Viruses are the most common source of meningitis in the United Kingdom and can cause considerable long-term morbidity, according to recent findings published in The Lancet Infectious Diseases.

Fiona McGill, DPhil, of the Institute of Infection and Global Health at the University of Liverpool, U.K., and colleagues also reported finding “concerning” delays in meningitis diagnosis, as well as high rates of unnecessary treatment, both of which were associated with longer hospital stays.

“To improve management and reduce costs, there is a pressing need for better diagnostic practices, including rapid tests and the delivery of high-quality viral diagnostics locally,” the researchers wrote. “Treatments also need to be developed and assessed that could allow quicker recovery and fewer long-term sequelae.”

International meningitis guidelines emphasize the importance of urgent diagnostic lumbar puncture for identifying the source of infection and reducing unnecessary antibiotic or antiviral treatment, according to the researchers. Theoretically, they said, lumbar puncture and diagnostic PCR can be completed within a few hours. But because patients in the U.K. are required to be transferred out of the ED within 4 hours of admission, physicians sometimes postpone lumbar puncture until a suspected meningitis case has been admitted to a ward, the researchers wrote. Diagnosis can be further delayed by several days if cerebrospinal fluid (CSF) samples are sent to an offsite laboratory for analysis.

For their study, McGill and colleagues analyzed data on 1,126 adults with suspected meningitis across 42 health care facilities in the U.K. Their goal was to determine the incidence, cause and impact of viral meningitis in the region from 2011 to 2014.

Overall, 57% of patients had confirmed meningitis. Most cases with a known cause were due to viruses (36%), predominately enteroviruses (55%) and herpesviruses (44%). Of the remaining cases, 16% were caused by bacteria and 42% had an unknown source.

Using clinical and laboratory data, the researchers estimated that the annual incidence of viral meningitis was 2.73 per 100,000, whereas bacterial meningitis was 1.24 per 100,000. When looking at all meningitis cases, including those with an unknown cause, the annual incidence was 13.47 per 100,000.

Over the first 12 months of the study, patients with viral meningitis had an average loss of 0.2 quality-adjusted life-years compared with an age-matched population. Patients with herpes simplex meningitis had significantly lower quality of life measurements than patients with other viruses. Twelve of 14 patients with herpes simplex meningitis reported having anxiety or depression.

More than 80% of patients with suspected meningitis underwent neurological imaging. Among them, 70% had the procedure done before lumbar puncture. However, based on national guidelines, only 12% of these patients had an indication for neurological imaging before lumbar puncture, according to the researchers.

The median time to lumbar puncture was 17 hours. Earlier lumbar puncture increased the chances of identifying the specific cause of meningitis. For every delayed hour of lumbar puncture, the odds of pathogen identification decreased by 1% (OR = 0.988; 95% CI, 0.982-0.995).

The average length of hospital stay for viral meningitis was 4 days, increasing to 9 days among patients who received antiviral drugs, which lack efficacy against enteroviruses, according to the researchers. Nearly 70% of patients with viral meningitis also received at least one dose of antibiotics.

In addition to antiviral use, having an unknown cause of meningitis also increased the length of hospital stay from 4 days among patients with confirmed viral meningitis to 5 days.

In a related editorial, Matthijs C. Brouwer, MD, PhD, and Diederik van de Beek, MD, PhD, of the department of neurology at the University of Amsterdam, said these findings underscore the need to improve diagnostic tests for suspected central nervous system (CNS) infections.

“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,” they wrote. Implementation of fast diagnostic tests and early identification 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 policymakers to improve care for patients with CNS infections.” – by Stephanie Viguers

Disclosures: Brouwer and van de Beek report no relevant financial disclosures. McGill reports receiving grants from the U.K. National Institute for Health Research. Please see the study for all other authors’ relevant financial disclosures.