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Are Humans Inducing Epidemic Outbreaks?

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When the Ebola virus first hits you, it starts with a headache. But with horrifying haste, it sets in like a stroke. Blood vessels break and intestines split open, turning internal organs into a toxic soup. Death comes in convulsions as the body crashes and bleeds out.

To paraphrase from The Hot Zone, the 1994 bestseller by Richard Preston, is arguably tasteless at a time like this. But despite his Stephen King-like dramatization of Ebola's gruesome effects, Preston was prescient in his parting sentence: "It will be back."

The Ebola virus has indeed come back with a vengeance. The infectious agent is tearing through Guinea, Liberia, and Sierra Leone in the worst outbreak on record. So far, the epidemic has stricken more than 1,000 people in West Africa. Two of those infected are U.S. citizens, one of whom is a doctor now undergoing treatment in special isolation at Emory University Hospital in Atlanta.

Ebola first penetrated the population in 1976 through a human encounter with a host, probably a small primate, although the precise origin remains unknown. Meanwhile, many West Africans remain in denial.

"Today the word 'Ebola' carries so much stigma that few ailing individuals even seek diagnosis," wrote Laurie Garrett, senior fellow for global health at the Council on Foreign Relations.

With early treatment, the 90 percent mortality rate drops to around 60 percent. But even as Ebola infections are managed in some patients through hospitalization, pockets of people who cover it up or deny its existence are exacerbating Ebola's effects. Out of fear, some hide their own condition or that of their loved ones. Lack of bio-containment means that those who are infected have more opportunities to spread the virus. Unabated, the crisis could become a denial-induced epidemic.

Denial is not endemic to West Africa or limited to Ebola. Every day, all over the world, humans choose immediate gratification over long-term or collective considerations. We are can already see the consequences of over-consumption in the obesity epidemic.

Now scientists are discovering that not only does deforestation harm the environment, it may also be directly responsible for the Ebola outbreak. As Terrence McCoy reported in The Washington Post:

Extensive deforestation and human activities in the depth of the forests may have promoted direct or indirect contact between humans and a natural reservoir of the virus.

The more humans trigger ecological changes, the greater the likelihood that we will come into contact with direct sources of epidemics. Such a conclusion is troublesome for West Africa, which has one of the world's highest rates of regional deforestation.

Denial ain't just a river in Egypt

West Africans may hesitate to seek treatment for Ebola out of fear, but wealthy Westerners are prone to their own sort of denial. We overload ourselves with pesticides and air conditioning in an attempt to dominate nature, never thinking our efforts could come back to bite us.

But in the summer of 2012, the largest epidemic of West Nile Virus in the world broke out in Dallas, Texas. The vector-borne virus, which spreads through contact with a common house mosquito, killed 19 people and caused fever and neurological problems in hundreds of others.

Interestingly, the most intense hot zone for the virus was the Park Cities, one of the wealthiest neighborhoods in the United States. This same clustering was found in both 2006 and 2012. The reason this was a hot spot was housing density: Since real estate is so valuable in this area, the houses are packed together -- and housing density predicts West Nile transmission.

As fear ripped through the neighborhood during the 2012 epidemic, parents hid children in their homes. The media did their part to sensationalize it, too. In fact, the story is back again, with Dallas residents sounding off about precautions. But nary a word has been said about a warming climate.

Many in the largely Republican community might dismiss climate change as a purely environmental problem, but they are not so dismissive about West Nile, which they perceive as health issue. But Dr. Robert Haley sees a connection between climate change and the increase in infectious disease.

Dr. Haley is the senior author of a study published in the Journal of the American Medical Association on the outbreak, which investigated 173 identified cases in 2012 (up from 67 cases in 2006, the first notable epidemic). Presenting his findings at a conference in Dallas several months ago, Dr. Haley predicted that a changing climate will escalate the numbers and efficiency of vector-borne diseases like West Nile.

Two degrees in 100 years is rapid change that stresses biological systems, which can cause and spread diseases.

As the climate warms, tropical zones expand. Warm air contains more moisture than dry air. More humidity, predicts Dr. Haley, will also bring an expanded range of vector-borne diseases such as dengue or "break bone" fever, malaria, and schistosomiasis.

"It's a neck-and-neck battle with microbes to stay ahead," warns Dr. Haley, who spent 10 years at the Center for Disease Control in 1970s where he saw emergence of new parasites and viruses.

Alongside more rapid emergence of novel infectious diseases (hantavirus), a warming climate could result in increased asthma and heart attacks from air pollutants; increased allergies and asthma from higher pollen pollution; greater risk of food-borne and water-borne diseases (cholera); famines from drought; glacial shrinkage and reduced aquatic abundance; and a higher mortality rate due to increasing heat and ozone levels.

"There is no more scientific debate over climate change," concluded Dr. Haley, "but the health effects are still misunderstood."

An all-too-human problem

Epidemics teach us a lot about how humans think and react. With infectious disease, when the immediate effects are destructive and the root cause is complex, the impulse is to focus on treating the symptoms and avoid dealing with the cause.

So far, the consequences of a warming planet have mainly afflicted the poor, but the West Nile outbreak reveals how health consequences of a warming planet strike the rich also. Climate change denial may continue to cause a drag on national policy, but we can no longer deny that our consumption is having an impact.

Although a long line of doomsday predictions have failed to materialize in precisely the ways we thought they would, we need not lull ourselves into a false sense of control. Pesticides and mosquito spray can't protect us from problems inherently produced within a hyper-consuming, hyper-connected world.

In the 20th year since The Hot Zone was published, we cannot predict the random moment or remote spot where the next outbreak of the Ebola virus or similarly infectious disease will occur. But continuing on our current trajectory, we can count on this: "It will be back."

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