A second U.S. case of the mysterious MERS virus has been found in Florida, federal health officials announced Monday.
Like the first U.S. patient, the second patient is a health care worker who lives in Saudi Arabia. "The patient is isolated in the hospital and is doing well," Centers for Disease Control and Prevention director Dr. Tom Frieden told reporters.
Frieden says the risk to the U.S. public is low, and the two cases are not related. But to be safe, officials are tracking down people the patient may have been in contact with while traveling from Jeddah, Saudi Arabia to London, Boston, Atlanta and then Orlando on May 1.
"It's a very big job," Frieden said.
"This patient was visiting family and did not visit any theme parks," Dr. John Armstrong, Florida state secretary of health, told reporters.
The 44-year-old man began feeling ill on May 1 while on the flight from Saudi Arabia but wasn't sick enough to seek medical treatment until he was in Orlando, CDC said. He was admitted to Dr. P. Phillips Hospital in Orlando May 9, officials said.
Dr. Kevin Sherin, director of the Orange County Health Department, said when the man came to the hospital emergency room on Friday afternoon, doctors quickly thought of MERS because he had been in Saudi Arabia and, even more tellingly, was a healthcare worker there.
"The patient is in good condition and is improving," said Dr. Antonio Crespo, infectious disease specialist and chief quality officer for the hospital. "We are taking every precaution, but believe the risk of transmission from this patient is very low since his symptoms were mild and he was not coughing when he arrived at the hospital."
The first known U.S. patient with Middle East respiratory syndrome — a health care worker in his 60s — went home on Friday from the hospital in Munster, Indiana, where he had been treated. Doctors said he recovered fully.
The Indiana patient was kept isolated while he was treated for the virus and health workers who cared for him before they knew he had MERS were kept quarantined and tested for the virus. So far, he does not seem to have infected anyone else and the normal incubation period has passed.
CDC says 538 cases of MERS have been reported to the World Health Organization, and 145 of these have died. WHO says the virus is on the upswing, but most cases are in Saudi Arabia.
WHO says for some reason hospitals in Saudi Arabia are not able to control the spread of the virus. CDC now has a team in Saudi Arabia helping to investigate the outbreaks.
Frieden says the increase in reported numbers of patients suggests that officials are looking harder for MERS.
"The more we find, the lower the case fatality rate gets, but it's still quite high," he told NBC News. "That's why we need to make sure of two essential things: the first is for health care facilities, hospitals and other places to make sure we do everything possible to stop it from spreading because that's where we've seen the big outbreaks and second, not to overreact elsewhere, because really, we have not seen spread through casual contact."
He says genetic tests suggest the virus is not spreading more because of mutations.
It’s been traced to camels and Saudi officials have cautioned people to take care when handling the animals, their meat or milk. But no one is sure yet how people are being infected, and most people who have been diagnosed have not had direct contact with camels.
Experts say careful infection control can keep the virus from spreading.
Many hospitals around the world have been phasing in such precautions as the world keeps an eye out for new pandemics, and as evidence piles up on how to stop all sorts of infections, from drug-resistant superbugs such as MRSA to avian influenza.
There's no vaccine and no specific treatment for MERS, which was only identified in 2012. It’s caused by a coronavirus, in the same family of viruses that cause common cold symptoms, but also a relative of the severe acute respiratory syndrome, or SARS, virus that swept the world in 2003. SARS sickened around 8,000 people and killed about 10 percent of victims before it was stopped.
WHO officials fear MERS could do the same thing. So far it has had about a 25 percent to 30 percent fatality rate, but it's less infectious than SARS was.
"This virus has not shown the ability to spread easily from person to person," the CDC's Dr. Anne Schuchat told reporters.
SARS spread around the world in a matter of months, infecting more than 8,000 people and killing 774 before it was stopped in 2004. The United States reported eight cases, of them in travelers who were infected somewhere else.