This leaflet provides brief information about common childhood infections and whether or not children should go to school, etc.
Doctors are often asked about incubation times for the common childhood infections, so that they can advise whether the child should go to school, etc. 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. Slightly fuller lists are provided by Public Health England, Health Protection Scotland, Public Health Wales and Public Health Northern Ireland.
Note: * indicates a notifiable disease. In the UK these are required (by law) to be reported to government authorities.
|Chickenpox||11-20 days||Up 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.||Traditionally excluded until all lesions are crusted but no transmission recorded after day 5.|
Contacts with a weak immune system or who are pregnant should receive preventative treatment.
1-11 days (Usually 2-5 days)
|Patients are probably not infectious if treated and diarrhoea has resolved.||48 hours from last episode of diarrhoea.||Exclude for 48 hours longer in children who are unable to maintain good personal hygiene.|
|Cold sores||1-6 days||While lesions are moist.||None.||Highly infectious, especially amongst young children.|
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 vomiting||8-10 days||6-16 days.||48 hours from last episode of diarrhoea or vomiting.||Exclude for 48 hours longer in children who are unable to maintain good personal hygiene.|
|Glandular fever||33-49 days||At least 2 months.||None.||None.|
|3-5 days||Up to 50% in homes and nurseries.||None.||Stool excretion continues for some weeks. Avoid infection in pregnant women.|
|Head lice||n/a||While harbouring lice.||None.||Treatment needed for cases and contacts shown to have live head lice.|
|Hepatitis A*||15-50 days||From 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.|
|See comment.||None.||These are blood-borne viruses and are not infectious through casual contact.|
|Impetigo||Skin carriage 2-33 days before development of impetigo (streptococci)||High (streptococci).|
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 days||Highly 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 (give preventative treatment).
|MRSA||Skin carriage||Low.||None.||Good hygiene, in particular handwashing, is important.|
|Mumps*||15-24 days||10-29 days.|
Moderately infective in the non-immunised population.
|5 days from onset of swelling.||Preventable by vaccination.|
|Ringworm||Varies||Until lesions resolve.||Exclusion not usually required.||Good hygiene helps. Treatment is required.|
|Rubella*||14-21 days||1 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.|
|Scabies||Varies||Until 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 days||Moderate within families.|
Infective first 3 days of treatment.
|24 hours after starting antibiotic treatment.||Moderate within families.|
|Shingles||14-16 days||Reactivation 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 receive preventative treatment.|
|Slapped cheek disease||13-18 days||30% in families.|
10-60% in schools.
|None.||Avoid infection in pregnant women and people with a weak immune system.|
|Threadworms||n/a||Until all worms are dead.||None.||Good hygiene helps.|
Case and family contacts should be treated.
|Tuberculosis*||n/a||Until 14th day of treatment.||Variable. Always consult the local health protection unit.||See "references" below.|
|Warts and verrucas||n/a||None.||None.||Care needed with verrucas in swimming pools, gymnasiums and changing rooms.|
|Whooping cough*||7-10 days||Mainly 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.
Clinical Editor's comments (September 2017)
Dr Hayley Willacy has noticed that Public Health England has recently updated its advice to schools and nurseries - see Further Reading below. This is a practical guide on infection prevention and control in schools, nurseries and other childcare settings. It is intended for staff working in these settings and reviews the general principles of infection control, how to manage cases of disease (including when an infected child/staff member should be excluded from their school/nursery in order to protect others) and when to seek specialist advice.
Further reading and references
Guidance on infection control in schools and other childcare settings; Public Health England (September 2017 - last updated March 2019)
Health Prevention and Control in Childcare Settings (Day Care and Childminding Settings); Health Protection Scotland.
Guidance on infection control in schools and other childcare settings; Health and Social Care Services Northern Ireland (October 2013)
Control and prevention of tuberculosis in the United Kingdom: code of practice 2000; Joint Tuberculosis Committee of the British Thoracic Society, Thorax 200055:887-901.
Immunisation against infectious disease - the Green Book (latest edition); Public Health England