May 6, 2013 (CIDRAP News) – Three new cases yesterday, with two deaths, increased a cluster of novel coronavirus (nCoV) cases in eastern Saudi Arabia to 13, and authorities confirmed that the illnesses are associated with a healthcare facility.

The new cases added to concern about possible person-to-person transmission of the novel virus. Human transmission has been clearly demonstrated only once before, in a family cluster of three cases in the United Kingdom in February.

Seven of the 13 patients in the current Saudi cluster have died. With the three new cases, the global count of confirmed nCoV cases has reached 30, including 18 deaths.

The three cases were reported yesterday by Ziad A. Memish, MD, Saudi Arabia's deputy ministry for public health, via ProMED-mail, the online reporting service of the International Society for Infectious Diseases. The World Health Organization (WHO) issued a short statement about the cases today.

"So far there is no apparent community transmission and transmission seem[s] linked to one HCF [health care facility]," Memish wrote. All the cases have been in Alhasa (also written as Al-Ahsa) in the country's Eastern Province.

The WHO statement said, "The government is conducting ongoing investigation into this outbreak which is linked to one health care facility."

Memish said the cases involve:

A 62-year-old woman with multiple comorbidities who fell ill on Apr 19 and died May 3

A 71-year-old man with multiple comorbidities who got sick Apr 15 and died May 3

A 58-year-old woman with comorbidities who became ill May 1, is on a ventilator, and is in critical but stable condition

He gave no details about their preexisting conditions and did not identify the hospital involved. Nor did he mention any connections between the cases, though two earlier patients in the cluster were said to be related.

The WHO reported the first seven cases in the region on May 2, and Memish cited three more on May 3. All 13 patients have been reported to have one or more comorbidities, and 11 of the patients are over age 50. The underlying illnesses and the localization of the cases prompted earlier speculation that they were all in one healthcare facility.

Illness-onset dates in the cluster have ranged from Apr 14 to May 1, a long enough period to suggest to some that the virus has spread from person to person in the facility, rather than that all the patients caught it from a common nonhuman source.

The virus's incubation period has not been clearly established, but researchers who analyzed the UK family cluster estimated that the period ranges from 1 to 9 days, according to a Mar 14 report in Eurosurveillance.

Michael T. Osterholm, PhD, MPH, said the information about the cluster suggests person-to-person transmission, possibly with more than one generation of cases, according to a Canadian Press story published yesterday. He is director of the University of Minnesota's Center for Infectious Disease Research and Policy, publisher of CIDRAP News.

"With no evidence of an animal reservoir in the hospital, the only conclusion that can be drawn is that this is person-to-person," he said. Concerning the range of illness-onset dates, he added, "This is far too wide to be an incubation period. This [event] is much more complicated than that."

Osterholm told CIDRAP News that the cluster could involve one person who passed the virus to others over a period of several weeks or "multiple person-to-person transmission episodes from different sources," with the latter scenario more likely.

The novel virus is related to coronaviruses found in bats, but experts have not succeeded in uncovering its animal source or the route it follows to get into humans.

One previous hospital cluster of nCoV cases has been reported. The illnesses occurred in a hospital in Jordan in April 2012, but they were not identified as nCoV until later in the year, after the virus was first identified in a Saudi Arabian man. The Jordan cluster included two confirmed cases and 11 probable ones, and 10 of the 13 people involved were healthcare workers, according to the WHO.

The new virus is in the same family as the SARS (severe acute respiratory syndrome) virus, which spread to about 30 countries and killed around 900 people in 2003. Experts have been alert for hospital outbreaks of nCoV, because such outbreaks played a major role in the rapid spread of SARS.

In other developments, a group of scientists and public health officials plans to recommend a new name for nCoV, according to a ScienceInsider report today. The proposed name is Middle East respiratory syndrome coronavirus (MERS-CoV).

The name is being suggested by the Coronavirus Study Group of the International Committee on Taxonomy of Viruses (ICTV), which took the initiative to find a new, widely accepted name, according to the story.

Raoul de Groot, a veterinary virologist at Utrecht University in the Netherlands, chair of the study group, said it plans to publish a paper recommending the new name. It will be up to researchers to decide whether to use it or not, since the study group has no power to require its use.

So far the virus has gone by a few different names. As noted in the story, the virus was first isolated in Saudi Arabia but was first characterized by a group at Erasmus Medical Center in the Netherlands, who picked the name "human coronavirus-Erasmus MC," or HCoV-EMC. That irritated some Saudi officials. Some researchers have dropped the "EMC" and just use HCoV (human coronavirus), while the WHO has used nCoV.

De Groot commented that the name his group chose refers to a large region and avoids singling out any country.

The countries involved in the nCoV outbreak and their numbers of cases and deaths, as tallied by ProMED, are: Saudia Arabia, 22 cases and 13 deaths; Jordan, 2 and 2; the United Kingdom, 3 and 2; Qatar, 2 and 1; United Arab Emirates, 1 and 1. (One Qatari patient is still being treated in the UK, and one Qatari and the UAE patient were treated in Germany.)

See also:

May 5 ProMED posting with Memish's report

May 6 WHO statement

Mar 14 Eursurveillance report on UK cluster

May 5 Canadian Press story

May 6 ScienceInsider story