Via CIDRAP, Robert Roos has an extremely good news story: Report on Tunisian MERS cases shows testing challenges.
A new report on three MERS-CoV infections identified in Tunisia last year points up the difficulty of identifying the disease in some cases.
The first patient in the cluster, a 66-year-old man, tested negative for the virus while he was critically ill, but a test of his stored serum months after his death was positive, says the report published yesterday in Emerging Infectious Diseases.
The man fell ill in April 2013 on returning home to Tunisia after a 5-week trip that included a visit to his daughter in Qatar and a pilgrimage to Mecca. He was hospitalized with dyspnea on May 6 (2013) and died 4 days later. A reverse transcription polymerase chain reaction (RT-PCR) test on lung fluid during his hospitalization was negative for MERS-CoV (Middle East respiratory syndrome coronavirus).
Later, on Aug 5, the US Centers for Disease Control and Prevention ran an RT-PCR test on a serum sample collected from the patient the day before his death, the report says. The result was positive, and genetic sequencing of the isolate showed that it was similar to geographically diverse MERS-CoV isolates from Saudi Arabia and the United Arab Emirates.
The authors write that the diagnosis by PCR of a serum sample that was collected 10 days after illness onset and tested weeks later "highlights the value of testing serum samples for MERS-CoV RNA." They add, "This finding also provides valuable information about viremia in MERS CoV–infected patients, contributing to our understanding of the natural history of MERS-CoV infection and kinetics of virus shedding."
The authors speculate that the man's preexisting diabetes and his early treatment with a corticosteroid (dexamethasone) might have made his illness worse.
Also infected were the man's 34-year-old son, who was a nurse who cared for him both at home and later in the hospital, and his 30-year-old daughter from Qatar, who traveled to Mecca with him.
Both of them got sick shortly after their father died, and both tested positive for MERS-CoV by RT-PCR. The daughter received oseltamivir and recovered, while the son recovered without treatment. The report does not explain why she was treated with oseltamivir, an influenza drug that has not been reported to be useful against MERS-CoV.