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This leaflet provides brief information about common childhood infections and whether or not children should go to school, nursery or other childcare.

Doctors are often asked about incubation times for the common childhood infections, so that they can advise whether the child should go to school, nursery or other childcare.Incubation time is the time between coming into contact with the source of the infection and the symptoms showing. Infectivity is the length of time that you are infectious. Both of these can be variable, so the following is only a guide. More detailed information and links to public health documents are in the further reading section.

This leaflet can only give general principles - the parents of children whose immune systems are weak (due to disease or due to taking immunosuppressive medication) may want to speak to their GP or consultant. This is particularly important if the weakened immune system has prevented full vaccination - eg, with the MMR vaccine.

Pregnant women (for example, those working in a school or nursery) who are exposed to chickenpox, German measles, parvovirus or measles should consult their GP or obstetrician immediately - in some cases an urgent blood test will be needed to check for immunity.

Note: * indicates a notifiable disease. In the UK these are required (by law) to be reported to government authorities.

DiseaseIncubationInfectivityExclude UntilComments
Chickenpox11-20 daysUp to 4 days before (usually only 1 day) to 5 days after.
Cases often transmit before appearance of rash.
5 days from the onset of rash.

Exclude until all lesions have crusted over and it is at least five days from the start of the rash.

Contacts with a weak immune system or who are pregnant should speak to their GP in case they need preventative treatment.

Cold sores1-6 daysWhile lesions are moist.None.Highly infectious, especially amongst young children.
Avoid kissing.
Conjunctivitis3-29 days
Mean = 8
While active (direct contact).
Infective up to 2 weeks.
None.Transmission more likely in young children by direct contact - very few data.
Cryptosporidiosis*1-12 days (usually 7 days)12-14 days (may be as long as 1 month).48 hours from last episode of diarrhoea.Exclusion from swimming for 14 days after diarrhoea has settled.
Diarrhoea and vomiting8-10 days6-16 days.48 hours from last episode of diarrhoea or vomiting.Exclude for 48 hours after the last episode of diarrhoea or vomiting.
Glandular fever33-49 daysAt least 2 months.None.None.

Hand, foot and mouth disease

3-5 daysUp to 50% in homes and nurseries.None.

Children can return to school once they feel better: they do not need to be excluded until blisters have healed.

Stool excretion continues for some weeks. Avoid infection in pregnant women. If large numbers of children in one setting are affected then public health should be contacted as they may consider exclusion.

Head licen/aWhile harbouring lice.None.Treatment needed for cases and contacts shown to have live head lice.
Hepatitis A*15-50 daysFrom 2 weeks before to 1-2 weeks after jaundice onset.Exclude until 7 days after onset of jaundice (or 7 days after symptom onset if no jaundice).Good hygiene needs emphasising.

Hepatitis B* Hepatitis C*


See comment.None.These are blood-borne viruses and are not infectious through casual contact. Settings should know what to do if there is an incident involving blood spillage.
ImpetigoSkin carriage 2-33 days before development of impetigo (streptococci)High (streptococci).
Low (staphylococci).
Variable infectivity depending on causative bacteria.
Until lesions have healed or crusted or 48 hours after starting antibiotic treatment.Antibiotics speed healing and shorten the infectious period.
Measles*6-19 daysHighly contagious in the non-immune population.
A few days before to 6-18 days after onset of rash.
4 days from onset of rash.

Check immunisation.
Risk of serious infection in people with a weak immune system, who should see their GP to consider preventative treatment if exposed to measles, particularly if their medical condition means that they were not able to have the MMR vaccine.

Meningitis2 - 10 days

Depends on which bacteria are causing it but can be highly infectious.

Until the child has recovered.

Public health will advise - in some cases school/nursery contacts may need preventative antibiotics. Siblings or household contacts do not need to be excluded.

MRSASkin carriageLow.None.Good hygiene, in particular handwashing, is important.
Mumps*15-24 days10-29 days.
Moderately infective in the non-immunised population.
5 days from onset of swelling.Preventable by vaccination.
RingwormVariesUntil lesions resolve.Exclusion not usually required.

Good hygiene helps. Treatment is required and can usually be bought over the counter.

Rubella*14-21 days1 week before to approximately 4 days after onset of rash.4 days from onset of rash.

Preventable by immunisation. Check all female contacts are immune - non-immune pregnant contacts should see their GP.

ScabiesVariesUntil mites and eggs are dead.Can return after first treatment.Risk of transmission is low in schools but outbreaks do occur.
Close contacts should also be treated.
Scarlet fever*1-3 daysModerate within families.
Low elsewhere.
Infective first 3 days of treatment.
24 hours after starting antibiotic treatment.

Moderate within families.
Low elsewhere.

If there is more than one case in a setting, public health should be informed.

Shingles14-16 daysReactivation of the virus that causes chickenpox but lower infectivity.5 days from the onset of the rash.

If the rash can be covered, exclusion is not usually necessary. Contacts with a weak immune system or those who are pregnant should contact their GP to see if they need preventative treatment.

Slapped cheek disease13-18 days30% in families.
10-60% in schools.
None.Avoid infection in pregnant women and people with a weak immune system.
Threadwormsn/aUntil all worms are dead.None.Good hygiene helps.
Case and family contacts should be treated.

Risk is similar to other colds and flu


Most cases are viral and do not need antibiotics.
Tuberculosis*n/aUntil 14th day of treatment.Variable. Always consult the local health protection unit.

Public health should always be contacted - spread is most likely where there is prolonged close contact.

Warts and verrucasn/aNone.None.Care needed with verrucas in swimming pools, gymnasiums and changing rooms.
Whooping cough*7-10 daysMainly early catarrhal stage, but until 4 weeks after onset of cough paroxysms.
Shorten to 7 days if given antibiotics.
48 hours from commencing antibiotic treatment, or 21 days from onset of illness if no antibiotic treatment.

Preventable by vaccination. Check immunisation of contacts.
Highly infectious in non-immune populations. Children may cough for many weeks after the exclusion period has finished.


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