Mysterious MERS: The Next SARS?

Do you remember SARS? People first showed up sick with it in late 2002, and from then until mid 2003, it caused the deaths of 775 people in China. SARS (short for severe acute respiratory syndrome) is a viral respiratory disease. Because it can be rapidly transmitted and has a high mortality rate (about 9.6% — there’s no effective treatment), the outbreak presented a global threat.

But what does a viral flare-up that ended a decade ago have to do with things today? As it turns out, there’s actually an outbreak happening right now, mostly in Saudi Arabia, that’s due to a similar virus. The disease, which was first identified in a man in June 2012, is called MERS (short for Midle East respiratory syndrome). (It’s actually so similar that for a while the virus was informally being called the Saudi SARS.) What is truly alarming about MERS is that it has the potential to be even more devastating than SARS – so far MERS has had a much higher fatality rate (about 47%), although this has been with many fewer cases (114 total).

While a lot remains unknown about MERS, such as where the virus came from exactly and how to treat it, its similarities to SARS have helped clinicians treat the outbreak. Both SARS and MERS are caused by a type of virus called a coronavirus, which typically infects the respiratory and gastrointestinal systems. (Many common colds and even cases of pneumonia are caused by coronaviruses.) Both SARS and MERS are thought to be transmitted between people from close contact, but, luckily for us, the ability of MERS to spread from one person to another seems to be very low.

Once we figure out the origins of MERS, it should help us better contain the outbreak. After the SARS outbreak, based on its genetics it was found that the SARS virus likely came from masked palm civets (Paguma larvata), which are eaten in China. However, the virus was also found in other local animals, including ferret badgers (Melogale spp.), raccoon dogs (Nyctereutes procyonoides), and domestic cats. Bats were also discovered to possibly be a reservoir for coronaviruses like SARS. And, in fact, based on its genetics, the MERS virus is actually suspected to have originated in bats, but how it got from bats to humans is unclear – there is likely a “middleman” we’re unaware of.

The treatment plan for MERS may also be improving – earlier this month, a research group published results on a treatment approach that was effective in rhesus macaque models of MERS (using interferon-a2b and ribavirin, a nucleoside inhibitor). If this combination therapy is effective in humans, it may help prevent the MERS outbreak from reaching the levels of the SARS outbreak.

The current MERS outbreak is just one more example of how important it is to learn from the past – there are countless ways in which it can be extremely helpful for understanding, and dealing with, the present.

For further reading:

• Tracy Vence’s article “The Many Mysteries of MERS” at The Scientist
• Centers for Disease Control and Prevention’s webpage “Frequently Asked Questions about SARS“
• Centers for Disease Control and Prevention’s webpage “Middle East Respiratory Syndrome (MERS)“
• Wikipedia’s article “Middle Easy respiratory syndrome coronavirus”