Testicular immunology
Mumps is a viral disease which causes swelling of the salivary glands and testes. The mumps virus lives in the upper respiratory tract and spreads through direct contact with saliva. Prior to widespread vaccination programs, it was a common childhood disease. Mumps is generally not serious in children, but in adults, where sperm have matured in the testis, it can cause more severe complications, such as infertility.
Measles
The virus is highly contagious and is spread by coughing and sneezing via close personal contact or direct contact with secretions. It can live for up to two hours in that airspace or nearby surfaces. Measles is so contagious that if one person has it, 90% of nearby non-immune people will also become infected. Humans are the only natural hosts of the virus, and no other animal reservoirs are known to exist.