Published Date: 2012-12-25 19:00:19
Subject: PRO/AH> Novel coronavirus - Eastern Mediterranean (06): comments
Archive Number: 20121225.1468821
NOVEL CORONAVIRUS- EASTERN MEDITERRANEAN (06): COMMENTS
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A ProMED-mail post
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Date: Mon 24 Dec 2012
From: Danuta Skowronski <Danuta.Skowronski@bccdc.ca> [edited]
[Re: ProMED-mail Novel coronavirus - Eastern Mediterranean (05): WHO, transmission route 20121223.1465597]
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We would like to comment on 2 epidemiologic issues included in recent postings regarding the 2012 novel coronavirus (nCoV):
1. Failure (to date) of nCoV to transmit easily or sustainably between people.
This has been cited as an epidemiologic feature distinguishing nCoV from the 2003 SARS CoV. It is worth remembering, however, that despite being a substantial global concern, SARS CoV was also not generally very transmissible. [1] It required certain conditions of close contact (hospital or household) or facilitated transmission (aerosol generating procedures) to achieve person-to-person spread and was strikingly a nosocomial-associated infection throughout. SARS CoV did not ultimately achieve the status of a pandemic, failing to exhibit widespread community transmission in most countries. Low inherent transmissibility combined with a delay in peak infectivity until well into the course of serious illness may explain why SARS was primarily a nosocomial infection; why so few countries experienced outbreaks; and why it could ultimately be extinguished. Seasonality may have also played a role. [1]
2. The "index case" for the April 2012 Jordan nCoV cluster could not be determined.
The index case in an epidemiologic investigation is the 1st recognized case. Lessons learned from SARS instead emphasize the importance of "Patient Zero", the 1st case whether initially recognized or not. [2] While this may seem a matter of semantics, the distinction has implications for the prevention of onward transmission. Mathematical models for SARS, incorporating contact network theory, have stressed the importance of Patient Zero in predicting epidemic likelihood -- determined by the transmissibility of the agent, the number of contacts of Patient Zero, and the number of people infected between Patient Zero (the 1st case) and intervention on the index case (the 1st recognized case). [3]
Patient Zero thus tests the baseline capacity of a system to respond to emerging threats before they are known or recognized. [2]
As such, Patient Zero commands advance and ongoing attention to infection control precautions in the management of all SARI [severe acute respiratory illness], notably that of unknown etiology; emphasizes the need for strong, well-coordinated surveillance systems, with particular vigilance for clusters involving health care workers as signal if not incipient events; and underscores the need for efficient communication networks to disseminate public health alerts and enhance awareness before additional cases or clusters occur.
References
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1. Skowronski DM, Astell C, Brunham RC, et al: Severe acute respiratory syndrome (SARS): A year in review. Annu Rev Med 2005; 56: 357-81. Doi: 10.1146/annurev.med.56.091103.134135. [Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/15660517].
2. Skowronski DM, Petric M, Daly P, et al: Coordinated response to SARS, Vancouver, Canada. Emerging Infect Dis 2006; 12(1):155-8. Available at <http://wwwnc.cdc.gov/eid/article/12/1/05-0327_article.htm.
3. Meyers LA, Pourbohloul B, Newman MEJ, Skowronski DM, Brunham RC: Network theory and SARS: predicting outbreak diversity. J Theor Biol 2005; 232(1): 71-81. [Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/15498594].
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Danuta Skowronski MD, FRCPC
Naveed Z Janjua MBBS, DrPH
Influenza & Emerging Respiratory Pathogens Team
BC Centre for Disease Control
Canada
<Danuta.Skowronski@bccdc.ca>
[ProMED-mail would like to thank Drs Skowronski and Janjua for their comments and observations on epidemiological issues related to this novel organism.
We are currently very early in our understanding of the epidemiology of this organism, including understanding what the mechanism of exposure and subsequent transmission of this organism to humans is, as it is genetically most closely related to a bat coronavirus seen in Hong Kong. If one postulates that the organism has not as yet evolved into an efficient person-to-person transmitted organism, then a key piece of information necessary at present is finding out the reservoir of the organism (? bats in the countries where human cases have occurred) and how these "species jumps" are occurring -- are the bats transmitting this organism (the nCoV) to another animal that is in the food chain so that humans then have contact with contaminated bodily fluids (similar to the situation with the SARS coronavirus and civet cats)? Or perhaps, as ProMED-mail subscriber Merritt Clifton has postulated, are these bats contaminating fruit with infected saliva that is then ingested by people in the area (similar to the transmission of Nipah virus in Bangladesh)? Hence, identification of the index case(s) in these clusters might help address these questions (as well as studies on the prevalence of the nCoV in bats and other animals having contact with people in the affected areas. - Mod.MPP]
See Also
Novel coronavirus - Eastern Mediterranean (05): WHO, transmission route 20121223.1465597Novel coronavirus - Eastern Mediterranean (04): receptor charact. 20121211.1446670
Novel coronavirus - Eastern Mediterranean (03): research, ISARIC (UK) 20121208.1443486
Novel coronavirus - Eastern Mediterranean (02): diagnostics 20121207.1442473
Novel coronavirus - Eastern Mediterranean: WHO, Jordan, conf., RFI 20121130.1432498
Novel coronavirus - Saudi Arabia (19): Singapore: NOT 20121129.1430397
Novel coronavirus - Saudi Arabia (18): WHO, new cases, cluster 20121123.1421664
Novel coronavirus - Saudi Arabia (17): 4th case, RFI 20121121.1418018
Novel coronavirus - Saudi Arabia (16): whole genome sequence 20121114.1409556
Novel coronavirus - Saudi Arabia (15): new case 20121104.1391285
Novel coronavirus - Saudi Arabia (14): KSA MOH 20121022.1358297
Novel coronavirus - Saudi Arabia (13): history, collateral damage 20121021.1356623
Novel coronavirus - Saudi Arabia (12): RFI 20121019.1353615
Novel coronavirus - Saudi Arabia (11): clin. lab. & epi. investigations 20121004.1324712
Novel coronavirus - Saudi Arabia (10): WHO, revised case def. 20120930.1315960
Novel coronavirus - Saudi Arabia (09): real-time RT-PCR, addition 20120929.1315725
Novel coronavirus - Saudi Arabia (08): real-time RT-PCR assay 20120928.1314254
Novel coronavirus - Saudi Arabia (07): Eurosurveillance reports 20120928.1313337
Novel coronavirus - Saudi Arabia (06) 20120927.1311743
Novel coronavirus - Saudi Arabia (05): WHO, case def., nomenclature 20120926.1309747
Novel coronavirus - Saudi Arabia (04): RFI, Jordan, April 2012 20120925.1308001
Novel coronavirus - Saudi Arabia (03): UK HPA, WHO, Qatar 20120923.1305982
Novel coronavirus - Saudi Arabia (02): additional cases, RFI 20120923.1305931
Novel coronavirus - Saudi Arabia: human isolate 20120920.1302733
2004
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SARS - worldwide (15): animal reservoirs 20040417.1059
2003
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SARS - worldwide (176): serosurvey China animal traders 20031016.2611
SARS - worldwide (04): etiology 20030325.0737
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