The incident, which happened on Japanese company K Line's ship Drive Green Highway, has concerned Maritime Union of Australia (MUA) officials who feel their members were put at risk by boarding the ship.

The ship left Japan on February 3 and has been at sea for longer that the 14-day quarantine period suggested for Coronavirus.

The MUA's National Training and Safety Officer Jake Field said a member of the Filipino crew was taken off the ship and transported to Wollongong Hospital by ambulance.

Read more: UOW student taken for Coronavirus testing

Members also told him other crew members on board were wearing masks.

"We had a crew member quarantined on board - that could have been for any number of illnesses," Mr Field said.

READ MORE: No risk from Japanese ship, says govt

"You've got ship's crew walking around with masks on and our members aren't being told why this person is in quarantine and whether that affects the rest of the crew.

"All they've heard from biosecurity is ' the ship's clear and away you go to work'."

Mr Field said dock workers heard the crew member may have had measles.

"No-one's told our members, who have to go up that gangway and be on that vessel, why that patient was in quarantine or was removed," he said.

"We're in a 24-hour news cycle where people are talking about Coronavirus constantly but our members have not been advised why this crew member was taken off the vessel."

An Illawarra Shoalhaven Local Health District spokeswoman said a crew member was taken to Wollongong Hospital on Tuesday, but was discharged later that day.

The patient did not have measles, though the nature of his illness is unclear.

However, another source said testing for Coronavirus was negative.

The Drive Green Highway left Port Kembla on Wednesday afternoon at its scheduled departure time.

Mr Field was unhappy that MUA workers, who had to go on board the ships "were the last to know" about the possibility of infectious diseases.

"We knock off work and go back into the community and unbeknownst to us we've been exposed to a virus," he said.

"We just want more stringent and more forensic processes put in place by these biosecurity agencies to inspect the vessels prior to being worked and notify the union and members, if necessary, who are having to go up the gangway and work these vessels."

The Agriculture Department, which looks after biosecurity, was contacted for comment.