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.
Paragonimus
Worldwide roughly 20 million people are infected with Paragonimus. Human infections are most common in regions with many human and animal reservoir hosts plus an abundance of intermediate hosts, such as snails, crabs, or crayfish, and where in addition consumption of raw or undercooked seafood is common. Consumption of insufficiently cooked meat from infected land animal hosts, such as wild boar, commonly transmits the infection. The domestic cat is a reservoir for a variety of lung flatworms and can transmit the infection to humans.