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Summary chart

Disease agent

Incubation period

Transmission

Contagious period

Report to public health*

Exclusion

Animal bites/bat exposure/rabies

Rabies virus

Rabies: Eight days to six years or more (usually  3-8 weeks)

Saliva of an infected animal, most commonly through a bite

As long as symptoms are present

Yes

(24 hours for animal bites)

None

for animal bites

Campylobacter

Campylobacter bacteria

1-10 days

(usually 2-5  days)

Fecal→oral spread, contaminated food/water, animals

While diarrhea is present; can spread for a few days after symptoms are gone

Yes

(Four days)

Yes

until 24 hours after diarrhea resolves, without the use of anti-diarrheal medications

Chickenpox (Varicella)

Varicella-zoster virus

10-21 days

(usually 14-16 days)

Droplet/infectious discharges, skin contact

One to two days before the rash appears until all the blisters have crusted over (usually days after onset)

Yes

(Four days)

Yes

until all blisters have formed scabs and crusted over. If immunized with mild symptoms, exclude until 24 hours since last bump/blister

Chlamydia

Chlamydia trachomatis bacteria

1-3 weeks

Sexual transmission

Until treated

Yes

(Four days)

None

C. diff

Clostridiodes difficile bacteria

Variable

Fecal→oral spread, contaminated surfaces

As long as bacteria are present 

Single cases: no

Outbreaks: immediately

Yes

until 48 hours after diarrhea resolves, without the use of antidiarrheal medications

CMV

Cytomegalovirus

Variable. Several weeks to several months

Body secretions (primarily saliva and urine)

As long as the virus is present in body secretions (months or years)

Single cases: no

Outbreaks: immediately

None

Common Cold

A variety of viruses

1-14 days

(usually 48 hours)

Droplet/infectious discharges

One day before symptom onset and while symptoms are present

None

None

It is recommended that symptomatic children be excluded from school/child care until they are fever-free for 24 hours without fever-reducing medication. 

COVID-19 

(SARS CoV-2 Disease)

14 days, with a median onset time of 4-5  days.

The incubation period may be shorter or longer, depending on the variant that is circulating

Droplet/infectious discharges

Two days before symptom onset and for 10 days after symptoms start

 

Yes

(Four days)

Yes

It is recommended that symptomatic children be excluded from school/child care until they are fever-free for 24 hours without fever-reducing medication and other symptoms are improving 

 

 

Croup

2-7 days

Droplet/infectious discharges

One week before symptom onset to one to three weeks after symptoms

Single cases: no

Outbreaks: immediately

None

It is recommended that symptomatic children be excluded from school/child care until they are fever-free for 24 hours without fever-reducing medication.

Cryptosporidiosis

Cryptosporidium parvum parasite

2-10 days

(usually seven days)

Fecal→oral spread, contaminated food/water, animals

While diarrhea is present; can spread for several weeks after symptoms are gone

Yes

 (Four days)

Yes

until 24 hours after diarrhea resolves; without the use of anti-diarrheal medications; do not participate in gardening/agriculture

Disease agent

Incubation period

Transmission

Contagious period

Report to public health*

Exclusion

E. coli O157:H7 and other Shiga toxin- producing E. coli (STEC) 

Escherichia coli bacteria

1-10 days

(usually 3-4 days)

Fecal→oral spread, contaminated food/water, animals

While diarrhea is present; can spread for one to four weeks after symptoms are gone

Yes

 (Four days)

Yes

until cleared by public health (negative stool testing may be required prior to return)

Fifth disease

Human parvovirus B19

4-21 days

Droplet/infectious discharges

One week before rash appears

Single cases: no

Outbreaks: immediately

None

Genital herpes

Herpes simplex virus

2-12 days

Sexual transmission

Potentially lifelong

None

None

Genital warts

Human papillomavirus

Variable

Sexual transmission

Potentially lifelong

None

None

Giardia

Giardia lamblia parasite

1-3 weeks

(usually 7-10 days)

Fecal→oral spread, contaminated food/water

While diarrhea is present; can spread for months after symptoms are gone

Yes

 (Four days)

Yes

until 24 hours after diarrhea resolves, without the use of anti-diarrheal medications

Gonorrhea

Neisseria gonorrhea bacteria

1-14 days

Sexual transmission

Until treated

Yes

 (Four days)

None

Hand, food, and mouth disease

Strains of enteroviruses

3-6 days

Droplet/infectious discharges, fecal→oral spread

One to three weeks for respiratory droplets; virus can be present in stool for several months

Single cases: no

Outbreaks: immediately

None

unless the child has mouth sores and is drooling uncontrollably

Head lice (Pediculosis)

