SARS? MERS? SOS!
Last week the Centers for Disease Control and Prevention (CDC) announced that MERS-CoV had made it to the United States. A man is being kept in isolation after testing positive for the virus.
What the heck is going on? Why are these deadly, acronym-inducing viruses popping up? Do we need to send an SOS to deal with SARS and MERS?
SARS raises its ugly head. Twelve years ago, a severe respiratory illness cropped up in Southern China. Patients reported typical flu/cold-like symptoms; fever, chills, body aches and headache. Some patients also reported diarrhea. Within a week, patients also had a dry cough, often accompanied by shortness of breath. Nearly all patients went on to develop pneumonia. 9-12% of younger people and >50% of people over 65 years of age died.
The illness was named by its symptoms: Severe Acute Respiratory Syndrome (SARS).
Within months, the illness spread to more than two dozen countries in North America, South America, Europe and Asia. There was a world-wide panic as people rushed to buy masks and the Singapore government handed out SARS Protection Kits. The virus was a prime example of what happens when a virus uses global transportation systems to traverse the world.
Global efforts to identify and contain the virus were also an example of science and medicine at its best. In an unprecedented effort, the virus that causes SARS was identified in just a year (a coronavirus). Shortly thereafter diagnostic tests were developed and the origin of the outbreak was identified. SARS is believed to come from small mammals. Without modern scientific techniques this process could have taken decades.
World-wide health organizations worked quickly to contain the epidemic. The World Health Organization (WHO) made daily reports on new cases and information was disseminated quickly to health care workers on how to prevent new infections.
And as quickly as it cropped up, the virus stopped spreading among people (I would love to say disappeared, but I am sure SARS is still around). No reported cases have been identified since 2004.
MERS is not SARS. And now it looks like we are in for another round. Middle East Respiratory Syndrome (MERS) is another coronavirus that was first identified in Saudia Arabia in 2012. People infected with the MERS virus have similar symptoms as those that have SARS, but the mortality rate is much higher – 30%.
MERS was limited to 6 countries in or near the Arabian peninsula until April of this year when a visitor traveled from Saudia Arabia to the United States, took ill and was diagnosed with MERS at an Indiana hospital.
MERS is a novel coronavirus and is different from coronaviruses that have been found in people before. Both bats and camels test positive for previous infection with MERS, suggesting they are a potential source of the virus.
What is a coronavirus? Coronaviruses are very common viruses in people and animals. Until SARS, only 4 human coronaviruses were known and they usually caused a mild to moderate respiratory illness, like the common cold. They are extraordinarily large RNA viruses and the virions look like they have a halo around them reminiscent of a solar corona (thus the name) when seen under the electron microscope.
Coronaviruses are spread through the air after coughing and sneezing. They are also spread through close contact such as kissing, sharing utensils, or caring for the sick (healthcare workers are often infected). Coronaviruses are hardier than other types of viruses (like herpesviruses!) so they may also stay on contaminated objects or surfaces and be spread by touching those surfaces and then touching your mouth, nose, or eyes.
Why are new viruses emerging? A lot of scientists study “emerging viruses;” viruses that have changed and emerged as a new disease-causing agent. Ebola, SARS and MERS viruses are good examples of emerging viruses. It is not always clear why a virus will suddenly show up in a population, but a number of factors can contribute:
- Population movements: When populations move, they carry all of their worldly and bodily (like bacteria and viruses) possessions. New diseases can be introduced into a population when populations begin to mix. The smallpox epidemic in Native Americans was introduced by Europeans arriving in the “New World.”
- Deforestation/Urbanization: As forests are cleared, animals are flushed out of their habitats and have increasing contact with humans. Some viruses gain the ability to infect new species and cause disease.
- Long distance air travel: We are no longer isolated from pathogens by oceans.
- Migration: Even though this is a population movement, it bears a special acknowledgement and nod to the influenza virus. New strains of influenza are created when birds migrate from one area to another and viruses intermix with other influenza strains in the different areas.
- Irrigation: Opening up new waterways can lead to expansion of mosquito breeding grounds and an increase in mosquito-borne illnesses.
So basically, as we traverse the world and build new homes, we are putting ourselves in contact with new pathogens.
Luckily our global communication can also be used to combat these diseases!