In the UK, diagnosis usually involves taking a blood sample for testing and the doctor may perform a lumbar puncture to confirm a diagnosis of meningitis. The lumbar puncture is also used to find out which germ is causing the illness and helps ensure that the patient is treated appropriately. A lumbar puncture involves taking a sample of spinal fluid from the spinal canal. The sample is examined and then sent for further laboratory testing, which can take more than 24 hours. The procedure is occasionally advised against, and because the results are not rapid, antibiotic treatment is usually started as a precaution before the results are available.
New tests have been developed with the aim of reducing delays to correct treatment. These tests are under evaluation. For the doctor deciding on treatment, they need to be sure of the reliability and accuracy of these tests.
In the area known as the ‘meningitis belt’ in Africa, which is particularly susceptible to meningitis outbreaks, the diagnostic test most often used is based on 40-year-old technology (latex agglutination). It requires refrigeration and laboratory equipment, relies on a sample of spinal fluid from the patient taken by lumbar puncture. Transporting samples to laboratories throws many logistical challenges at countries in the meningitis belt. There are other drawbacks in relying on lumbar puncture too. Some countries require lumbar puncture to be performed by trained medical staff who are in too few numbers in primary health care settings and remote areas.
As well as making the right diagnosis when laboratories are not available or overstretched, the priority here is to find out the cause of the outbreak and whether a vaccine can be used to control the outbreak. The quicker this can be done, the quicker the vaccine can be given to those affected by the outbreak, and the more lives that can be saved.
Ideally a RDT that works on saliva, urine or blood would be preferable, but it may not be straightforward to develop an accurate test that does not require a sample of spinal fluid. Any RDT must be: simple to use, affordable, reliable, and capable of providing an accurate diagnosis at the point of care within minutes of testing.
The World Health Organization (WHO) has recently called for manufacturers of rapid diagnostic tests for meningitis to submit expressions of interest for assessment against WHO requirements and standards.
Research into diagnosis is ongoing but it’s encouraging that a new sense of urgency has been highlighted.