Why We Need a Better Method for Ruling Out a Diagnosis of Meningitis

[This article has been published in Spanish in Planeta Futuro-El País]

The mere mention of a possible diagnosis of meningitis is enough to send shivers down the spine of anyone familiar with the potentially devastating effects of this dreaded infection. And the reaction requires little explanation. Infection of the meninges—the membranes that enclose the brain—is associated with a high fatality rate and causes about 380,000 deaths every year. Most of these deaths, as many as a quarter of a million, are in newborn babies and infants under five years of age.

Infection of the meninges—the membranes that enclose the brain—is associated with a high fatality rate and causes about 380,000 deaths every year

Over the past twenty years, the incidence of bacterial meningitis has been reduced, particularly in industrialized countries, through the use of highly effective new vaccines that offer protection against the main causative pathogens. However, the infection is still a scourge in poorer countries, particularly in Africa, where the prevalence is disproportionately high. Apart from the intermittent and recurring epidemics of meningeal infection that sweep across the Sahel belt and can cause tens of thousands of cases every year, a number of other factors favour the very high incidence of meningitis in Africa, including the fragility of health systems, failure to immunise the population or the lack of a vaccine for some of the causative pathogens, and the high prevalence of co-infections (such as HIV) that predispose patients to this kind of severe bacterial infection. But the worst news of all is that the number of cases reported and discussed by the scientific community today probably only represents a small fraction of the total number of cases that occur every year.

Cerebrospinal fluid, diagnosis of meningitis. Author: Quique Bassat

The disparity between the number of cases diagnosed and the real incidence of meningitis is due, at least in part, to the difficulty of diagnosing the infection

The disparity between the number of cases diagnosed and the real incidence of meningitis is due, at least in part, to the difficulty of diagnosing the infection. For a definitive diagnosis, the patient's cerebrospinal fluid must be analysed and the necessary sample can only be collected by a technique that involves inserting a needle into the patient’s spinal canal. Lumbar puncture is an invasive procedure that can only be carried out by a clinician in an appropriate hospital setting because it involves risks to the patient's health, particularly in the case of very young infants.  In addition, the fluid can only be analysed in sophisticated laboratory facilities, which are often unavailable in hospitals and health care centres in the world's poorest countries. Consequently, few lumbar puncture are carried out to confirm or exclude meningitis in the poorest areas, where the incidence of the disease is highest, which is why the burden and real impact of meningitis on health are grossly underestimated. Furthermore, as the clinical symptoms of the disease are quite nonspecific, particularly in very young children, meningitis is often confused with other less serious and more common infections in early childhood. Undoubtedly, we are only seeing the tip of the iceberg that this problem represents.

Paradoxically, in rich countries the problem is precisely the opposite: lumbar puncture is a common procedure routinely required by hospital protocols to ensure that no cases of meningitis are missed. While reasonable, the application of this systematic approach means that the results of about 95 out of every 100 lumbar punctures performed for this reason are negative. In this case, caution leads to a very high rate of unnecessary punctures.

Author: Quique Bassat

We urgently need to rethink and improve the methods used to diagnose or rule out meningitis

Given these two, contradictory, scenarios, it seems reasonable to reflect that we urgently need to rethink and improve the methods used to diagnose or rule out meningitis, and that it is precisely this bottleneck that presents an opportune scenario for innovation and a circumstance in which technology can come to our aid. One solution that has been proposed is the use of high frequency ultrasound taking advantage of the natural window into the brain provided by the fontanelle in young infants in whom the cranial bones have not yet closed. Using this technique it would be possible to count the cells in the patient’s cerebrospinal fluid without collecting a physical sample through lumbar puncture. Such a method could offer a radically innovative alternative for the effective screening of meningitis and a real possibility of ruling out meningitis without recourse to specialised procedures seldom available in African health centres. The complete absence of cells in the cerebrospinal fluid would rule out a diagnosis of meningitis and a result giving rise to a high suspicion of infection could trigger immediate treatment or at least provide evidence that a lumbar puncture is needed to confirm the diagnosis. Owing to its absolute safety, the procedure could be repeated as many times as necessary if the result is unclear and any doubt remains.

The idea is simple, but its execution involves certain technical difficulties. The first prototype has been designed by the Spanish engineer Xavier Jiménez, a young entrepreneur who has been named Innovator of the Year for his Newborn Solutions project. The device has not yet been formally validated and the Barcelona Institute for Global Health has now received specific funding to carry out a proof of concept study in Mozambique, where the incidence of bacterial meningitis is as much as ten times that of Spain.

This is a first step—a resolute and very ambitious one—in a process aimed at definitively revolutionising the diagnosis of meningitis

Clearly, this is a first step—a resolute and very ambitious one—in a process aimed at definitively revolutionising the diagnosis of meningitis, enhancing the early detection and management of the disease and improving the chances of survival in affected patients. It is also another excellent example of how the most creative minds in the country can use their talents to improve the quality of life of those most in need of help.