At least 40 Americans aboard a cruise ship have been infected with the coronavirus, in a development that suggest the dangerous disease may transmit more rapidly than the public in the western world realizes.

Immunologist Anthony Fauci, an official with the National Institute of Allergy and Infectious Diseases, confirmed that 40 Americans had been diagnosed with the disease in an appearance on 60 Minutes Sunday.

Some reporting indicates that even more people have been infected with the disease, with figures ranging up to 355. These estimates include passengers of all nationalities. Those afflicted with coronavirus are being taken to Japanese hospitals to receive medical treatment.

The Americans were on board the cruise ship Diamond Princess, which is currently quarantined in Yokohama, Japan. The ship is host to the most pervasive outbreak of the coronavirus epidemic outside of China, where it originated. American passengers who tested negative of the disease have been evacuated from the ship and brought back to the United States on charter planes. Those infected with the virus will be treated in Japanese hospitals.

At least one American passenger who was traveling on board the Diamond Princess is refusing to take a U.S government charter plane back to the country, stating his belief to USA Today that the evacuation process the government is using to retrieve its citizens is not safe.

There’s considerable cause to believe the global public is being largely kept in the dark by the authoritarian Chinese government on the dangers posed by the quickly spreading virus. Estimates of the total count of people infected by the disease are largely unclear, with the Chinese government suspected of releasing deflated statistics in an effort to blunt criticism of their response to the epidemic.