Tuesday, August 27, 2013

Confusion abounds over the number and geographic distribution of MERS-CoV cases

Slightly more than 100 cases of Middle East Respiratory Coronavirus  (MERS-CoV) infections have been reported from around the world. Despite these few numbers, the actual count of cases is uncertain as is the geographic distribution of the cases.  The case count varies from 94 to 104 as noted in the table below compiled from several sources. [1,2,3,4] 
A review of these reports indicates that the variability in the counts results from several factors. First, some reports such as those from the World Health Organization (WHO) are not current and up-to-date. The fact that WHO is not stating the count by individual member states indicates uncertainty about how to report the geolocations of individual cases (see discussion below). Second, some agencies such as WHO only count officially confirmed cases, while other case lists seem to include probable and suspected cases as well. Third, compounding the enumeration problem is that sometimes asymptomatic cases that test positive for the disease are not counted as a confirmed case.

As noted in the table, there is a differential assignment of cases by geographic location.  There is general agreement on eight countries where MERS-CoV infections have taken place, France Italy, Jordan, Qatar, Tunisia, Kingdom of Saudi Arabia, United Arab Emirates, and the United Kingdom(see map below). However, The European Centre for Disease Prevention and Control (ECDC) appears to consider the location of treatment rather than where the infection was acquired as the primary geographic location. That is why the two cases that were infected in the Middle East but were treated in Germany are counted as cases from Germany by the ECDC. 

A similar reporting discrepancy of the geolocation of cases occurred for the public information on A(H7N9) cases in the People’s Republic of China earlier this year. In some cases the geographic location of an individual’s residence was reported in one town or province,  even though the individual was infected in a different province. In another case, an infected individual was transported to a health care facility in another province for treatment and the individual was counted as a case in that province rather when the individual was infected.

Public health officials should collaborate to develop formal definitions for assigning a geolocation to an individual case. Should it be based on where the individual was infected, the individual’s place of residence, or where the individual was treated?

Fnally, more than 75% of all of MERS-CoV cases have been reported from the Kingdom of Saudi Arabia. Much of the confusion about the number of cases and number of deaths from this deadly disease could be cleared up if the Ministry of Health in Saudi Arabia was more forthcoming and provided more detailed information about the MERS-CoV cases that are occurring in this country.


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