My last two posts have focused on the WHO Essential Diagnostics List (EDL). The EDL, modeled after the Essential Medicines List, is meant to serve as a model guide for countries to use in the development of laboratory services for diagnosis, treatment, and monitoring of common diseases. The EDL is meant to be tailored to an individual nations disease burden, and India is on track to be the first country with a country-specific EDL. I think this is a tremendous step forward for the field of laboratory medicine worldwide, but I do wonder how this will roll out Low or Middle Income Countries (LMIC). How we will got from a list (actually a draft of a list) to real-time diagnostics in the developing world? Let’s take a step back and look at what access to laboratory testing really looks like, and then discuss some innovative diagnostics that might help increase access to useful diagnostics.
In the US, we have many labs tests available – so much so that laboratory utilization has become a very real area of study with groups like Choosing Wisely, PLUGS, and Preventing Overdiagnosis dedicated to helping guide appropriate use of in-vitro diagnostics (IVDs). The US has over 250,000 accredited laboratories, and 18,000 clinical pathologists. That’s about 5.7 pathologists per 100,000 people. In contrast, the continent of Africa has about 1 million people per pathologist, and some African countries have over 5 million people per pathologist. It’s difficult to find a number of laboratories in LMICS, because many are mom and pop type shops that aren’t registered with the Ministry/Department of Health. Test menus are often limited to cell counts and rapid testing, and proficiency testing or quality control is not practiced.
Challenges to building laboratory capacity in LMICs are environment, economics, and education. Environmental challenges include extreme temperatures, limited electricity, and limited access to water. Some point of care options that might be able to work in these environments just aren’t affordable. Many people in LMICS make around $2 USD a day and a $10 iStat/Piccolo/your favorite POC chemistry device cartridge is just out of reach especially if the testing needs to be repeated frequently for monitoring disease progression. Lastly, education remains a challenge as laboratory medicine including not not only technical skills but also the use and interpretation of lab tests is not frequently taught in LMICS.
However, there are many different innovative diagnostics being debuted or in development with these challenges in mind. There are definitely trends in the area of new diagnostics for the developing world. The most distinctive trends are: smartphone imaging, smartphone spectrophotometers, transdermal testing, and paper based sample collection. In my next few posts, I’ll take us through examples of each of these, and I’ll start now with smartphone imaging.
Smartphone imaging is essentially using light boxes, cameras, or apps, to turn a smartphone into an imaging device. Smartphones are even being used as simple ultrasounds! A smartphone microscope can be useful in diagnosing tropical infectious diseases. A good example is the LoaScope, developed by the Fletcher Lab at UC Berkeley. Dr. Daniel Fletcher is known as the “father of the cell phone microscope”. The LoaScope is a mobile phone based microscopy platform plus an app-based algorithm for the detection of L. Loa. The device is elegantly simple: a 3D printed case with a rest of the mobile phone. The case contains a USB port, bluetooth controller board, and LED array, and a carriage for a capillary slide. Blood is introduced to the capillary slide and imaged by the phone. A 5 sec video is captured by the phone, and then analyzed via app that uses a algorithm based on the the wiggling motion of the loa worm. The algorithm actually distinguishes the movement of blood cells as the loa worms move between them! The interpretation of the video lets the user know if the parasite is present or not present. Another bonus the device is that a georeference is captured with every video, which is great for epidemiological studies. In 2017, the LoaScope was used by the NIAID to testing over 16,000 subjects in Cameroon. Because of the LoaScope, over 15,000 subjects were successfully treated with ivermectin without serious complications.
There are some key elements to the LoaScope that are common across the new, innovative diagnostics for the developing world. First, the 3D printed case. 3D printing seems to really be helping this field jump ahead by decreasing the costs associated with creating the physical structure of the devices. Secondly, the device does not require special specimen preparation, nor does it need reagents. Lastly, a simple read-out is a available to the user in real time.
In summary, the EDL is great for telling us what test are, well, essential. Innovative diagnostics are going to help us get to those hard-to-reach places. I look forward to continuing to investigate these with you!
–Sarah Riley, PhD, DABCC, is an Assistant Professor of Pediatrics and Pathology and Immunology at Washington University in St. Louis School of Medicine. She is passionate about bringing the lab out of the basement and into the forefront of global health.