Pediculus humanus, the head louse

Nits hatch in 10-14 days, adults live 3-4 weeks

Direct contact with a person or object with infestation

As long as live lice are present

None

From end of school day until after first treatment

Hepatitis A

Hepatitis A virus

2-6 weeks

(usually four weeks)

Fecal→oral spread, contaminated food/water

Most contagious two weeks before symptom onset to one week after jaundice onset

Yes

 (One working day)

Yes

until cleared by public health

Hepatitis B 

Hepatitis B virus

45-160 days

(usually 90 days)

Infective blood or body fluids, sexual transmission

Several weeks before symptom onset and throughout the illness, some people carry virus for life

Yes

(Four days)

None

Disease agent

Incubation period

Transmission

Contagious period

Report to public health*

Exclusion

Hepatitis C

Hepatitis C virus

14-180 days

(usually 45 days)

Infective blood

One or more weeks before symptom onset and as long as the virus is present in the blood, which can be lifelong

Yes

 (Four days)

None

Herpes (cold sores, fever blisters)

Herpes simplex virus

2-14 days

Direct contact

As long as the sores are present

None

None

unless the child has open sores and is drooling uncontrollably

HIV and AIDS

Human immunodeficiency virus

Variable

Infective blood and some body fluids

Lifelong

Yes

(Four days)

None

Impetigo

Streptococcal or staphylococcal bacteria

7-10 days for streptococcal; Variable for staphylococcal

Direct contact

Until treatment with antibiotics for at least 24 hours, or lesions are no longer present

Single cases: no

Outbreaks: immediately

Yes

until 24 hours after antibiotic treatment 

Influenza

Influenza virus

1-4 days

(usually two days)

Droplet/infectious discharges

From slightly before symptom onset to about day five to seven of illness

Yes 

(hospitalized cases or deaths in children under 18 years — Seven days)

Yes

It is recommended that symptomatic children be excluded from school/child care until they are fever-free for 24 hours without fever-reducing medication and other symptoms are improving 

 

Measles (Rubeola)

Measles virus

8-14 days

Airborne/droplet/

infectious discharges

Four days before rash onset to four days after

Yes

 (Immediately)

Yes

until four days after rash onset

Meningitis (Bacterial)

Bacteria such as Neisseria meningitidis (meningococcal), Haemophilus influenzae (H. flu), Streptococcus pneumoniae (pneumococcal)

Meningococcal: 1-10 days (usually less than four days)

Haemophilus influenzae (H. flu): unknown (probably a few days)

Pneumococcal: as short as 1-3 days 

Droplet/infectious discharges

Until completing 24 hours of antibiotic treatment

Yes

meningococcal: immediately

H. flu: One working day

pneumococcal: Four days 

 

Yes

until 24 hours after treatment

Meningitis (Viral)

Several different viruses

Depends on agents

Droplet/infectious discharges, fecal→oral spread

Depends on agent

Single cases: no

Outbreaks: immediately

None

Molluscum

2-7 weeks to six months

Direct/indirect contact

As long as lesions are present

Single cases: no

Outbreaks: immediately

None

Mononucleosis

Epstein-Barr virus

4-6 weeks

Saliva

Weeks to months after the initial infection

Single cases: no

Outbreaks: immediately

None

Disease agent

Incubation period

Transmission

Contagious period

Report to public health*

Exclusion

Mpox

3-17 days

Direct skin to skin contact

Until rash has fully healed

Yes
(Four days)

Yes
If mpox is suspected, exclude until evaluated by a health care provider;
If mpox is confirmed, isolate until all scabs fall off and healthy skin has formed;
Work wiht health care provider and public health to end isolation

MRSA

Methicillin-resistant

Staphylococcus aureus

Variable

Skin contact or contaminated items

As long as bacteria are present

Single cases: no

Outbreaks: immediately

None

unless required by health care provider; athlete exclusions may be necessary

Mumps

Mumps virus

12-25 days

(usually 16-18 days)

Droplet/infectious discharges, saliva

Two days before swelling onset to five days after

Yes

 (Four days)

Yes

until five days after swelling onset

Norovirus & viral gastroenteritis

Various viruses, such as norovirus

Varies by virus

(usually1-3 days)

Fecal→oral spread, contaminated food/water

While diarrhea or vomiting is present and several days after symptoms are gone

Single cases: no

Outbreaks: immediately

Yes

until 48 hours after diarrhea and/or vomiting resolves, without the use of anti-diarrheal or anti-emtic medications

Pink eye (Conjunctivitis)

Various bacteria and viruses, allergies, chemical irritation

Variable for all causes (Bacterial, viral, allergies, and chemicals)

