No cases of Mers have been reported among pilgrims who have arrived in Saudi Arabia for the Haj, the health ministry said on Thursday.
But the ministry confirmed on Thursday that two more Saudis in Riyadh had died after contracting the virus.
Their deaths take the number of Mers-related fatalities in the kingdom to 51, underscoring concerns of global health officials who say the virus could spread to some of the 2 million pilgrims expected to perform the Haj in Mecca next week.
“So far, no case for any epidemic has been recorded among the pilgrims, especially the coronavirus,” Abdullah Al Rabia, the Saudi health minister, told Al Riyadh newspaper.
Despite the confirmation of two more Mers-related deaths in Saudi Arabia, experts say it is the more than 100 countries from which pilgrims travel that may face the greatest risk when they return home.
“A very large volume of travellers leaving the Haj will be returning to South Asia, including countries that have very limited healthcare resources,” said Kamran Khan, an infectious disease physician at St Michael’s Hospital in Toronto and founder of the outbreak-tracking site BioDiaspora.
The key question, he said, would be: “If this virus were to come back, would they even be able to detect it?”
So far, transmission has been slow, affecting mostly elderly patients and those with chronic illnesses, such as the two latest confirmed deaths in Saudi Arabia. The two men, aged 78 and 55, had also suffered from other chronic diseases, the ministry said on its website on Thursday.
But the mortality rate is high: about 50 per cent of the patients who are known to have contracted the illness have died.
Saudi Arabia has been the centre of the Mers outbreak with 119 cases and 51 deaths,
Saudi health authorities have implemented rules to try to limit the spread of the virus. Pilgrims are being asked to wear face masks in crowded areas and pilgrims with underlying health conditions were asked to postpone their journeys.
Mr Al Rabia said extra surveillance was in place for Haj, which starts on Sunday.
“The ministry has put in place very strict measures this year,” Mr Al Rabia said. “Employees have been given strict orders to isolate any suspected case and carry out the necessary laboratory tests.”
But the transmission of the disease is still mysterious, as scientists have yet to find the source of the virus, though it is believed to have originated from an animal host, said Dr Marc Sprenger, director of the European Centre for Disease Prevention and Control.
The mode of transmission remains unknown, said Dr Marc Sprenger, director of the European Centre for Disease Prevention and Control.
“We aren’t seeing the virus going from one person to another to another. One red flag would be if we start to see sustained human-to-human transmission: people infecting others who then infect more people and so on.”
Another challenge is the incubation period, which can range from several days to two weeks, meaning that someone who is infected may not realise they are sick until the leave the kingdom.
Mr Khan recently co-authored a study for the journal PLOS Current: Outbreaks estimating that nearly two-thirds of pilgrims will return to lower and lower-middle income countries, with limited health budgets and abilities to spot outbreaks.
Last month, the Dr Keiji Fukuda, the World Health Organisation’s assistant director general for health security and environment, also said that “levels of surveillance remain suboptimal” in many of the countries set to receive pilgrims from the Haj.
Among the concerns is the timing: respiratory illnesses are common in mid-November, when many pilgrims go home, making it even more difficult for health workers to pinpoint cases of Mers, which initially has many of the same symptoms as influenza.
Dr Sprenger said that for the moment European countries would not increase their surveillance for Mers among returning pilgrims, but his agency was working with laboratories across the European Union to make sure they can quickly identify the virus.
“The international community is watching this event very carefully,” said Mr Khan. “We all share a part of the risks.”