By Warren Lancaster
I was chatting with friends over coffee and I began to talk about our work on river blindness in Africa. One person at the table, who had lived in an African country for many years, interrupted helpfully saying, ‘I thought the World Bank eliminated it by spraying rivers years ago’. Well yes and no I responded; yes spraying largely eliminated the very worst of the disease, actual blindness but there is still a long way to go to eliminate transmission of the disease.
River blindness is spread through the repeated bites of black flies that live on rocks and in vegetation in fast moving water. Tiny parasitic worms from the bites migrate in the body to the eyes, causing terrible itchy skin and eventually blindness if left untreated. Before there was a cure, entire villages were displaced because of the risk of blindness causing poverty for millions of people
As I reflected on this conversation later, the adage of Voltaire not to let perfect get in the way of good came to mind. Good advice when we need to get things done. Effectively, that is what we have done in the effort to stop African river blindness. Millions of people have been cured of the disease and huge tracts of riverside land have been returned to productivity.
But good in the case of river blindness is actually not good enough. Yes, the work to end river blindness is already a story of a great public health endeavor, a Nobel Prize and the pursuit of a stunning global health vision to eliminate the disease entirely as a public health problem in Africa.
The program has been good, very good. Firstly to eliminate actual blindness which the World Bank largely accomplished by spraying west African rivers, then the discovery and distribution of the Nobel Prize winning medicine called Mectizan that effectively cured millions of people and now we are pursuing the interruption of transmission of the parasite.
Great, we could say. Well, again yes and no. In parts of West Africa there is another parasite called Loa Loa or Eye Worm and it can exist with river blindness in a victim. When a person with a heavy infection of eye worms is treated with Mectizan for river blindness it can cause a very serious reaction that can be life threatening. So, when loa loa and river blindness are both present in an area we do not administer Mectizan. It is possible to test a person in such an area for eye worms and if they are free of Loa to treat that person with Mectizan for river blindness. But that is very expensive. Especially, when we work on the basis of mass administration of preventative medicine costing generally less than $0.50 per person.
Sadly, this problem presently means that about 80 million people at risk of river blindness can not be treated and thus the truly great goal of eliminating transmission of the parasite can not be accomplished for these people .
But there is a solution to this problem now that could take the endeavor to eliminate river blindness to truly great. Scientists at Berkeley University have invented a handheld scanner called the Loa scope, that can detect eye worms in a blood sample taken on site through a finger prick. What we know is that if infection of eye worm is below 20,000 per ml in the blood sample, then it is in fact safe to administer Mectizan without fear of the severe adverse reactions. Using the loa scope as a tool for population surveys we can determine if it is safe to treat large numbers of people in that area.
This means that we expect that of the 80 million people currently excluded from this extraordinarily low cost treatment, millions of them would become eligible for safe treatment campaigns.
The Loa Scope costs approximately $600. We would need perhaps $10 million to procure Loa Scopes and undertake surveying in the tracts in west and central Africa where the two parasites are co-endemic. The identification of communities that can be safely treated with Mectizan would offer immediate hope of the elimination of the disease through simple community wide administration of this drug that is donated generously by the pharmaceutical company Merck. Coming back to Voltaire, we have not achieved perfect until we can treat every person with river blindness, even those with high eye worm loads and that too is possible but not yet financially feasible through ‘test and treat’ – the next level use of the Loa Scope.
I am glad we did not let perfect hinder achieving good, but I can see that with a comparatively small philanthropic investment we can achieve far beyond just good to truly great and I can imagine one day reaching perfect.