Dry cough, fever and difficulty breathing are the most common symptoms of COVID-19, but specialists are starting to learn more about less common potential symptoms such as loss of one's sense of smell, disorientation and even seizures.

Some doctors are trying to understand how widespread these symptoms are in order to assist with diagnosing patients.

Dr. Sherry Chou, a Canadian neurologist at the University of Pittsburgh Medical School with training in critical care and strokes, said it's important to know whether a small portion of patients with COVID-19 present with neurological symptoms rather than fever or cough.

"We need to figure that out as quickly as we can because we need to know to screen those patients for COVID-19," Chou said.

Effective screening is an important way to slow the spread of the virus, which has killed more than 420 Canadians.

Patients with neurological symptoms would also require different treatment than those with respiratory symptoms, Chou said.

What a team of specialists is looking for

To learn more, Chou is leading a team of investigators from the Neurocritical Care Society, an international organization of health-care providers based in Chicago whose goal is to improve outcomes for patients with life-threatening brain and spinal cord injuries.

The specialists caution the research is at an early hypothesis stage and they still need to find out specifically how the pandemic virus affects the neurological system, or whether, for example, such symptoms simply result from low oxygen levels in the blood.

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Deborah Copaken, an author in New York, has been sick with COVID-19 since March 18. Her main symptom is not being able to take a deep breath. She said she's exhausted and was prescribed a nebulizer and inhaler to help with her breathing.

Then, on March 23, Copaken decided to reorganize her spice rack.

"I started taking the spices out of their old containers and putting them in new containers and I realized I had to label the containers quickly because I couldn't smell anything," Copaken recalled in an interview. "I couldn't differentiate between, say, basil and herbs de Provence. All the green spices smell the same."

Her husband and youngest son were also infected. Their symptoms were a bit different.

Copaken said her husband endured three days of intense fever and was unable to get out of bed. He also had diarrhea — another of the less common symptoms that have caught the attention of researchers.

Her 13-year-old son lost his senses of taste and smell and ate less than normal for a few days but was otherwise fine, she said.

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In another case, Kym Murphy of New Brunswick experienced a painful headache and fatigue.

"I was shocked that it came back positive," Murphy said of her COVID-19 test in Saint John. "I didn't have the fever. I didn't have the shortness of breath. I didn't have the coughing, but I just felt that there was something not right."

In Italy, where there have been more than 135,000 cases, physicians set up separate units to treat patients with COVID-19 who also have neurological symptoms that resemble a type of encephalitis, which is an inflammation of the brain that is more common as a rare complication of influenza or flu in children.

Encephalitis can have many underlying causes such as viral or bacterial infections.

Chou cautioned it is too soon to comment on what neurologists are seeing with COVID-19 because the numbers are so small.

CT scan for stroke

Dr. Erin O'Connor is an emergency room physician at Toronto General Hospital, where she said they're seeing some suspected COVID-19 patients who have respiratory symptoms as well as nausea and other stomach discomfort and difficulty with their senses of smell and taste.

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"It seems to be more of a loss of sense of smell without having the runny nose and the blocked nose at the same time," O'Connor said.

She said there are anecdotes circulating in the medical community about how stroke-like symptoms could also be an indication of COVID-19 as well.

"All of our patients who present with stroke symptoms we're testing and we're actually doing … CT scans on their chest as well to look for signs of COVID infections," O'Connor said.

The U.S. Centers for Disease Control and Prevention lists emergency warning signs associated with severe cases of COVID-19 that warrant immediate medical attention. They include:

Trouble breathing.

Persistent chest pain or pressure .

. Bluish lips or face.

New confusion or lethargy.

The agency cautioned the list is not all inclusive and people are advised to consult a health-care provider for any other symptoms that are severe or concerning.