Los Angeles has declared a mumps outbreak as dozens of gay men are treated for the virus.
More than 40 people, mostly men who have sex with men, were diagnosed in recent weeks, according to Los Angeles County health officials.
An alert, released on Thursday night, said most of the infections could be traced to gyms, bars and nightclubs.
They added that most of the infected patients had not been vaccinated.
‘A major factor contributing to outbreaks of mumps is being in a crowded environment,’ according to the alert.
‘Also, certain behaviors that result in exchanging saliva, such as kissing or sharing utensils, cups, lipstick or cigarettes, may increase the spread of the virus.’
The outbreak is the latest of many in America this year.
CDC figures show 2570 people were diagnosed with mumps between January and April of this year.
That is almost half the total amount recorded in 2016, which saw 5,833 cases.
There have been other pockets of outbreaks across the continent this year, including the University of Missouri, which reported more than 320 confirmed and probably cases earlier this month.
There was 485 mumps infections reported in the United States in January, which already surpasses the 229 cases reported in 2012.
Since 2000, there have been only two years — 2006 and 2016 — in which the number of mumps cases have topped 3,000.
Mumps can be spread by saliva or mucus. The virus has a 12- to 30-day incubation period.
It’s typical symptoms are fever, headache, muscle aches and loss of appetite, followed by swollen salivary glands.
The CDC notes that while mumps are ‘no longer very common’ in the U.S., outbreaks do occur particularly in places where people have had prolonged close contact with a person with the virus, such as school, dorms or sports teams.
WHAT IS MUMPS?
Mumps is a virus of the salivary gland.
It is spread through saliva, commonly on glasses, plates and cutlery.
Mumps infection is incurable and can lead to devastating health concerns in adults.
Sufferers have lost their hearing, become infertile, and had swollen brains.
Some people do not experience any symptoms.
Typically, symptoms include puffy cheeks, swollen glands, headaches, a fever, chills, fatigue, muscle aches, and a lack of appetite.
Sufferers have described feeling pain in their stomach, neck, pelvis, and testicles.