- The number of confirmed cases of COVID-19 surges past 2.2 million globally and deaths surpass 150,000.
- Clinicians and pathologists struggle to understand the damage wrought by the coronavirus as it tears through the body.
- They realize that although the lungs are ground zero.
- Its reach can extend to many organs including the heart and blood vessels, kidneys, gut, and brain.
Meredith Wadman, Jennifer Couzin-Frankel, Jocelyn Kaiser and Catherine Matacic write for ScienceMag about the ferocious rampage of Coronavirus through the body, from brain to toes.
To understand the disease completely
Understanding the rampage could help the doctors on the front lines treat the fraction of infected people who become desperately and sometimes mysteriously ill.
Here is a snapshot of the fast-evolving understanding of how the virus attacks cells around the body. Especially in the roughly 5% of patients who become critically ill.
The start of infection
When an infected person expels virus-laden droplets and someone else inhales them, the novel coronavirus, called SARS-CoV-2, enters the nose and throat. Once inside, the virus hijacks the cell’s machinery, making myriad copies of itself and invading new cells.
Symptoms may be absent at this point. Or the virus’ new victim may develop a fever, dry cough, sore throat, loss of smell and taste, or head and body aches.
If the immune system doesn’t beat back SARS-CoV-2 during this initial phase, the virus then marches down the windpipe to attack the lungs, where it can turn deadly.
An invader’s impact
In serious cases, SARS-CoV-2 lands in the lungs and can do deep damage there. But the virus can injure many other organs. Let us see how various important parts of the body are affected.
Brain: Some COVID-19 patients have strokes, seizures, confusion, and brain inflammation. Doctors are trying to understand which are directly caused by the virus.
Eyes: Conjunctivitis, inflammation of the membrane that lines the front of the eye and inner eyelid, is more common in the sickest patients.
Nose: Some patients lose their sense of smell. Scientists speculate that the virus may move up the nose’s nerve endings and damage cells.
Lungs: A cross section shows immune cells crowding an inflamed alveolus, or air sac, whose walls break down during attack by the virus, diminishing oxygen uptake. Patients cough, fevers rise, and breathing becomes labored.
Heart and blood vessels: The virus (teal) enters cells, likely including those lining blood vessels, by binding to angiotensin-converting enzyme 2 (ACE2) receptors on the cell surface. Infection can also promote blood clots, heart attacks, and cardiac inflammation.
Liver: Up to half of hospitalized patients have enzyme levels that signal a struggling liver. An immune system in overdrive and drugs given to fight the virus may be causing the damage.
Kidneys: Kidney damage is common in severe cases and makes death more likely. The virus may attack the kidneys directly, or kidney failure may be part of whole-body events like plummeting blood pressure.
Intestine: Patient reports and biopsy data suggest the virus can infect the lower gastrointestinal tract, which is rich in ACE2 receptors. Some 20% or more of patients have diarrhea.
Lungs failure and renal failure
The worldwide fears of ventilator shortages for failing lungs have received plenty of attention. Not so a scramble for another type of equipment: dialysis machines. “If these folks are not dying of lung failure, they’re dying of renal failure,” says neurologist Jennifer Frontera of New York University’s Langone Medical Center, which has treated thousands of COVID-19 patients.
Years of painstaking research required
It will take years of painstaking research to sharpen the picture of its reach, and the cascade of cardiovascular and immune effects it might set in motion. As science races ahead, from probing tissues under microscopes to testing drugs on patients. The hope is for treatments more wily than the virus that has stopped the world in its tracks.
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Source: ScienceMag
