A total of 898 detained adult migrants had mumps in the last year, the US Centers for Disease Control and Prevention reported Friday.
Some cases were confirmed by testing, others were considered "probable" based on symptoms, the public health agency stated.
The cases were reported at 57 facilities in 19 states.
An additional 33 staff members were also diagnosed with the contagious disease caused by a virus spread through saliva and mucus, the CDC said.
The numbers were reported from last September to last week.
Of the 315 facilities in use, 18 percent had a single case or outbreak of mumps, the CDC said, and 44% of the cases were reported in Texas.
Private companies operated 34 of the affected facilities, 19 were county jails, and four were operated by US Immigration and Customs Enforcement.
All the usual places
Crowding and close contact fuel the spread of mumps. The usual settings for outbreaks are places where people congregate -- schools, college dorms, Army barracks and athletic events. In such places, saliva is transferred person to person due to coughing, sneezing, kissing and the sharing utensils, lipstick or cigarettes.
Since 2015, about 150 mumps outbreaks and 16,000 cases have been reported in the United States.
This is the first time the CDC has reported on mumps outbreaks in detention facilities.
Most patients (84%) became exposed to the mumps while in custody, the agency found. The majority (94%) were men at an average age of 25 years old.
Symptoms and prevention
Mumps typically begins with fever, headache, muscle aches, tiredness and loss of appetite lasting a few days. Most people will then see swollen glands, causing puffy cheeks and jaw.
The incubation period for mumps ranges from 12 days to 25; symptoms last at least two and usually more than 10 days. Mumps can occasionally cause complications, especially in adults.
Thirteen patients were hospitalized, while 15% of the infected men developed testicular inflammation, a mumps' complication that infrequently causes sterility, the CDC found.
Different detention facilities have different mumps vaccination programs. Each should follow local and state health department recommendations -- including reporting cases to state health departments, the CDC stated.
Detainees and staff who are at increased risk for mumps should be offered the measles, mumps and rubella (MMR) vaccine during outbreaks, noted the CDC.
Developed in the 1970s, the MMR vaccine is usually given to young children in two shots spread out over a few years. When two doses are given, it is 88% effective, less so in people who receive just one shot.
"As of August 22, 2019, mumps outbreaks are ongoing in 15 facilities in seven states, and new introductions into detention facilities through detainees who are transferred or exposed before being taken into custody continue to occur," the CDC concluded.