SOURCE: MAYO CLINIC

Español

Where Do Coronaviruses Come From

Coronaviruses are common in many different species of animals, including camels and bats. Rarely, these coronaviruses can evolve and infect humans and then spread between humans. Recent examples of this include SARS-CoV and MERS-CoV.

Most coronaviruses infect animals, but not people. In the future, one or more of these other coronaviruses could potentially evolve and spread to humans, as has happened in the past. We still don’t understand why only certain coronaviruses are able to infect people.

Common human coronaviruses

Common human coronaviruses, including types 229E, NL63, OC43, and HKU1, usually cause mild to moderate upper-respiratory tract illnesses, like the common cold. Most people get infected with these viruses at some point in their lives. These illnesses usually only last for a short amount of time. Symptoms may include

• runny nose
• headache
• cough
• sore throat
• fever
• a general feeling of being unwell

Human coronaviruses can sometimes cause lower-respiratory tract illnesses, such as pneumonia or bronchitis. This is more common in people with cardiopulmonary disease, people with weakened immune systems, infants, and older adults.

Transmission

Human coronaviruses most commonly spread from an infected person to others through

• the air by coughing and sneezing
• close personal contact, such as touching or shaking hands
• touching an object or surface with the virus on it, then touching your mouth, nose, or eyes before washing your hands
• rarely, fecal contamination

In the United States, people usually get infected with common human coronaviruses in the fall and winter. However, you can get infected at any time of the year. Most people will get infected with one or more of the common human coronaviruses in their lifetime. Young children are most likely to get infected. However, people can have multiple infections in their lifetime.

Other human coronaviruses

Most people confirmed to have MERS-CoV infection have had severe respiratory illness with symptoms of:

• fever
• cough
• shortness of breath

Some people also had diarrhea and nausea/vomiting. For many people with MERS, more severe complications followed, such as pneumonia and kidney failure. About 3 or 4 out of every 10 people reported with MERS have died. Most of the people who died had a pre-existing medical condition that weakened their immune system, or an underlying medical condition that hadn’t yet been discovered. Medical conditions sometimes weaken people’s immune systems and make them more likely to get sick or have severe illness.

Pre-existing conditions among people who got MERS have included

• diabetes
• cancer
• chronic lung disease
• chronic heart disease
• chronic kidney disease

Some infected people had mild symptoms (such as cold-like symptoms) or no symptoms at all.

The symptoms of MERS start to appear about 5 or 6 days after a person is exposed, but can range from 2 to 14 days.

The coronavirus that originated in Wuhan, China, raised global concerns but, after a two day meeting, the World Health Organization has issued a statement saying the situation is not yet an emergency of international concern.

Meanwhile, the Centers for Disease Control and Prevention is monitoring the situation and will provide updated information as it becomes available.
In addition, Mayo Clinic continues to closely monitor the coronavirus outbreak and says staff is trained and prepared to care for patients, should the need arise.
Dr. Pritish Tosh, a Mayo Clinic infectious diseases specialist, says health care providers need to ask patients with respiratory illness and fever about their recent travel.
“It’s important we focus on patients with fever and respiratory symptoms, not just for the novel coronavirus, but also for other respiratory viruses that are circulating, such as influenza,” says Dr. Tosh. “Once these patients are identified, they should be given a mask to wear and put into a room where a health care provider can ask them about recent travel.”
Dr. Tosh adds, “They may have been to a part of the Middle East where there is ongoing MERS (Middle East respiratory syndrome) infections. They may also have been in Wuhan, China, or been close to someone who has been there.”
The coronavirus is in the same family of viruses as SARS (severe acute respiratory syndrome) and MERS.