The Bergen County Jail is under quarantine after at least five inmates were diagnosed with the mumps.
A doctor at the jail clinically diagnosed the patients based on their symptoms. But official test results are still pending.
The quarantine means that no new inmates will be accepted at the jail until the outbreak is over. Visitors and attorneys may still go to the jail, but cannot have direct access to the inmates.
Inmates who would have been sent to Bergen County will instead go to the Hudson County Jail.
If no new cases are discovered, the quarantine will be declared over by July 6.