The viral respiratory disease MERS, first identified in 2012 in Saudi Arabia, is apparently more widespread but less deadly than originally thought, according to a German study.
While the mortality rate for MERS - an acronym for Middle East respiratory syndrome - was earlier put at about 30 percent, the international study found that the majority of infections likely caused no significant symptoms.
Led by the University of Bonn and the German Centre for Infection Research (DZIF), the new study, published in the London-based medical journal The Lancet Infectious Diseases, tested blood samples from more than 10,000 Saudis.
Although none had had a serious illness in recent years, 15 were carrying antibodies to the MERS virus.
"More than 40,000 people in Saudi Arabia have probably been infected with MERS over the past 10 years without noticing it," remarked DZIF scientist Christian Drosten.
He said the study's findings supported the hypothesis that MERS affects mainly camels.
Under certain conditions the virus can occasionally pass to humans, but human-to-human transmission is probably fairly rare, he added. So there is no reason to fear an Ebola-like epidemic.
The World Health Organization has registered more than 1,000 laboratory-confirmed cases of MERS worldwide to date. Over 400 people have died. Outbreaks of the disease are centered in Saudi Arabia.
Explore further: MERS kills 10 in Saudi after surge in virus deaths