The new infections, including one fatal case in a 73-year-old Saudi man and three in Saudi health workers who showed no adverse symptoms, bring the total confirmed cases of the respiratory disease to 176, of which 74 have died, the United Nations health agency said.
MERS emerged in the Middle East in 2012 and is from the same family as the SARS virus. It can cause coughing, fever and pneumonia.
Although the worldwide number of MERS infections is fairly small, the more than 40% death rate among confirmed cases and the spread of the virus beyond the Middle East is keeping scientists and public health officials on alert.
Source in question
Cases have been reported in Saudi Arabia, Qatar, Kuwait, Jordan, United Arab Emirates, Oman and Tunisia as well as in several countries in Europe, and scientists are increasingly focused on a link between the human infections and camels as a possible "animal reservoir" of the virus.
In a disease outbreak update, the WHO said the new confirmed case of MERS in the United Arab Emirates (UAE) was in a 59-year-old woman, the wife of a man previously confirmed as being infected. Although she has no adverse symptoms, she is in hospital in isolation.
Dutch and Qatari scientists published research earlier this month that proved for the first time that MERS can also infect camels – strengthening suspicions that these animals, often used in the region for meat, milk, transport and racing, may be a source of the human outbreak.
The WHO says people at high risk of severe disease due to MERS should "avoid close contact with animals when visiting farms or barn areas where the virus is known to be potentially circulating".
For the general public it advises normal hygiene steps such as hand washing before and after touching animals, avoiding contact with sick animals, and good food hygiene practices.
Read: more about MERS