Could one of the largest religious events in the world jumpstart the next worldwide pandemic?

A supplicating pilgrim at Masjid Al Haram. Mecca, Saudi Arabia. Credit: Ali Mansuri. Licensed under Creative Commons.

In January, more than 2.5 million Muslims made the annual pilgrimage to Mecca to complete the series of rituals known as the Hajj. During the holy trek, the “guests of God” take part in ceremonies retracing key events in the history of Islam, after which they’re given the honorific title of “Hajjee” and considered absolved of past sins.

For the pilgrims who travel thousands of miles at great expense to complete the weeklong ritual, the Hajj is a profound expression of their faith and a requirement for every Muslim with the means to participate. For epidemiologists the Hajj is an unparalleled public health challenge.

The Hajj has all the ingredients necessary to seed an epidemic: It brings together millions of people from over 70 countries, some of which have poor health care systems still plagued by preventable infectious diseases, like polio and cholera. The pilgrims live, travel and pray in extremely close quarters, creating the ideal atmosphere for communicable diseases to spread and possibly mutate. If an outbreak were to occur on the road to Mecca, pilgrims could exacerbate the problem when they returned home and passed their infection on to others.

“This mass migration entails some of the world’s most important public-health and infection-control problems,” reports a study just published in the British medical journal The Lancet. “Although distances are small, the congestion of the Hajj poses high physical, environmental, and health-care demands…The severe congestion of people means that emerging infectious diseases have the potential to quickly turn into epidemics.”

Outbreaks have occurred during the Hajj before, with documented cases of cholera epidemics reported as far back as 1846. More recently, meningitis became a primary concern after an international outbreak following the Hajj in 1987. Since then, the Saudi Arabian Ministry of Health has made meningitis vaccinations mandatory for all pilgrims and rates of meningococcal disease have fallen dramatically.

Ziad Memish of the King Abdul Aziz Medical Center in Riyadh, and a co-author of the Lancet study, acknowledges that the Saudis are doing everything in their power to keep the Hajj disease-free.

“There are many emerging infectious diseases of concern during any large gathering and the Hajj is no exception,” Memish said via e-mail. “The Saudi government has taken many concrete steps to prevent and treat several infectious diseases that were known to spread during the Hajj, like meningitis, hepatitis B, and pneumonia.”

In particular, the Saudi government takes seriously the threat posed by emerging infectious diseases like avian flu, SARS, and Ebola, none of which has a vaccine to immunize against it. When the Ebola virus killed 170 Ugandans in 2001, Saudi Arabia banned all pilgrims from that country until the extent of the threat became clear. A few years later, during the SARS scare, the government effectively quarantined visitors from any country where SARS had been reported, allowing them to enter only after monitoring them for 10 days to make certain they did not exhibit symptoms. The airports in Riyadh, Jeddah and Dammam are even equipped with thermal cameras to detect pilgrims entering the country with dangerously high fevers that could be an indication of SARS.

Despite these improvements, Memish and other experts remain concerned that the pilgrimage could serve as an “epidemiological amplifying chamber” for the avian flu.

“At the World Bank, we’re assessing countries’ capacities to track the avian flu, and how they’re prepared for the epidemic,” said Francisca Akala, a public health specialist who focuses on the Middle East and North Africa. “One of the places we’re particularly looking at is Saudi Arabia, because of this issue of the Hajj. It’s just the perfect opportunity for an epidemic to become full-blown. People are coming from all over the world to one place.”

If just one person among the massive crowds carries the bird flu virus, the odds of the disease mutating into a human-to-human strain would increase by orders of magnitude. Several countries of origin for pilgrims on the Hajj, including Indonesia, Iraq, Azerbaijan and Egypt, have documented cases of human deaths from bird flu.

“Of course, avian influenza (H5N1) is the disease of the hour,” said Memish. “But I can assure you that the government of Saudi Arabia did not spare the money or effort in preparing for the avian influenza during the 2006 Hajj.”

About a month before the pilgrimage began, an international meeting was held in Riyadh that brought representatives from the WHO, the UN Food and Agriculture Organization and the US military together with the local ministries of health, agriculture and the Hajj. Among other recommendations that came out of that conference, the Ministry of Health placed restrictions on poultry imports into the country and staffed nearly 10,000 doctors and medics on hand at nearby hospitals, ready to diagnose and contain any possible outbreak.

This year, these measures proved enough: There were no reported cases of avian influenza. But were H5N1—or some other virus—to mutate and spread during a future Hajj, its severity would likely be exacerbated by the greater health care deficiencies in the Middle East. The region’s range of very rich and very poor nations makes it hard to generally characterize the state of its health care system, but overall, experts see a lack of mechanisms for detecting and reporting a possible epidemic.

“I think the systems are in a better state than the sub-Saharan African region, for instance,” said Akala. “At the same time, they have problems with disease surveillance; they have a problem with data collection. They have a problem with tracking epidemics. We’re seeing that in newer diseases like HIV/AIDS. Very few of the countries have surveillance systems that can actually track the epidemic.”

The goal, of course, is to prevent an outbreak from reaching epidemic proportions by containing it. Using the Hajj as an example, the The Lancet article makes a pressing point: Monitoring the Hajj and other international events for possible cases of virulent disease must be an integral part of the world community’s plan to avert a pandemic.

“Any large gathering that happens anywhere on the globe could be the epicenter of the next avian flu pandemic,” said Memish. “This doesn’t mean we stop the Hajj or the Olympics, but the experts in the field need to work harder to formulate a scientific plan to monitor avian flu at these large gatherings.”

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Originally published April 23, 2006

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