Thursday, June 19, 2014

Discrepancies in the World Health Organization’s Count of MERS Cases in Saudi Arabia

With Saudi Arabia reporting more than 80% of all Middle East Respiratory Syndrome (MERS) cases to date, detailed information about the individual cases from Saudi Arabia is critical to understanding the nature and spread of this novel disease. There are some discrepancies among the MERS cases reported by World Health Organization (WHO) from Saudi Arabia. Of course, WHO is constrained by the quality of data provided by its various member states.

Generally, WHO provides detailed information on the initial cases of a novel disease outbreak in its online publication, Disease Outbreak News (DON). The first WHO report of a MERS [novel coronavirus] infection was published on September 23, 2012. Between September 2012 and April 16, 2014, WHO reported details on 228 MERS cases with varying levels of details provided by the reporting member states. Of the 228 cases reported by WHO though that date, 181 were individually reported cases from Saudi Arabia. The DON of April 14, 2014 (15 reported cases from Jeddah and Riyadh) was the last Saudi Arabian case-by-case report from WHO. After that date, WHO only provided aggregate case totals from Saudi Arabia. These aggregate totals were embedded in 6 DON reports between May 7, 2014 and June 13, 2014 as noted in the table below.

On June 13, 2014, WHO provided a summary of these aggregated cases. According to WHO, 402 cases were summarized. However, a tally of the WHO totals from the previous DONs indicates that only 401 cases were actually aggregated. A comparison of the WHO total with media reports from the Saudi Arabia Ministry of Health indicates that 404 MERS cases were publicly reported by the Ministry of Health.

For the period between April 11, 2014 and May 4, 2014, WHO reports 229 cases from Saudi Arabia, although the Saudi Arabia Ministry of Health only publicly reported 228 cases during that period. One possible explanation is that the 51 one-year-old individual from Riyadh reported on April 9, 2014 by  the Saudi Arabia Ministry of Health (link FluTrackers case # 227), not previously enumerated by WHO, was added to the aggregate total (see: link). Also,  between May 5, 2014 and May 9, 2014 Saudi Arabia Ministry of Health reported 62 MERS cases. During this same period WHO only reported 58 cases in aggregate (see: link). It is possible that WHO failed to incorporate four cases into its cumulative tally for this 5-day period in Saudi Arabia.

With the reporting of specific case details of two individuals from Saudi Arabia in DON on June 16, 2014,  WHO has now apparently returned to reporting individual case details from Saudi Arabia. Better individual case details may again be flowing from Saudi Arabia to WHO.

Depending on the quality and accuracy of the data provided by Saudi Arabia, a discrepancy of 3 or 4 cases among more than 500 reported cases falls within a reasonable error factor. Such differences will not appreciably affect interpretations or speculations drawn from such a large sample of cases.

Of more serious concern is a report on June 3, 2014  by the Saudi Arabia Ministry of Health indicating retrospective reporting of more than 100 additional MERS cases in Saudi Arabia (and acknowledged by WHO - link) going back to May 2013 (See: The Saudi Arabia Ministry of Health Quietly Announces an Additional 113 Cases of MERS). This means that from May 2013 through April 2014, about 15% of all MERS cases in Saudi Arabia were unreported. A 15% error factor is unacceptable when public health officials and the rest of the world are trying to understand the nature of a novel infectious disease with a high fatality rate.

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