Saudi Arabian health officials are bracing for the Hajj, the annual pilgrimage to Mecca expected to draw more than 2 million Muslims from around the world.
This year's pilgrimage, set to begin Oct. 24, will come one month after the discovery of a SARS-like virus linked to the death of a Saudi man earlier this year. Another man, who is from Qatar but had recently traveled to Saudi Arabia, is in critical condition with the same infection.
The Saudi Ministry of Health is "keeping a close eye on all developments" and urging all those who wish to participate in the pilgrimage -- the fifth pillar of Islam -- to keep their hands clean and wear masks in crowded places, according to its website.
"We pray for Allah to protect our beloved country from all such harms and diseases," the website says.
The new virus belongs to a family called coronaviruses, which are typically spread by coughs and sneezes. Coronaviruses include the common cold as well as SARS, which swiftly spread from Asia to America and Europe a decade ago, killing nearly 800 of the more than 8,000 people it infected.
"The Hajj brings people from all over world to one small place," said Dr. William Schaffner, president of the National Foundation for Infectious Diseases and chairman of preventive medicine at Vanderbilt University Medical Center. "People can carry infections with them, and we have to be aware of that."
In 2009, fears about swine flu stoked rumors that the Hajj had been canceled. But then Health Minster Dr. Abdullah Al Rabeeah said the thought never crossed his mind.
"I think the government is confident in its health facilities, is confident in its capabilities and, from day one, we told them that we would put guidelines and recommendations but we will not prevent people from coming to Hajj," he told ABC News at the time.
People participating in the pilgrimage are required to be vaccinated against yellow fever, meningitis and polio, if they come from polio-endemic countries. The Ministry of Health also recommends the seasonal influenza vaccine.
"Vaccinations are important; identifying people who are ill and isolating them is equally important," said Schaffner. "You need an environment where someone who's ill gets prompt medical attention, and the illness is called into health authorities to make sure it's an individual event and not the beginning of an outbreak."
Schaffner said public health officials play a key role in keeping crowds safe.
"Every time there's large gathering, whether it's the Hajj, the Olympics, a Papal visit or even a football game, public health officials are very much included in the planning and execution," he said.
And viruses aren't the only health hazard at mass gatherings. Bacteria lurking in food and restrooms can cause diarrheal illness, and hot weather can cause heat stroke. Current highs in Mecca are upwards of 110 degrees.
"You have to make sure people don't get dehydrated," Schaffner said.
Because there are only two confirmed cases of the SARS-like virus, people planning to travel to the Middle East should continue with their plans, according to the Health Protection Agency, an independent advisory panel in the U.K.
The World Health Organization also "working closely with Saudi Arabia, as in previous years, to support the country's health measures for all visitors participating in the [Hajj] pilgrimage to Mecca next month," according to a WHO statement.