A coronavirus was first isolated in 1937 - it was an avian infectious bronchitis virus which had (and still has) the ability to seriously devastate poultry stocks. According to the Health Protection Agency (HPA), UK, it can also infect the uro-genital tract of chickens, and eventually spread to various organs in its body.
Over the last 70 years, scientists have found that related coronaviruses can infect mice, rats, dogs, cats, turkeys, horses, pigs and cattle.
- What are human coronaviruses?
- Coronavirus symptoms and treatments
- What is the novel coronavirus (NCoV)?
- NCoV transmission
- Symptoms of NCoV infection
- How many human coronaviruses are there?
Here are some key points about coronaviruses. More detail and supporting information is in the main article.
- Coronaviruses cause up to 30% of common colds.
- There is no cure for the common cold.
- SARS and MERS are both caused by coronavirus.
- Coronavirus infect many different species.
- The novel coronavirus (NCoV) first appeared in the Middle East in 2012.
- NCoV has claimed nearly 500 lives since 2012.
- There are six known human coronaviruses.
- SARS spread from China to infect people in 37 countries, killing 774 people.
What are human coronaviruses?Human coronaviruses (HCoV) were first identified in the 1960s from the naval cavities of patients with the common cold. Approximatley 30% of common colds are caused by two human coronaviruses - OC43 and 229E.
Coronaviruses are thus called because of their crown-like projections on their surfaces. "Corona" in Latin means "halo" or "crown."
Coronaviruses viewed under an electron microscope, with their halo, or crown-like (corona) appearance
Scientists know of several coronavirus strains that can infect humans. One of the strains, known as SARS-CoV, causes SARS (Severe Acute Respiratory Syndrome). SARS is the most widely-reported coronavirus, alongside the "Novel Coronavirus" (also called Novel Coronavirus 2012, or London1_novel CoV 2012).
SARS-CoV is completely different from all other known coronaviruses - it is unique in that it can infect both the upper and lower respiratory tract - it can also cause gastroenteritis.
Human coronaviruses are said to account for between 10% and 30% of all common colds. Incidence of infection among humans is highest during the winter months as well as early spring. It is not uncommon for somebody to become ill with a coronavirus cold, and then to catch it again about four months later. Experts say this is because coronavirus antibodies do not last for very long - also, the antibodies for one coronavirus strain may be useless against other strains.
Scientists say the coronavirus' ability to mutate is what makes it so contagious.
Coronavirus symptoms and treatmentsCold- or flu-like symptoms usually set in from two to four days after coronavirus infection, and they are typically mild. Symptoms include:
There is no cure, so treatments include taking care of yourself and over-the-counter medication:
- 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.
What is the novel coronavirus?The novel coronavirus (NCoV) is a new strain that emerged in 2012 in the Middle East. Also known as Middle East respiratory syndrome (MERS), it was first discovered in early 2012 when a man in Saudi Arabia became ill with SARS-like symptoms - he subsequently died in June 2012.
In September 2012, a patient from Qatar who had recently traveled to Saudi Arabia was transferred to the United Kingdom for treatment; he suffered severe respiratory problems as well as renal failure.
When samples from both the Qatari and Saudi patients were tested, scientists found that they had been infected with the same virus - the 'novel coronavirus'.
NCoV is sometimes referred to as the "Saudi SARS" informally, in order to differentiate it from the SARS pandemic that occurred in 2002/2003 (Hong Kong/Canadian SARS).
In mid-November 2012, the HPA published the complete genome sequence for the first UK patient who was infected with NCoV. The Agency said that this will help researchers in their quest to determine the origin of the virus, its diversity, as well as developing strategies for prevention and treatment.
Since 2012, sporadic cases, small clusters, and large outbreaks of illness have been reported in 24 countries, with over 1,300 lab-confirmed cases of the virus and over 480 deaths (two in the US). It appears to cross from human to human, but not with great ease.
Another NCoV outbreak reared its head in South Korea in July 2015. In total, 186 MERS-CoV cases were reported, which included 33 deaths.
Some believe MERS might spread from camel to human.
Experts say that some may have been infected by close contact with animals, people or a combination.
More recently, evidence has shown that the virus may be able to travel between camel and human. In November 2013, a man became ill with NCoV after tending to a sick camel. The man eventually died.
DNA samples from the man and the camel were virtually identical which provides strong evidence that the man had indeed picked up the virus from the camel.
Symptoms of NCoV infectionAccording to WHO (World Health Organization), in confirmed cases of human illness, the most common signs and symptoms have been:
- Acute serious respiratory illness
- Shortness of breath
- Breathing difficulties
- Diarrhea (rare).
The novel coronavirus does not appear to transmit easily between people, which is a major difference from the SARS-CoV, which was much more human transmissible.
Currently there is no treatment for NCoV.
How many human coronaviruses are there?During the SARS pandemic of 2002/2003, virologists became much more interested in coronaviruses. From the mid 1960s until 2002, we only knew about two coronaviruses - HCoV-229E and HCoV-OC43.
Then SARS-CoV was discovered in 2002/2003, adding another human coronavirus to the list.
By the end of 2004, a fourth human coronavirus was discovered. As several labs discovered it, there has been some controversy regarding this fourth human coronavirus' name. Various research groups refer to it as NL63 (New Haven coronavirus).
In 2005, a fifth human coronavirus was discovered at the University of Hong Kong in two patients with pneumonia. They named it HKU1
In 2012, the Novel Coronavirus was discovered, as described earlier in this text. It is most commonly known as NCoV or Novel coronavirus 2012.
Another coronavirus was discovered in a patient who presented with pneumonia and renal (kidney) failure - known as HCoV-EMC/2012. Virologists say it is a close relative to the BtCoV-HKU4 ( Tylonycteris bat coronavirus) and BtCoV-HKU5 ( Pipistrellus bat coronavirus HKU5), which prototype two species in lineage C of the genus Betacoronavirus.
The following human coronaviruses are currently known to virologists:
- NL63/NL/New Haven coronavirus
SARS (SARS CoV)SARS (Severe Acute Respiratory Syndrome) was a contagious disease caused by SARS CoV (SARS coronavirus). It typically led to a life-threatening form of pneumonia. SARS started off in the Guangdong Province in southern China in November 2002. Eventually it reached Hong Kong, from where it rapidly spread around the world, infecting people in 37 countries.
During the epidemic (many called it a pandemic), there were 8,098 confirmed cases of SARS, 774 of them died - a death rate of 9.6%. 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. For more comprehensive information on SARS, go to "What is SARS? What are the symptoms of SARS?".
Written by Christian Nordqvist