Thanks to Greg Folkers for sending the link to this December 23 report in The Lancet by Jaffar A. Al-Tawfiq and Ziad A. Memish: Emerging respiratory viral infections: MERS-CoV and influenza. Excerpt:
Infection with MERS-CoV was initially described in a patient from Saudi Arabia and then retrospectively identified in patients from Zarqa, Jordan. As of Dec 2, 2013, 163 cases of infection with MERS-CoV have been reported, with 71 fatalities. MERS-CoV can cause sporadic infection, infection among families, and, of particular concern, infection among health-care workers.
The largest outbreak of MERS-CoV was described in Al-Hasa, the eastern province of Saudi Arabia. Fever and cough was present in most cases, with shortness of breath in almost half of all cases, and gastrointestinal symptoms in about a third.
A study of the largest reported outbreak of MERS-CoV6 estimated the median incubation period to be 5·2 days (95% CI 1·9—14·7), and reported a high rate of person-to-person transmission in 21 of 23 cases in health-care settings. Case-fatality rate was high (65%) in this outbreak.
Of more than 417 household and health-care contacts, symptoms of MERS-CoV developed in only seven people. A subsequent large-scale phylogenetic analysis of 21 genome sequences and inclusion of the previous nine published MERS-CoV genomes showed that multiple introductions of MERS-CoV and lower R0 values were possible. Thus MERS-CoV has not yet reached pandemic potential.
Transmission within Saudi Arabia was consistent with movement of an animal reservoir, animal products, or infected people. The source of the infection has yet to be identified, although bats and camels have been implicated.
A clinical and epidemiological analysis of 47 cases showed that infection with MERS-CoV occurred predominantly in men, although this finding did not hold after an interim analysis of 133 cases. Most patients who were initially infected with MERS-CoV had underlying comorbid medical conditions and laboratory testing showed that most of these cases had raised concentrations of lactate dehydrogenase and aspartate aminotransferase associated with thrombocytopenia and lymphopenia.
In preparation for the Hajj this year, the largest recurring religious mass gathering worldwide, the Saudi Ministry of Health recommended that certain individuals postpone their participation. Groups particularly at risk from infection include pregnant women, children younger than 12 years, adults older than 65 years, and those with chronic or acute diseases.
The concern over the pandemic potential of MERS-CoV was estimated in two recent publications.9 In one optimistic view, the estimated MERS-CoV R0 was 0·69 compared with the R0 for prepandemic severe acute respiratory syndrome-coronavirus of 0·80. This optimistic estimate downplayed the possibility of a MERS-CoV pandemic, which supported the recommendations of the Third Meeting of the International Health Regulations Emergency Committee, that MERS-CoV does not warrant international measures to curtail Hajj-related travel.
Sporadic cases MERS-CoV continue to be reported, and thus continued vigilance and further studies are needed to close the knowledge gap in MERS-CoV epidemiology and clinical presentations.