Updated April 28, 8:30pm
Late yesterday, the CDC "recommended" people avoid "nonessential" travel to Mexico. It appears that the cruise lines hadn't been anticipating that action coming so soon, and are still dealing with the issue.
The bottom line is that all of the major cruise lines have said they are temporarily suspending calls at all Mexican port for the immediate future.
Each of the lines said they will have specifics of the itinerary changes sometime during the day on Wednesday. Today, most all ships substituted a sea day, but the lines have promised most in the future will substitute another port where possible.
The biggest (literally) question is what Carnival and Royal Caribbean will do with the post-Panamax ships they each just positioned in Southern California for year round 7-day Mexican Riviera cruises, since their itineraries are all Mexico. Royal Caribbean answered the question in general terms today by saying theirs would sail an all-new US West Coast program with a call in Canada. Carnival would not be specific about Carnival Splendor.
Carnival has stated that if there is any passenger who does not want to sail the revised itinerary, they will be allowed to reschedule their travel plans without penalty. The other lines are still formulating their plans and will have them available on Wednesday.
All of the lines confirm they have had no cases of suspected swine flu on their ships. Most have, however, elevated their sanitation protocols to be similar to the ones they use when there is a norovirus outbreak. If a case of swine flu should be brought aboard. this would retard its spread as much as possible.