With the new movie “Contagion” in theatres, there has been some debate over whether its premise -- an infectious disease spreads uncontrollably worldwide and kills millions of people rapidly -- could really happen. Regardless of how well-versed you are in infectious diseases, reading different mainstream press articles leaves an uneasy feeling. What are the chances we will be faced with a doomsday scenario such as the one described in the movie “Contagion”? Before answering that, let’s get something straight: “Contagion” is just a movie and understanding the complexity of disease outbreaks cannot be summarized in a couple of hours.
In more recent times, there has been the emergence of Severe Acute Respiratory Syndrome (SARS) and the recent 2009 H1N1 Influenza Pandemic which have threatened to become serious global epidemics. In both instances, these viruses appeared to be very lethal, highly infectious and spread quickly. That was exacerbated by global travel. Rightly so, officials worldwide were concerned that the spread of these highly contagious viruses could infect millions of people and lead to large numbers of casualties. While there were many deaths associated with both of these diseases, the expected mass casualties did not materialize.
Another example is the present day spread of the Human Immunodeficiency Virus (HIV), which leads to Acquired Immune Deficiency Syndrome or AIDS. AIDS is only second to road traffic accidents as the leading cause of death among people 20-24 years of age worldwide. We currently have no vaccines available and the costly, and many times, ineffective antiviral therapeutics for AIDS patients have had limited success. Furthermore, HIV infections are on the rise because the virus is developing resistance to antiviral therapies, most likely leading to a resurgence of AIDS cases in industrial nations.
Virus pandemics are a clear and present danger, and there may be some merit to the worry of a “Contagion”-like event happening. The SARS virus and HIV spread as quickly as the virus in the movie. SARS was expected to be our real life version of this Hollywood script. When HIV first appeared, there was so much concern President Ronald Reagan convened his staff in 1981 to determine whether HIV/AIDS was a bioterrorism weapon because many men began to die rapidly. However, the likelihood of a situation like “Contagion” is low.
One reason, in part, can be explained by the biology of viruses. Very simply put, viruses are organisms that require a host to reproduce and spread. If the virus destroys the host then the virus dies, too. Viruses that are the most successful in nature are able to infect a host, reproduce and spread, without killing the host (e.g., cold sores in your mouth are caused by the virus Herpes simplex, which is a life-long, non-lethal infection). Granted, if an emerging infectious disease has a first contact with people, chances are very high that those people initially infected will die. As the epidemic progresses, conditions will change and fewer people will die. Some infected persons will survive and develop immunity, while others will have an inherent immunity against the infectious agent. This prevents the epidemic from uncontrollably spreading; thereby giving us a chance to contain and stop the virus spread in its tracks. Many other factors also affect the outcome of an emerging epidemic (its discussion is beyond the scope of this blog article). With every new infectious agent we encounter we can learn more about the biology of viruses and how they infect and spread throughout the population. This also helps us be better prepared to deal with the next potential threat.
The most significant reason we are not experiencing deadly epidemics is a direct result of federally-funded basic science research and public health awareness programs. Basic research has made important strides to improve our understanding of the biology of viruses. We continue to generate novel antiviral therapies and are increasing our arsenal of vaccines against infectious diseases. Augmenting scientific discoveries are public outreach programs and a rapid response towards containment or mitigation. As with any natural or man-made disaster, preparedness is the key to preventing the worst.
The spread of SARS was expected to lead to a devastating death toll, as rapidly and as lethal as it was spreading. Yet the death toll was limited to less than a thousand. Despite a more inter-connected world and no vaccine against SARS, this highly infectious disease was stopped in its tracks. The reason for this was a rapid global health response and effective containment strategies to prevent further spread. Of course it helped that scientists were able to quickly develop a first vaccine for SARS within one year of its initial contact with humans. Similarly, public health awareness campaigns in the ‘90s helped temporarily mitigate the extent of HIV/AIDS-related mortality rates and helped control the spread of HIV. Basic research was able to supplement the prevention of HIV from spreading by generating available antiviral therapies
Many institutions tasked with disease surveillance (e.g., the Centers for Disease Control) are excited to have Hollywood highlight the hard work by public health officials, mainly because their work is often taken for granted. Others see this as an opportunity to direct the public’s attention towards the fact that basic research is underfunded. For many diseases we are still lacking the necessary tools to be well-equipped. Finally, some even suggest this should be the Centers for Disease Control’s version of “Top Gun” to attract more people into public health service.
As an infectious disease specialist having worked to identify novel targets for developing therapies and vaccines against viruses, I perceive any of these outcomes to be positive for the public health arena. But the work of public health officials and scientists can only go so far; therefore, the main message we should take away from watching “Contagion” is that the first line of defense against any type of epidemic is a strong public health awareness, which begins with you and me.