Credit FAO
# 8812
For nearly a year we’ve watched the evidence mount up that camels play a major role in the hosting, and probable spread, of the MERS coronavirus which was first discovered two years ago in the Middle East. Dromedaries aren’t viewed as being the only possible animal reservoir of the virus, nor are they believed responsible for he majority of human cases.
But the virus (or antibodies to the virus) have certainly been found in camels (see Kuwait Tests Camels - Finds 6% Positive For MERS-CoV), and we’ve seen a few instances where camel-to-human transmission is strongly suspected (see CIDRAP: More Evidence for Camel-to-Human MERS-CoV Transmission).
Last month, in Eurosurveillance: MERS-CoV Antibodies & RNA In Camel’s Milk – Qatar we looked at research supporting the notion that consumption of unpasteurized camel’s milk might be a route to infection.
Some of the most compelling research has been associated with Dr. Ian Lipkin, including a study published last February (see mBio: MERS-CoV In Saudi Arabian Camels) that established MERS-CoV to be a common, likely mild or asymptomatic, infection in young camels in Saudi Arabia and that suggested that they may well be the source of at least some portion of the human infections we’ve seen over the past two years.
Another study, again involving Dr. Lipkin, was published the end of April (see mBio: MERS-CoV Carriage By Dromedaries) that recovered the MERS-CoV from nasal swabs of camels, and demonstrated that whole-genome consensus sequences were indistinguishable from MERS coronaviruses recovered from humans.
An accompanying press release, Columbia University's Mailman School of Public Health, states:
"The finding of infectious virus strengthens the argument that dromedary camels are reservoirs for MERS-CoV," says first author Thomas Briese, PhD, associate director of the Center for Infection and Immunity and associate professor of Epidemiology at the Mailman School. "The narrow range of MERS viruses in humans and a very broad range in camels may explain in part the why human disease is uncommon: because only a few genotypes are capable of cross species transmission," adds Dr. Briese.
Despite the preponderance of evidence, not everyone is ready to accept these findings as `proof’ of the role of camels in the spread of the MERS coronavirus (see Saudi MOA Spokesman: Camel Link Unproven).
Today the open access journal mBio has published a long letter, written by Emad M. Samara Ph.D and Professor Khalid A. Abdoun, both of the Department of Animal Production at King Saud University that call into question the findings of the two previously mentioned studies involving Dr. Lipkin.
After listing a number of the findings in these previous studies, the authors argue that they cannot be taken as `conclusive evidence’ that dromedary camels carry the infectious form of MERS-CoV or have ever infected humans.
They suggest it is equally plausible (albeit, unproven) that humans are the ones who have infected camels.
It’s a long letter – far too long to reproduce here – and so in fairness to their argument, I would invite my readers to follow the link to read it in its entirety. When you return, I’ll have a link to a reply from Dr. Lipkin et al.
Concerns about Misinterpretation of Recent Scientific Data Implicating Dromedary Camels in Epidemiology of Middle East Respiratory Syndrome (MERS)
Emad M. Samara, Khalid A. Abdoun
LETTER
This letter addresses some concerns about two recent articles published by the same authors in mBio (1, 2), specifically many uncertainties regarding the potential applicability of their epidemiological data, which were obtained from dromedary camels (DCs) infected with Middle East respiratory syndrome coronavirus (MERS-CoV), to human public health.
(Continue . . . )
The reply to this critique is fairly brief - where the authors stand by their work - can be read at the following link:
Reply to “Concerns About Misinterpretation of Recent Scientific Data Implicating Dromedary Camels in Epidemiology of Middle East Respiratory Syndrome (MERS)”
Abdulaziz N. Alagailia, Thomas Brieseb, William B. Kareshc, Peter Daszakc, W. Ian Lipkinb
It is absolutely true that one can rarely say `case closed, time to etch our findings in stone’ with any field of scientific research. `Conclusive evidence’ is a very high, sometimes unobtainable, standard of proof.
And few would argue that more work doesn’t need to be done on the virology, ecology, and epidemiology of the MERS coronavirus.
But until that can happen, we pretty much have to go by the preponderance of evidence. And for now, despite the misgivings of these authors from King Saud University, that evidence strongly suggests camels play an important role in the hosting, and spread of MERS-CoV.
