Middle East respiratory syndrome coronavirus (MERS-CoV) has been spreading very slowly on the Arabian peninsula since 2012. The original source of the illness, previously not seen in humans, remains unknown but camels have been a suspect for some time. On Jan. 6, the Emerging Infectious Diseases journal release, ahead of its April publication, a study titled "Antibodies against MERS Coronavirus in Dromedary Camels, United Arab Emirates, 2003 and 2013."
MERS-CoV, as discussed in the study, belongs to the genra Betacoronavirus, which are found in mammals, especially bats. Insect-eating bats are known to carry viruses that are very similar to MERS-CoV but the study's authors point out that human contact with these animals is rare. It is more likely that the origin of the virus is in an animal more closely associated with man.
Two previous studies have shown that dromedary camels throughout Africa and the Arabian peninsula have antibodies to MERS-CoV. This study looked at blood samples from camels in the United Arab Emirates taken in 2003 and in 2013. Camels carry other coronaviruses, that are similar to MERS-CoV, and the study's authors went to great lengths to create a testing protocol that would exclude positive results for these other viral species.
The results of the testing showed that blood drawn from camels in 2003 carried antibodies for MERS-CoV, as did blood draws from 2013. The authors conclude that camels have been experiencing infections from this virus for at least a decade. This does not settle the questions about the source of the infection in humans.
The number of coronavirus species, and the intra-species variations in genetic makeup, are great enough, the authors suggest, that much more research is needed before the camel can be named as the source for MERS-CoV. Finding a virus with a genetic sequence similar to both bat and camel coronaviruses, an intermediate version bridging the two mammalian species, is necessary. The same is true for camels and humans. And, finding the identical geneticly-sequenced virus in both camels and humans would be the most desirable research result.
Since Sept. 2012, the World Health Organization has received reports of 177 confirmed cases of MERS-CoV and 74 deaths. All of the patients became infected on the Arabian peninsula, primarily in Saudi Arabia. Some of the patients are known to have had extensive contact with camels in their daily lives.
Are camels the source of this deadly but slow moving outbreak? Medical science cannot answer that question, yet, but the answer is getting close. Perhaps researchers are finally over the hump.