Communicable Diseases



Incubation Period

School Action & Comments on Communicability

Source of Infection & Mode of Transmission


Slight fever, general feeling of illness, skin rash that begins on chest, back, underarm, neck and face. Starts out as red bumps that turn into small blisters. Scabs appear in a few days.

10 to 21 days, usually 14 to 16 days

Contagious a few days before eruption and until vesicles are dry. Exclude until day 6 after rash began or sooner if all blisters have dried into scabs.

Spread from person to person by direct contact with touching the blister fluid or secretions from the nose or mouth of a person with chicken pox. One attack usually confers immunity. Children on immuno-suppressive drugs at high risk. If you take your child to the doctor, they will want to keep your child separate from other children to prevent further spread.

Common Cold

Acute upper respiratory signs, including watery eyes, sneezing, running nose, general feeling of illness.

Up to 10 days

No restriction unless ill. Communicable shortly before symptoms begin and for the duration of the acute symptoms.

Spread person to person by direct contact with secretions from the nose and mouth. Also from hands, tissues or other items that may have secretions on them.

Fifth Disease

Rash, sometimes fever or sore throat, redness on cheeks. Rash could come and go for days or weeks.

4 to 21 days, usually 4 to 14 days

Exclude until diagnosed by M.D. If other rash-causing illnesses are ruled out, student can be in school.

Most contagious before rash appears. Pregnant women and anyone with an impaired immune system may want to consult their doctor if exposed.


Chills, body ache, headache, fever sore throat, followed by cough, running nose, and possibly stomach ache.

Up to 10 days

Exclude from school until well, usually 2-7 days. Should be without fever for 24 hours.

Virus spread directly through coughing, sneezing, and contact with nose or throat discharges of patient. Possibly airborne.


Blisters, pustules rapidly covered with honey-colored crusts. May be confused with cold sores. Usually seen first near mouth or nose. Can spread rapidly.

1 to 10 days, occasionally longer.

Exclude from school until verification of treatment, or until lesions are dry. Contagious until lesions are healed or 24 hours after initiation of oral antibiotics.

Bacteria spread by direct contact with sores, sometimes with contact from discharges from nose or throat of person can be spread through droplets in coughing or sneezing. Usually caused by Streptococcus or Staphylococcus bacteria.


Fever, sore throat, swollen lymph glands (neck), headache, tiredness. Can be a rash.

Probably 4 to 6 weeks.

No restriction unless ill. Period of communicability unknown.

Spread person to person through saliva.

Lice (Pediculosis)

Infestation of the head hair or other hairy parts of the body with lice or nits. Scratching causes reddened, rash-like area. Nits are tiny gray/white eggs, stuck to hair, usually close to scalp at neckline and/or behind ears.

Variable; eggs hatch in 7-10 days.

Exclude until live lice have been adequately treated and removed. Advise exam of household contact for nits and lice. For more information go to the Minnesota Department of Health Web site or call the licensed school nurse in your school building. 

Louse transmitted primarily by direct contact with infested persons. Lice can also be transmitted through combs, brushes, bedding, wearing apparel, and upholstered furniture.

Pink Eye (Conjunctivitis)

Redness of conjunctiva. May or may not have purulent discharge. Eye irritation.

24 to 72 hours

Pink eye without purulent discharge - no exclusion necessary. Pink eye with purulent discharge (pus) - excluded 24 hours after antibiotic treatment begins.

Most are caused by virus; some bacterial. Redness of eye may also be results of allergic reaction. May be spread through contact with secretions from eyes, nose or mouth.

Strep Throat Scarlet Fever

Fever, sore throat, headache, nausea, vomiting. (If associated with rash, it is called Scarlet Fever.)

2 to 5 days

Contagious until 24 hours after antibiotic treatment begins. Exclude for first 24 hours of treatment and until feeling well enough to be in school.

Bacteria spread directly from nose and throat discharges of infected persons.

Cold Sores (Herpes Simplex)

Blister-like sores, usually on lips but may occur anywhere on skin or in mucous membranes. May be confused with Impetigo.

2-14 days

No restriction Contagious period is unknown. Virus may be present for 5 to 7 days or in some cases for months.

Virus is transmitted by direct contact with infected persons, a majority of whom have unapparent infections.

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