Tuesday September 25 2012
Coronaviruses are named for their crown-like projections
A new “SARS-like” virus has been detected in the UK, according to widespread media reports. The headlines are based on press releases from the UK’s Health Protection Agency (HPA) and the World Health Organization (WHO) about a new coronavirus.
SARS (severe acute respiratory syndrome) is a serious and potentially life-threatening viral infection that mostly affects the lungs. SARS is caused by a family of viruses known as coronaviruses. These types of virus can vary widely in their severity. Some types of coronaviruses can just trigger the symptoms of a common cold. Others can be life threatening.
There was a large outbreak of cases (pandemic) of SARS that occurred during 2002 and 2003, with most cases being confined to east Asia.
The HPA has confirmed the diagnosis of a severe respiratory illness associated with a new type of coronavirus in one man from Qatar, in the Middle East, who is receiving intensive care treatment in an NHS London hospital.
The man had travelled to Saudi Arabia and has had the infection diagnosed after travelling to London. The HPA reports that this human coronavirus was also identified in a patient with acute respiratory illness in Saudi Arabia, who has since died. The HPA says that preliminary enquiries have revealed no evidence of illness among people who have had contact with these two cases, including any healthcare workers.
The HPA says it is aware of a small number of cases of serious respiratory illness in the Middle East in the past three months, which it is investigating further. The HPA reports no evidence at present of a link to suggest these illnesses were caused by the same virus or indeed linked to the two confirmed cases. No other confirmed cases have been identified to date in the UK.
What are coronaviruses?
Coronaviruses are a group of viruses that cause respiratory infections (such as the common cold) in humans and animals. Coronaviruses can also include strains that cause more severe illness, such as the virus responsible for SARS.
Human coronaviruses were first identified in the mid-1960s and are named after their crown-like projections on the surface of the virus. The HPA reports that this new virus, confirmed in two people worldwide, is different from any that have previously been identified in humans.
Coronaviruses are fairly fragile, and outside of the body their survival time is only around 24 hours. They are easily destroyed by usual detergents and cleaning agents.
What official advice has been given?
The HPA reports that there is not enough information at this stage to make specific treatment recommendations. However, it is likely that the standard treatment protocol for people with serious respiratory infections (such as admission to hospital and the use of ventilators, if required, to assist with breathing) is currently being used to treat the patient.
Professor John Watson, head of the respiratory diseases department at the HPA, said: “Further information about these cases is being developed for healthcare workers in the UK, as well as advice to help maintain increased vigilance for this virus. This information is also being shared with national and international authorities including the World Health Organization and the European Centre for Disease Control.
“At present there is no specific advice for the public or returning travellers to take but we will share any further advice with the public as soon as more information becomes available.”
The World Health Organization (WHO) is seeking further information about the two confirmed cases and is not recommending any travel restrictions.
Why was the patient with this infection allowed entry to the UK?
Many of the details surrounding this case are being kept out of the media for reasons of patient confidentiality.
The facts that have been made public are that a Qatari national who developed a severe chest infection flew into the UK to seek treatment at a private hospital. That he had this new type of viral infection was not established until after his arrival.
Once the nature of his condition became known, he was transferred to an (as yet unnamed) NHS facility.
It is also unclear whether the man had any pre-existing health conditions that made him more vulnerable to the effects of the infection.
How do new viruses come about?
Like all living species, viruses change and evolve over generations. Mutations occur when some of the genetic information that is stored inside an organism changes. Because viruses replicate so quickly, there is a greater chance for genetic mutations to occur. Mutations can occur randomly, and most are not particularly significant. However, a mutation sometimes changes the outer surface proteins of a virus. These proteins determine which cells of which species a virus is able to infect. By rare chance, the mutated virus may develop the ability to infect humans.
Many of the worldwide epidemics (known as pandemics) that have occurred in recent history are thought to have been caused by a virus found in animals, which was previously incapable of infecting humans, but then mutated to become capable of infecting humans. Some examples of this include:
- SARS: thought to be a mutated version of a virus found in small mammals called civet cats, which are a popular delicacy in the region
- HIV: thought to be a mutated version of a virus found in monkeys
- avian flu: a mutated version of a flu virus found in birds
- swine flu: thought to have originated in pigs
What happened during the SARS epidemic?
The SARS epidemic that occurred in 2002 and 2003 originated in southern China. It is thought that a strain of the coronavirus, usually only found in animals, mutated to enable it to infect humans.
The SARS infection quickly spread from mainland China to other Asian countries and a small number of cases appeared in countries further afield, including the UK. These were understood to be caused by infected travellers. The SARS pandemic was eventually brought under control in July 2003 following isolation of all suspected cases and screening of all air passengers travelling from affected countries for signs of the infection.
During the period of infection, there were 8,096 cases of SARS and 774 deaths. This means that the virus killed about 1 in 10 people who were infected (the case fatality rate, or CFR).
A CFR of 10% is exceptionally high compared with most viral infections, and explains why so much effort went into containing the spread of SARS. (It is rare because a virus that kills its host is, in long-term biological terms, “doomed”, as it is eventually going to run out of hosts in which to reproduce.)
People over the age of 65 were particularly at risk. As many as half the people in this age group died from the SARS infection.
How likely is it that the virus will spread?
Coronaviruses are typically spread like other respiratory infections such as influenza (the flu). This new infection is therefore likely to be passed from person to person when an infected person coughs or sneezes.
In terms of how contagious the virus is, the HPA notes that as with any newly identified virus, it is better to err on the side of caution. Infection-control precautions to prevent the spread of the virus are therefore being taken in the case of the confirmed case in London, including isolation of the patient, barrier nursing (such as erecting screens around the bed) and making sure that all staff wear the appropriate protective equipment, such as masks. The HPA notes that not much is known at this stage but that no other confirmed cases have been identified in the UK.
The HPA currently estimates that the virus is not highly contagious. This estimation is based on several factors, including:
- There have only been two confirmed cases in the last few months, as opposed to the swine flu pandemic, which spread from Mexico to across the globe in a matter of months.
- There have been no reports of healthcare professionals involved with the patient succumbing to infection. This is in sharp contrast with the SARS epidemic, which quickly spread through hospital staff in China.
Most virologists would agree that there is no need to rush out and buy face masks.
Professor John Watson of the HPA said: “In light of the severity of the illness that has been identified in the two confirmed cases, immediate steps have been taken to ensure that people who have been in contact with the UK case have not been infected, and there is no evidence to suggest that they have.”
I have just visited the Middle East and now I have signs of a cold/fever – what should I do?
The first thing is not to panic. It is highly likely that you just have a cold or the flu.
But if symptoms worsen or you experience significant breathlessness, contact your GP for advice. If this is not possible then call NHS Direct on 0845 46 47.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.