Incubation and Contagious Periods of Infections

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 remain in isolation 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 health care 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 health care provider, most children exposed to this disease do not become infected. Venereal (genital) diseases are usually noncontagious 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.


SKIN INFECTIONS


 Disease             


Period (days)    


Contagious Period


Chickenpox 


10 to 21  


5 days before rash  until all sores have  crusts (5-7 days)                    


Fifth disease (Erythema infectiosum) 


 4 to 14 


7
days before rash
until
rash begins



Hand, foot, and mouth  disease


 3 to 6   


Onset of mouth ulcers  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



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 for chickenpox) 


14 to 16 


Onset of rash until 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 


 Disease             


Period (days)    


Contagious Period


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                      


1 to 2 


Onset
of symptoms until
fever
is gone



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 


 Disease             


Period (days)    


Contagious Period


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 


 Disease             


Period (days)    


Contagious Period


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  (viral) 


1 to 5 


See footnote A 


Pinkeye with pus              


(bacterial)



 2 to 7 


Onset
of pus until 1 day on antibiotic eye drops



TABLE
FOOTNOTES


(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.






 
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