There is a lag time between being exposed to an infection and coming down with the disease. This time frame is called the incubation period. 

The value of knowing
the incubation periods for common infections is that you can better gauge if you have “dodged a bullet” regarding something you or your child has come in contact with. Here are the incubation periods for some well-known childhood infections.

• common cold: 1 – 3 days
• conjunctivitis (“pink eye”): 1 – 3 days
• croup: 2 – 7 days
• fifth disease: 4 – 14 days
• hand/foot/mouth disease: 3 – 6 days
• herpes (“cold sores”): 2 – 12 days
• impetigo: 1 – 7 days
• Influenza: 1 – 4 days
• molluscum contagiosum: 1 week – 6 months
• mononucleosis: 4 – 6 weeks
• pertussis (“whooping cough”): 1 – 2 weeks
• pinworms: 2 – 6 weeks
• roseola: 5 – 12 days
• RSV: 2 – 8 days
• strep throat: 1 – 3 days
• viral gastroenteritis (“stomach flu”): 1 – 3 days