A little more than a week before the start of the Hajj, Saudi Arabic continues to report only widely scattered, sporadic MERS cases - with just the 8th case of the month reported today from Hafoof.
Hofuf (aka `Hafoof’, `Hafuf’, etc.) - which saw a large nosocomial outbreak in 2015 - has a history of primary MERS infection linked to camel contact (see here, here, and here).
Much of this summer's lull can be traced to a lack of large nosocomial outbreaks, which last summer led to well over 100 cases at Riyadh's King Abulaziz Medical City alone (see MMWR: A Large Nosocomial Outbreak Of MERS In Riyadh - Summer 2015).
While MERS has become a perennial concern for the Hajj, the most likely infectious disease outbreak scenarios involve less exotic threats; mosquito borne illnesses (like Dengue & Chikungunya, and now Zika), tuberculosis, mumps, measles, chickenpox, norovirus and respiratory viruses like seasonal influenza & Rhinovirus.
The CDC has published an extensive list of health precautions and advice for travelers to this year's Hajj, which may be read at Hajj and Umrah in Saudi Arabia Alert - Level 2, Practice Enhanced Precautions.