“When you see the kids who have nothing, it changes you,” said Dr. Ben Jacob, “and when you see the ones who are blind on top of it, it changes you even more. You come back to your American life here, you cruise around town, go to McDonald’s, whatever, but you can’t help thinking about them.”
Jacob, a research assistant professor in the USF College of Public Health’s Department of Global Health, recently returned from working “towards eradication,” he is careful to say, of onchocerciasis, or river blindness, in Uganda and Burkina Faso, the third-poorest nation on the African continent and one of the poorest on the planet. He is part of an initiative that is making rapid headway there, and he is excited to be part of the reason.
“Onchocerciasis is a disease caused by Simulium Damnosum s.l., a species of fly that habitats along rivers – along the river edges, to be exact,” Jacob explained. “It’s commonly seen in Africa. It used to be in South America, but the incidence is getting less and less in the western hemisphere. Unfortunately, in Africa, it’s still very predominant. The problem is that it causes blindness, especially in children, and the tragedy behind it is that it’s preventable if we focus on the habitat instead of post-treatment clinical strategies solely.”
The tragedy also goes well beyond the blinded child, he said. In northern Africa’s nations wracked by civil war and abject poverty, there are no schools for the blind, and in an agro-economic society, every child lost to blindness represents a missing workforce and “a very big disadvantage,” he said, to a family already practically defined by disadvantage.
Jacob, who has been working to fight disease in Africa for five years, is part of a global initiative backed by The Carter Center, the World Health Organization and the Gates Foundation to halt transmission of the disease. Since it’s spread by black flies, eliminating the flies has become the focus.
Brought into the effort by Global Health’s chair, Dr. Tom Unnasch, Jacob has applied his specialties – geographic information systems and spatial modeling – to the effort. So far, it’s proving to be a dramatic step in the right direction after decades of failed efforts to control the disease.
“In the ’70s, what they were doing was treating the rivers with insecticide,” Jacob said. “It was non-targeted, very global. It was just sprayed along the rivers to inhibit the larval production of the habitat.”
Among the major drawbacks of that approach, Jacob said, was the expense, since the only practical way to spray such vast areas was by helicopter.
“Rivers can go on forever, especially African rivers,” he said. “They have multiple tributaries, so even though you may treat one location, it may not affect the whole area. So, it was not a cost-effective methodology, nor was it good for prevention.”
Unnasch thought Jacob’s work with global information systems to identify mosquito habitats to combat malaria could just as easily be applied to the war on black flies.
“I was brought in as a mathematician/modeler to determine where the high-prevalence canopied S. Damnosum s.l. habitats were using newer state-of-the-art cartographic- and informatic-based technology,” Jacob said. “I started using GIS, and I was able to get a spectral imprint – i.e., target reflectance biosignature – off one habitat. Every object,” he explained, “has a unique spectral signature that is reflected off its surface – you, a car, a tree, anything.”
Jacob took a spectral signature off a particular habitat along a river and withdrew the wavelengths by color to determine the percentage of each in the signature. The rest is every bit as technical as it is fascinating.
“I was able to spectrally extract and decompose a pixel that represented the percentage of red, green, blue and all the other canopy colors of that habitat,” he said, “and then, within the GIS, utilize that percentage contribution of each wavelength and find every single other one inside of a scene. Initially, I ran an algorithm inside of GIS using a large riverine scene of an area in western Africa to determine a signature that I originally withdrew from a capture point habitat, and then found all the other ones that were similar.”
Jacob had first tested his idea two years ago in Togo, he said.
“I found one signature,” he said, “and I took that one spectral signature and displaced the percentage components of the wavelengths on a whole image, and the GIS found me all the georeferenceable sites of the canopied habitats – a predictive geo-spectrotemporal model, in other words.”
The results of that test in Togo were nothing less than startling: Human follow-up investigations on the ground – known as “ground-truthing” – put the predictive method’s accuracy at 100 percent. Excited by his findings, Jacob returned to COPH to share the news with Global Health colleagues, especially Unnasch and Dr. Robert Novak, a professor of medical entomology. The message was a simple revelation with profound implications: They could find all the habitats without having to move field teams, a particularly cost-prohibitive exercise in Africa.
The response from COPH’s renowned vector-borne disease experts was to give it a double-blind study: Apply the methodology to another region – specifically, northern Uganda, on the other side of Africa – and we’ll see how good it is.
“In other words, they would show me a country, but they wouldn’t tell me where the disease was,” Jacob said. “I would show them where it was. They obviously knew.”
The result of that second test was almost as encouraging as the first.
“When I took the percentage signature and then ran it in a scene from northern Uganda,” Jacob said, “I found all the habitats predicted in my model using GIS. The second phase of it was to ground-truth it. We found 92.8 percent, which was remarkable. We were using a signal that was extrapolated in west Africa, and we interpolated habitats in east Africa. So now, what that’s really telling us is, we have the capability, today, to find all the habitats.”
The next step, he said, was going to be the harder part.
“Yes, our model performance was extremely adequate. The problem is, now what do we do for prevention? We found it scientifically. We have a great model, but what about controlling the disease?”
Jacob’s answer is a campaign he calls “Slash and Clear.”
“The idea is, once we’ve found these canopied trailing vegetation, based on the predictive model, we will seek and train individuals at the village level to remove them, using machetes, and that’s exactly what we did in our last project,” he said. “And then we conducted clinical trials. We put up some fly traps in the initial stage. We saw reductions well over 60 percent in some of our targeted villages within a week.
“Once we are able to control the adult emergence of the disease – the flies – obviously, we would have fewer flies biting, and logically we would have less disease transmission. So, we’re just using common sense,” he said. “Destroy the location where the immatures are being produced, you have less emergence of adults, you have less transmission of disease. Very simple concept.”
Jacob is pumped with enthusiasm to see the project through to a successful conclusion, and the closer he gets to making that reality, the more pumped he gets.
“We are able now not only to find the habitats very cost-effectively and in very quick time,” he said pointedly, “but we are actually able to go ahead and remove the significant habitats. I think the next year of our project will be to remove all habitats around these village complexes, to eliminate and to eventually eradicate the disease.”
And sometimes, in science or anything else, the best defense is a good offense.
“We’re focusing on the habitat,” Jacob said. “Instead of playing defense – putting up bed nets, for example – we’re playing offense. That’s actually the campaign we’re running in Uganda: ‘Slash and Clear.’”
Jacob said he’s confident of the method’s universal applicability and is already expanding its use.
“Now we’re using that same signal in Angola, we’re moving towards Nigeria, and we’re also using it in Togo. If you gave me a scene in Zimbabwe, I could find you all the oncho habitats by the end of the day,” he said emphatically, “by the end of the day!”
“I’ve taken it personally, honestly,” he continued, “because I know we’re close to coming to a conclusion, and I feel, as a scientist, that this is the closest I’ve ever come. I’m really excited about being a part of this team. I think, in this type of environment, the only thing we as scientists can do is be more vigilant about how we can pursue eradication tools, and I think what we have right now – and obviously, I’m being biased – but I think we have one of the best capabilities. I don’t think we’ve come this close on any other disease that I’ve ever worked on – none, and I’ve worked on a lot. That’s why I feel very excited about this project. I really think we can make this disease go away.”
Story by David Brothers, photos courtesy of Dr. Ben Jacbob, College of Public Health.