U.S. reports first person-to-person MERS transmission

The two men shared a handshake, officials say

CDC officials recently confirmed a third U.S. case of the Middle East Respiratory Syndrome (MERS) coronavirus that was likely the result of person-to-person transmission inside the United States.

TSA is posting MERS warnings at airports. Should you be worried?

Background on MERS and the first U.S. cases

In September 2012, the World Health Organization (WHO) issued a global alert after a Qatari man was diagnosed with a new respiratory illness similar to the Severe Acute Respiratory Syndrome (SARS) virus that killed nearly 800 people worldwide in the early 2000s.

Since then, there have been more than 570 confirmed cases of the virus across 18 countries. According to CDC, 171 of the cases have resulted in death, and up to 20% of the cases involved health care workers.

On May 2, CDC confirmed the first U.S. case of MERS at a hospital in Indiana. The patient—a health care worker who traveled to Saudi Arabia—was successfully treated for MERS and has been released from the hospital.

How an Indiana hospital contained the first U.S. MERS case

On May 12, CDC confirmed the second U.S. case of MERS. The patient, also a health care worker, lives in Saudi Arabia and works at a hospital where patients have been treated for MERS. Two health workers treating the second case fell ill with MERS-like symptoms, but later tested negative for the coronavirus.

The first and second U.S. MERS cases were unrelated.

Details on the third case

The Indiana patient and the latest patient to test positive for MERS—an Illinois man—met twice in business meetings before the first patient was hospitalized with the virus. Health officials say the men met for a 40-minute meeting that involved no more physical contact than handshakes.

Health officials believe the virus is not highly contagious, although there have been cases of it spreading from close contact with an infected person—many of those infected have been family members or health care workers.

Although the man tested positive for the virus, he has not experienced any of the virus' symptoms and has never required medical treatment, CDC officials say. Officials say there have been other MERS-positive cases where the patient experienced no symptoms.

The man was among many people asked to be tested for the virus as health officials sought to contain its spread.

"We don't think this changes the risk to the general public," which remains low, says CDC's David Swerdlow. Moreover, WHO officials announced last week that there is no proof of MERS's sustained human-to-human transmission, so the outbreak so far has not been deemed a global health emergency (AP/Modern Healthcare, 5/17 [subscription required]; Carter/Hellerman, CNN, 5/19).

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