Via MedPage Today, a blog post by Michael Smith: Culture Shock: MERS Still a Puzzle. Excerpt:
All told, the WHO has been informed of 170 laboratory-confirmed cases of infection with MERS-CoV, including 72 deaths, since the first cases were reported in 2012.
The high case-fatality rate suggests the disease is a very serious threat, but the two asymptomatic cases reported Dec. 27 by the WHO suggest that some people may have very mild illness.
Indeed, investigators have previously noted that the case-fatality rate is probably an artifact: Only those with severe symptoms are likely to seek treatment, which would inflate the rate, especially in the early days of an outbreak.
But as more and more mild cases are reported, the rate is slowly coming down. The current numbers yield a case-fatality rate of 42%, but earlier analyses pegged it at about 60%.
And in Saudi Arabia, where officials are very much on the alert, healthcare workers -- especially those caring for MERS cases -- are being carefully monitored, although the WHO did not give details on how the two asymptomatic cases came to light.
The reservoir of the virus is also a question. It's thought to be circulating in animals and a recent study suggested that domesticated camels might play host to the virus. Similar viruses have been found in bats.
But in many cases, there is no obvious link to animals. In the most recent cases, the man who died -- a 73-year-old from Riyadh who died 3 days after admission to the hospital -- had been exposed to animals, although the WHO did not say whether camels were among them.
But the other man -- a 53-year-old from Riyadh, now under intensive care -- was not exposed to animals, although he did have exposure to another patient with confirmed disease.
Still, a look through the WHO lists shows that clear epidemiological links can't be pinned down for many patients.
On the other hand, there is also no sign -- so far -- of sustained human-to-human transmission, despite several cases in which patients had contact with other patients.
Shorter version: The Saudis aren't telling WHO very much. And almost two years after the first known MERS cases in Jordan, we're still clueless about how you catch MERS unless you come in contact with an existing MERS case.