6 to 12 days. Eating undercooked bullfrog can cause parasitic infection, and its incubation period is 6 to 12 days. If you want to rule it out, you can go to the local health and epidemic prevention station to do some inspections. Parasite is a kind of eukaryote, which is characterized by living and obtaining nutrition by parasitizing on other living bodies or surfaces, and is usually harmful to the host.