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oronaviruses are types of viruses
that typically affect the respiratory tract of mammals, including humans. They
are associated with the common cold, pneumonia, and severe acute respiratory
syndrome (SARS) and can also affect the gut.
A coronavirus was first isolated in
1937 from an infectious bronchitis virus in
birds that has the ability to seriously devastate poultry stocks.
These viruses are responsible for between 15 and 30
percent of common colds.
Over the last 70 years, scientists have found that
coronaviruses can infect mice, rats, dogs, cats, turkeys, horses, pigs, and cattle. Most
recently, authorities identified a coronavirus outbreak in China that has now
reached other countries.
This MNT
Knowledge Center article will focus on the different types of human
coronaviruses, their symptoms, how they are transmitted, and two particularly
dangerous diseases that can be caused by coronaviruses: SARS and MERS.
Fast facts on coronaviruses
- There
is no cure for the common cold.
- A
coronavirus causes both SARS and MERS.
- Coronaviruses
infect many different species.
- There
are six known human coronaviruses.
- SARS
spread from China to cause infection in 37 countries, killing 774 people.
Share on PinterestCoronaviruses
can cause flu-like symptoms and respiratory symptoms.
Human coronaviruses (HCoV) were first identified in the
1960s in the noses of patients with the common cold. Two human coronaviruses
are responsible for a large proportion of common colds OC43 and 229E.
Coronaviruses were given their name based on the crown-like
projections on their surfaces. “Corona” in Latin means “halo” or “crown.”
Among humans, infection most often occurs during the winter
months as well as early spring. It is not uncommon for a person to become ill
with a cold that is caused by a coronavirus and then catch it again about four
months later.
This is because coronavirus antibodies do not last for a
very long time. Also, the antibodies for one strain of coronavirus may be
useless against other strains.
Cold- or flu-like symptoms usually set in from two to four
days after coronavirus infection, and they are typically mild. However,
symptoms vary from person to person, and some forms of the virus can be fatal.
Symptoms include:
- sneezing
- a runny nose
- fatigue
- a cough
- in rare cases, fever
- a sore throat
- exacerbated asthma
Human coronaviruses cannot be cultivated in the laboratory
easily, unlike the rhinovirus, another cause of the common cold. This makes it
difficult to gauge the coronavirus’ impact on national economies and public
health.
There is no cure, so treatments include taking care of
yourself and over-the-counter (OTC) medication:
- Rest and avoid overexertion.
- Drink enough water.
- Avoid smoking and smoky areas.
- Take acetaminophen, ibuprofen
or naproxen to reduce pain and fever.
- Use a clean humidifier or cool
mist vaporizer.
The virus responsible can be diagnosed by taking a sample of
respiratory fluids, such as mucus from the nose, or blood.
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Different types of human coronaviruses vary in the severity
of illness they cause and how far they can spread.
There are currently seven recognized types of coronavirus
that can infect humans.
Common types include:
- 229E (alpha coronavirus)
- NL63 (alpha coronavirus)
- OC43 (beta coronavirus)
- HKU1 (beta coronavirus)
Rarer, more dangerous types include MERS-CoV, which causes
Middle East Respiratory Syndrome (MERS), and severe acute respiratory syndrome (SARS-CoV),
the coronavirus responsible for SARS. In 2019, a dangerous new strain started
circulating, but it does not yet have an official name. Health authorities are
currently referring to it as 2019 Novel Coronavirus (2019-nCov).
Share on PinterestContagious
diseases can spread through coughing without covering the mouth.
There has not been a great deal of research on how a human
coronavirus spreads from one person to the next.
However, it is believed that the viruses transmit using
secreted fluid from the respiratory system.
Coronaviruses can spread in the following ways:
- Coughing and sneezing without
covering the mouth can disperse droplets into the air, spreading the
virus.
- Touching or shaking hands with
a person that has the virus can pass the virus from one person to another.