Bacterial and viral: infectious discharges

Allergies and chemicals: not contagious

Bacterial: as long as symptoms are present or until treatment has been started

Viral: as long as symptoms are present

Single cases: no

Outbreaks: immediately

No

unless the child meets other exclusion criteria, such as fever or behavioral change 

Pinworm

1-2 months or longer

Feca→oral, indirect contact

As long as eggs are present

Single cases: no

Outbreaks: immediately

None

unless proper control measures cannot be followed

Pubic lice (crabs)

Phthirus pubis, the pubic louse

Average life cycle is 15 days; infestation begins with transfer of louse

Sexual transmission

As long as lice are present

None

None

Ringworm (Tinea)

Several fungi species

4-14 days

Skin contact/direct contact

As long as rash is present on skin

Single cases: no

Outbreaks: immediately

Yes

from end of school day until after first treatment

Roseola (Sixth disease)

5-15 days

(usually nine to 10 days)

Droplet/infectious discharges

As long as virus is present in nose/threat secretions

None

None

other exclusion criteria apply

Rotavirus

1-3 days

Fecal→oral spread

As long as virus is in feces; from before symptom onset to 21 days after

None

Yes

until 48 hours after diarrhea has resolved

Disease agent

Incubation period

Transmission

Contagious period

Report to public health*

Exclusion

RSV

(Respiratory Syncytial Virus)

2-8 days

(usually 4-6 days)

Droplet/infectious discharges

Three to eight days after symptom onset; for infants and people with weakened immune systems can be over four weeks 

Hospitalized cases in Denver metro area: yes

Outbreaks: immediately

None

It is recommended that symptomatic children be excluded from school/child care until they are fever-free for 24 hours without fever-reducing medication and other symptoms are improving

Rubella (German Measles)

Rubella virus

14-21 days

(usually 16-18 days)

Droplet/infectious discharges

Seven days before rash onset to five to seven days after

Yes

 (One working day)

Yes

until seven days after rash onset

Salmonellosis

Salmonella bacteria

 

6-72 hours, but up to seven days

(usually 12-36 hours)

Fecal→oral spread, contaminated food/water, animals

 

While diarrhea is present; can spread for a variable (weeks - months) period of time after symptoms are gone

Yes

 (Four days)

Yes

until 24 hours after diarrhea has resolved without the use of anti-diarrheal medications (negative stool testing may be required prior to return)

 

Scabies

Sarcoptes scabiei, a mite

2-6 weeks if never infected, 1-4 days if infected before

Skin contact/direct contact

Until the mites and eggs are destroyed with medical treatment

Single cases: no

Outbreaks: immediately

Yes

from end of school day until after first treatment

Shigellosis

Shigella bacteria

1-7 days

(usually 1-3 days)

Fecal→oral spread, contaminated food/water

While diarrhea is present; can spread for weeks after symptoms are gone

Yes

 (Four days)

Yes

Until cleared by public health (negative stool testing may be required prior to return)

Shingles (Herpes Zoster)

Varicella–zoster virus

10-21 days

(usually 14-16 days)

Skin contact

Until all the blisters have crusted over

None

None

as long as the blisters are covered

Staph infection

Variable

Skin contact or contaminated items

As long as the bacteria are present

Single cases: no

Outbreaks: immediately

None

unless required by a health care provider; athlete exclusions may be necessary

Strep throat

Streptococcus pyogenes bacteria

2-5 days

Droplet/infectious discharges

Until treated with antibiotics for 24 hours, or 10-21 days for untreated cases

Single cases: no

Outbreaks: immediately

Yes

until 12 hours after antibiotic treatment

Syphilis

Treponema pallidum bacteria

10 days to three months

(usually three weeks)

Sexual transmission

Until treated

Yes

 (One working day)

None

Tetanus

Clostridium tetani bacteria

Two days to several months (usually 8-14 days)

Through breaks in the skin

Not spread person-to-person

Yes

 (Four days)

None

Disease agent

Incubation period

Transmission

Contagious period

Report to public health*

Exclusion

Tick-borne diseases

Varies

Bites from infected tick

Not spread person-to-person (except Colorado tick fever)

Yes

 (Four days)

None

Tuberculosis

Mycobacterium tuberculosis

2-10 weeks

Airborne

As long as symptoms are present or until case is on the treatment

Yes

 (One working day)

Yes (active cases) 

until on treatment and cleared by public health

Tularemia

Up to 14 days

(usually 3-5 days)

Varies

Not spread person-to-person

Yes

(One working day)

None

Whooping cough (pertussis) 

Bordetella pertussis bacteria

5- 21 days

(usually 7-10 days)

Droplet/infectious discharges

Until after the third week of coughing, or until after five days of treatment

Yes

 (one working day)

Yes

until five days after treatment or until three weeks after cough onset

*Outbreaks of any disease are reportable to public health immediately