When a 60-year-old man from Bisha in Saudi Arabias Asir province reported to his local hospital with respiratory problems on 10 June 2012, no one could have predicted he had fallen prey to a new form of coronavirus that has claimed 60 lives to date.
At that time, we did not know anything about MERS-CoV, said Ziad Memish, Saudi deputy minister of public health and a specialist in infectious diseases, speaking at the University of Floridas Emerging Pathogens Institute.A sample was sent to our influenza lab to test for H1N1 [swine flu] and came back negative. It was [only] later in September that we were notified of a new, unusual pathogen: MERS-CoV.
The testing was carried out at the Erasmus Medical Centre (EMC) in the Netherlands and was not without some controversy at the time. The Saudi-based specialist that took the original sample had sought further advice on the unknown virus from the Dutch institute, which subsequently discovered it was a new strain of coronavirus from the same family as SARS (Severe Acute Respiratory Syndrome). The EMC named the new virus HCoV-EMC and promptly became embroiled in a row with the kingdom over intellectual property rights.
In May 2013, the International Committee on Taxonomy of Viruses renamed the illness MERS-CoV. By this point, 44 cases had been reported, most of them in Saudi Arabia, and the number has been steadily rising. At the end of September, 136 cases had been confirmed worldwide, with 114 of these in the kingdom.
As it stands, the situation does not constitute a public health emergency, although the World Health Organisation is carefully monitoring the situation. One concern is that the morbidity rate for the illness is high, with 60 of the 136 cases ending in death. However, a contributing factor to this is that the virus is more easily contracted by those with conditions causing suppressed immune systems.
The pressing problems at the moment as I see them are that we still havent found the source of this virus, says Ali Zumla, professor of infectious diseases and international health at University College London (UCL). My main worry is that the virus may evolve into a more virulent form by mutating. At the moment, it is at levels that should not be worrying.
Research published in mid-September by UCL and the UKs Wellcome Trust Sanger Institute revealed there were three types of the virus in samples taken from cases in Riyadh, likely to have come from animals. A link to bats has been studied and samples examined from 1,000 bats in the kingdom. A 100 per cent genetic match to the Bisha case was found in one sample, but such a small correlation is not considered definitive and the sample itself was not good, said Memish, having been delayed in customs and not kept at the required temperature.
Exactly how the virus spreads is also unknown. Extensive mapping of the existing cases by researchers has discovered human-to-human transmission and spontaneous cases. The symptoms, which include fever, coughing, shortness of breath and a sore throat, are usually more mild in the secondary cases passed between sufferers, with the most severe cases being the original index patients, for whom the source of contraction is as yet unknown.
|MERS-CoV cases as of early October 2013|
|Sources: US Centre for Disease Control and Prevention; Saudi Health Ministry|
What is clear is that the elderly and those with chronic diseases and immune deficiency are more at risk. This prompted the Saudi government to recommend that these people along with pregnant women, children under 12 and anyone with a terminal illness not perform Hajj in 2013. In 2012, more than 1.75 million pilgrims from 187 countries arrived in the kingdom for Hajj, with 1.41 million Saudi nationals also participating. Another 1.4 million unregistered pilgrims are also thought to have attended.
With the cause unknown, transmission routes unclear and a cure unavailable, there is certainly much to do including development of a point-of-care test to more easily diagnose MERS-CoV, which is currently identified using a complex testing process in Jeddah. This is another concern for pilgrims, many of whom travel from countries where there are no testing facilities. We havent defined the whole outbreak yet, what we are seeing at the moment is probably the tip of the iceberg, says Zumla.
However, the good news is that no cases of MERS-CoV have been recorded among the millions of Umrah pilgrims that have visited the kingdom since the outbreak began and the overall spread has been much slower than SARS, which was contracted by more than 8,000 people in just 6 months. It does not seem to behave like SARS, says Memish. It seems to selectively cause severe disease in [certain] people. We dont know why this is, but we are working hard to identify the causes.
136: Confirmed cases of MERS-CoV worldwide at start of October 2013
114: Confirmed cases of MERS-CoV in Saudi Arabia at start of October 2013