- Making contact with a surface
or object that has the virus and then touching your nose, eyes, or mouth.
- On rare occasions, a
coronavirus may spread through contact with feces.
People in the U.S. are more likely to contract the disease
in the winter or fall. The disease is still active during the rest of the year.
Young people are most likely to contract a coronavirus, and people can contract
more than one infection over the course of a lifetime. Most people will become
infected with at least one coronavirus in their life.
It is said that the mutating abilities of the coronavirus
are what make it so contagious.
To prevent transmission, be sure to stay at home and rest
while experiencing symptoms and avoid close contact with other people. Covering
the mouth and nose with a tissue or handkerchief while coughing or sneezing can
also help prevent the spread of a coronavirus. Be sure to dispose of any used
tissues and maintain hygiene around the home.
In 2019, the Centers for Disease Control and Prevention
(CDC) started monitoring the outbreak of a new coronavirus.
Authorities first identified the virus in Wuhan, China. They have named it 2019
Novel Coronavirus (2019-nCov).
More than 1,000 people have contracted the virus in China.
Health authorities have identified several other people with 2019-nCov around
the world, including five individuals in the United States. On January 31,
2020, the virus passed from one person to another in the U.S. The World Health
Organization (WHO) have declared a public health emergency relating to 2019-nCov.
Some of the first people with 2019-nCov had links to an
animal and seafood market. This initially suggested that animals transmit the
virus to humans. However, people with a more recent diagnosis had no
connections with or exposure to the market, suggesting that humans can pass the
virus to each other.
Information on the virus is scarce at present. In the past,
respiratory conditions that develop from coronaviruses, such as SARS and MERS,
have spread through close contacts.
However, while some viruses are highly contagious, it is
less clear with coronaviruses as to how rapidly they will spread.
Symptoms vary from person to person with a 2019-nCov infection. It
may produce few or no symptoms. However, it can also lead to severe illness and
may be fatal. Common symptoms include:
- fever
- breathlessness
- cough
It may take 2–14 days for a person to notice symptoms after
infection. As of January 31, 2020, the virus carries a death rate of 10%, according to a study of 99 people with 2019-nCov.
No vaccine is currently available for 2019-nCov. However,
scientists in China and now Australia have replicated the virus. This could allow
for early detection and treatment in people who have the virus but are not yet
showing symptoms.
Severe acute respiratory syndrome (SARS) was a contagious
disease caused by the SARS-CoV coronavirus. It typically led to a
life-threatening form of pneumonia.
The virus started off in the Guangdong Province in southern
China in November 2002, eventually reaching Hong Kong. From there, it rapidly
spread around the world, infecting people in 37 countries.
SARS-CoV is unique. It can infect both the upper and lower
respiratory tract and can also cause gastroenteritis.
The symptoms of SARS develop over the course of a week and
start with a fever. Early on in the condition, people develop flu-like
symptoms, such as:
- dry coughing
- chills
- diarrhea
- breathlessness
- aches
Pneumonia, a severe lung infection, may develop afterward.
At its most advanced stage, SARS causes failure of the lungs, heart, or liver.
During the epidemic, there were 8,098 confirmed cases of
SARS with 774 fatalities. This is equal to a mortality rate of 9.6 percent.
Complications were more likely in older adults, and half of all infected people
over the age of 65 years who became ill did not survive. It was eventually
brought under control in July 2003.
Share on PinterestMERS is
a potentially fatal coronavirus.
MERS, caused by the MERS-CoV coronavirus, was first
recognized in 2012. This severe respiratory illness first surfaced in Saudi
Arabia and, since then, has spread to other countries. The virus has reached
the U.S., and the largest outbreak outside the Arabian Peninsula occurred in
South Korea in 2015.
Symptoms include fever, breathlessness, and coughing. The illness
spreads through close contact with people who have already been infected.
However, all cases of MERS are linked to individuals who have recently returned
from travel to the Arabian Peninsula.
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