Infection Exposure Questions - Contagiousness  
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  • This topic includes information about the transmission of common infections, including how long to stay out of school or child care.
  • Incubation Period:  Time interval between exposure to the infection and onset of symptoms.
  • Contagious Period:  Time interval during which a sick child's disease is contagious to others.  With precautions, children sometimes can return to child care and school before this period is over.
  • Infections that are not Contagious:  Many common bacterial infections are not contagious (e.g., ear infections, sinus infections, bladder infections, kidney infections, and pneumonia).  Sexually transmitted diseases are not contagious to children unless there is sexual contact or shared bathing.

Infection Exposure Table

Skin Infections/Rashes:
Chickenpox 10-212 days before rash until all sores have crusts (6 - 7days)
Fifth disease (Erythema infectiosum) 4-147 days before rash until rash begins
Hand, foot, and mouth disease 3-6Onset of mouth ulcers until fever gone
Impetigo (strep or staph) 2-5Onset of sores until 24 hours on antibiotic
Lice 7Onset of itch until 1 treatment
Measles 8-124 days before rash until 4 days after rash appears
Roseola 9-10Onset of fever until rash gone (2 days)
Rubella (German measles) 14-217 days before rash until 5 days after rash appears
Scabies 30-45Onset of rash until 1 treatment
Scarlet fever 3-6Onset of fever or rash until 24 hours on antibiotic
Shingles (contagious for chicken pox) 14-16Onset of rash until all sores have crusts (7 days) (Note: No need to isolate if sores can be kept covered.)
Warts 30-180Minimally contagious
Respiratory Infections:
Bronchiolitis 4-6Onset of cough until 7 days
Colds 2-5Onset of runny nose until fever gone
Cold sores (herpes) 2-12Footnote 1
Coughs (viral) or croup (viral) 2-5Onset of cough until fever gone
Diphtheria 2-5Onset of sore throat until 4 days on antibiotic
Influenza 1-2Onset of symptoms until fever gone over 24 hours
Sore throat, strep 2-5Onset of sore throat until 24 hours on antibiotic
Sore throat, viral 2-5Onset of sore throat until fever gone
Tuberculosis 6-24 monthsUntil 2 weeks on drugs (Note: Most childhood TB is not contagious.)
Whooping cough 7-10Onset of runny nose until 5 days on antibiotic
Intestinal Infections:
Diarrhea, bacterial 1-5Footnote 2 for Diarrhea Precautions
Diarrhea, giardia 7-28Footnote 2 for Diarrhea Precautions
Diarrhea, traveler's 1-6Footnote 2 for Diarrhea Precautions
Diarrhea, viral (Rotavirus) 1-3Footnote 2 for Diarrhea Precautions
Hepatitis A 14-502 weeks before jaundice begins until jaundice resolved (7 days)
Pinworms 21-28Minimally contagious, staying home is unnecessary
Vomiting, viral 2-5Until vomiting stops
Other Infections:
Infectious mononucleosis 30-50Onset of fever until fever gone (7 days)
Meningitis, bacterial 2-107 days before symptoms until 24 hours on IV antibiotics in hospital
Meningitis, viral 3-6Onset of symptoms and for 1-2 weeks
Mumps 12-255 days before swelling until swelling gone (7 days)
Pinkeye without pus (viral) 1-5Mild infection, staying home is unnecessary
Pinkeye with pus (bacterial) 2-7Onset of pus until 1 day on antibiotic eyedrops


  1. Cold sores:  Less than 6 years old, contagious until cold sores are dry (4-5 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.

Author and Senior Reviewer: Barton D. Schmitt, M.D.

Content Set: Pediatric HouseCalls Symptom Checker

Pediatric HouseCalls Symptom Checker