The USS Fort McHenry warship (pictured) is currently operating in the Persian Gulf
Of the 703 sailors and marines aboard the USS Fort McHenry, 25 have been diagnosed with parotitis, a viral infection similar to mumps, according to US military officials.
The ship is currently operating in the Persian Gulf in the Middle East.
The virus broke out in December and the most recent case was reported on March 9.
The patients were quarantined and treated in the ship's medical facility after the parotitis spread across the ship.
Communal spaces and living areas were also disinfected.
'None of the cases are life-threatening and all have either already made or are expected to make a full recovery,' a statement from the Fifth Fleet said.
'Fort McHenry's operational schedule has been modified while the ship's medical team monitors crew health to ensure the readiness of her Sailors and Marines.
'Out of an abundance of caution, all service-members aboard Fort McHenry have received measles, mumps and rubella (MMR) booster vaccinations.'
Comment: It'll be interesting to see whether the vaccinations actually lead to worsening of the outbreak.
'Routine unit-level training and operations have continued.'
None of the crew members had to leave the ship after the virus spread.
Parotitis is an inflammation of the parotid glands, located between the ear and jaw.
It can be a consequence of mumps, which can be prevented by vaccination.
A military official said that when a major disease breaks out, it could be decided to halt port visits until 30 days after the last reported illness, due to incubation periods.
The US warship made a port call in early January in Romania before travelling back to the Mediterranean and heading towards the Middle East, where it is currently quarantined.
Officials are currently considering whether it would be safe to make a port call.
Since the first case broke out in December, 24 of the 25 patients have returned to duty.
Comment: Outbreaks of all kinds appear to be on the increase all over the planet, check out the links below to see just how often these unusual outbreaks are being reported: