crsheader Index Spanish version Infections: Incubation and Contagious Periods

Young children get infectious diseases 10 to 15 times per year. As they get older, children get sick less often. This is because with each new infection their bodies build up antibodies that will defend the body if the same germ attacks in the future.

What is an incubation period?

The incubation period is the time between being exposed to a disease and when the symptoms start. If your child was around someone who is sick and the incubation time has gone by, then your child was probably not infected and won’t get sick. It is also possible that your child’s body had already developed antibodies to fight the infection.

What is the contagious period?

The contagious period is the amount of time during which a sick child can give the disease to others.

For major illnesses (such as hepatitis), a child will need to stay at home or in the hospital until all chance of spread has passed. For minor illnesses (like the common cold) the guidelines are less strict. Most healthcare providers would agree that a child should stay home at least until he feels well enough to return to school, and the fever has been gone for 12 hours.

What infections are not contagious?

Try not to become preoccupied with infections. Some of the more serious ones are not even contagious. Some infections are due to blockage of a passageway followed by an overgrowth of bacteria. Examples of these are ear infections, sinus infections, and urinary tract infections. Lymph node and bloodstream infections are also rarely contagious. Pneumonia is a complication of a viral respiratory infection in most cases and is usually not contagious. While exposure to meningitis requires consultation with your child’s healthcare provider, most children exposed to this disease do not become infected. Sexually transmitted diseases are usually not contagious unless there is sexual contact or shared bathing arrangements.

What are the guidelines for the common contagious infections?

Below is a chart that shows some common infections. It shows how long the incubation time is for each disease. This information should help you know when your child might get sick if he has been exposed to a disease. The chart also shows the amount of time your child will be contagious. Knowing this helps you know how long your child may need to stay home from school or child care.

Incubation Disease Period (days) Contagious Period ————————————————————— ————————————————————— SKIN INFECTIONS Chickenpox 10 to 21 5 days before rash until all sores have crusts (5-7 days) Fifth disease 4 to 14 7 days before rash (Erythema infectiosum) until rash begins Hand, foot, and mouth 3 to 6 Onset of mouth ulcers disease until fever is gone Impetigo (strep or staph) 2 to 5 Onset of sores until 24 hours on antibiotic Lice 7 Onset of itch until one treatment Measles 8 to 12 4 days before until 5 days after rash appears Meningitis 3 to 6 Onset of symptoms and for 1 to 2 weeks Roseola 9 to 10 Onset of fever until rash is gone (2 days) Rubella (German measles) 14 to 21 7 days before until 5 days after rash appears Scabies 30 to 45 Onset of rash until one treatment Scarlet fever 3 to 6 Onset of fever or rash until 24 hours on antibiotic Shingles (contagious 14 to 16 Onset of rash until for chickenpox) all sores have crusts (7 days) (Note: No need to isolate if sores can be kept covered.) Warts 30 to 180 See footnote A ————————————————————— RESPIRATORY INFECTIONS Bronchiolitis 4 to 6 Onset of cough until 7 days Colds 2 to 5 Onset of runny nose until fever is gone Cold sores (herpes) 2 to 12 See footnote B Coughs (viral) 2 to 5 Onset of cough until fever is gone Croup (viral) 2 to 6 Onset of cough until fever is gone Diphtheria 2 to 5 Onset of sore throat until 4 days on antibiotic Influenza (Seasonal) 1 to 3 Onset of symptoms until fever is gone over 24 hours Influenza (H1N1) 4 to 6 Onset of symptoms until fever is gone over 24 hours Sore throat, strep 2 to 5 Onset of sore throat until 24 hours on antibiotic Sore throat, viral 2 to 5 Onset of sore throat until fever is gone Tuberculosis 6 to 24 Until 2 weeks on months drugs (Note: Most childhood TB is not contagious.) Whooping cough 7 to 10 Onset of runny nose until 5 days on antibiotic ————————————————————— INTESTINAL INFECTIONS Diarrhea, bacterial 1 to 5 See footnote C Diarrhea, Giardia 7 to 28 See footnote C Diarrhea, traveler’s 1 to 6 See footnote C Diarrhea, viral (Rotavirus) 1 to 3 See footnote C Hepatitis A 14 to 50 2 weeks before until 1 week after jaundice begins Pinworms 21 to 28 See footnote A Vomiting, viral 2 to 5 Until vomiting stops ————————————————————— OTHER INFECTIONS Infectious mononucleosis 30 to 50 Onset of fever until fever is gone (7 days) Meningitis, bacterial 2 to 10 7 days before symptoms until 24 hours on IV antibiotics in hospital Mumps 12 to 25 5 days before swelling until swelling gone (7 days) Pinkeye without pus 1 to 5 See footnote A (viral) Pinkeye with pus 2 to 7 Onset of pus until (bacterial) 1 day on antibiotic eye drops —————————————————————


(A) Staying home is unnecessary because the infection is very mild and/or minimally contagious.

(B) Cold sores

  • Under age 6 years: Your child should stay home until the sores are dry (4 to 5 days). However, if the sores are on a part of the body that can be covered, your child does not need to stay home.
  • Over age 6 years: Your child does not need to stay home if he is beyond the touching, picking stage.

(C) Diarrhea

  • Not toilet trained: Your child should stay home until stools are formed.
  • Toilet trained: Your child should stay home until the fever is gone, diarrhea is mild, blood and mucus are gone, and your child has control over loose bowel movements.
  • Talk your child care provider about attendance restrictions.

Written by Barton D. Schmitt, MD, author of “My Child Is Sick”, American Academy of Pediatrics Books. Published by RelayHealth.
Last modified: 2011-06-29
Last reviewed: 2011-06-06 This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional. Pediatric Advisor 2011.4 Index
© 2011 RelayHealth and/or its affiliates. All rights reserved.