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MERS and the Hajj: Uncertain of the outcome
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Each year during the 12th month of the Islamic calendar, millions of Muslims make an annual pilgrimage to Mecca, and some also to Medina, Saudi Arabia, to celebrate the Hajj. This is the largest yearly mass meeting in the world. Because the Islamic calendar is 11 days shorter than the Gregorian calendar, the Hajj moves about 2 weeks earlier each year. In 2013, the Hajj will be in mid-October. About 3 million people attended each year from 2010 to 2012, with about 35% to 45% of pilgrims coming from Saudi Arabia and the rest from all over the world.
This year, we have the complication of a new disease — Middle East respiratory syndrome (MERS) coronavirus. This is caused by a novel coronavirus, which has Saudi Arabia as its epicenter. MERS was first identified in a patient in Saudi Arabia who died in June 2012, with relatively few new cases by the time of the 2012 Hajj. There was no uptick of cases after the Hajj.
This year’s Hajj
Since the onset of the outbreak, and as of Aug. 29, there have been 104 cases with 49 deaths worldwide. Most of the cases have been related to Saudi Arabia, 82 cases with 41 deaths. All of the other cases have been related to other Arabian Peninsula countries (Jordan, Qatar and the United Arab Emirates). Unfortunately, currently, important aspects of the epidemiology of the outbreak remain a mystery. Although similar viruses have been found in bats, and an identical virus was found in one bat in Saudi Arabia, the definitive actual animal vector has not been identified.
Donald Kaye
It is clear that person-to-person spread can occur with close contact, especially in the health care setting, but it has not been common. We know that there may be mild illness or even no illness in infected people, but we don’t know whether transmission can occur from these individuals. Most severely ill patients had a history of chronic comorbidities.
Ideal conditions for transmission
There is little question that the Hajj provides an ideal situation for the spread of respiratory viruses. In a study published in Clinical Infectious Diseases of French participants during the 2012 Hajj, there was a dramatic increase in respiratory viruses demonstrated in nasal swabs. Before the pilgrimage, 4.8% of the participants in the study had nasal swabs positive for at least one respiratory virus. During the pilgrimage, more than 40% developed respiratory symptoms and 38.6% of these were positive for at least one respiratory virus; this represented an increase from 4.8% to more than 16% of the whole group.
Cases of MERS have been reported in different parts of the country, and the fact that up to 45% of participants are from Saudi Arabia (presumably from all over the country) adds to the concern that infected Saudis could spread the infection to a foreigner, as well as concerns that visiting pilgrims may also be exposed to the as-yet undefined source of transmission of the virus.
An obvious comparison is with the worldwide outbreak of the severe acute respiratory syndrome (SARS) in 2002 and 2003, which infected more than 8,000 people worldwide and killed close to 10% of those infected. SARS was caused by a coronavirus that made a species jump from bats to humans through the intermediate host of farmed civet cats bred for human consumption in China. A fateful elevator ride in a Hong Kong hotel, which sparked the worldwide dissemination, presumably occurred because a “super spreader” was in the elevator in close contact with international visitors who returned home. We don’t know if super spreaders occur with people infected with MERS, but because clear-cut person-to-person spread has occurred, the concern must be great with the Hajj.
Fewer pilgrims attendings
Saudi Arabia has urged the elderly and chronically ill, as well as children and pregnant women, not to perform the Hajj this year. Furthermore, the authorities have reduced by half the number of pilgrims coming from within Saudi Arabia, and by about 20% those from abroad. These efforts will diminish the likelihood of spread of MERS but certainly not eliminate it.
References:
Benkouiten S. Clin Infect Dis. 2013;doi:10.1093/cid/cit446.
For more information:
Donald Kaye, MD, is a professor of medicine at Drexel University College of Medicine, associate editor of ProMED-mail, section editor of news for Clinical Infectious Diseases and is an Infectious Disease News Editorial Board member.
Disclosure: Kaye reports no relevant financial disclosures.