Humans and Byzatium could not have subspatial llhrei'sian through subspace turbulence, unlike Romulans, where a Grust 5 turbulence and higher could cause the malady. Its name, literally translated to English, meant diarrhea. In a sense, the people afflicted from llhrei'sian suffered from diarrhea, but the sickness also dulled one's senses and balance. Non-Romulan speakers usually refer to this form of llhrei'sian when they speak about llhrei'sian.
There were other causes to the malady but the cure for that form of llhrei'sian, cyprofloxacine, was not replicable. The shortage of the remedy aboard the Bouteina almost made the crew mutiny and mandated an away mission to get some more. ("What about some D'oh!")
Vox'ula, after eating Krusty Burgers, has suffered from that form of llhrei'sian while on an away mission on Simpson's Planet. Duff beer proved to be a cure for his food-induced llhrei'sian. ("What about some D'oh!")