Lindblad Expeditions has paused passenger operations and canceled three Alaskan voyages on the National Geographic Sea Bird following a fourth gastrointestinal illness outbreak in under two months.
The Centers for Disease Control and Prevention reported that 13 of the 83 people on board fell ill during the July 15 to 20 sailing, including eight guests and five crew members.
Symptoms included abdominal cramps, vomiting, and diarrhea.
This outbreak follows three previous incidents on the small expedition vessel since late May. Norovirus caused the first two outbreaks in late May and late June.
The causative agent for the third and fourth outbreaks remains unknown.
The recent infections account for four of the nine gastrointestinal illness outbreaks recorded on cruise ships by the CDC during the 2026 season.
Across the two most recent July sailings combined, a total of 32 passengers and crew members became ill.
Lindblad canceled scheduled departures on July 20, July 25, and July 30 to perform enhanced sanitation procedures across the ship.
"We are working directly with affected guests to provide refunds, support and alternative travel arrangements," the cruise line said.
The vessel implemented heightened cleaning procedures and isolated affected guests and staff in accordance with health protocols.
The CDC noted that norovirus outbreaks are facilitated by a low infective dose, easy person-to-person transmission, and resistance to standard cleaning.
The agency added that there is no vaccine for norovirus.
Epidemiological data shows cruise ships account for about one percent of reported norovirus cases, despite the high visibility of maritime outbreaks.
"Really, when we have these areas where people … are in really close contact, things like day care facilities, nursing homes and cruise ships, it’s more likely (to be) diagnosed, reported and brought to our attention," said Sarah R.
Michaels, assistant professor at Tulane University’s Celia Scott Weatherhead School of Public Health and Tropical Medicine.
Health authorities emphasize that the virus spreads through contaminated hands and communal surfaces in high-density environments.
"That just means that we've handled something that is contaminated and once it’s on our hands, we do all kinds of things with our hands," said Dr. Robyn F.
Chatman, a family physician in Cincinnati.
Medical professionals note that individuals recovering from norovirus can continue to shed the pathogen for up to two weeks after symptoms clear.
"People who have norovirus can shed the virus for up to two weeks after their symptoms are gone," said Dr. Joanna Turner Bisgrove, family physician and member of the AMA Council on Science and Public Health.
The 31-cabin National Geographic Sea Bird is currently in its final year of offering expedition cruises in Southeast Alaska.
