Experts warning: only around half of young babies with meningitis display fever

• Only around half of babies under three months of age who have bacterial meningitis present with fever which has for decades been the trigger for further medical investigation
• Other features associated with meningitis in infants like a bulging fontanelle - the gap on the top of skull where the bones have not yet come together, coma, seizures and neck stiffness were found to be uncommon
• Clinical presentation in young babies is often non-specific and hard to distinguish from mild illnesses - common features were found to be poor feeding, lethargy and irritability

Experts are warning that doctors may miss correctly diagnosing babies with deadly bacterial meningitis as they may assume infants without a fever (a classic sign of the disease) do not have the illness.

Researchers at St George’s, University of London, say their new study shows the classic symptoms associated with bacterial meningitis are uncommon in young infants less than three months of age – the group at highest risk of the disease.

Only around half of babies under three months of age who have bacterial meningitis display fever, which has for decades been the trigger for further medical investigations. 

Professor Paul Heath, one of the study investigators at St George’s, University of London, said: “The classic features of meningitis were uncommon in many cases. The symptoms displayed by young infants when they are seen by doctors at first in hospital are often non-specific and only half of cases showed signs of a fever.

“Guidelines focusing on serious infections in children - including meningitis - have been introduced in the UK and the USA but all specify fever as a key feature of infection.

“Unfortunately, neither the rates of bacterial meningitis in babies, nor the numbers of deaths, has changed since the 1980s.

“Clinicians must, therefore, still consider bacterial meningitis in the diagnosis of an unwell infant that doesn’t present with fever.”

The study, Clinical Characteristics and Risk Factors for Poor Outcome in Infants Less Than 90 Days of Age with Bacterial Meningitis in the United Kingdom and Ireland, is published in the Paediatric Infectious Diseases journal.

The study led by experts at St George’s University of London, funded by charity Meningitis Research Foundation (MRF), involved 263 infants across the UK and Ireland and found that fever (temperature above 38^oC) was reported in only 54% of cases, seizures in 28%, bulging fontanelle in 22%, coma in 6% and neck stiffness in only 3%.

In the UK, babies under three months of age are 70 times more likely to get bacterial meningitis than adults. Newborn babies are at the highest risk of all.

The study found that infants who did present with fever tended to be older than infants without fever. The median age for this symptom was around 21 days old.

Common features were found to be poor feeding, lethargy and irritability, all of which can be difficult to distinguish from mild illness.

The study suggests that there should be a low threshold for performing investigations on young infants when they arrive at hospital.

Of note, 52% of the infants without fever did have other features suggestive of bacterial meningitis, such as apnea (33%), seizures (32%), bulging fontanelle (16%), coma (7%) and neck stiffness (3%).

Earlier research from the same experts, in collaboration with the British Paediatric Surveillance Unit, found there to be in the region of 350 cases of bacterial meningitis in infants under three months of age per year in the UK and Ireland. Group B streptococci (GBS) and Escherichia coli remain the main causes of bacterial meningitis in this age group.

Vinny Smith, Chief Executive at MRF, said: “Young babies are particularly vulnerable to bacterial meningitis. Meningitis and septicaemia are deadly diseases that strike without warning. Rapid diagnosis and treatment provides the best chance of survival.

“Based on this research, we have collaborated with the study investigators to create a teaching package aimed at doctors and health professionals to aid rapid diagnosis and treatment.

“The package includes an eTool to help clinicians recognise bacterial meningitis in young infants; a lumbar puncture information sheet to help explain this procedure to parents; and an algorithm to aid management of bacterial meningitis. We hope that this can ultimately improve outcomes for this vulnerable age group. We have also updated our symptoms information for parents so that they know not to rely on fever alone as the main symptom to look out for in babies.”

MRF’s teaching package including the eTool and Babywatch card for parents can be accessed at www.meningitis.org/HCPresources.