The most common cause of acquired testicular failure is viral orchitis. Responsible viruses include mumps, echovirus, lymphocytic choriomeningitis, and group B arboviruses.
Orchitis is due to viral invasion of the tissue, occurs in as many as twenty-five per cent of adult men with mumps, and is unilateral in over sixty-five per cent of the cases. The testis may return to normal size and function or undergo atrophy. Bilateral atrophy, which occurs in approximately ten per cent of subjects with bilateral orchitis, may cause decreased testosterone production. The exposed position in the scrotum renders the testis susceptible to both thermal and physical trauma, the second most common cause of acquired testicular failure.
