Saudis report 2 silent MERS infections; WHO notes Qatar cases

A Saudi Arabian official reported two new asymptomatic cases of Middle East respiratory syndrome coronavirus (MERS-CoV) today, as the World Health Organization (WHO) acknowledged two MERS cases that authorities in Qatar reported recently.

Ziad A. Memish, MD, Saudi Arabia's deputy minister for public health, said the asymptomatic infections were found in a 16-year-old boy and a 7-year-old girl, both of whom are family members of a 38-year-old man who died of MERS on Aug 17 and whose case was announced yesterday. The man, who had diabetes, was from Hafr Al-Batin.

Memish reported the cases via ProMED, the online reporting service of the International Society for Infectious Diseases. A number of asymptomatic MERS-CoV infections have been reported in recent months, most of them in young, healthy people.

Memish also reported that the other Saudi patient whose case was announced yesterday, a 55-year-old man from Medina, probably had contact with one of the Qatari patients in a healthcare facility there. "Close collaboration in the investigation is ongoing between the Qatari and Saudi health authorities," he wrote. "No animal contact reported."

The WHO, in recognizing the two cases reported recently in Qatar, added a little more information about them. The cases involve a 59-year-old man who recently visited Saudi Arabia and a 29-year-old man who has not traveled outside Qatar recently, the agency said.

The 59-year-old, who has an underlying medical condition, became ill on Aug 15 and is hospitalized in stable condition. He visited Medina for 6 days, returning home Aug 15, but did not take part in Umrah (a pilgrimage to Mecca) and did not visit the Mosque of the Prophet in Medina, the WHO said.

The 29-year-old also has an underlying health problem, the agency said, without giving any other details. An Aug 26 news report said he was in critical condition in an intensive care unit.

The WHO said both cases were confirmed by an international reference laboratory. A total of 138 healthcare worker, family, and community contacts of the two men have been screened, and so far all have tested negative for the virus, the statement said.

The WHO has not yet acknowledged the two Saudi cases reported yesterday or the two asymptomatic infections reported by Memish today. The agency's MERS count at this writing is 104 cases and 49 deaths. The four latest Saudi cases would raise that to 108 cases and 50 deaths.

In other developments, a team of German and Dutch researchers have reported developing an experimental MERS-CoV vaccine that generates high levels of antibodies to the virus in mice. Their report was published yesterday as an early release from the Journal of Virology.

The team used Modified Vaccinia virus Ankara (MVA), a smallpox vaccine based on a weakened strain of vaccinia virus, to make the MERS-CoV vaccine. The group constructed a recombinant form of MVA that expresses the MERS-CoV's spike (S) protein, which enables the virus to bind to human cell receptors. They dubbed the vaccine MVA-MERS-S.

"When tested as a vaccine in mice, recombinant MVA expressing the S protein induced high levels of circulating antibodies that neutralize MERS-CoV in tissue culture infections," the report says. It concludes that MVA-MERS-S "may serve for further development of an emergency vaccine against MERS-CoV."

See also:

Aug 29 WHO statement

Aug 29 ProMED post with Memish report

Aug 28 J Virol abstract

Aug 26 CIDRAP News item on Qatari case

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