When people with Covid-19 develop a cough and fever, John Wilson, president-elect of the Royal Australasian College of Physicians and a respiratory physician. says this is a result of the infection reaching the respiratory tree – the air passages that conduct air between the lungs and the outside.
He says: “The lining of the respiratory tree becomes injured, causing inflammation. This in turn irritates the nerves in the lining of the airway. Just a speck of dust can stimulate a cough.
“But if this gets worse, it goes past just the lining of the airway and goes to the gas exchange units, which are at the end of the air passages.
“If they become infected they respond by pouring out inflammatory material into the air sacs that are at the bottom of our lungs.”
If the air sacs then become inflamed, Wilson says this causes an “outpouring of inflammatory material [fluid and inflammatory cells] into the lungs and we end up with pneumonia.”
He says lungs that become filled with inflammatory material are unable to get enough oxygen to the bloodstream, reducing the body’s ability to take on oxygen and get rid of carbon dioxide.
“That’s the usual cause of death with severe pneumonia,” he says.
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