Meningitis, climate and forecasting Africa’s public health connection
As part of the global effort to combat climate change, the World Meteorological Organization (WMO) has issued its first annual Airborne Dust Bulletin to better understand how dust and sand storms impact humans – and how humans contribute too.
“Every year, an estimated 2,000 million tons of dust is emitted into the atmosphere,” said Enric Terradellas, chairman of WMO’s atmospheric dust initiative and an expert on dust forecasting. “While much of this is a natural part of the Earth’s cycles, a significant amount is generated by human-induced factors, especially unsustainable land and water management.”
The authors warn that the new product, released on Wednesday, still relies on incomplete data sets and that means they needed to generate models to complete the research. What they found was that 2016 saw less windblown Saharan dust transported over the Atlantic, and more of it was shifted southward into West African nations at the Gulf of Guinea and the rest of Equatorial Africa.
The greatest anomalies were seen in countries that included Nigeria, Cameroon, Central African Republic and east into Sudan, where the dust levels all were higher. Airborne dust is linked to health problems like respiratory ailments and meningitis, the WMO report notes, in addition to causing airport closures, dangerous road conditions, and disruptions for business, agriculture and schooling.
The public health implications of sand and dust storms – especially where climates are changing, and heat and drought are occurring – means that better forecasting can help protect lives. Dust kicked up by storms can affect people hundreds or thousands of kilometers away, creating a public health crisis.
Outbreaks across the sub-Saharan ‘meningitis belt’ region
Meningitis has seen a wicked resurgence across northern Nigeria in an outbreak that has now claimed almost 500 lives. Almost 5,000 cases have been reported since November, according to Chikwe Ihekweazu, the National Coordinator of Nigeria Centre for Disease Control. Other nations including Togo, Niger, Cameroon, Chad and Burkina Faso have reported meningitis cases as well.
These countries exist geographically in what epidemiologists and other public health officials call the “meningitis belt” of sub-Saharan Africa. Some 450 million people live in 26 countries affected by deadly meningitis outbreaks, and past outbreaks have claimed tens of thousands of lives.
The infection of the meninges – the thin lining layer of the brain and spinal cord – can be either viral or bacterial, but the latter is usually more serious. Bacterial meningococcal meningitis is fatal in 50 percent of cases if it’s not treated, according to the World Health Organization, and it’s readily spread from person to person.
Vaccination campaigns have specifically targeted citizens in the countries affected by the meningitis outbreaks that so often were blown in on the seasonal winds. “Every winter for decades, communities from Senegal to Sudan braced themselves for a killer,” explains the PATH global health and technology organization. “As the rains dried up and the Harmattan winds began to blow south from the Sahara across this vast region, the swirling sands kicked up something just as predictable: meningitis.”
The MenAfriVac® vaccine was developed to protect people from Meningitis A, and PATH – working closely with WHO, UNICEF and other groups – says vaccinations have reached 235 million people. The A strain accounts for 80 to 85 percent of all cases in Africa’s meningitis belt, but with this latest outbreak, Nigerian officials say they’re seeing a new meningitis strain instead. That’s left them scrambling for more than 1.3 million doses of a different vaccine they are administering with help from international partners.
Contagion and the climate connection
While the pattern of seasonal dust storms followed by meningitis outbreaks is tragically well known, scientists haven’t always known why. A 2016 study conducted in Niger demonstrated links between airborne dust and hot temperatures, and outbreaks of bacterial meningitis.
The Sahel region of West Africa has the highest number of bacterial meningitis cases in the world, the University of Liverpool authors note. So alongside partners in Niger and Malawi, they aimed to find out why weather affects meningitis infections and outbreaks.
Climate scientists and epidemiologists working in Niamey conducted daily disease surveillance and weather monitoring over an eight-year period and found that outbreaks of bacterial meningitis occurred shortly after sandstorms and extreme high temperatures.
“Niger sits right in the middle of the meningitis belt that runs east to west across Africa just below the Sahara desert,” said Dr. Daniel Neill. “Sandstorms blowing into Niger from the Sahara kick up huge quantities of dust and sand that severely reduce visibility and significantly increase temperature.”
The researchers demonstrated that both dust inhalation and exposure to high temperatures are risk factors for development of life threatening invasive bacterial infections, but when the two factors combine, as they do in Niger, it raises the risk even further.
The combination of dust and heat led to increased numbers of bacteria in the upper airways, impaired immune system protection, and an increase in the release of damaging bacterial toxins. As a result, severe infection was more common, they said.
“Long-term forecasting and identification of climatic risk factors would help public health decision makers improve early warning systems,” the journal study concluded. “Statistical forecasting models that integrate climatic factors, linking environmental and epidemiologic surveillance, could act as early warning systems of infectious disease epidemics.”
That’s just what the new WMO hopes to achieve as well, particularly in a time of greater air quality challenge and climate change. To view a WMO video on how to better forecast and protect people during dust storms, see this link.
Image: NASA EOSDIS
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