Most of us have experienced one of our best solutions backfiring and unintentionally creating a bigger problem in the future. One historical example of an unintended consequence occurred in the early 1900s in Hanoi, Vietnam. Under French Colonial rule, the city was proud of the sanitation benefits of its indoor toilets supported by a vast sewer system. Soon, however, rats gravitated to the underground network of pipes and began to proliferate wildly. In an effort to reduce the exploding rat population, health authorities embarked on the Great Hanoi Rat Massacre.
Civilians were paid a bounty for each rat they killed. In order to reduce the space needed for entire corpses, only the severed rat tail was required for payment. While the rat population decreased initially, large numbers of tail-less rats suddenly appeared on the streets. It turned out that rat hunters simply cut off the tails, received their payment, and released the rats for further breeding and tail-making. Even worse, health inspectors discovered new farms on the outskirts of Hanoi dedicated to importing and breeding rats.
What was missing from this effort, and what can we learn about unintended consequences?
First, define your desired outcome. As Alice in “Alice in Wonderland” says, “If you don’t know where you’re going, any road will get you there.” Perhaps the health authorities in Hanoi did not realize that income for food and shelter was more important to the civilians, or the civilians did not understand that rats were vectors for serious diseases. In other words, the day-to-day realities of the people were not aligned with the public health goal.
Now, as we roll into 2019, how can we learn from the past to control one of the most threatening public health problems: antibiotic-resistant bacteria? Clearly, our wide-scale use of antibiotics has created a terrible problem of increased disease and death from infections resulting from bacteria that are resistant to such medications.
In 1960, the U.S. Surgeon General stated, “We have won the war on bacteria [with antibiotics]”. Fifty years later, we know that this statement is far from the truth. Could antibiotic resistance have been predicted? I believe that the answer is, “Yes.” The development of resistance was not instantaneous. Rather, it was a progressive problem starting in the 1940s when more and more bacteria developed resistance to penicillin and other antibiotics. Our relief from having a way to fight infections made us ignore the seriousness of this trend and obliterated our desire to see what was clearly happening. The World Health Organization now states that if new antibiotics are not discovered by 2050, deaths caused by drug-resistant bacterial infections will surpass 10 million per year.
To provide additional ways to control bacteria in hospital buildings, environmental strategies are now being used. Some examples of these are the incorporation of metal (copper, silver) in surface materials, use of ultraviolet light in ductwork, and cleaning unoccupied patient rooms with hydrogen peroxide mist. While these strategies may be successful in the short term, we need to be sure they will not cause a new problem with super-resistant bacteria in the future.
Data from metagenomic analysis of bacteria recovered from space stations are reminding us of the evolutionary and survival capabilities of bacteria. Worrisomely, it has now been documented that bacteria exposed to metals can become resistant to both the metallic compounds and to unrelated antibiotics. In addition, there are also signs that bacteria can develop resistance to ultraviolet light exposure by increasing their production of anti-oxidant molecules.
This is not to say that UV-C and other environmental infection control strategies, which are rapidly gaining traction in hospitals, are not without value. The lesson from the past is: understand the downstream consequences of our actions by both researching the long-term efficacy of our solutions and by heeding early warning trends.
Almost all of us can anticipate the immediate results of our actions; however, a truly elegant solution accomplishes its intended purposes while minimizing unintended actions, side effects, and consequences. We know that humans do not exist on planet earth in isolation. Trying to extinguish all microbial life is not only impossible, it would not be desirable.