By Josh Levs, Elizabeth Landau and Ashley Hayes
The spread of the potentially fatal Middle East respiratory syndrome has become more serious and urgent, the World Health Organization said Wednesday.
But it does not constitute a global health emergency at this point, a WHO committee determined.
Declaring an emergency is "a major act" that can "raise anxieties," said Dr. Keiji Fukuda, the organization's assistant director-general for health security.
Despite concerns about the syndrome, researchers have not found "any increasing evidence of person-to-person transmissibility," he said.
There have been more than 500 cases of MERS in 17 countries, including 145 deaths, according to the World Health Organization. Many off the cases are in Saudi Arabia and the United Arab Emirates.
Two cases have been confirmed in the United States -- both health care providers who were working in Saudi Arabia. The first was in Indiana; the second in Florida. Two health care workers went to an emergency room with flu-like symptoms after coming into contact with the Florida patient.
Representatives of 13 countries made up the emergency committee that convened Tuesday through a phone conference, the WHO said.
Affected countries need to take immediate steps to improve infection prevention and control, the WHO said. The majority of infections have taken place inside hospitals.
MERS is a coronavirus, the same group of viruses as the common cold. It attacks the respiratory system. Symptoms can lead to pneumonia or kidney failure.
There is no vaccine or special treatment.
Hagel, others checked for fever
Defense Secretary Chuck Hagel got a firsthand brush Wednesday with fear of the disease in the land of its likely origin.
Before a meeting in Saudi Arabia with Crown Prince Salman Abdulaziz in Jeddah, everyone entering the room with Hagel unwittingly passed by a device screening for fever.
Its operators told reporters that they were checking for people who might be infected with the virus that causes Middle East respiratory syndrome. They found no one with a raised temperature.
CNN's Miriam Falco, Elizabeth Cohen, Jen Christensen and Athena Jones contributed to this report.
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