Corona strains: Watch out for the changing viral behaviour

A researcher prepares reagents for testing the samples for the Covid-19 coronavirus at the laboratory of Kenya Medical Research Institute on April 23, 2020.

Photo credit: File | Nation Media Group

What you need to know:

  • Some people have had less typical symptoms, including nausea, diarrhea, delirium, loss of smell and taste.
  • As blood oxygen levels begin to reduce, a person may experience shortness of breath, also called dyspnea.

Fever, dry cough, fatigue, sore throat, headache and muscle pains are the common symptoms of Covid-19. To the layman, these are the clear signs that your body’s immune system is fighting the virus.

But those aren’t the only symptoms that have been linked to the respiratory infection. Some people have had less typical symptoms, including nausea, diarrhoea, delirium, loss of smell and taste.

Scientists have been learning more about the virus and the new ways it affects the body. Of all the new symptoms — such as stroke and blood clotting, and in children, the rare Kawasaki disease and purple toe rashes — ‘silent hypoxia’ might be the most confusing.

“Respiratory symptoms tend to be the most common, obviously, but we’ve also seen symptoms that involve other organ systems,” Dr Yubrine Moraa, an internal medicine expert, told the Nation.

Among the more baffling mysteries of the pandemic has been the frequency of a decrease in the partial pressure of oxygen in the blood, a phenomenon scientifically known as silent hypoxemia, (happy hypoxia).

Director-General’s warning

As blood oxygen levels begin to reduce, a person may experience shortness of breath, also called dyspnea. If blood oxygen levels continue to fall, the organs may shut down, and the issue becomes life-threatening.

 Given that Covid-19 is a respiratory illness, and a severe case can reduce the amount of oxygen that the lungs can absorb, prompting the need for supplementary oxygen or ventilation. In some patients, blood oxygen levels have been found to be very low.

Normal blood-oxygen saturation is between 95 and 100 per cent. Low oxygen levels in the body — also known as hypoxia — can lead to shortness of breath, which is one of the most well-known symptoms. But just because a patient does not appear ill, doesn’t mean they are not infected, said Director-General of Health Dr Patrick Amoth.

“You can have a serious symptom and not know until you present yourself to hospital,” he warned. Increasingly, patients are presenting with “silent” or “happy hypoxia”, a condition where the body’s oxygen levels are well below 90 per cent, yet they are still able to breathe normally without shortness of breath, fast or shallow breathing, and likely no signs, symptoms, or sense that something may be off.

Patients are often unaware their bodies are deprived of oxygen and while they should be gasping for air, they appear to be perfectly normal and comfortable, explained Dr Amoth.

A new study published last month provides possible explanations for Covid-19 patients who present with extremely low, otherwise life-threatening levels of oxygen, but no signs of difficulty in breathing (dyspnea).

“The condition is especially bewildering to physicians as it defies basic biology,” said the study authors.

The research, published in the American Journal of Respiratory and Critical Care Medicine, described the phenomenon as ‘confusing’ and ‘bewildering’.

“In some instances, the patient is comfortable and using a phone at a point when the physician is about to insert a breathing (endotracheal) tube and connect the patient to a mechanical ventilator which while potentially lifesaving carries its own set of risks,” said Dr Martin J. Tobin, the lead author of the study which included 16 Covid-19 patients with very low levels of oxygen (as low as 50 per cent; normal blood oxygen saturation is between 95 and 100 per cent), without shortness of breath or dyspnea.

More classic symptoms

People with vague (atypical) symptoms of the infection may develop more classic symptoms as well, such as fever, muscle aches, sore throat, and trouble breathing.

“Individuals differ and therefore, the same disease might present with entirely different symptoms from one individual to the next. That is why we are advising people to go to the hospital should they detect any change in their body,” Dr Moraa added.

According to Dr Moraa, learning about some less common symptoms may help both the public and clinicians recognise Covid-19 a bit faster before the patient presents to the hospital too late. For this to happen, doctors as well as the public must have a high index of suspicion.

“We have seen patients collapse and die of heart attacks or develop strokes soon after they arrive in hospital. Others have become too sick to even get to the nearest facility,” she commented.

In June the Centres for Disease Control (CDC) added loss of taste or smell to its list of Covid-19 symptoms after scientists at the University of California, San Diego studied responses from 59 patients. Increasingly, Kenyan patients who test positive for the virus are also reporting that they cannot taste or smell.

Other relatively new symptoms include diarrhoea, acute kidney failure, low blood pressure due to inflammation of the heart muscles.

“As we are learning this virus, we are noticing symptoms that are not a classic presentation of Covid-19 such as personality changes of confusion because the virus has affected their central nervous system,” Dr Moraa added.

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