Develop a model of the viral infection mumps. Symptoms include painful and swollen salivary glands, painful swallowing, fever, weakness, fatigue, and a tender, swollen testicle. Infection is spread through breathing of infected saliva droplets. About one-third of those with mumps experience no symptoms. If present, symptoms usually start 2 to 3 weeks after infection. The person is contagious from approximately 1 day before salivary gland swelling occurs and remains contagious for at least another 3 days. As the swelling diminishes, so does the degree of the contagion. Before licensing of the mumps vaccine in 1967, the United States had more than 200,000 cases per year. Since then, the country has had fewer than 1000 cases per year (Mayo Clinic Staff 2012).