Coronaviruses are a large family of viruses that cause diseases ranging from the common cold to the severe acute respiratory syndrome (SARS).
According to the World Health Organisation, the SARS outbreak in 2003 affected 8,098 people, in more than two dozen countries, with 774 deaths, before it was controlled.
The Middle East Respiratory Syndrome (MERS) is a respiratory illness caused by the Middle East Respiratory Syndrome Coronavirus, or MERS-CoV.
This virus, which was first reported in 2012 in Saudi Arabia, is different from any other coronavirus previously found in humans. Since then, cases have been identified elsewhere in the Arabian peninsula, Asia, Europe, Africa and the United States.
MERS-CoV has been deemed a potential serious public health epidemic threat because millions of pilgrims converge in Saudi Arabia annually for the Haj pilgrimages.
The exact source of MERS-CoV and its mode of transmission to humans has still to be fully elucidated. A coronavirus that is very similar to MERS-CoV has been isolated from camels in Saudi Arabia, Oman, Qatar and Egypt.
However, no trace of MERS-CoV have been found in tests on animals like cows, goats, sheep and wild birds. As such, the belief is that the likely source of infection in humans are camels.
How humans are infected by MERS-CoV is still not well understood. It is possible that some individuals get infected following direct or indirect contact with camels, the former from the camels’ nasal discharge, saliva or perhaps, excreta, and the latter from meat handling or the consumption of unpasteurised camel dairy products, which is not uncommon in Saudi Arabia.
Human-to-human transmission has occurred in situations where there is direct contact with an infected patient.
The majority of such clusters of cases have occurred in healthcare settings involving patients, their family members, doctors and nurses, especially when the infected patient is provided unprotected care.
The precise mechanism of the spread of the virus from an infected patient is not well understood. It has been assumed that spread has been mainly through large droplets and contact, although there is the possibility of airborne or fomite transmission.
Managing the condition
Severe infection is more likely to occur in the elderly and patients with chronic conditions like obesity, diabetes, cancer, chronic lung disease, kidney failure and impaired immunity.
However, patients without underlying diseases can also be infected, although most develop asymptomatic or mild clinical disease.
The clinical manifestations of MERS are non-specific, thus hampering early diagnosis. Some infected persons have no symptoms or mild cold-like symptoms. The incubation period has been estimated to be more than five days, but could be as long as two weeks,
MERS typically begins with fever, cough, chills, sore throat and muscle and joint aches, followed by difficulty breathing, and progressing rapidly to pneumonia within the first week, often requiring care in an intensive care unit with ventilatory and other organ support.
Although most patients present with respiratory illness, the immunocompromised can present with fever, chills and diarrhoea, and later develop pneumonia.
At least a third of patients with MERS have gastrointestinal symptoms, like vomiting and diarrhoea.
About three in four patients with MERS had at least one medical illness, with patients who died more likely to have an underlying condition. Index or sporadic cases from the first wave of the outbreak in 2013 were older and more likely to have severe disease requiring admission to hospital than were secondary cases, who were the only ones who had mild disease or asymptomatic infection.
Mortality rates are high, with three or four out of every 10 infected persons dying. Most of those who succumbed to the infection had an underlying medical condition(s).
The diagnosis of MERS is made by laboratory studies of specimens from the lower respiratory tract and antibody detection.
There is no specific antiviral treatment for MERS-CoV infection and supportive treatment is the mainstay of management.
Medicines can be prescribed to help relieve symptoms. Current treatment of severe cases includes care to support vital organ functions.
Those in close contact with a MERS patient are at higher risk of infection, and have the potential to infect others if they begin to show symptoms.
Close observation of such persons for 14 days from the last day of exposure will help these person(s) obtain care and treatment, and will prevent further transmission of the virus to others.
The monitoring process is termed contact tracing. Initially, it involves contact identification, in which contacts are identified by asking about the activities of the infected person, and the activities and roles of the people around him or her since the onset of illness.
All persons considered to have had significant exposure are listed and they are informed of their contact status, what it means, the actions that will follow, and the importance of receiving early care if they develop symptoms.
The contacts are provided with preventive information, and in some instances, quarantine is required for some contacts, either at home or in hospital for those with a high risk of severe disease if they get infected.
All listed contacts are followed-up daily.
Most MERS infections resulted from person-to-person spread, emphasising the importance of appropriate contact and droplet precautions to prevent viral transmission.
The preventive measures that protect against respiratory illnesses will provide protection against MERS.
Frequent washing of hands with soap and water for 20 seconds is necessary. Alternatively, alcohol-based hand sanitisers can be used.
It is important to cover the nose and mouth with tissue whenever sneezing or coughing, after which the tissue has to be disposed of.
The eyes, nose and mouth should not be touched with unwashed hands. When one is with an ill person, personal contact like kissing and hugging or the sharing of eating utensils, cups or glasses should be avoided.
Objects or surfaces that are often touched, e.g. doorknobs, should be cleaned and disinfected often.
There are still many unanswered questions about MERS. Although it is currently sporadic, everyone should be prepared for the emergence of MERS-CoV with an increased capacity for transmission and pandemic potential.
Dr Milton Lum is a member of the board of Medical Defence Malaysia. The views expressed do not represent that of any organisation the writer is associated with. For further information, e-mail firstname.lastname@example.org. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.