Tropical bug
A tropical bug or tropical bacterium was a type of disease prevalent only in tropical climates, rather than temperate ones.
Hoshi Sato recalled being under the weather with a tropical bug the first time Jonathan Archer came to visit her in Brazil. Though she felt miserable, she nonetheless wanted to make a good impression on him. He promised her in 2154 that as soon as they returned to Earth, he'd make sure she got R&R in either Norway or Canada, where there weren't any such bugs. (ENT: "Zero Hour")