|Locations where animal samples were taken relative to|
human outbreaks of MERS in 2012 (Eurosurvellience)
Samples were collected from camels, cattle, sheep, goats and chickens in areas where the disease has been found in humans, including Riyadh and Al Ahsa in the Saudi Kingdom and in Zarqa, Jordan where the first cluster was discovered in 2012.
100% of the camels tested in Jordan (11 of 11) and about 90% of camels tested in Saudi Arabia (280 of 310) tested positive for antibodies to MERS or a close form of the disease.
MERS antibodies had been found previously in camels form Spain, Oman, Egypt, Saudi Arabia and Qatar.
Some of the samples from Saudi camels may have been cross reactions with the bovine coronavirus (BCoV). Researchers caution that there appears to be a 'broad pattern of cross-reactivity' between these similar diseases and this should be considered when testing for the viruses.
It appears the camels in the area are exposed to the virus early in life. Researchers found that about 72% of young camels, under a year old, had been exposed to the disease and 95% of dromedary camels over a year old showed past exposure.
As of December 2, the World Health Organization has confirmed 163 cases of MERS, including 71 deaths. However, recent studies show the disease is under reported and the majority of cases are not being diagnosed.
In the past, testing for the virus has focused only on the most severe patients. For example, in the Jordanian cluster described in the report, eleven probable cases were involved, but only the two fatalities in the group were tested and verified to have had MERS.
Approximately 40% of infections are considered 'sporadic' or index cases and these have occurred in Jordan, Oman, Kuwait, Qatar, UAE and Saudi Arabia.
The Jordanian study stated,
"Human to human transmission has been observed in healthcare and family settings. Various studies indicate that the observed MERS-CoV diversity in humans results from multiple independent introductions in the human population in the Middle East and the number of these sporadic, primary infections is still increasing."Despite the findings of widespread MERS exposure in dromedarys, it is still unclear if camels are the reservoir which researchers suspect has repeatedly infected humans. Most victims have reported no contact with camels. "Neither the proximate animal source of human infection nor the natural reservoir of the virus is known," states the report. For now, the search for the origin of the illness continues.