#14,491
In yesterday's MERS update I wrote:
The Saudi MOH has added their 1st MERS case of Epi Week 44 (M,43) and added a second case (apparently belatedly on Sunday) to their Epi Week 43 list (M,10). Both cases hail from Unayzah (aka`Onaizah' or `Onizah'), and both are listed as `primary'.Today, without explanation, the 10 y.o. has been removed from the Epi Week 43 list and the case count chart (see above) has been reset to 1 for last week.
Without more information, it is impossible to know what happened, although the lab tests for MERS are not 100% reliable (see EID Journal: Sensitivity and Specificity Of MERS-CoV Antibody Testing).
False negatives, however, are more common than false positives.Last October, in AJIC: Intermittent Positive Testing For MERS-CoV,
we looked at a study, that found intermittent positive results for MERS-CoV on reverse-transcription polymerase chain reaction (RT-PCR) tests. The authors (including Memish and Al-Tawfiq) wrote:
Our data indicate that 2 to 3 nasopharyngeal samples are needed to produce the highest yield of positive results for MERS-CoV. In addition, 2 negative results 48 hours apart with clinical improvement or stabilization are needed to clear patients from MERS-CoV. Evaluation of the yield of sputum samples is needed to assess the effectiveness against nasopharyngeal swabs.Hopefully we'll find out what happened, but in the meantime the MOH has reported the second MERS case of Epi Week 44, involving a 94 y.o. male with recent camel contact
This is the third case reported from Khamis Mushait - and the 4th from this general region - in the month of October.
- The first involved a 26 y.o. female listed as a `secondary case') on Oct. 10th, possibly linked to another case (M, 34) who was reported from a nearby community (Abha City, about 17 miles from Khamis Meshalt) on Oct 2nd.
- The 2nd was a 73 y.o. male listed as `primary, with unknown camel contact' on Oct. 19th.
