After winning funding from ALM’s ‘NTD Innovation Prize’ in 2020 and further support from St Francis Leprosy Guild, our teams have been working on a new project that could allow us to use smartphones, equipped with spectral imaging technology, to diagnose leprosy instantly in the field.
Below, Tim Burton from the International Office talks to the project’s lead researcher, Dr Suwash Baral, a Consultant Dermatologist and Dermatopathologist at Anandaban Hospital in Nepal.
TB: Dr Suwash, why is this a project that TLM should be excited about?
SB: We currently have around 200,000 people diagnosed with leprosy each year. However, researchers estimate that there are ‘missing millions’ who go undiagnosed. Spectral imaging technology on smartphones will not help us to find every one of those missing millions, but it will certainly help us to close the gap.
At the moment, field workers and healthcare staff have to diagnose leprosy with skin smear tests. There are two main problems with this.
Firstly, the tests take a long time to run; they must be sent out to a lab, they must be looked at with a microscope, and then the results need to be sent back to the potential patient and relevant clinician. This process can take weeks. Leprosy may be a slow moving disease, but the sooner we can begin someone on MDT, the better. This prevents the development of preventable disabilities and it stops transmission.
The time lag between initial test and final result is also a problem for people who are not easy to locate. While a skin smear may be done in one place, that individual may have moved on by the time the result comes. If that happens, we have missed the chance to treat them; they may continue to be infectious and they will probably develop preventable disabilities.
© Ruth Towell
Secondly, we have limited capacity with these tests. We are not able to take skin smears from every person who has a skin lesion. It takes too long and is too complicated. If a person has a skin lesion and the lesion still has feeling, most fieldworkers will not take a skin smear because it does not appear to be leprosy. This is an appropriate way to prioritise, given the tools we have available to us. However, with better tools we would be able to test every skin lesion we come across.
Of the ‘missing millions’, there could be many who have skin lesions that we cannot test. There could be many more who have been diagnosed with leprosy, but we cannot find them and cannot treat them. We should be excited about this project because it could help us to find and treat far more people in a much shorter period. It helps us to stop both transmission and disability.
Above: Dr Arie de Kruijff explains more
TB: What is spectral imaging and how is it going to help us diagnose leprosy faster?
SB: Spectral imaging allows us to see beyond the range of vision that is available to the human eye. We are able to see a skin lesion on the skin, but spectral imaging can see the lesion below the skin, as well.
Humans can only see things in the visual light spectrum, which is around 400-600 nanometres. Spectral imaging allows us to see up to 900 nanometres. This makes all the difference.
Spectral imaging is currently being used in many places across the world to detect skin cancer, so we know that it can work to identify dermatological problems. We believe spectral imaging will be able to help us identify a leprosy lesion, as well. Prof Janis Spigulis and his team at the University of Latvia have lots of experience in this and have set up the hardware and software for us to trial it with leprosy.
As part of this project, we need to take spectral imaging scans of lesions from a minimum of 100 patients in Nepal. Some of these lesions will be leprosy and some will be doubtful. We will test these lesions under a microscope to confirm whether they are or are not leprosy lesions. We will then send the spectral imaging scans to the team at the University of Latvia. They will be looking at the scans to try to identify patterns that are unique to the lesions that have tested positive for leprosy.
We think there may also need to be some testing done in Africa, as skin cancer is less common in Africa and so spectral imaging has not been tested on darker skin.
Leprosy skin lesions are a lot bigger than skin cancer lesions, so we are going to have to be patient through this research and take many scans, covering each section of a lesion. Despite this, we are hopeful that the precedent set by skin cancer will be the same for leprosy. Once we have identified what is unique about a scan of a leprosy lesion, a fieldworker should be able to identify a leprosy lesion with just one scan of part of a lesion.
Above: The winning proposal video that was submitted to the NTD Prize
TB: How will this technology work on smartphones?
SB: At the moment, the spectral imaging scanner is a fairly large piece of kit. We will be carrying it with us to the field in Nepal in its own bag. However, once we have established that spectral imaging can be used to diagnose leprosy, the cost of mass-producing the scanner will be reduced and we will have a spectral image-scanning device that can be fitted over the top of a smartphone.
Clinicians are currently using smartphone scanners to diagnose skin cancer, so once more we have a helpful precedent to work with. We believe this field-friendly smartphone kit will be scalable and affordable, so that one day all fieldworkers can take one with them when they are doing case finding work. They could diagnose leprosy in the moment and prescribe the necessary MDT. The clinicians’ opinions of the lesion will still be important in the field, but we hope that this will be an invaluable tool for them.
TB: How long will it be before fieldworkers are bringing smartphone scanners with them?
SB: The pandemic has delayed our progress on this. We have not been able to conduct scanning in the field in Nepal due to government lockdown restrictions. It is hard to predict the trajectory of the pandemic, but we are hopeful that we may be able to start scanning in the next few months.
From then, we will take about a year to enrol the 100 patients that we are looking for, but we will be sending scans to the team in Latvia throughout this time.
We will aim to publish results sometime in 2022 and if we are successful, spectral imaging could be a regular part of leprosy work in 3-5 years’ time. If that happens, we think it will be a breakthrough; it will transform the process of leprosy diagnosis.
Cover image copyright: Ricardo Franco
