If you’re a parent, it’s probably safe to assume that you have at one time or another received the dreaded call. You know the call. You get it while you’re in a meeting or getting coffee. You look down at the caller ID. “Kid’s school.” You let it go to voicemail so you have time to mentally prepare yourself for explaining why your child thought giving the class hamster a mohawk was a good idea. You press “play” on the voicemail and you hear, “Good afternoon. Please come pick up your child. She came to the nurse’s office, and she has a fever.” First, you sigh with relief that the hamster still has its luscious locks. Second, and more importantly, you ask yourself: When can my kiddo go back to school?
Incubation and contagious periodsThe answer depends on what’s causing your child to feel sick. Every cough, cold, rash and upset stomach has unique characteristics for diagnosis and treatment. And when you ask your child’s doctor when your little one can return to a play group or school, your doctor is thinking about two specific characteristics of the pathogens that make kids sick:
- Incubation period: The time between exposure to an illness or infection and the start of symptoms. Each cold or rash has a different incubation period.
- Contagious period: The interval during which a child’s illness is contagious to others.
No one size fits allSometimes incubation and contagious periods overlap, and sometimes they don’t. For instance, erythema infectiosum, known as fifth disease or “slapped cheek” rash, is contagious from about halfway through its incubation period until you see the characteristic cheek rash on your child.
In comparison, hand, foot and mouth disease has an incubation period of up to one week, but it isn’t contagious until its symptoms -- mouth sores and a rash on the hands and feet -- are noticeable.
The list below gives the incubation and contagious periods for many common childhood illnesses.
Disease, Incubation period, and Contagious period
- Chickenpox 10-21 days; Two days before rash until all sores have crusts (Six to seven days)
- Fifth disease (erythema infectiosum) 4-14 days; Seven days before rash until rash begins
- Hand, foot and mouth disease 3-6 days; Onset of mouth ulcers until fever gone
- Impetigo (strep or staph) 2-5 days; Onset of sores until 24 hours on antibiotic
- Lice 7 days; Onset of itch until one treatment
- Measles 8-12 days; Four days before rash until four days after rash appears
- Roseola 9-10 days; Onset of fever until rash is gone (two days)
- Rubella (German measles) 14-21 days; Seven days before rash until five days after rash appears
- Scabies 30-45 days; Onset of rash until one treatment
- Scarlet fever 3-6 days; Onset of fever or rash until 24 hours on antibiotic
- Shingles (contagious for chicken pox) 14-16 days; Onset of rash until all sores have crusts (seven days) (Note: No need to isolate if sores can be kept covered.)
- Warts 30-180 days; Minimally contagious
- Bronchiolitis 4-6 days; Onset of cough until seven days
- Colds 2-5 days; Onset of runny nose until fever gone
- Cold sores (herpes) 2-12 days; Footnote 1
- Coughs (viral) or croup (viral) 2-5 days; Onset of cough until fever gone
- Diphtheria 2-5 days; Onset of sore throat until four days on antibiotic
- Influenza 1-2 days; Onset of symptoms until fever gone
- Sore throat, strep 2-5 days; Onset of sore throat until 24 hours on antibiotic
- Sore throat, viral 2-5 days; Onset of sore throat until fever gone
- Tuberculosis 6-24 months; Until two weeks on drugs (Note: Most childhood TB is not contagious.)
- Whooping cough 7-10 days; Onset of runny nose until five days on antibiotic
- Diarrhea, bacterial 1-5 days; Footnote 2 for diarrhea precautions
- Diarrhea, giardia 7-28 days; Footnote 2 for diarrhea precautions
- Diarrhea, traveler's 1-6 days; Footnote 2 for diarrhea precautions
- Diarrhea, viral (Rotavirus) 1-3 days; Footnote 2 for diarrhea precautions
- Hepatitis A 14-50 days; Two weeks before jaundice begins until jaundice resolved (seven days)
- Pinworms 21-28 days; Minimally contagious, staying home is unnecessary
- Vomiting, viral 2-5 days; Until vomiting stops
- Infectious mononucleosis 30-50 days; Onset of fever until fever is gone (seven days)
- Meningitis, bacterial 2-10 days; Seven days before symptoms until 24 hours on IV antibiotics in hospital
- Meningitis, viral 3-6 days; Onset of symptoms and for one to two weeks
- Mumps 12-25 days; Five days before swelling until swelling is gone (seven days)
- Pinkeye without pus, viral 1-5 days; Mild infection, staying home is unnecessary
- Pinkeye with pus, bacterial 2-7 days; Onset of pus until one day on antibiotic eye drops
1. Cold sores: Less than 6 years old, contagious until cold sores are dry (four to five days). No isolation if sores are on part of body that can be covered. More than 6 years old, no isolation necessary if beyond touching, picking stage.2. Diarrhea Precautions: Contagious until stools are formed. Stay home until fever is gone, diarrhea is mild, blood and mucus are gone, and toilet-trained child has control over loose stools. Shigella and E. coli 0157 require extra precautions. Consult your child care provider regarding attendance restrictions.
A lot of childhood fevers aren’t easily categorized, or children may have vague symptoms and “just don’t feel good.” What we like to tell parents is that their child is most likely not contagious and is safe to return to school -- hamster haircuts and all -- if the child:
- Is fever-free for 24 hours
- Has enough energy and willingness to go to school
- Can stay well hydrated
- Is able to tell a teacher or the school nurse if they aren’t feeling well
Save the information provided here for future reference. It’s bound to come in handy.If your child is sick and you aren’t sure of a diagnosis, call Swedish Pediatrics at 800-793-3474 to schedule an appointment. You can find a primary care clinic here.
Incubation and contagion chart: Copyright 1994-2015, Barton D. Schmitt, M.D., all rights reserved