Review the CDC Outbreak updates page and look at some of the http://www.cdc.gov/nceh/vsp/surv/gilist.htm
between 2015 and 2020. Choose one that is interesting to you based on the cruise line or causative agent.
In the text of your initial post,
Indicate the virus that caused the outbreak (“unknown” is not an option) and common symptoms and treatments for the virus.
Distinguish the cruise line and cruise ship it occurred on.
Express the raw number and percentage of passengers and crew impacted by the outbreak.