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Practical advice on managing common childhood infections

Dr Maria O'Callaghan discusses the implications of paediatric infectious diseases, including the

need to exclude from school or nursery, for how long, and whether exclusion is likely to be effective

iral infectious diseases remain a major component of childhood illnesses presenting to GPs. Whenever a rash accompanies a childhood illness there is pressure to exclude the child from school or nursery. Exclusion is sometimes necessary, but sometimes it is not.

Chickenpox (varicella) and herpes zoster (shingles)

Chickenpox is caused by primary infection with the varicella zoster virus whereas shingles is reactivation of latent varicella zoster.

Chickenpox usually affects children under the age of 10. It is highly infectious and tends to occur as outbreaks at school with an attack rate of up to 87 per cent in susceptible children. Most individuals have acquired immunity by adult life.

Infection is either spread by respiratory droplets or direct contact with the vesicles. The incubation period is between 10 and 21 days. The disease is usually infectious from one day (but up to four days) before the first appearance of the rash and continues until the vesicles are dry.

In the young child there may be no prodromal features and the illness presents with fever and a macular rash on the scalp, face and trunk. At this non-specific stage the presence of lesions in the scalp can help confirm it as chickenpox. Exclusion will not necessarily prevent transmission, but should be for five days from the start of the rash. There is no evidence of transmission after this period so it is not necessary to keep the child isolated until all the skin lesions have crusted.

Chickenpox can be a serious disease with potentially fatal consequences. Those at risk include:

limmunocompromised children including those who have received prednisolone in a dose of 2mg/kg/day for at least one week or 1mg/kg/day for one month at any time during the previous three months

linfants whose mothers develop chickenpox (but not shingles) from seven days before delivery to 28 days after

lvaricella zoster antibody negative infants (those whose mother is not immune) exposed to chickenpox or herpes zoster in the first 28 days of life.

All the above should be referred urgently to the local paediatric unit for possible zoster immunoglobulin prophylaxis. If they then develop chickenpox they will need high-dose intravenous aciclovir.

Herpes zoster (shingles) is contagious but is less infectious than primary varicella infection. Susceptible individuals in contact with shingles may subsequently develop chickenpox. A child with shingles can return to school if the lesions are covered.

Fifth disease (erythema infectiosum, slapped cheek disease, parvovirus)

Erythema infectiosum is the commonest manifestation of infection with parvovirus B19. There may be a non-specific prodromal phase followed by the appearance of the 'slapped cheeks', followed by a rash on the trunk and limbs. It is highly infectious, usually affecting school-age children, but also has an attack rate of up to

30 per cent within families. Exclusion from school is not recommended as fifth disease is a minor illness in most children and patients are probably only infective during the prodromal disease. If possible, infection should be avoided in patients with immunosuppression and haematological conditions as it can cause bone marrow suppression and an aplastic crisis.


Impetigo can be caused by both streptococcal and staphylococcal infection. Transmission rates are highest with streptococcal infection. In both cases the children should be treated with antibiotics and excluded from school until the lesions have crusted.

Hepatitis A

Hepatitis A is spread by the faeco-oral route. It commonly spreads between children in the same household, especially where there is overcrowding or poor sanitation. The incubation period is usually about four weeks and a non-specific prodromal period starts about one week before the development of jaundice.

There is a decrease in viral shedding once the jaundice appears. Patients' faeces are infectious for up to three weeks before and one week after the appearance of jaundice. Hepatitis A is a mild illness in children but can be more severe in adults.

For this reason exclusion for five days from the onset of jaundice should be attempted in children under the age of five to reduce the risk of transmission to adults. As most transmission occurs in the prodromal phase, exclusion would be ineffective and there is no need to exclude children over the age of five from school as the risk of transmission to adults is lower. Vaccination is recommended for travellers to high-risk areas and may be considered for close contacts of confirmed cases within seven days of onset of disease in the primary case.

Hand, foot and mouth disease

Hand, foot and mouth disease is an enteroviral infection commonest in the pre-school population. There is an attack rate of up to 50 per cent in household and nursery contacts. The mode of transmission is probably by droplet spread, although the virus is also shed in the faeces. It is generally a mild illness and exclusion is not recommended, although the child may not be well enough to attend as the lesions are painful.

Non-specific diarrhoea

A range of viruses can cause gastroenteritis and routine testing for viruses other than rotavirus is not justified. Exclusion from school should be for 24 hours from the last episode of diarrhoea or vomiting.


Unfortunately the incidence of measles is increasing in some districts due to the decline in uptake of the MMR vaccine. The classical presentation is of a child with coryza, conjunctivitis, malaise and fever followed by Koplik's spots one to two days later and then the morbilliform rash after another one to two days.

Measles is highly contagious in a non-immune population. The affected child should be excluded from school for five days from the onset of the rash but exclusion may not be completely effective as viral shedding occurs for at least two days before the rash appears.

There is a risk of serious infection in immunocompromised patients. In such a situation the diagnosis should be confirmed by antibody testing in the index case and if positive the immunosuppressed contact should be referred for human normal immunoglobulin as soon as possible.


Rubella (German measles) is mild in young children. Children should be excluded for five days from the onset of the rash but exclusion will not be totally effective as patients are most infectious in the prodromal stage and many cases are asymptomatic. The only risk is to non-immune pregnant women.


The incidence of mumps has increased recently due to the decline in MMR immunisation rates. Asymptomatic infections are common in children and the disease is usually mild in children (but not adults). Exclusion is for five days from the onset of parotitis but infection is often transmitted before there are symptoms.

Scarlet fever

Scarlet fever usually occurs in school-age children. The risk of transmission is low outside family contacts but there are occasional outbreaks in schools.

The disease is characterised by abrupt onset of fever and pharyngitis followed by the typical rash. The child should have a 10-day course of penicillin. Exclusion should be for five days from the onset of the rash.

Recommended exclusion periods from school or nursery

Disease Mode of transmission Definition of onset Exclusion period

Chickenpox Contact, droplets Rash 5 days

Fifth disease Droplets Slapped cheeks None

Impetigo Contact Skin lesions Until lesions crusted

Hepatitis A Food, water, faeco-oral Jaundice < 5="" years:="" 5="" days=""> 5 years: none

Hand, foot and Droplets or contact Vesicles None

mouth disease

Diarrhoea Droplets, food, Vomiting or 24 hours from

water, faeco-oral diarrhoea last episode

Measles Droplets Rash 5 days

Rubella Droplets Rash 5 days

Mumps Droplets Parotitis 5 days

Scarlet fever Droplets Rash 5 days

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