Just because a cruise ship is called luxurious, doesn't mean that it's clean. One of most luxurious cruise ships in the world recently failed a health inspection carried out by the U.S. Centers for Disease Control and Prevention.

It is rare for a cruise ship to fail a health inspection, but the CDC gave the Silversea Cruises' 382-passenger Silver Shadow a failing score of 84 out of 100 points, Cruise Critic reports. This may be surprising for the all-suite luxury cruise with room for two starting at more than $1,000 a night.

The ship underwent a surprise health inspection in Skagway, Alaska on June 17th, but the results of the inspection are just coming out now.

The CDC performs health inspections as part of its Vessel Sanitation Program and it is not announced. Health inspections are done twice a year while a ship is docked at a U.S. port and a passing score is an 86 out of 100 points.

The CDC hasn't released a list of reasons for the failing score as of yet. They typically post report details on the CDC website within a few months of a failing inspection.

Silversea Cruises released a statement about the inspection to Cruise Critic.

"On June 17, Silversea's Silver Shadow received an atypical score of 84 during the Vessel Sanitation Program inspection in Skagway," the line said in a prepared statement. "Silversea is deeply disappointed by this specific and only unsatisfactory score and has taken immediate measures to address the issues identified in the inspection report."

"Following a thorough review of Silver Shadow's procedures, we have taken the necessary measures to ensure that that standards are the best in the industry," the line said.

The company claims that the cruise has never failed any other health inspections in its 13-year history. In fact, the ship received high scores ranging from 95 to 99 during the last six inspections, CDC records show.