-- Introduction of vaccines has successfully reduced prevalence of bacterial meningitis and most cases in the UK today are caused by viruses.
Viruses are the most common cause of meningitis in adults aged 16 and older in the UK, according to new research published in The Lancet Infectious Diseases journal. Although generally seen as a benign condition, this new observational study shows that recovery from viral meningitis can be a long haul for patients, with many still experiencing memory and mental health problems months after they are released from hospital.
Importantly, the findings also reveal substantial delays in diagnostic testing and unnecessary treatment in hospitals across England, which are associated with longer hospital stays. The median time from admission to a lumbar puncture to distinguish between bacterial and viral meningitis was 17 hours - in a quarter of patients it took more than 29 hours.
"Ideally, this crucial diagnostic test should be completed within a few hours," says Dr Fiona McGill, the Institute of Infection and Global Health at the University of Liverpool, UK, who led the research. "It's possible that the 4-hour accident and emergency treatment target is creating unintended pressure, leading to key investigations like lumbar puncture being postponed until patients have been admitted to a ward. Additional delays of several days can also occur if samples are sent to offsite laboratories for analysis." [1]
The study is the first of its kind to examine the incidence, causes, and impact of viral meningitis in UK adults.
Meningitis occurs when there is inflammation of the membranes that protect the brain and spinal cord caused by infection with viruses, bacteria, other microorganisms, and less commonly, drugs. Although symptoms can be similar, individuals with viral meningitis usually get better in a few weeks, while bacterial meningitis can kill within hours and requires urgent treatment with antibiotics.
International guidelines stress the urgency of lumbar puncture in order to rule out bacterial meningitis and reduce unnecessary antibiotic treatment, shorten hospital stays, and lessen healthcare costs. However, this testing is often delayed, leading to difficulties in making a diagnosis.
Since the 1990s, widespread introduction of conjugate vaccines have seen the incidence of bacterial meningitis decline across England. Whilst meningitis cases caused by viruses seem to be on the rise, until now the true burden of viral meningitis was unknown.
The study included over 1100 patients with suspected meningitis presenting to 42 hospitals (including all 24 acute hospitals in the northwestern region) across England between September 2011 and September 2014. All participants either had a lumbar puncture or a bacterial or viral pathogen identified in their blood test or culture. The researchers examined the association between time to lumbar puncture and receiving a microbiologically proven diagnosis. Participants were sent questionnaires to assess their quality of life and cognitive function a year after admission.
Of 1113 patients included in the final analysis, over half (638) were diagnosed with meningitis. Of these, more than a third of cases (231) were caused by a virus; 99 cases (16%) were bacterial; 267 (42%) had an unknown cause; and 41 cases (6%) had other causes identified.
Enteroviruses were the most common viruses identified, accounting for 55% of viral meningitis cases, and 20% of all meningitis cases. Streptococcus pneumoniae was the most common bacterial cause, responsible for 54% of bacteria cases, but just 8% of overall meningitis cases (table 2).
Results showed that unnecessary treatment with antivirals was associated with longer hospital stays - with patients infected with viral meningitis who did not have treatment staying for an average of 3 days compared with 9 days in those treated with antivirals (because most had intravenous treatment requiring inpatient care).
And there was evidence that earlier lumbar puncture resulted in more patients having a specific cause identified than those in whom testing was delayed - with the chances of having a pathogen detected in viral meningitis reduced by 1% for every hour delay in lumbar puncture following admission (figure 2).
"Improved rapid diagnostic testing so that more patients can have a specific cause determined quickly could reduce unnecessary use of antimicrobials (ie, both antibiotics and antivirals) and therefore reduce hospital stays and other investigations." say the authors.
All individuals with viral meningitis reported substantially poorer quality of life in the year following illness compared with the age-matched UK population, with an excess of pain, anxiety, depression, and reduced activity levels up to 48 weeks after admission.
Using data on the incidence of viral meningitis in the northwest region, the researchers estimate that the annual incidence of viral meningitis in UK adults is 2.73 per 100,000 compared with 1.24 per 100,000 for bacterial meningitis.
According to Dr McGill: "It's becoming increasingly clear that individuals with viral meningitis experience many lasting effects on their mental health and quality of life. We must better support them during and after hospitalisation with more rapid diagnostics and better treatments and rehabilitation to ensure quicker recovery and to help improve outcomes." [1]
The authors note some limitations, including that the prospective nature of the study means that some eligible patients may not have been recruited. They also point out that they extrapolated the incidence of viral meningitis from the northwest to the whole country, which assumes that there is minimal variation in incidence across the UK. Finally, they note that they only looked for the most common viruses, and cannot exclude the possibility that other rare or emerging viruses may have been responsible for some cases.
Writing in a linked Comment, Matthijis Brouwer and Diederik van de Beek, the Academic Medical Centre, Amsterdam, the Netherlands, say: "We need to speed up care for patients with CNS infections. There is a clear need to improve diagnostic tests for patients with suspected CNS infections because a substantial proportion of patients do not have a cause-specific diagnosis, which impedes early directed treatment and hinders trials of new treatments. New methods, such as pathogen discovery sequencing, use of RNA biosignatures, and point-of-care PCR tests might improve the yield of CSF examination, and should be tested in large prospective studies, including cost-effectiveness analyses. Implementation of fast diagnostic tests and early identification of pathogens in CSF will, however, be of little use if lumbar puncture is delayed considerably. The current study should be a wake-up call for policy makers to improve care for patients with CNS infections."