South African scientists are among the frontrunners in Long Covid research, as a new study, which sheds light on what causes the disease and how to detect it, shows.
Long Covid has about 200 symptoms and is extremely debilitating to an estimated 400-million people globally. For example, the muscles of a person with Long Covid who walked for six minutes were more fatigued (showed higher lactic-acid levels) than those of a healthy person who ran a marathon, one UK study has found.
Prof Resia Pretorius, a physiology expert at Stellenbosch University, said: “Many people with Long Covid have normal blood test results, even though they still feel very unwell. That’s because routine tests don’t look for microclotting or the immune material trapped inside the microclots. By identifying these new signals in the blood, we’re opening the door to better tests that can confirm whether someone’s symptoms are linked to inflammation and microclotting. These kinds of tests could also help doctors track whether treatments are working.”
Her team collaborated with French scientists to develop novel biomarkers for Long Covid, and the results were published in the Journal of Medical Virology.
Pretorius said of their results: “First, we already know people with Long Covid have far more microclotting in their blood than healthy people — sometimes about 20 times more.
“Second, we found very high levels of immune-cell traps called neutrophils (NETs), and the more NETs we saw, the more microclotting there was.
“Third, when we looked [at the blood of Long-Covid patients] under powerful microscopes, we could actually see that the two are linked … This shows that Long Covid involves both inflammation and clotting, happening together in a way that keeps reinforcing itself.”
Long Covid involves both inflammation and clotting, happening together in a way that keeps reinforcing itself
— Prof Resia Pretorius, Stellenbosch University
Her associate Dr Massimo Nunes has been investigating a “zombie cell hypothesis” — damaged blood cells that go into hibernation (senescence) in the endothelial lining of blood vessels — in people with Long Covid. The zombie cells still consume energy and might cause blood clots and limit blood flow, Nunes’s research suggests.
Long Covid advocate Sam Pearce said: “This is a most exciting hypothesis. [What the researchers have described] would result in cellular oxygen starvation, leading to a wide array of symptoms and accounting for the terrible symptoms we have. A healthy person’s protective killer cells should naturally clear senescent endothelial cells, but in a sick person the ”zombie cells" actively evade the immune system’s defences, creating a mounting threat of vascular and immune dysfunction.”
The team from Stellenbosch University presented their findings at the second International Conference on Scientific and Clinical Advances in ME and Long Covid in Portugal last week.
Dr Jaco Laubscher, from Stellenbosch Mediclinic, has treated more than 900 people for Long Covid. He targets the microclots in their blood, detected through testing by Pretorius, and most of his patients have recovered. His treatment involves giving his patients triple blood thinners to eliminate the microclots, and — despite the lack of an approved protocol for this risky approach — he has not had a brain bleed or death, though two patients developed gastric ulcers.
“These patients’ blood is thick like honey. If I gave the same treatment to healthy patients, they would bleed to death,” he said.
The physician sees about five to 10 new patients a week, some of whom are in bed “looking at the ceiling all day” and desperate for treatment.
University of Cape Town allergist Prof Jonny Peter, head of the allergy and immunology unit, said: “The predominant symptoms that people describe are fatigue and neurocognitive-related symptoms … [including] short-term memory impairment and concentration.”
Infectious diseases expert Prof Francois Venter, head of Wits University’s Ezintsha research centre, said Ezintsha had a study, one of the first on pulmonary abnormalities in Long Covid in South Africa, published last month in the Southern African Journal of Infectious Diseases.
“Sadly a lot of the researchers studying Long Covid had their research defunded, so we may not get the treatments we need.”
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