Three more people in Saudi Arabia have become infected with the Middle East respiratory syndrome (MERS) coronavirus and one has died, the World Health Organization (WHO) said on Thursday, and it also confirmed the first MERS case in Oman.
In a disease outbreak update, the Geneva-based United Nations health agency said the four new cases bring the number of people worldwide struck by the MERS virus to 149, of which 63 have died.
Health authorities and scientists are still trying to figure out what kind of animal "reservoir" may be fuelling the MERS outbreak.
The virus, which is from the same family as the one that caused a deadly outbreak of severe acute respiratory syndrome SARS in 2002, is thought to have originated in bats.
One study published in August found strong evidence that it is widespread among dromedary camels in the Middle East.
MERS, which was unknown in humans until this earlier year, has also since been reported in people in Tunisia, France, Germany, Italy, and Britain.
The WHO said the patient in Oman is a 68-year-old man from Al Dahkliya region who became ill on October 26.
"Investigations are currently ongoing to determine what exposures might be responsible for his infection," it said.
The three patients in Saudi Arabia, one woman and two men, all had underlying medical conditions but all reported having had no contact with animals before falling ill.
One of the Saudi patients, however, was reported to have been in contact with another person infected with MERS.
The WHO says MERS patients to date have most commonly had respiratory disease as their primary illness. Diarrhoea is commonly reported among the patients and severe complications include kidney failure and acute breathing difficulties.
"Health care facilities that provide care for patients suspected or confirmed with MERS...should take appropriate measures to decrease the risk of transmission of the virus to other patients, health care workers and visitors," it said.