Basically a disease breaks out on a passenger ship; not everyone starts falling down ill, but they have all been exposed, so the ship is now wary of any dock it tries to enter.
There was also Cassandra Crossing from 1979 and SST: Deathflight to Nowhere, both with all-star casts, Cassandra was a train, Deathflight obviously was a plane.
Each one had a virus running rampant through the transportation and the passengers were quarantined.
Perhaps it was Killer On Board's title that was so misleading.
The cast wasn't that remarkably standing out. Claude Akins? It just seemed very well done, television-wise.
Like Cassandra Crossing, there was a drug-user on the ship. He ended up jumping overboard. On Cassandra, it was Martin Sheen who was the drug-runner.
About the only two incidents I can recall really well (aside from the drug addict) was Patty Duke Astin in another one of her 1970s abused roles; here, she is thrown down a flight of stairs in front of her young son.
The other event was the woman whose husband died and they debated if they should do an autopsy, tho she objected. They decided they had to, to see if he had the disease, and she was very enraged.
My sister thought this woman was Patricia Neal, I thought it was Fritzi Burr, who appeared on episodes of "Sanford & Son" and "What's Happening?" I see now that it was Beatrice Straight (Network), but it may have been Burr as well, because she is listed in the cast also.
Just can't remember how significant this woman's role was.
Not a bad movie, not a badly done subject. Could be redone as this Michael Bay movie "The Island" or whatever it was, was a remake of "Parts: The Clonus Horror".