Children suffer a large number of infections. Most of these are self-limiting
viral illnesses which are frequently spread in nurseries and classrooms where
children have close contact. Some infections will, of course, be bacterial in
origin and a few others caused by more unusual organisms such as fungi or parasites.
The severity of an infection in a child will depend not only on the type of
organism but also the immuno-competence of the child which varies with age.
Neonates have relatively naive immune systems, but as they grow their ability
to fight infection generally improves. Hence the types of infections seen in
small babies are frequently different to those seen in older children. A few
children will have certain immunodeficiency syndromes and are more susceptible
to certain types of infections or, in severe cases, all infections.
Significant Bacterial Infections
The main task of the paediatrician is to differentiate self-limiting infections
from more serious ones that require treatment and then to provide the reassurance
or treatment where necessary. Needless to say this is easier said than done.
The American literature frequently uses the concept of the 'Significant Bacterial
Infection' (SBI) to indicate an infection that requires treatment with antibiotics
as opposed to other infections which only require symptomatic treatment. (Children
can, of course die form non-bacterial infections, HIV is a well know example;
they can also die of adenovirus pneumonia and pertusis while enteroviral infections
and varicella can be fatal in the neonatal period.)
Symptoms and Signs
The commonest symptom of an infection in a child is probably a pyrexia. Sometimes
there are other symptoms and signs; most commonly these include a poor appetite
and being generally miserable. Depending on the age of the child these may manifest
themselves in different ways.
Much time and effort has been directed towards finding clear features that
differentiate SBIs from other illnesses. A few useful guidelines have been suggested
but none of these is absolutely reliable. If history and examination fail to
give a clear answer then investigations may be necessary to guide clinical judgement.
The younger the child the less useful clinical features are and the lower
the threshold for investigations.
Useful Clinical Features
Temperature - a temperature >40OC is more likely to be associated
with a SBI. The US literature defines a pyrexia as >38OC. This is frequently
interpreted as 'the higher the temperature the more likely the cause is bacterial'
which is not strictly true. In a neonate or young infant a severe infection
may cause hypothermia.
A Clear Focus - is often helpful. The miserable child with a runny nose
probably has a cold. A bulging red eardrum; hot, swollen, painful joint; large,
red tonsils; headache, neck stiffness and photophobia etc are all useful features
to support a diagnosis. Some sources use the concept of a 'fever without source'
(FWS) for pyrexias with no clear focus. (This is to distinguish it from a 'pyrexia
of unknown origin' [PUO] which by definition must have been present for 10-14
days depending on which book you read).
Lethargy/Irritability - We all feel miserable when we are unwell. Younger
children cannot communicate these feelings well. Furthermore they may not understand
them and may be frightened. They may also be frightened by the fact their parents
are inexplicably anxious (because they worried about their child). Young babies
who do not wake for feeds probably require further investigation. Similarly
children who remain inconsolable even when comforted in their parent's arms
should raise concerns.
Meningism - may