Five variants of the deadly Middle East respiratory syndrome (MERS) coronavirus have circulated between people and camels, a new study finds.
Meanwhile, a second study reported that an experimental vaccine for camels showed promise.
Several outbreaks of MERS have occurred in the Middle East and South Korea in recent years. About 35 percent of people who contracted the virus died, the researchers said.
Arabian camels are the most common host for the virus and one of the most likely sources of infection in people, the study authors said. The virus can mutate in camels and then be passed to humans, but little was known about how common the virus is in camels or how it’s transmitted to people.
For the study, researchers collected samples from more than 1,300 camels in Saudi Arabia — which has had the highest number of MERS cases. The investigators found that 12 percent of the animals were infected.
Genetic analysis of the samples revealed five variants of the virus, according to the team led by Jamal Sabir from King Abdulaziz University in Jeddah, Saudi Arabia. All of the variants contained evidence of human and camel MERS, which makes it easier to pass the infection between the two species, the researchers explained.
The findings suggest that there will be more variations in the future, the study authors said. They also concluded that preventing animal-to-human transmission is the best way to reduce the threat from the virus.
In the second study, researchers found that within three weeks after receiving an experimental vaccine, camels developed detectable levels of antibodies against MERS.
When infected with the virus, the vaccinated camels developed only mild symptoms and had much lower levels of the virus than camels that did not receive the vaccine, the researchers said.
Findings from both studies were published Dec. 17 in Science.
The World Health Organization has more about MERS.