The Centers for Disease Control and Prevention (CDC) officials have confirmed a second case in the country of MERS, a virus that has killed at least 145 people, mostly in Saudi Arabia.
The CDC identified the patient as a healthcare worker who travelled from Saudi Arabia to Orlando, Florida.
Middle East respiratory syndrome (MERS) causes fever and kidney failure but is not considered highly contagious.
The patient has been isolated in hospital, health officials said.
MERS belongs to the coronavirus family, which includes the common cold and SARS, or severe acute respiratory syndrome, which caused some 800 deaths globally in 2003.
MERS belongs to the coronavirus family, which includes the common cold and SARS
Health officials say MERS only appears to spread through close contact, but there is no known cure.
“This is unwelcome but not unexpected news,” CDC director Tom Friden told reporters on Monday of the Florida case.
The Florida patient is not connected to the first confirmed US case, reported two weeks ago in Indiana, although the patients’ circumstances are similar.
A healthcare worker who “works and resides” in Saudi Arabia, the Florida patient took a flight on May 1st from Jeddah to London’s Heathrow Airport, then continued on to Boston, Atlanta and finally Orlando.
Health officials said they were contacting passengers on those flights “out of an abundance of caution” and directing them to look out for symptoms which include high fever, cough and shortness of breath.
The first confirmed MERS patient, also a healthcare worker in Saudi Arabia, has been released from hospital and is “fully recovered”.
CDC officials said they had found no secondary infections from the Indiana case and genome testing suggested the virus was not changing, despite a growing number of cases reported in Saudi Arabia since March.
According to the World Health Organization (WHO), 538 MERS cases have been reported worldwide since 2012, with 145 deaths. The vast majority of cases have been found in Saudi Arabia, especially among healthcare workers.
On Sunday, Saudi Arabia urged its citizens to wear masks and gloves when dealing with camels so as to avoid spreading MERS.
A new research suggests that dromedary camels could be responsible for passing to humans the deadly MERS coronavirus that emerged last year.
Tests have shown the MERS (Middle East Respiratory Syndrome) virus, or one that is very closely related, has been circulating in the animals, offering a potential route for the spread.
The study is published in the journal Lancet Infectious Diseases.
But the scientists say more research is needed to confirm the findings.
The MERS coronavirus first emerged in the Middle East last year. So far, there have been 94 confirmed cases and 46 deaths.
While there has been evidence of the virus spreading between humans, most cases are thought to have been caused by contact with an animal. But until now, scientists have struggled to work out which one.
To investigate, an international team looked at blood samples taken from livestock animals, including camels, sheep, goats and cows, from a number of different countries.
Dromedary camels could be responsible for passing to humans the deadly MERS coronavirus
They tested them for antibodies – the proteins produced to fight infections – which can remain in the blood long after a virus has gone.
Professor Marion Koopmans, from the National Institute of Public Health and the Environment and Erasmus University in The Netherlands, said: “We did find antibodies that we think are specific for the MERS coronavirus or a virus that looks very similar to the MERS coronavirus in dromedary camels.”
The team found low levels of antibodies in 15 out of 105 camels from the Canary Islands and high levels in each of the 50 camels tested in Oman, suggesting the virus was circulating more recently.
“Antibodies point to exposure at some time in the life of those animals,” Prof. Marion Koopmans explained.
No human cases of the MERS virus have been reported in Oman or the Canary Islands, and the researchers say they now need to test more widely to see if the infection is present elsewhere.
This would include taking samples from camels in Saudi Arabia, the country where the virus is the most prevalent.
Prof. Marion Koopmans said: “It is a smoking gun, but it is not definitive proof.”
Health officials say confirming where the virus comes from is important, but then understanding how humans get infected is a priority.
Gregory Hartl, from the World Health Organization, said: “Only if we know what actions and interactions by humans lead to infection, can we work to prevent these infections.”
Data suggests that it is not yet infectious enough to pose a global threat and is still at a stage where its spread could be halted.
The new Middle East Respiratory Syndrome (MERS) virus, which has killed half of those infected, is “unlikely” to reach the same scale as SARS, ministers in Saudi Arabia say.
Most of the 90 MERS cases reported so far have been in Saudi Arabia.
MERS is from the same group of viruses as the common cold and SARS, which killed 774 people.
However, a detailed analysis of the Saudi cases, published in Lancet Infectious Diseases, did warn of “major gaps” in understanding of the virus.
The MERS coronavirus emerged in 2012 and has infected 90 people worldwide, 45 of them have died.
MERS is from the same group of viruses as the common cold and SARS, which killed 774 people
The global concern is that cases could spread much further, echoing the SARS outbreak.
Cases have been centered on the Middle East – with patients in Jordan, Qatar, Saudi Arabia and the United Arab Emirates. Additional cases in France, Germany, Italy, Tunisia and the UK have all been linked to travel to the Middle East.
Researchers in Saudi Arabia have published details of the 47 cases reported in the country.
They suggest a pattern of mostly older men being infected. Most cases were also in people with other medical problems, more than two-thirds of the reported cases also had diabetes.
The lead researcher and Deputy Minister for Public Health, Prof. Ziad Memish, said: “Despite sharing some clinical similarities with SARS, there are also some important differences.
“In contrast to SARS, which was much more infectious especially in healthcare settings and affected the healthier and the younger age group, MERS appears to be more deadly, with 60% of patients with co-existing chronic illnesses dying, compared with the 1% toll of SARS.
“Although this high mortality rate with MERS is probably spurious due to the fact that we are only picking up severe cases and missing a significant number of milder or asymptomatic cases.
“So far there is little to indicate that MERS will follow a similar path to SARS.”
However, the latest Saudi investigation both highlighted the need to find where the virus was coming from.
Prof. Ziad Memish’s report said: “Reducing the rate of introduction of MERS coronavirus into human beings is unpredictable because the source of the virus is not yet known.