![\"News](\"https:\/\/media.healthday.com\/Images\/icimages\/cruise_ship01142.jpg\"\/)
By E.J. Mundell<\/b>
HealthDay Reporter<\/i><\/p>\n
WEDNESDAY, July 29, 2020 (HealthDay News)<\/p>\n
The fate of more than 3,600 quarantined passengers and crew on the cruise ship Diamond Princess<\/i> made headlines in the early weeks of the coronavirus pandemic in February.<\/p>\n
An outbreak aboard the ship eventually led to nearly 700 infections and seven deaths from COVID-19<\/a>.<\/p>\n Now, a genetic retracing of events shows the outbreak likely stemmed from just one infected person, with the virus spreading rapidly as people mingled at crowded shipboard events, Japanese researchers report.<\/p>\n One thing is certain, however: Quarantine and containment measures enacted after the virus was discovered did limit cases — and probably saved lives.<\/p>\n The first known case of coronavirus infection on the Diamond Princess<\/i> was reported Feb. 1 in an ill 80-year-old passenger who left the ship in Hong Kong on Jan. 25.<\/p>\n By Feb. 4, a quarantine was in place throughout the ship and passengers were largely restricted to their cabins.<\/p>\n At that point, the incidence of new cases “abruptly declined,” according to a team led by Makoto Kuroda, of the National Institute of Infectious Diseases, in Tokyo.<\/p>\n That indicates that “the movement restriction policy was highly successful in greatly reducing the number of secondary transmissions on board the Diamond Princess<\/i>,” the researchers reported.<\/p>\n One prior study had also estimated that quarantine and other public health measures “prevented more than 2,000 additional cases” aboard the Diamond Princess<\/i>, compared to doing nothing at all, Kuroda’s group noted.<\/p>\n In the new study, the Japanese team sought to determine the origins of the cruise ship outbreak. To do so, they analyzed the DNA of samples of SARS<\/a>-CoV-2 in nasal swab tests obtained from almost 900 passengers and crew during the outbreak.<\/p>\n The genetic analysis suggests “that there was a single introduction of SARS<\/a>-CoV-2, which disseminated among passengers on the ship through possible mass gathering events in the recreational areas,” according to the study.<\/p>\n The dominance in samples of coronavirus with a particular gene “cluster” also suggests possible “superspreading” onboard, long before the quarantine began, the study authors said.<\/p>\n The virus may have silently spread in events as innocuous as a shared dinner table or during “dancing, singing, shopping, and watching performances,” Kuroda’s group said.<\/p>\n While cruise ships may be a unique environment, the outbreak — and quarantine — aboard the Diamond Princess<\/i> reveals “how SARS<\/a>-CoV-2 can be spread in the community” more generally, the research team said.<\/p>\n Dr. Amesh Adalja is an infectious disease expert and senior scholar at the Johns Hopkins Center for Health Security, in Baltimore. Reading the new report, he said it “illustrates how a contagious<\/a> respiratory virus can disseminate widely from just one person in the right context.”<\/p>\n And for anyone still contemplating a cruise, the new findings show that “most of the cases may have been contracted at mass gathering events on the ship — an important factor to consider as cruise lines begin to think about resuming operations,” Adalja said.<\/p>\n The study was published July 28 in the Proceedings of the National Academy of Sciences<\/i>.<\/p>\n ![\"MedicalNews\"](\"https:\/\/images.medicinenet.com\/images\/HealthDay\/healthday.png\")
Copyright \u00a9 2020 HealthDay. All rights reserved.<\/p>\n
\n
\n ![](\"https:\/\/images.medicinenet.com\/\/images\/slideshow\/bacterial-infections-101-s1-what-is-bacteria.jpg\"\/)
\n