MERS missing cases

The World Health Organization has released a demographic and geographic breakdown of the MERS coronavirus infections that Saudi authorities announced three weeks ago. (National Institute for Allergy and Infectious Diseases/The Canadian Press)

Saudi Arabia's surprise 113 MERS cases have lost a little of their mystery.

Saudi authorities startled the global public health community on June 3 when they announced they had found 113 MERS cases that had previously gone unreported, and 92 additional deaths to the disease.

At the time, the Saudis offered no details about the new cases, but now the World Health Organization has released a demographic and geographic breakdown of the infections.

But while the WHO's statement answers some questions, it raises another.

It talks about 34 deaths among the 113 cases; it does not explain where or when the remaining 58 deaths occurred.

The majority of the previously missed infections with the Middle East respiratory syndrome coronavirus occurred after March 1 of this year, though 29 were contracted between May 2013 and the end of February.

A huge surge in infections in Saudi Arabia started in March of this year, with spread among hospital patients and health-care workers fuelling the rapid rise in cases. Saudi Arabia, which has been the country hardest hit by MERS, has recorded more than 500 cases since the beginning of March.

The WHO said Thursday that it has been informed of 820 cases of MERS globally since the first known infections with the coronavirus took place in April 2012. Most of those have been recorded this spring; at the beginning of March, the global count was 188.

The 113 cases came to light during a retrospective review of hospital records done by Saudi health authorities in early May, the WHO statement says.

More than half of the previously missed cases were from Jidda (44) and Riyadh (21), though there was a smattering of cases from a range of locations within the country.

The cases ranged in age from three months to 89 years, with the median age being 41 years. Men made up 57 per cent of the cases.

Just over a quarter of the cases were asymptomatic — they had no symptoms, but were found by testing done on contacts of known cases. Seventy of the cases were hospitalized for their symptoms and three of those people remain in hospital.

Health-care workers made up 37 per cent of the cases. Of the 42 health-care worker cases, 39 have since recovered, one is still in hospital and two died.

The WHO says it has been informed of at least 286 MERS-related deaths worldwide. It is not clear why that number is that low, given that Saudi Arabia is reporting 292 deaths on its ministry of health website. MERS deaths have also been reported in Jordan, Britain, France, Germany, Tunisia, the United Arab Emirates, Oman, Yemen, Malaysia and Algeria.