In recent weeks, the threat to South Korea from Middle East Respiratory Syndrome, better known as MERS, has exploded. Over the last 18 months or so, Ebola has hit West Africa hard and penetrated the borders of the United States and Europe. During the previous decade, H1N1 Flu and Severe Acute Respiratory Syndrome (SARS) infected people around the globe.

What is going on in the world and what does it bode for the future?

Clearly these infectious diseases are cause for alarm. Each of these virus-induced illnesses damages the lungs and poses a major health threat. But interestingly, even those caused by similar viruses vary in origin, ease of spread and the danger posed to human life.

And unlike the antibiotics available to fight bacterial infections, we have few medical treatments for viruses. Rather, we depend on our immune systems to produce antibodies, proteins capable of fighting diseases like the flu.

Most troubling about the emergence of these viral infections is no one can predict where and when the next epidemic will hit. All we know with certainty is that it will occur. If one known virus mutates, or a new virus emerges, a pandemic could result with devastating consequences.

The good news is that even though we face a problem of epic dimensions, we also have powerful new tools to prevent or fight the next outbreak. Already, advances in our understanding and treatment of these types of infectious disease have enabled us to limit the spread of these newer viruses. Medical researchers are figuring out how emerging diseases like MERS are transmitted. And, as a result, we’re better prepared for the future than at any time in the past.

Even so, we’re hardly in the clear. As each new viral disease develops, we need to rapidly identify the virus, develop an effective vaccine, ensure that we achieve strict quarantine and gain world-wide collaboration to contain these dangerous threats to global health.

Let’s look at these viruses to understand their biology and how we might best respond to a new threat in the future.

The Virus Briefly Explained

A virus is a tiny infectious agent, too small to see through a traditional light microscope. They can replicate only inside the living cells of other organisms such as humans, birds, and pigs. Viruses contain small amounts of DNA or RNA in a thin protein and lipid shell. Because of their simple form, they’re unable to survive outside of animal or plant hosts, but can change quickly and go from innocent to lethal.

Some viruses are easily transmitted from person to person, but others are not. Transmission can occur through a variety of body fluids, including sputum, blood, genital secretions, or fecal material. Of course, when a virus is easily passed between people, the risk of spread across borders increases, and the threat of a pandemic grows.

Why MERS Is Distinctive

Although the current outbreak in South Korea has infected more than 100 patients and led to a handful of deaths, MERS appears relatively difficult to transmit. It requires both close physical contact and an underlying medical vulnerability. To date, almost all victims have been elderly patients in hospitals. The likelihood of healthy, young people developing it appears low. To date, only one child has been infected.

But were it more contagious, containing the spread would have been far more difficult. In spite of quarantine, one infected individual from Korea was able to get on an airplane, fly to Hong Kong and take a bus to China, where he ultimately was hospitalized. Fortunately, it does not seem he infected anyone along the way.

We know that the first individual diagnosed with MERS during the current breakout had visited Saudi Arabia. No surprise there; most outbreaks have occurred in Middle Eastern countries. MERS was first reported in 2012 in Jordan – hence the “Middle East” in its name – according to the Centers for Disease Control and Prevention (CDC). And similarly, the two patients identified in the United States also were returning from Saudi Arabia.

MERS is caused by a coronavirus, but genetically distinct from other human diseases caused by that particular family of viruses. Like many viral illnesses, it began as an animal virus, in this case one common in camels. And similar to many viral diseases, MERS-related symptoms usually consist of fever, cough and shortness of breath.

Still, once a patient is infected, the chances of dying are high. No specific treatment is currently available.

The Subtext On Ebola

Ebola dominated the headlines a year ago, as it decimated villages in Africa and infected people in the United States. The virus that causes the disease is an equal-opportunity killer, affecting healthy people as often as it does those with chronic disease. The fatality rate varies by geography, but in most cases exceeds 50%. The first symptoms are fever, muscle pain and sore throat, frequently followed by nausea, vomiting, and diarrhea. Some individuals will also develop internal and external bleeding, often through the gums or the intestines.

