Leprosy Mailing List – May 14, 2022
Ref.: (LML) COVID set off a boom in diagnostics; the pandemic accelerated the development of cutting-edge PCR tests.
From: Pieter AM Schreuder, Maastricht, the Netherlands
Dear colleagues,
In a recent Scientific American edition (Scientific American, March 2022; by Roxanne Khamsi; pages 37-41) I found the following interesting article: "COVID set off a boom in diagnostics; the pandemic accelerated the development of cutting-edge PCR tests".
The quotes below are from this article (with high respect and gratefulness to Willy Ssengooba and Roxanne Khamsi):
"A decade ago Willy Ssengooba, scientific director of the mycobacteriology research unit at Makerere University College of Health Sciences in Kampala, Uganda, began crisscrossing the country, training heath-care workers on how to use a new machine to detect tuberculosis. These new machines used rapid molecular testing to yield results within a couple of hours, meaning patients who tested positive could immediately be referred for lifesaving treatment. 265 of these devices in clinics around the country were set up.
Not long after the first case of covid was reported in Uganda on March 21, 2020, the Ministry of Health asked him to set up screening posts at border crossings. Ssengooba and his team began facilitating the collection of nasal swabs taken from truckers at popular entry points. Those samples, sometimes more than 1,000 a day, needed to be shuttled 150 miles to Kampala, the nearest place with laboratory technology set up to run a polymerase chain reaction. The Ssengooba's team had to shuttle the samples themselves; a crew of about 50 workers collected the samples and in pickup trucks delivered them to the lab in Kampala, then turned around to go back for the next batch, spending long, exhausting nights on the road. As the pandemic intensified, they could not keep up. Truckers awaiting their test results were stalled at the border for days, in part because the sample analysis in Kampala would sometimes take up to 72 hours to return a result. A queue of trucks formed, stretching for kilometers, holding import of everything. On top of that the authorities had closed the airport.
The government was desperate to alleviate the backlog. Ssengooba considered the 265 machines he has set up throughout Uganda over the years to test for tuberculosis. He realised he could repurpose some of these small PCR machines to test for the coronavirus by using a different sample-processing cartridge. He reallocated that equipment directly to the border entry points and engineered some basic infrastructure (electric power; benchtop safety spaces) to support their use. Unlike the lab setup in Kampala, which requires multiple machines spread across different rooms and experienced technicians to prepare and process the samples, these so-called GeneXpert modules were automated and about the size of a printer. They still used the PCR technology but could return results on the spot in around half an hour.
By May the first COVID testing systems were working at the crossing point on the Kenya-Uganda border, reducing the waiting time from days to around half an hour.
However, after successfully setting up the fast-turnaround GeneXpert, Ssengooba soon run out of the cartridges and reagents the machines rely on and because of USA export restrictions did receive only very limited additional cartridges for the rest of 2020."
"How Covid is shaping the future of diagnostics:
Modern PCR machines use plastic trays that traditionally have each contained 96 or 384 small wells to hold samples. To circumvent the need for expensive plastic "consumables" such as tubes and caps, a U.K. company replaced the tray with a long flexible polymer tape. That allows to do up to 150,000 tests per machine per day, ten times more than any machine in the world, and at ten times less cost.
Another bottleneck with PCR is that "you have to get the sample very, very purified" before running the test. Adams and Haselton at Vanderbilt University, had the idea of adding DNA that is a mirror version of the target genetic sequence the PCR test is trying to detect. By reducing the need for purification with the left-handed DNA (naturally occurring DNA is right-handed) – which costs about 11 cents per test – lab could save significant labour and material costs."
"Now that COVID has shown how important is for testing to be accessible, there is more enthusiasm for portable PCR devices, and rapid developments like the above-mentioned. Diagnostics developers are continuing to tinker with PCR.
Public health has always been stymied by the hours or days between collecting a sample and delivering the results to the patient. Imaging a future where portable PCR tests with on-site results are commonplace."
My question is obvious: what about leprosy, and will the coming congress pay attention to this topic?
Pieter AM Schreuder
LML - S Deepak, B Naafs, S Noto and P Schreuder
LML blog link: http://leprosymailinglist.blogspot.it/
Contact: Dr Pieter Schreuder << editorlml@gmail.com
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