Meningitis has long been associated with the dry season in the Sahelian region of Africa, but data availability and quality limitations have prevented scientists from quantifying this relationship. Recent advancements in satellite technology and access to epidemiological data have made it possible to robustly study how wind, dust, temperature, and other climate variables relate to meningitis incidence in Africa.
This video highlights newly published research in Niger, which suggests that climate variables, along with health data, may be able to serve as predictors of meningitis outbreaks. By working with local decision makers, researchers are able to create forecast models with end-user needs integrated into the development process.
Read the paper! Carlos Pérez García-Pando et al. 2014. Soil Dust Aerosols and Wind as Predictors of Seasonal Meningitis Incidence in Niger. Environ Health Perspectives. In press. doi:10.1289/ehp.1306640
Video produced by Elisabeth Gawthrop and Francesco Fiondella
MADELEINE THOMSON: The reason why we care about meningococcal meningitis is that it is a devastating disease. There are historically huge epidemics of the disease that have occurred across the Sahelian belt of Africa actually known as the Meningitis Belt. And in this region, what we would consider to be a major epidemic happen routinely every year. The disease, if you like, is a very feared disease in the region.
RON MILLER: So it's been observed for a long time that these outbreaks occur during the dry season, typically from November to April. This is a time of year when the winds are coming off the Sahara Dessert, they're very dry they're very dusty, this is called the Harmattan Wind. And so for a long time, scientists have hypothesized that maybe there's a connection between the dust and the low humidity of the air and the outbreaks.
CARLOS PEREZ GARCIA-PANDO: What is interesting about this research is a quantification of relationship between climate and meningitis in one of the most affected countries through history which is Niger. So we have been trying to create models that could eventually predict the disease months or weeks in advance.
MILLER: So ideally we would have observations of the arrival of dust at the surface at the same time that we observe outbreaks. The problem is that this is a region of the world where we don't have many observations at the ground. NASA sends satellites to this part of the world twice a day. What this tells us is the total amount of dust in the atmosphere. It doesn't tell us how much dust is at the surface. So what we use models for is to tell us how much dust is at the surface. They are models that are based on physical laws, like Newton's Laws of Motion. These are the tools we use to basically convert from the satellite measurements made by NASA down to the amount of dust at the surface that we use to test the hypothesis that there's some relations with the meningitis outbreaks.
GARCIA-PANDO: So the essential finding is that we found a pretty strong association between what happens in the early season, so November, December in terms of wind and dust conditions in the region and the magnitude of the disease later during the meningitis season. We're able to create [a] forecast model that has significant skills to predict the disease in the region. There are three main original aspects of this research/ We have used for the first time estimates of surface concentrations of dust. The second is that we have placed ourself at two different spatial scales. At the national scale and also the district scale. Typically previous studies have only looked at the large scale, but public health measures in the Belt are undertaken at the district level. And the third and important aspect of the research is that it has been tailored to respond to the needs of decision makers in the Belt by providing them with a tool with which they could take decisions about reactive vaccination.
THOMSON: So the research, if you like, has been developed to first initially focus on the reactive vaccination strategy and subsequently we're also now thinking about how we might assist with the new vaccination strategy which is going to be rolled out right across the belt.
GARCIA-PANDO: One of the main limitations that we currently have is a lack of knowledge on the specific mechanisms that drive the epidemics. When I talk about mechanisms I mean how climate may be affecting the spread of disease. So is this affecting transmission is this affecting the bacteria, or it's affecting the host. There are two areas that I would identify for future research which is lab studies with animal models to look at mechanisms of transmission. Second is to translate those mechanisms into more mechanistic models to further understand the dynamics of the disease and eventually improve our predictions of the disease.