What Does Coronavirus Do to the Body?


As circumstances of coronavirus an infection proliferate round the world and governments take extraordinary measures to restrict the unfold, there may be nonetheless plenty of confusion about what precisely the virus does to individuals’s our bodies.

The signs — fever, cough, shortness of breath — can sign any variety of diseases, from flu to strep to the widespread chilly. Here is what medical consultants and researchers have discovered to date about the development of the an infection attributable to this new coronavirus — and what they nonetheless don’t know.

The virus is unfold by means of droplets transmitted into the air from coughing or sneezing, which individuals close by can soak up by means of their nostril, mouth or eyes. The viral particles in these droplets journey rapidly to the again of your nasal passages and to the mucous membranes in the again of your throat, attaching to a selected receptor in cells, starting there.

Coronavirus particles have spiked proteins protruding from their surfaces, and these spikes hook onto cell membranes, permitting the virus’s genetic materials to enter the human cell.

That genetic materials proceeds to “hijack the metabolism of the cell and say, in effect, ‘Don’t do your usual job. Your job now is to help me multiply and make the virus,’” stated Dr. William Schaffner, an infectious illness specialist at Vanderbilt University Medical Center in Nashville.

As copies of the virus multiply, they burst out and infect neighboring cells. The signs typically begin in the again of the throat with a sore throat and a dry cough.

The virus then “crawls progressively down the bronchial tubes,” Dr. Schaffner stated. When the virus reaches the lungs, their mucous membranes turn into infected. That can injury the alveoli or lung sacs they usually have to work tougher to perform their operate of supplying oxygen to the blood that circulates all through our physique and eradicating carbon dioxide from the blood in order that it may be exhaled.

“If you get swelling there, it makes it that much more difficult for oxygen to swim across the mucous membrane,” stated Dr. Amy Compton-Phillips, the chief scientific officer for the Providence Health System, which included the hospital in Everett, Wash., that had the first reported case of coronavirus in the United States, in January.

The swelling and the impaired flow of oxygen can cause those areas in the lungs to fill with fluid, pus and dead cells. Pneumonia, an infection in the lung, can occur.

Some people have so much trouble breathing they need to be put on a ventilator. In the worst cases, known as Acute Respiratory Distress Syndrome, the lungs fill with so much fluid that no amount of breathing support can help, and the patient dies.

Dr. Shu-Yuan Xiao, a professor of pathology at the University of Chicago School of Medicine has examined pathology reports on coronavirus patients in China. He said the virus appears to start in peripheral areas on both sides of the lung and can take a while to reach the upper respiratory tract, the trachea and other central airways.

Dr. Xiao, who also serves as the director of the Center For Pathology and Molecular Diagnostics at Wuhan University, said that pattern helps explain why in Wuhan, where the outbreak began, many of the earliest cases were not identified immediately.

The initial testing regimen in many Chinese hospitals did not always detect infection in the peripheral lungs, so some people with symptoms were sent home without treatment.

“They’d either go to other hospitals to seek treatment or stay home and infect their family,” he said. “That’s one of the reasons there was such a wide spread.”

As a result, some patients may endure damage that is inflicted not just by the virus, but by their own immune system as it rages to combat the infection.

Experts have not yet documented whether the virus can affect the brain. But scientists who studied SARS have reported some evidence that the SARS virus could infiltrate the brain in some patients. Given the similarity between SARS and Covid-19, the infection caused by the new coronavirus, a paper published last month in the Journal of Medical Virology argued that the possibility that the new coronavirus might be able to infect some nerve cells should not be ruled out.

About 80 percent of people infected with the new coronavirus have relatively mild symptoms. But about 20 percent of people become more seriously ill and in about 2 percent of patients in China, which has had the most cases, the disease has been fatal.

Experts say the effects appear to depend on how robust or weakened a person’s immune system is. Older people or those with underlying health issues, like diabetes or another chronic illness, are more likely to develop severe symptoms.

Dr. Xiao conducted pathological examinations of two people in China who went into a hospital in Wuhan in January for a different reason — they needed surgery for early stage lung cancer — but whose records later showed that they had also had coronavirus infection, which the hospital did not recognize at the time. Neither patient’s lung cancer was advanced enough to kill them, he said.

One of those patients, an 84-year-old woman with diabetes, died from pneumonia caused by coronavirus, Dr. Xiao said the records showed.

The other patient, a 73-year-old man, was somewhat healthier, with a history of hypertension that he had managed well for 20 years. Dr. Xiao said the man had successful surgery to remove a lung tumor, was discharged, and nine days later returned to the hospital because he had a fever and cough that was determined to be coronavirus.

Dr. Xiao said that the man had almost certainly been infected during his first stay in the hospital, since other patients in his post-surgical recovery room were later found to have coronavirus. Like many other cases, it took the man days to show respiratory symptoms.

The man recovered after 20 days in the hospital’s infectious disease unit. Experts say that when patients like that recover, it is often because the supportive care — fluids, breathing support, and other treatment — allows them to outlast the worst effects of the inflammation caused by the virus.

A lot. Although the illness resembles SARS in many respects and has elements in common with influenza and pneumonia, the course a patient’s coronavirus will take is not yet fully understood.

Some patients can remain stable for over a week and then suddenly develop pneumonia, Dr. Diaz said. Some patients seem to recover but then develop symptoms again.

Dr. Xiao said that some patients in China recovered but got sick again, apparently because they had damaged and vulnerable lung tissue that was subsequently attacked by bacteria in their body. Some of those patients ended up dying from a bacterial infection, not the virus. But that didn’t appear to cause the majority of deaths, he said.

Other cases have been tragic mysteries. Dr. Xiao said he personally knew a man and woman who got infected, but seemed to be improving. Then the man deteriorated and was hospitalized.

“He was in I.C.U., getting oxygen, and he texted his wife that he was getting better, he had good appetite and so on,” Dr. Xiao said. “But then in the late afternoon, she stopped receiving texts from him. She didn’t know what was going on. And by 10 p.m., she got a notice from the hospital that he had passed.”



Source link Nytimes.com

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