番茄社区

Thinking back, I can easily remember when cases of acute bacterial meningitis (ABM) due to Haemophilus influenzae type B (Hib), Neisseria meningitidis (meningococcus), and Streptococcus pneumoniae (pneumococcus) were so common that many doctors, especially pediatricians, were remarkably skilled at performing a lumbar puncture from start to finish in 10 minutes flat.

Frontline professionals like my friend Tony Dajer, MD, a long-time emergency medicine physician at NewYork-Presbyterian Lower Manhattan Hospital, also had this special skill, stemming from an urgency to diagnose and treat ABM as quickly as possible. Until he retired last summer, Dajer never hesitated to insert a thin, hollow needle into the back of anyone with even a whiff of the devastating blight.

From 1987 through 1989, Dajer also performed spinal taps on very young patients at New Mexico's Shiprock-Northern Navajo Medical Center. Why? Back then, Shiprock's Native American children -- many not yet a year old -- experienced Hib meningitis at rates higher than anywhere else in the country.

Then came the approval of two Hib conjugate vaccines whose benefits were breathtaking -- and not just in Shiprock.

Bottom line: every year before 1991, when the conjugate shots entered widespread use, roughly 25,000 children in the U.S. developed Hib meningitis. By 1996, meningitis or sepsis due to Hib among children under age 5 was down by . The new vaccines also reduced respiratory carriage and pneumonia among unvaccinated people.

As Dana Hu, MD, a maternal child health consultant for the Indian Health Service, recently of her own experience witnessing the "miracle" of Hib vaccination: "Most of the other 45 board-certified pediatricians on Navajo, many of whom are younger, have never seen a case of Hib meningitis in their careers, not even in training."

Another Miracle in Africa

Now to meningococcus, a second invader that tends to cause meningitis in older children, adolescents, and even young adults.

Dateline 1971, Kaduna State, Nigeria. A dedicated physician-researcher has recently arrived to help set up a new medical school at Ahmadu Bello University in Zaria, a town located in Africa's extended "meningitis belt," which spans from Senegal in the west to Ethiopia in the east. The medical school's clinical work was based at a nearby district hospital. At the time, now-professor Sir Brian Greenwood, MD, (in 2012, Greenwood was knighted for his service in malaria research in Africa) had not yet seen a patient with meningococcal meningitis. But soon his experience would dramatically change.

"One day we had a [single] case," Greenwood recently shared with me, "then the next day, five [cases]...the next week, we were up to 50 a day." To local people, it was an all-too-familiar story: the start of one more deadly, seasonal epidemic facilitated by low humidity, dust, and close human contact.

Amazingly, while caring for waves of sufferers in a make-shift structure with "grass matting walls and roof," Greenwood and his recently deceased colleague Anthony Bryceson, MD, also worked in Bryceson's outside kitchen -- which had been transformed into a basic lab -- and developed simple agglutination tests that distinguished meningococcal from pneumococcal meningitis, a very different woe.

At the time, sulfonamides were still the recognized treatment, but the meningococcus became resistant. However, a single injection of procaine penicillin or of an oily form of chloramphenicol (Tifomycine) cured 90% of meningococcal sufferers, Greenwood said, while the occasional pneumococcal patient required far longer treatment and, even so, was more likely to die.

Switching from treatment to prevention, Greenwood also tried an early polysaccharide vaccine on 500 family contacts of Nigerian meningitis patients and showed that it worked. Eventually, after moving to The Gambia, West Africa, where he led the U.K.'s Medical Research Council laboratories for 15 years, he and many others continued attempting to prevent the continent's centuries-old, epidemic scourge through ever-larger trials.

Finally, from 2010 through 2014, a meningococcal serogroup A polysaccharide-tetanus toxoid conjugate vaccine called MenAfriVac was used to vaccinate more than people in 26 African countries -- for just per dose. One documented a 94% drop in meningitis due to any cause among 1.8 million recipients in Chad.

"This is one of the most from a public health intervention that I have seen during a long career of research in Africa," commented Greenwood, who was one of the paper's authors.

Vaccines Remain Key

Fast forward to October 2023, when an email arrived in my inbox: "Last week was an important one for me," Greenwood wrote, "as, on Monday, WHO approved deployment of the and also the , which should prevent all five types of meningococcus-causing epidemics in Africa."

That same month, another vaccine targeting five meningococcal serotypes was also by the FDA as a two-dose series for Americans ages 10 to 25.

In fact, our worldwide progress in conquering the three leading causes of bacterial meningitis in different age groups (Hib meningitis in infants and young children, meningococcal meningitis in people under 30, and pneumococcal meningitis in anyone from a baby to a grandparent) is almost entirely due to excellent conjugate vaccines. While the success is satisfying, complacency is not an option.

For one thing, threatens to expand seasonal epidemics of meningococcal meningitis due to several serotypes. At the same time -- in the words of a recent in The Lancet -- newer polyvalent vaccines both for meningococcus and pneumococcus are still "out of reach for populations across sub-Saharan Africa, in part due to their high costs and scarcity of vaccines and stockpiles."

Another is developing an effective vaccine for group B streptococcus. In high-income countries, this microbe transmitted from mothers to newborns is now the principal cause of sepsis and meningitis in babies under age 3 months.

WHO's 2030 Roadmap

From 2000 through 2016, the world saw a in total deaths due to meningitis. Nonetheless, in 2019, the global incidence of bacterial meningitis was still 2.5 million, resulting in 236,000 deaths and long-term such as deafness, seizures, or worse in roughly one in five survivors. Further analysis identified meningococcus as the most common pathogen and pneumococcus as the deadliest.

On the other hand, long-time meningitis warriors like Greenwood know that, given political will, continued wins could be just around the corner. As a result, in November 2020, he and two colleagues published a outlining three specific developed by a WHO task force. They include:

1. Eliminating all meningitis epidemics
2. Reducing cases of vaccine-preventable bacterial meningitis by 50% and deaths by 70%
3. Reducing disability and improving quality of life following meningitis due to any cause

Working together as healthcare professionals, can we each do our part to promote these ambitious-but-achievable goals? This is my 2024 New Year's wish.

Comment