Human-Animal Infections: A Primer for Clinicians

Tara C. Smith, PhD


December 16, 2013

In This Article

MERS-CoV Leaves the Belfry

In September 2012, a 49-year-old man from Qatar was diagnosed with a case of acute respiratory syndrome with renal failure in a United Kingdom hospital. Initially seen in his home country after traveling to Saudi Arabia, he was transferred to the United Kingdom by air ambulance after 8 days in the hospital. Upon arrival in the United Kingdom, laboratory testing was done, and the presence of a novel coronavirus was confirmed.

Later testing showed that this virus was almost identical to one that had been isolated from a case reported earlier in 2012: a 60-year-old Saudi national who had died of a lung infection. More cases appeared in November 2012 after enhanced surveillance in the Middle East. As of November 2013, a total of 157 laboratory-confirmed cases of this novel virus, dubbed "Middle Eastern respiratory syndrome coronavirus" (MERS-CoV), have been reported, 66 (42%) of which were fatal.

Like the last emergent human coronavirus, severe acute respiratory syndrome (SARS), evidence suggests that MERS-CoV has a nonhuman reservoir: bats.[1] Although bats appear to be the ultimate reservoir for both of these coronaviruses, other intermediate hosts may play a role in transmitting these viruses to humans. In the case of SARS, this may be civet cats,[2] and for MERS-CoV, camels have been implicated as a possible intermediary between bats and people.

New Influenza Viruses

As MERS-CoV has been capturing attention in the Middle East, another emergent zoonotic virus has been evoking concern in China. The world has been tracking an avian influenza virus called H5N1 for the past 10 years across Asia, Europe, and Africa, in the fear that this bird strain may adapt to humans and cause a pandemic. Instead, it has caused only sporadic human cases over the past decade, almost exclusively in people who have had close contact with domestic poultry or wild waterfowl.

In February 2013, another avian influenza virus -- called H7N9 -- was found in humans in China. Since that time, this virus has been detected in 10 of China's eastern provinces, causing 137 infections and 45 deaths to date.

Meanwhile, as we were watching H5N1 and other avian viruses, a swine influenza virus adapted to humans and quickly spread around the world, causing the 2009 H1N1 pandemic.


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