The Mers coronavirus kills 40 per cent of those who contract it, but has so far been restricted mostly to Saudi Arabia. As the nation prepares to welcome three million pilgrims for Haj, precautions are being put in place as far as they can be, given the uncertainties.
Haj and the great Mers mystery
The Haj pilgrimage to Mecca, which begins next week, is a gathering of extraordinary scale. Each year three million people take part, completing one of the five pillars of Islam.
The event is a powerful personal affirmation of faith. But with so many people in such proximity to one another, it can also be a breeding ground for illness.
It has long been the case that many pilgrims return to their home countries with minor respiratory ailments, the “Haj cough”.
And while such diseases clear up without major consequences, this year’s pilgrims, about 1.75 million of whom are likely to come from outside Saudi Arabia, may be at risk of contracting something more serious – Mers coronavirus.
The virus was identified last year, and named Middle East Respiratory Syndrome coronavirus, after the region where most cases have originated. While it is highly likely the virus transferred to humans from animals, it is still unclear exactly which creatures it came from.
What is clear, though, is that it is deadly. Of the 136 people confirmed to have been infected, 58 of them, or 42.6 per cent, have died.
Understandably, doctors are worried. In the space of just a few days, the pilgrims return from Mecca to their homes across the planet.
The World Health Organisation (WHO) has already set up an emergency committee to monitor and control the spread of the virus.
In an attempt to work out which countries were most at risk, a team led by Dr Kamran Khan, a specialist in infectious diseases at St Michael’s Hospital in Toronto, looked at airlines’ data about where travellers leaving Saudi Arabia and other countries where Mers has been identified – the UAE, Qatar and Jordan – were going.
The study, published in the Public Library of Science Currents, a collection of journals, found the biggest destinations were India (which received about 16 per cent of passengers in previous years), Egypt (10 per cent), Pakistan (8 per cent), Britain (4 per cent), Kuwait (4 per cent) and Bangladesh (3 per cent).
That list makes wealth an issue – about two-thirds of the total number of Haj pilgrims are from countries towards the poor end of the scale, where health authorities are likely to be less funded. In those circumstances, what are the chances of them being able to marshal the resources to detect and deal with any outbreak?
Not good, according to Keiji Fukuda, the WHO’s assistant director general for health, security and environment. He said that while Saudi Arabia itself had made efforts to limit the spread of disease among pilgrims, “levels of surveillance remain suboptimal” in many pilgrims’ countries of origin.
That makes it even more important to prevent pilgrims from catching the virus during their time in Saudi Arabia.
One measure unlikely to be of much help is airport screening. Heat sensors, which try to detect passengers with a fever, are already a familiar sight at airports, especially since the 2009 swine flu scare.
But in the case of Mers, according to Dr Khan, such screening is all but useless.
“Screening can allay public fears, but it’s not going to be an intervention that’s particularly effective,” he said.
The incubation period of Mers – the time between a person being infected and showing symptoms – averages five days and can be as long as a two weeks.
That means infected pilgrims will probably still seem perfectly healthy as they leave the Middle East and as they arrive back in their home countries.
More useful would be measures to prevent individuals from picking up the virus in the first place – simple hygiene protocols such as regular handwashing and coughing in your hand or arm instead of into the air.
But educating pilgrims about the importance of such measures is a massive challenge.
“It’s difficult when you’re dealing with a heterogeneous group from different cultures and languages,” said Dr Khan.
Because of that difficulty, it will be vital after Haj for doctors in the returning pilgrims’ home countries to be on the lookout for cases that may appear to be a mere Haj cough but could be something more serious.
“The most important thing is to make sure your front-line medical providers are anticipating the arrival of individuals with the virus. They must know what it’s going to look like clinically,” said Dr Khan.
If doctors fail to spot cases quickly, patients will not be isolated rapidly and person-to-person spread will become far more likely.
Already, Mers is known to have spread to France, Germany, Italy, Tunisia and Britain, although Dr Khan believes there may be unidentified cases in other countries with less well-developed healthcare systems.
Just as scientists are trying to predict where the virus might appear next, others are shedding light on how the virus replicates and where it originates from.
A recent study using rhesus macaque monkeys, published in the Proceedings of the National Academy of Sciences of the United States of America, found the virus replicated most heavily in the lower respiratory tract, especially the lungs. That may explain why infections can be so serious.
Another study, published in The Lancet Infectious Diseases in August, found that retired racing camels in Oman had antibodies against a protein found in Mers, indicating they had been exposed to the virus – and could still be infected by it.
But a crucial part of the puzzle is camels from the country where most cases of Mers have been diagosed – Saudi Arabia. The Saudi authorities have not made camel blood samples available, and there has been criticism from scientists in Europe and the US of what they see as a lack of effort to identify the source of outbreaks.
Michael Osterholm, the director of the Centre for Infectious Disease Research and Policy at the University of Minnesota, was quoted in the journal Nature as saying the absence of population studies to help identify where the virus is coming from when it infects people is “absolutely unacceptable”.
Although it seems likely that humans are picking the virus up from camels, they may not have been its original source. It is believed to come from bats, which are also thought to be the ultimate source of other coronaviruses, including severe acute respiratory syndrome (Sars), which led to hundreds of deaths in 2002 and 2003.
Research being published next month’s Emerging Infectious Diseases, published by the US Centres for Disease Control and Prevention, found that bats in Saudi Arabia were infected with coronaviruses, with one species, the Egyptian tomb bat showing an exact match for Mers. It remains unclear how this species could have passed it on to humans.
One theory suggested is that Mers originally came to the Middle East after bats in Africa or Australia, where novel coronaviruses have been identified, infected camels there with the virus. When these camels were shipped to the Middle East, they took the virus with them. But no one knows for sure, and the United Nations’ Food and Agriculture Organisation sent experts to the Arabian Gulf region to continue the research.
Ultimately, while counselling caution, he remains optimistic this year’s Haj will not lead to vast number of new cases.
“This virus has trickled along, it hasn’t exploded,” he said. “My sense is that we may see some cases associated with the Haj, but not on a large scale. That’s the hope.”
“But the reality is that no one knows at this time.”