The best defense is good infection control practices and avoiding contact with infected blood and body fluids. Quarantine to minimize human-to-human spread is essential. Because transmission doesn’t happen until a patient becomes sick and feverish, limiting exposure is easier than with the other viral diseases. All staff caring for infected patients should wear protective coverings and respiratory devices. A few experimental medications are being studied to determine effectiveness.

Researchers believe this virus began with wild animals and spread to humans. The current Ebola virus can be traced back to the first outbreak, in 1976, near the Ebola River in the Democratic Republic of Congo, from which the disease gets its name. Scientists know Ebola persists in fruit bats and infects people through contact with the blood of ill or dead animals, including chimpanzees, antelope or the bats themselves. Transmission from animals to humans happens only by direct contact through broken skin or mucous membranes. Human-to-human transmission can occur through direct exposure to the bodies of Ebola victims during burial practices, and contributed to the recent spread through the West African countries of Liberia, Guinea, and Sierra Leone.

But much of the spread can also be traced to travelers carrying the virus, crossing borders into adjacent nations and infecting others.

The SARS Conundrum

SARS filled headlines a decade ago, but has gone quiet since then. But before SARS was ultimately controlled through quarantine in 2003, it infected 8,000 people and killed nearly 10 % of those affected. First reported in Asia in 2002, it spread through travelers to other countries.

SARS starts with fever and cough, then progresses to pneumonia, often with a high fever and severe body aches. It, too, is a coronavirus, but unlike MERS, no major underlying illness is needed to catch it. Close person-to-person contact, via coughing or sneezing – usually within three feet of another individual – is sufficient for transmission. It can also be conveyed when a healthy person touches a surface or object contaminated with mucus and then touches his own mouth, nose or eye with his hand.

The mainstay of treatment is supportive care, often in an intensive care unit, until the patient’s immune system has had enough time to respond. No specific medication is currently available.

Influenza: A Cautionary Tale

Influenza – or more commonly “the flu” – infects people around the globe each year, and on occasion has erupted into an epidemic, killing millions. Effective vaccines have recently reduced the dangers from influenza, but history offers a harrowing warning about the prospects of recurrence.

In 1918, a new strain arose, infecting one-fifth of the world’s population and killing an estimated 50 million people. The first wave, referred to as the “three-day fever,” was relatively benign. But when it returned six months later, it was lethal. People died hours or days after the first symptoms appeared. Those most affected were young and healthy.

How do we explain this epidemic? We now understand that the influenza virus is “sloppy” – it replicates and creates frequent new mutations. Most of these changes are minor and the severity of disease and spread are limited.

But big changes in the viral genome can bring about pandemics like the one that struck in 1918. And the more the genetic material mutates, the greater the risk for everyone. Under such circumstances, even now, we would have no way to prevent a pandemic.

Next Steps For The Next Generation Of Viruses

Why is all this happening? The increase in international travel in recent decades has dramatically shrunk the time a virus takes to spread from here to there around the globe. And, in the process, drastically elevates the risk of infection spreading from the first victim to unsuspecting strangers thousands of miles away.

Case in point: the virus in the 1918 influenza pandemic took months to span the world. The 2009-2010 pandemic needed just days.

Even in light of such realities, hopes today run high. Scientists can now identify new viruses quickly. It took four years to identify the virus that causes HIV/AIDS, but only a few weeks to identify the ones that led to SARS and MERS. Through public health advances, we have learned how techniques such as quarantine, masks, protective clothing and hand washing can limit the spread of new viral illnesses.

We now have effective vaccines against some of these viruses. We have new tests to rapidly diagnose many diseases when they occur. And in laboratories around the globe, researchers are developing potential vaccines and treatments for diseases like Ebola. In addition, physicians now can prescribe the latest antiviral medications to lessen the symptoms of milder forms of disease.

In the future, we will need worldwide collaboration on programs to identify new outbreaks immediately and thereby limit transmission. We will need governments and research institutes to invest in developing effective, low-cost and easily administered immunizations and antiviral treatments. And when we have effective vaccines, everyone will need to be vaccinated.

At one time, protecting the public’s health was considered a local community responsibility. But in this new world that’s no longer so. With people and goods now moving so freely across borders, we are all now citizens of a global community. We must now undertake a collaborative world-wide enterprise.

Nothing less will do.

This article appeared on JUNE 25, 2015 @ 1:00 PM,