In the world of pediatric healthcare, one disease has historically caused great fear: “When a family comes to the hospital with a very sick child, their first question is almost always: could it be meningitis,” said Professor Martinon-Torres, Head of Pediatrics and Director of Translational Pediatrics and Infectious Diseases at the Hospital Clínico Universitario de Santiago in Santiago, Spain.
Meningococcal meningitis is a complex disease. It is caused by several different strains of bacteria called Neisseria meningitidis that circulate in unpredictable ways around the world. Most people can carry and transmit the bacteria without showing any symptoms of disease and teenagers and young adults often transmit the bacteria this way. But in rare cases, and in a disproportionate number of young children, teenagers and young adults, an infection can lead to catastrophic, life-altering illness or even death.
Despite all the advancements in medical treatments, “We’ve reached a plateau in outcomes with about 10% of people who have severe meningitis still dying, sometimes within just 24 hours of falling ill,” noted Professor Martinon-Torres. “Up to 20% face lifelong consequences. Complications include sepsis that can lead to amputations, as well as severe neurological problems, including hearing loss.”1
Before widespread vaccination programs were in place in many countries around the world, meningitis epidemics were a more frequent occurrence.
Dr. David Greenberg is currently Global Medical Franchise Head at Sanofi Pasteur, where the company’s teams have been fighting meningococcal disease for 45 years. But back in 1981 Dr. Greenberg was a young medical student in an ICU unit in Houston, Texas when a meningococcal meningitis outbreak struck a half-dozen school children in the city. “During this time, we’d come into the hospital to find parents arriving with their sick children, showing all the telltale signs of meningitis and sepsis. They would describe how quickly it struck: the day before the kids had been perfectly healthy,” Dr. Greenberg noted.
“It was just horrible to see some of those children progress in the disease, no matter what we did to try to stop it. In those days it was a regular thing you had to expect. There were going to be meningitis outbreaks and hospitals caring for children, not all of whom could be saved.”
While reducing the incidence of meningococcal meningitis through vaccination is now possible, it is also a delicate status quo that needs constant attention and improvement.
There are various types of vaccines available in different countries and regions around the world, ranging from those that help prevent just one strain of the disease (monovalent) to vaccines that help prevent four strains (quadrivalent).
Vaccination programs can vary by country and can target different age groups and populations. In many countries, programs for the very young target at least one strain of the meningococcal bacteria–usually the strain that had caused localized meningitis outbreaks in the past. But that’s not enough to avert every preventable death or potential disability that may occur due to the infection. Many national health authorities have increased the reach of vaccination over time, both to cover more strains as well as to cover wider age groups.
With all types of vaccination, it’s critically important to keep vaccination rates in the population at a high level to provide herd immunity, particularly until meningitis is better understood.
Professor Martinon-Torres is trying to understand what specifically makes some people more susceptible to severe meningococcal meningitis than others, to tailor medical interventions further.
“When you have a geographically widespread infectious disease but with severe outcomes in only a small minority of people infected, there’s something going on in the biology of those people that allows the bacteria to do so much damage,” he said. “So far we believe this is related to a genetic variation in peoples’ immune systems. We’re getting closer to targeting how those variations allow such severe impact, and in the future, I believe we can advance more tailored interventions.