The ‘halo bug’ bites

GROWING concern over the MERS virus continues as the death toll rises in neighbouring Saudi Arabia from what experts describe as the ‘halo bug’.

MERS-CoV infection generally presents as pneumonia, but has also caused kidney failure. The most common symptoms observed are fever, cough and breathing difficulties.

Last week Saudi Arabia announced 16 new deaths from MERS, raising the death toll to 168 since it first appeared two years ago.

Coronaviruses are species of RNA (ribonucleic acid) viruses. They are called coronaviruses because under an electron microscope the virus appears to have a characteristic crown or halo around it.

There are many species and strains of coronavirus which have different characteristics, causing a range of clinical signs – from mild to severe disease – in humans and in different animal species. Several different species of coronavirus infect both animals and humans.

The World Organisation of Animal Health (OIE), a global organisation with headquarters in the French capital of Paris, has issued a special question and answer document, to offer facts and figures behind the outbreak and urge more research into its link to camels.

MERS-CoV is a particular strain of coronavirus which is thought to cause Middle East Respiratory Syndrome (MERS). The respiratory disease had not been reported in humans before April 2012. The majority of reported cases are a result of human-to-human transmission, although in some cases the origin of human infection is unexplained.

MERS-CoV and antibodies to MERS-CoV have also been detected in samples taken from camels.
 
Although recent studies suggest that camels may be a source of some human infections the exact relationship between MERS-CoV infections in humans and animals remains unclear and further investigations are needed.

OIE together with its partner organisations the World Health Organisation (WHO), the Food and Agriculture Organisation (FAO) and national animal health authorities of affected countries, is closely following investigations which aim to better understand the epidemiological aspects of the disease.

There is the possibility for several potential routes of transmission within and between species. So far, three patterns of infection have been reported:
* Community acquired cases (the exposure sources remains unknown and are believed to  include direct or indirect contact with animals, especially camels, or environmental source)
* Hospital acquired infections
* Infection acquired through close household human-to-human contact
Between November 2013 and May 2014 Qatar also reported to OIE that MERS-CoV has been identified in four camels.
 
Current evidence does not indicate that MERS-CoV causes significant illness in camels. According to published literature other species of animals, including sheep, goats, cows, water buffalo and wild birds, have tested negative.

It is important to remain open-minded about all potential sources of exposure for human and camel cases until more information is available, the OIE says. It is working closely with its partner organisations to collate and share data to gain a better understanding about the possible disease situation in animals and to assess implications for animal and human health.

WHO advises travellers to avoid close contact with people suffering from acute respiratory infections, wash hands frequently, especially after direct contact with ill people or their environment, adhere to food safety and hygiene rules such as avoiding undercooked meats, raw fruits and vegetables unless they have been peeled, or unsafe water and avoid close contact with live farm or wild animals.

Scientists leading the fight against MERS say the next critical front will be understanding how the virus behaves in people with milder infections, who may be spreading the illness without being aware they have it.

Establishing that may be critical to stopping the spread of MERS, which emerged in the Middle East in 2012 and has so far infected more than 500 patients in Saudi Arabia alone. It kills about 30 per cent of those who are infected.