation. Testicular involvement is generally unilateral but rarely may be bilateral. It may lead to atrophy of the involved testis, but rarely causes sterility. Rubella Rubella is one of the most benign of all infectious diseases in children.