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Toward a world without meningitis

April 24, 2019 by Mark Alderson

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A young man gets vaccinated with MenAfriVac at the vaccine's 2010 launch in Burkina Faso. MenAfriVac has virtually eliminated group A meningitis wherever it has been used. Photo: PATH/Gabe Bienczycki.

PATH is on the front lines of an effort to defeat meningitis by 2030.

It arrives suddenly. It brings severe fever and vomiting, stiff neck and pounding headache; it can kill within hours. It doesn’t necessarily spare survivors, leaving many with lifelong disabilities such as deafness and neurological impairments.

It is meningitis, and it is a global threat—though, like many diseases, children and those in low-resource countries suffer the greatest burden.

A serious infection of the thin lining surrounding the brain and spinal cord, meningitis has many causes, usually viruses or bacteria. Viral cases typically resolve on their own without treatment; bacterial cases, however, are extremely serious and often fatal without treatment. Infants, children, and young adults are most likely to suffer from bacterial meningitis. An estimated 2.82 million cases of meningitis occur globally each year, with more than 300,000 deaths—a third of which occur in children between one month and five years of age.

Vaccines exist against some of the major causes of bacterial meningitis. Nine years ago one of them changed the course of meningitis in Africa. The introduction of MenAfriVac®, a conjugate vaccine against meningococcal meningitis group A—then the most prevalent form of the disease in Africa—was an historic achievement and its impact still reverberates: the vaccine has so far been introduced in 22 of 26 countries in the African meningitis belt, virtually eliminating meningitis A epidemics wherever it has been used. By 2020 MenAfriVac® is expected to protect than 400 million people in the meningitis belt from devastating disease.

You might think the introduction of such a game-changing vaccine would signal the end of the story and a pat on the back. But we’re not stopping there. Not when we have the opportunity to protect millions more by building new and better vaccines against the other deadly causes of meningitis.

Because group A meningitis is only one type of meningococcal meningitis—which itself is only one cause of bacterial meningitis. To truly tackle meningitis, and to do so on a global level, will require a multifaceted approach that targets the four big causes of acute bacterial meningitis: Neisseria meningitidis (meningococcus), Streptococcus pneumoniae, Haemophilus influenzae type B, and Group B Streptococcus.

The World Health Organization (WHO) is leading this effort through development of a roadmap to defeat meningitis by 2030. WHO has just released a baseline situation analysis to inform roadmap development. This document details the global burden and identifies knowledge gaps; it also highlights priority areas in which to focus effort, including prevention and epidemic control, diagnosis and treatment, disease surveillance, support and after-care for families and survivors, and advocacy and information.

PATH is contributing to development of the roadmap, but even more importantly we’re contributing on the front lines, with vaccines against three of the four major causes of bacterial meningitis in development.

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A health worker prepares a vaccine at the 2010 MenAfriVac launch in Burkina Faso. The vaccine has so far been introduced in 22 of 26 meningitis belt countries. Photo: PATH/Gabe Bienczycki

Stamping out epidemic meningitis

With more than one million cases reported since 1988 and tens of thousands of deaths to its name, meningococcal meningitis is a scourge on the lives of those in sub-Saharan Africa’s meningitis belt, which stretches across 26 countries from Senegal to Ethiopia. Every year, people living in these countries face the threat of meningococcal meningitis epidemics during the dry season from January to June. Epidemics can reach massive proportions, placing enormous burdens on local health systems and inflicting damage that remains long after the diseases passes. Even with timely antibiotic treatment, one in ten infected people will die within two days of the onset of symptoms; without treatment, 50 percent of those infected die.

Until recently, group A meningitis was responsible for more than 80 percent of Africa’s epidemics. But since the introduction of MenAfriVac—the result of a nine-year partnership between PATH, WHO, and the Serum Institute of India Pvt. Ltd. (SIIPL) called the Meningitis Vaccine Project—the disease has faded into memory, and the world has seen the power of affordable meningococcal conjugate vaccines.

But group A meningitis isn’t the only form of the disease that plagues Africa; groups C, W, X, and Y also circulate and can cause outbreaks and epidemics. In fact, ongoing group C meningitis outbreaks in Nigeria and Niger infected more than 14,000 people in 2017 alone.

PATH is once again partnering with SIIPL, this time to develop an affordable meningococcal conjugate vaccine against serogroups A, C, W, X, and Y. Development of this new vaccine is supported by the UK Department for International Development and the vaccine candidate is poised to enter Phase 3 clinical trials in Mali and The Gambia—a crucial step on the pathway to licensure, and to potentially eliminating all forms of epidemic meningitis in the meningitis belt.

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A toddler at an immunization clinic in The Gambia receives routine childhood vaccinations, including pneunococcal conjugate vaccine (PCV). Existing PCVs are expensive, and the world needs more affordable options. Photo: Lauren Newhouse/PATH

Affordable prevention

Pneumococcal disease, caused by the bacterium Streptococcus pneumoniae, kills nearly 300,000 children every year before their fifth birthday—mostly in low-resource countries in Africa and Asia. In addition to pneumonia, pneumococcus can cause deadly infections like sepsis and meningitis. In fact, pneumococcal meningitis is the most common cause of non-epidemic meningitis in sub-Saharan Africa, and it has a higher case-fatality ratio than other causes of bacterial meningitis—meaning that, even though it is less likely to strike a community with the same force as meningococcal meningitis, it is no less feared.

Effective pneumococcal conjugate vaccines (PCVs) already exist and save lives around the world. They are designed to protect against the most common of the more than 90 varieties of pneumococcus that cause disease, but their high cost means that many countries can’t afford them without substantial donor assistance. Or sometimes even at all.

A new PCV designed to perform on par with existing PCVs but at a significantly lower cost—produced by SIIPL and supported by PATH—is nearing the end of its development and is targeting WHO prequalification, which could be possible in the next year.

Vaccines save countless lives by allowing us to prevent disease rather than treat it.

Protection for the very youngest

One of the earliest and most dangerous health threats young infants face is one many have never even heard of: Group B Streptococcus (GBS), which causes a bacterial infection that can take hold at or within a few hours of birth. The leading cause of sepsis and meningitis in young infants, GBS reportedly causes more infant deaths than HIV, and more than tetanus, pertussis, and respiratory syncytial virus combined. It can even cause problems during pregnancy: GBS has been linked to pre-term birth, miscarriage, and stillbirth.

No vaccine yet exists against GBS. The disease is managed in some parts of the world by screening pregnant woman and administering prophylactic antibiotics during labor if they’re found to have certain risk factors or are carriers of GBS (the bacteria live in the gastrointestinal tract and the vagina and can be passed from mother to baby in the womb or during birth). But this method contributes to antibiotic overuse and resistance, and is expensive and logistically challenging—especially for the low-income countries that need intervention the most.

PATH is working with the Biovac Institute in South Africa (a country that suffers one of the highest GBS disease burdens in the world) to develop a vaccine against GBS that can be delivered to pregnant women, who will then pass along protective antibodies to their babies—a strategy referred to as maternal immunization.

Though vaccines are only part of the defeating meningitis by 2030 strategy WHO is developing, they are an essential part, and one of the platforms upon which all other strategies hinge. Vaccines save countless lives by allowing us to prevent disease rather than just treat it. And with a disease as virulent as meningitis—prevention is key.

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