By Warren Lancaster, Former Senior Vice President of Programs
It’s interesting how something can suddenly capture your attention, maybe it should have captured your attention before, but like Cinderella something unique can get overlooked and that is the case of me and the story of the UCP-LF CAA Schistosomiasis diagnostic.
I have been involved in the endeavor to control and eliminate schistosomiasis for many years. Our aim has historically been focused on the control part by eliminating sickness among children due to schistosomiasis. Schistosomiasis is a parasite spread by humans but which has an intermediate host, a freshwater snail. Communities who live near infected areas are likely to have these parasites and through excreting in the open, they participate in the life cycle of the parasite and continue the cycle of transmission. In children, this disease can be devastating for their development.
For years, we have diligently applied ourselves to the objective of reducing the sickness caused by schistosomiasis. Recently, we have dared to imagine a future where even transmission of the parasite to people is eliminated. However, to achieve this we are missing an important tool. We must be able to pinpoint, with a laser focus, villages and communities where the disease is actively transmitted especially at low levels.
In our ambition to achieve reduction in disease among children, we have been able to use tests that are less precise, but that detect fairly high levels of infection. This is what we needed because this is where actual disease is most likely to be prevalent. We wanted to treat areas where the disease is most prevalent because that is where it is causing the most sickness. Although the UCP-LF CAA test existed, nevertheless for people like me, it labored in the background for use by scientists not practitioners. In fact this is still the case, research studies on schistosomiasis rely on this test for the precise survey data that rigorous research needs. What has transpired is that the test has been used and has received investment from agencies needing the scientific use of the test, but although the UCP-LF CAA has existed and been utilized for more than 10 years, its investment did not include bringing it to be friendly for mass use. This is why I am referring to it as the Cinderella test.
But, with this emerging ambition to actually eliminate transmission of infection, this very sensitive test becomes critical. This is because we now need to go beyond just identifying high levels of infection and now identify where infection persists even at low levels after years of regular preventative treatment with the donated medicine, praziquantel.
Before going further readers should understand that eliminating a disease as a public health problem is different from trying to eliminate transmission of the parasite that causes the disease. The first is much easier than the second. In areas where we have been treating the schistosomiasis infection already for some years and have reduced it to low levels in the community, we have reduced the burden of disease but made the infection more difficult to find. The UCP-LF CAA schistosomiasis was developed just for this purpose, so what, you may ask, is the problem, why has the glass slipper not yet been fitted? Well, one reason is that we need a test that meets three criteria. First, it needs to be accurate at detecting low levels of infection. Second, it must be easy to collect the sample that will be analyzed. And third, the result needs to be easy and clear to read. The UCP-LF CAA (perhaps even name change would help) meets the first two of these criteria, but not the third. And, the third is a deal breaker. No matter how simple it is to collect the urine sample, if it is complicated or expensive to test the result, the test will not be widely used, remaining the Cinderella working diligently but only in the lab.
In a blog like this, I like to present the problem, articulate a potential solution and imagine a preferred future. You’ve already read the first two. The preferred future imagines a testing team arriving at a community, collecting a urine sample from about 50 children and 50 adults, and then taking the pooled samples back to a local lab or perhaps a regional lab where it’s analyzed using a laboratory format of an RDT with a simple strip reader to reach the accuracy needed. The next day we have a high-resolution map of every village in a health district where schistosomiasis is prevalent and we have a reading of how heavy or serious the level of infection is among these few hundred villagers instead of a whole health district of perhaps 100,000 people. This preferred future would revolutionize how we tackle this disease going forward in a much more sophisticated targeting of low infection areas, finding where the parasite is lurking, and treating people who really need treatment.
In closing, the vast praziquantel donation is broadly sufficient to treat every child who needs treatment for schistosomiasis. If we can be more deliberate in locating schistosomiasis hot spots and treat those who really need it, we can certainly reach the WHO 2030 NTD roadmap target to eliminate schistosomiasis as a public health problem. But with such a laser accurate test, we can potentially move beyond this laudable goal to actually eliminating the transmission of the parasites and ultimately eliminate the need for preventative community wide preventative treatment.
We need to get Cinderella to the ball.