Feb 19, 2013 (CIDRAP News) – One patient in a British family cluster of novel coronavirus (NCoV) infections, a 38-year-old man with an underlying medical condition, has died, and fresh details about a recently reported mild case have sparked new questions about how the virus is spreading and how big a threat it poses.
The man died Feb 17 in the critical care unit at Queen Elizabeth Hospital Birmingham, where he had been undergoing treatment for a chronic health condition, the hospital said in a statement today. He was immunocompromised, and health officials believe he was exposed to NCoV by sustained close contact with a sick relative, a 60-year-old man who was hospitalized in Manchester shortly after traveling in Pakistan and Saudi Arabia.
He received extracorporeal membrane oxygenation (ECMO), a heart-lung-bypass procedure designed to allow disease-damaged lungs to heal. His death raises the number of fatalities from the new virus to 6 of the 12 cases reported so far.
Mild infection raises transmission questions
The UK Health Protection Agency (HPA) today released new information about the third patient in the family cluster, who has recovered from a milder version of the illnesses after more limited contact: visiting the older man in the hospital on three occasions. The third patient had no contact with the man who died and, according to a new risk assessment from the European Centre for Disease Control and Prevention (ECDC), is a 30-year-old woman.
Neither the woman nor the patient who died had a recent travel history, and HPA and ECDC officials have said both cases provide further evidence of person-to-person NCoV spread, but so far there is no sign of sustained transmission.
The woman's limited contact with the man who died raises the possibility of an intermediary case within the extended family, the HPA said. The ECDC also noted the limited time the woman spent with the older patient, which it said might point to an intermediary case or fomite spread. "However, the investigation and intensive case finding around the three cases remain ongoing and the results cannot be prejudged," the agency said.
Public health authorities are tracing the contacts of the family members, including people who sat within two rows of the older man on a flight from Saudi Arabia to London, during which he first felt ill. Follow-up is also underway on health workers, patients, family, and friends who were in contact with the patients in hospital settings.
Health officials reconsider threat assessments
John Watson, MB BS, MSC, the HPA's head of respiratory diseases, said in the statement that the routes of NCoV transmission haven't been fully determined, but the recent UK cases show strong evidence of human-to-human spread in some circumstances.
"The three recent cases in the UK represent an important opportunity to obtain more information about the characteristics of this infection in humans and risk factors for its acquisition, particularly in the light of the first ever recorded instance of apparently lower severity of illness in one of the cases," he said.
The risk of infection in contacts is still considered low, and the threat to the general UK population remains very low, the HPA said.
Meanwhile, the ECDC said recent developments with the three UK cases increase the threat to the European Union, because the infection came to Europe on a commercial flight and resulted in two more illnesses, though the cluster is isolated to one family.
Emergence of a mild secondary case, the first of its kind, is worrisome, because other mild illnesses that are missed during NCoV detection efforts could spread the infection, the ECDC said. More work is needed to flesh out the illness spectrum, such as whether it causes severe disease of uncommon zoonotic origin, as well as mild or even asymptomatic infections, it said in the risk assessment.
Also, the emergence of the mild illness and the possibility that surveillance will find more of them raises questions about whether new case-finding strategies are needed, the ECDC said, noting that it is reviewing the issue with its member countries and global health partners.
Though it's reassuring that health officials have found no expanding case clusters, "the fact remains that there is a lot more that we do not know than we know about this virus," the ECDC said, adding that discussions are underway to provide guidance on research priorities.
Study finds NCoV easily infects lung lining
In a related development today, a European research group reported that the NCoV easily penetrates human airway passages and evades the immune system like other coronaviruses, such as one responsible for the common cold. The findings were published today in mBio, the online journal of the American Society for Microbiology (ASM).
The team used cultured bronchial cells that were engineered to mimic the epithelial lining to explore how well the new virus could infect and multiply. Their findings suggest that the airway cells are highly susceptible to NCoV infection, and the virus multiplied faster than the SARS virus, another member of the coronavirus family.
Volker Thiel, a study coauthor with the Institute of Immunobiology at Kantonal Hospital in St. Gallen, Switzerland, said today in an ASM press release that though data suggest the virus may have jumped from animals to humans very recently, it is just as well-adapted to infecting the human respiratory tract as other more familiar coronaviruses, which was surprising.
The investigators suspected that the NCoV uses the same strategy as other common coronaviruses to evade the immune system, and they tested the notion by pretreating epithelial cells with lambda-type interferon to boost their immune response.
They reported that the treatment significantly reduced the number of infected cells, which is encouraging, given that interferons are promising for treating SARS and hepatitis C.
In another lab-related development, the World Health Organization (WHO) today issued updated interim recommendations for managing NCoV lab risks. The document includes epidemiological developments that have occurred since the last update on Oct 31.
The guidance urges labs conducting routine tests to follow biosafety level 2 (BSL 2) practices, that labs working with viral isolates from clinical samples use additional containment practices, including those recommended for BSL 3, and that work with animals infected with NCoV take place in an animal BSL 3 facility.
Feb 19 HPA statement
Feb 19 HPA clinical update
Feb 19 Queen Elizabeth Hospital Birmingham statement
Feb 19 ECDC risk assessment update
Feb 19 mBio study
Feb 19 EurekAlert press release
Feb 19 WHO updated interim lab safety guidance