Symptoms usually develop 5–8 days after exposure to an infected person and last up to 20 days.
On Cardassia, Craat’s disease is usually only contracted by children between the age of two and five. Before the introduction of a vaccine in 2357 and widespread vaccination, major epidemics occurred approximately every 2–3 years with as many as 400,000 cases per year. Due to the lack of hygiene and medical amenities after the Dominion War, Craat's disease once more proved deadly to unvaccinated children. 
Craat’s disease mutated during the Occupation of Bajor , and is known to be contracted by Bajoran adults who show similar symptoms as Cardassian children. In Bajorans however, Craat’s disease is considered harmless and symptoms last between two and five days.