The Middle East respiratory syndrome coronavirus (MERS-CoV) has claimed four more lives, according to the World Health Organization
Oman saw its first laboratory case confirmed, while the other three were from the eastern region of Saudi Arabia.
Since September 2012, WHO has been informed of a total of 149 laboratory-confirmed cases of infection with MERS-CoV, including 63 deaths.
MERS, which causes fever, coughing and sometimes kidney failure, may have developed from a virus found in bats. It is similar to the SARS virus, which killed nearly 800 people around the world in 2003.
Using data from the known cases of MERS, the researchers found that, on average, someone with the disease will most likely infect at most only one other person. SARS patients were likely to infect three others. That level of contagiousness made it a pandemic.
Although MERS is deadlier than SARS was, its lower level of contagiousness means that it may eventually fade away on its own.
However, the researchers call for continued surveillance and caution. They point out that SARS became more contagious over time, and that MERS could do the same.