Officials with the Los Angeles County Health Department are reporting a mumps outbreak affecting more than 40 people.
The majority of the cases are among men who have sex with men (MSM) but some are women and heterosexual men with social connections to MSM cases.
Most transmissions appear to have occurred at large venues such as athletic clubs, bars, theaters and nightclubs.
The majority of cases have had no documentation of complete vaccination; however, some cases were fully vaccinated.
Mumps incubation period ranges from 12-25 days, but symptoms typically develop 16 to 18 days after exposure to mumps virus.
Mumps typically begins with a few days of fever, headache, myalgia, fatigue, and anorexia followed by development of salivary gland swelling, pain, and tenderness. Mumps usually involves one or both parotid salivary glands but in 10% of cases other salivary glands (submandibular and sublingual) are symptomatic. In vaccinated patients, symptoms may be non-specific.
Complications of mumps may include orchitis, oophoritis and neurologic manifestations (including meningitis, encephalitis, and deafness).
According to the Centers for Disease Control and Prevention (CDC), there has been 3,176 mumps cases reported nationally through May.