Nelb: Diagnosis 2008: Infected by political plague

The news coverage about the presidential election has reached epidemic proportions. Even when there is nothing substantial to report, journalists resort to endless analysis of the candidates’ strategies and tactics. In the end, all this back and forth is enough to make your head spin.

Rather than add to this deluge of analysis in this column, I’ll try to offer a different perspective on interpreting the dynamics and the stories of the presidential election — the public health perspective. Just like infectious diseases spread from person to person, the information and ideas of the political candidates can become an epidemic. Thus, epidemiology, the science of public health, may offer some clues about why some stories stick and others don’t and what we can do about it.

Three basic principles form the core of understanding any epidemic — agent, host, and environment. The agent is what infects the person, the host is who is infected with the disease and the environment is where the individual is affected. Together, these three elements of the “epidemiological triangle” can help us predict how diseases will spread and plan what we can do to stop them.

In recent years, many social scientists have begun applying the principles of epidemics to ideas, fads and even politics. The evolutionary biologist Richard Dawkins even coined a term for these infectious ideas, “memes,” and a field of research known as memetics has sprung up to analyze these issues. In the context of electoral politics, rumors and beliefs about the candidates are the epidemiological agents, voters are the hosts and our interconnected world of 24-hour news is the environment.

When any outbreak occurs, one of the first things that epidemiologists do is try to identify the agent and where it comes from. “Common-source epidemics” come from a single source, such as unclean water, and can be relatively easily addressed by removing the source (as John Snow famously did in 1854 when he removed the handle of the broad street pump in the London cholera epidemic). “Propagated-source epidemics,” on the other hand, are spread from person-to-person and can often me more difficult to control.

Unfortunately, in the world of election epidemiology, ideas spread quickly from person to person and can’t be controlled through the traditional common-source tactics. As the McCain campaign recently learned, criticizing Katie Couric or Tina Fey for their representations of Sarah Palin after the show has already aired is too late to mitigate any of the damage that YouTube and other viral video sites have inflicted.

If the source of the infection can not be easily eliminated, then epidemiologists must understand who is affected (the hosts) to try to mitigate the impact of the disease on a population level. The distribution of who is affected by the disease has a huge impact. Most diseases attack those with the weakest immunity (the young and old) in a V-shaped curve when mortality rates are plotted against age, but sometimes special strains, such as Spanish flu epidemic of 1918-1920, have a deadly W-curve mortality curve meaning that the disease impacts the young, healthy adults in our society as well. Overall, the Spanish flu epidemic took a devastating toll of as many as 100 million lives.

In political campaigns, who is infected also matters. The candidates obviously want to target undecided voters in swing states, but persuading this group can be especially difficult. Just like most strains of the flu virus with a “V-curve” affect the young and old, the extremes of either party are easiest to convince; finding a “W-curve”-like attack that can persuade those in the middle of spectrum is the greatest challenge.

Once the agent and hosts are identified, epidemiologists then turn to the environment to try and stop the spread of the disease. Not surprisingly, epidemics tend to spread faster if the environment is more interconnected and the disease more contagious. Yet perhaps counterintuitively, all populations will reach a point of herd immunity where so many people have already been infected or acquired immunity that the spread of the disease will begin to decline; those that are the fastest to spread through the population may begin to decline sooner than the diseases that have longer latency periods.

The election environment is obviously one of high contagion and interconnectedness, which helps explain why this election has been full of so many rumors. More interesting however, the principles of epidemics may explain why stories with a high shock value, such as the Reverend Wright scandal, tend to die out as quickly as they came, while ideas with more subtle and latent effects like perceptions of Obama’s religion, tend to linger — for example, a recent Pew Research survey found that only about half of voters correctly know that Obama is a Christian.

Unfortunately, few epidemic diseases can ever be completely eradicated, but by following the principles of epidemiology, we can reduce the devastating impact of disease on the population at large.

Similarly in politics, we may not be able to convince everyone to support a particular position, but by keeping rumors under control, voters can begin to focus on the issues that really matter.

Robert Nelb is a student at the School of Public Health. His column runs occasionally. Contact him at