Since its discovery in 2012, the MERS virus has been worrying health officials who have yet to decode its mysterious make up and means of transmission. Now concern grows as the first confirmed report of the virus in the United States adds to the dramatic spike in cases reported in the Middle East last month.

The virus was discovered in early 2012 and until March of this year recorded cases averaged about 15 a month. Then, in April 2014, this number shot up to 217 for that month alone, more than the 207 cases known to have occurred since the virus’ discovery. Prior to April, the mortality rate for the virus had been as high as 45 percent.

Part of the reason why this hike in occurrence is so troubling to researchers and health officials is that no one knows yet how the MERS virus is transmitted. There have been confirmed infections in bats and camels as well as humans. In fact, it is believed that camels are at least partially responsible for the transmission, though testing of their meat and fluids has yet to reveal exactly how this would occur.

Other research has revealed that the virus tends to infect people with weakened immune systems. Recently, two antibodies were isolated that may play a role in preventing proteins on the surface of the virus from attaching themselves to cells in the body. It appears that the virus is able to take some evasive actions to avoid immune responses, but that these actions compromise the virus, weakening its infectious potential.

Researchers emphasize that while there is cause for concern, all is not doom and gloom. Their work suggests that part of the spike in reported cases could stem from better detection of mild or asymptomatic cases, the presence of which has lowered the mortality rate to around 30 percent. There is hope that the isolated antibodies could help with the development of a vaccine and more effective testing procedures are in the works. Though the virus is picking spreading more rapidly, experts are optimistic that with proper precautions, the virus could still be contained.