Cartalian fever was a type of viral infection.
In 2373, a visit to a medical conference in 2373 didn't provide Jake Sisko with enough material to write an interesting article about Julian Bashir. He then mused that an outbreak of Cartalian fever would be good since it would be the story of "the brave doctor battles the deadly virus", though he chastised himself for actually hoping for a disease. (DS9: "Nor the Battle to the Strong")