A New Human Coronavirus Causing SARS-Like Illness: WHO Casts Wide Net, no Definitive Human-to-Human Transmission

Abstract & Commentary

By Stan Deresinski, MD, FACP, FIDSA, Clinical Professor of Medicine, Stanford University, Hospital Epidemiologist, Sequoia Hospital, Redwood City, CA, is Editor for Infectious Disease Alert.

Source: Zaki AM, et al. Isolation of a novel coronavirus from a man with pneumonia in Saudi Arabia. New Engl J Med 2012;367:1814-20

On June 13, 2012, a 60-year-old Saudi man was admitted to a hospital in Jeddah, Saudi Arabia, with severe pneumonia after 7 days of fever and worsening respiratory symptoms. Following transfer to intensive care the following day, he required mechanical ventilation but died due to progressive respiratory and renal failure on hospital day 11. Various bacteria had been isolated from respiratory secretions during his hospitalization, but examination by indirect inmmunofluorescence for common respiratory virus pathogens was negative. Cytopathic effects were observed in LLCMK2 cells inoculated with sputum obtained on the day of hospital admission and the patient’s serum collected on hospital days 10 and 11 strongly reacted to infected cells in an IgG immuofluorescence assay – a finding not duplicated in 2400 samples from patients seen in Jeddah. While PCR assays for other respiratory virus families were negative, amplicon fragments were generated with primers designed to detect coronaviruses. Examination of the results of sequencing identified a novel betacoronavirus most closely related to 2 bat coronaviruses, called hCoV-EMC/2012 (human coronavirus- Erasmus Medical Center, the latter indicating the Rotterdam, Netherlands institution at which the viral discovery was performed, although the initial isolation in cell culture was performed in Saudi Arabia).

On September 23, authorities in the United Kingdom reported that the same virus had been detected in a 49-year-old Qatari with a severe respiratory infection who had been transferred to England for intensive care. Since then additional cases have occurred. On November 30, the World Health Organization reported that 2 fatal cases in Jordan occurred in April, 2012, but the virus had only recently been identified as the cause. Overall to date, a total of 9 laboratory-confirmed cases of infection with the novel coronavirus have been reported to WHO — five cases (including 3 deaths) from Saudi Arabia, two cases from Qatar and two cases (both fatal) from Jordan. The infections in each case had been locally acquired and, although there have been 2 clusters — a family in Riyadh and hospital health care workers near Amman — there is as yet no definitive evidence of human-to-human transmission.1

Commentary

WHO recommends that infection with this virus should be suspected in patients with pneumonia or ARDS without an alternative etiologic diagnosis and who have a history of residence in or travel to the Arabian Peninsula within previous 10 days.2 Also suspect are individuals with acute respiratory illness of any severity who have had close contacts with patients with proven or suspected hCoV-EMC/2012 infection within the previous 10 days. In addition, case clusters of severe respiratory infection of unknown etiology — whether or not the patients have traveled to the Arabian Peninsula — should also be suspect. Similarly suspect are health care workers with pneumonia who have cared for a patient with severe respiratory symptoms without etiological diagnosis and without regard to travel history. Thus, WHO has cast quite a wide net.

Prior to the 2003 SARS outbreak, only 2 human coronaviruses (which caused only cold symptoms) were known, but subsequent to that outbreak, 2 additional ones (HCoV-NL63 and HCoV-HKU1) were soon identified. HCoV-EMC now represents the sixth coronavirus known to cause disease in humans. The illness caused by this virus resembles that caused by the SARS virus, but sequencing has demonstrated that the viruses are only distantly related. A major difference from SARS is that the latter was very efficiently transmitted between humans, which, to date, does not appear to be the case with this new coronavirus. It should also be recognized with regard to this new virus that Koch’s postulates — the criteria establishing a causal relationship between a microbe and a disease — have not been formally fulfilled.

References

  1. WHO. Global Alert and Response (GAR). Novel coronavirus infection – update http://www.who.int/csr/don/2012_11_30/en/index.html
  2. WHO. Interim surveillance recommendations for human infection with novel coronavirus.
  3. December 2012 http://www.who.int/csr/disease/coronavirus_infections/InterimRevisedSurveillanceRecommendations_nCoVinfection_03Dec12.pdf