The MERS disaster averted for now
Is the virus that appeared for the first time in the Middle East last year, a scary emergent infection or a false alarm? Norman Swan looks at the developments.
The eyes of the world’s Muslims weren’t the only ones focused on last year’s Hajj in Saudi Arabia. Thousands of public health officials were also watching – very nervously – this massive accumulation of people from the four corners of the globe.
The reason was the chance that a newly discovered coronavirus belonging to the same family as Severe Acute Respiratory Syndrome (SARS), would run riot through the pilgrims, who would then take it back to their far-flung homes creating a global pandemic of acute respiratory illness, kidney failure and death.
That disaster scenario didn’t happen, so the questions are: Why? and Is it safe to relax about MERS?
As with most apparently new infections, it’s not clear how or why this one emerged. What we do know is where: the Arabian Peninsula and the Middle East. The first two known cases were in March and April of 2012, both in patients who died of an unknown illness. Only later was the cause tracked down. In September 2012 a sample from a 60-year-old Saudi businessman, who died several days after presenting with a severe pneumonia, showed that he’d been infected with a coronavirus that had never before been seen. While Saudi Arabia has carried the burden of the disease, cases have turned up in the Gulf oil states of Qatar and Abu Dhabi as well as in people travelling back to Europe from the Middle East. Sometimes there has been contact with farm animals, sometimes not. Sometimes there has been contact with sick individuals, sometimes not.
MERS does spread from human to human and appears to be built with a tough outer coat similar to other viruses that survive on surfaces and are spread by what’s called the oral-faecal routine – in other words from poo to mouth. Men have been more commonly infected than women, which led some observers to suggest that Saudi women have been protected by the veil. People with diabetes and other chronic diseases appear to be more at risk and as with SARS, MERS has been shown to spread in hospitals where people with the condition are being treated. In fact the largest outbreak to date has been in a group of hospitals in Saudi Arabia.
As with most new infections, it’s not clear how or why this one emerged.
The idea that the MERS coronavirus had its origins in animals emerged early on in the course of the disease, since there are many similarities to SARS whose natural host is bats. Camels were suggested as a source,
which could explain the Middle East connection. Coronaviruses very similar to MERS, or their antibodies, have been found in high proportions of camels in the Gulf but bats in the region also carry coronaviruses with almost identical genomes to MERS.
What seems to be occurring at the moment is a slow burn in human populations from human to human spread with occasional “leakage” from animals. At the time of writing there have been around 170 laboratory confirmed cases of MERS with a death rate of more than 40%. That’s many times higher than the death rate in the 1918 flu pandemic, although it’s suspected that over 1,000 people have been infected but not diagnosed, which if true, would dilute the death rate. By comparison, between 2002 and 2003, 8,000 people were infected with the SARS coronavirus and 800 died. So MERS is moving more slowly.
No one is able to predict whether MERS will evolve into a significant human epidemic. The virus may have been around since 2007. But the maximum rate of spread, and the potential for it to mutate, is highest where people have close and prolonged contact. That’s why the Hajj was such a worry. It had all the necessary elements to turn a slow-spreading organism into the biological equivalent of a wildfire.
Luckily for the world, there appear to have been few if any MERS cases traced to the 2013 Hajj and science is the reason. The international public health community has become much more effective. The virus was sequenced early, which allowed accurate, rapid testing through a technique called PCR (polymerase chain reaction) that can detect tiny amounts of the virus itself. The way the virus is transmitted was analysed fairly quickly, which allowed institutions to take precautions and nations to be on alert. Saudi authorities issued warnings to pilgrims and advised the elderly, infirm and those with chronic diseases to stay away from Mecca. As a result the numbers performing the Hajj were lower than usual.
The message for all of us – particularly governments who might be tempted to cut funding to public health infrastructure – is, to paraphrase an aphorism, that the price of freedom from disease is eternal vigilance.