In the latter stages of the 20th century and the early 21st century, medical researchers have noted a worrisome increase in the number of new conditions caused by infectious agents, many of which can be fatal, have pandemic potential, or both. The HIV virus that causes AIDS has been the most devastating, but recent decades have also seen the emergence of the ebola virus, hantavirus, e. coli virus, hepatitis C virus, SARS coronavirus, and many others that get little publicity outside of medical circles. The increase in newly discovered viral respiratory pathogens has been especially striking.
But why? Where are all these new infectious agents and new diseases coming from? Why now?
There are a number of contributing factors that have been proposed, including the following:
* Population growth puts more people in closer proximity to each other, which facilitates the spread of contagious infectious diseases.
* The planet is in the midst of a warming trend. Certain infectious diseases, such as those borne by mosquitoes, increase when the climate is more hospitable to their carriers. More such species can thrive in warmer weather.
* In areas devastated by war or other natural or unnatural disasters-of which there have been all too many in recent years-public health matters that we take for granted suffer greatly. In many countries around the world, clean drinking water is unavailable, the most basic sanitation measures are neglected. Many people don’t realize what a great portion of the dramatic improvement in human life expectancy in the last century or so came not from miracle cures for diseases and heroic interventions by life-saving doctors, but by mundane public health improvements to sewer systems and the like. When a step backwards is taken in these areas, it has a corresponding negative impact.
* Some of the apparent increase isn’t really an increase at all. In some cases, it’s not that the viruses and the diseases are new; it’s that we’d never been aware of them or given them a name before. Progress in molecular biology and more sophisticated laboratory methods have enabled researchers to identify many pre-existing pathogens. For example, it is now believed that the pathogens that cause such conditions as Lyme disease and Legionnaires’ disease were around long before they were ever isolated in the laboratory. People who suffered from these conditions were simply diagnosed with something else, if they were diagnosed at all.
* As significant as any factor is the rapid evolution of pathogens. The HIV virus multiplies so rapidly, to take one example, that it goes through a phenomenal number of “generations” in a short period, thus the process of natural selection plays out in extraordinarily fast motion. Anything that can kill 99% of it, or 99.9% of it, is soon rendered useless, because the 1% or 0.1% that happens to have resistance to it soon restores the population. This is why the indiscriminate use of antibiotics can have really bad consequences. New resistant strains of pathogens make conditions that used to be easily curable much more formidable.
* In some circles, a growing anti-science, anti-intellectual, anti-“Western” attitude leads people to not take the suggested measures that could reduce the spread of infectious diseases. From political leaders in Africa insisting HIV doesn’t cause AIDS and championing traditional medicines, to activists urging people to refrain from vaccinating their children due to supposed connections with autism, evidence-based medicine is losing out in many people’s minds to alternatives based on emotionalism and anecdote, loyalty to their culture, conspiracy thinking, or a general distaste they have for anything they associate with old white guys in lab coats in advanced Western nations.
* New medical technologies, such as blood transfusions and organ transplants, when not very tightly controlled and regulated, provide new paths for the spread of pathogens.
Some of these and other relevant factors show no sign of getting better in the foreseeable future, so there’s every reason to believe new and deadly infectious diseases will continue to emerge and spread.
It’s entirely plausible, in fact, that things will get worse. Imagine, for example, the mass intentional use of biological warfare techniques in the future, which could certainly happen. As hard as it is to deal with these threats that arise “naturally,” the last thing we need is to have to deal with that plus whatever augmentations the most diabolical human minds can come up with.
“Emergence of Infectious Diseases in the 21st Century.” Gideon.
“Infectious Diseases in the 21st Century.” Brigham and Women’s Hospital.