Connecting the dots

This is probably the last original article I shall ever get published in a prestigious peer-reviewed scientific journal (Journal of Epidemiology and Community Health, 2010, 64:105-108). I was especially chuffed to be able to quote one of David's thoughtful essays (my reference #3)


CONNECTING THE DOTS: THE POWER OF WORDS AND THE DIVERSITY OF EPIDEMIOLOGICAL INFORMATION

Words are supposedly reliable tools to communicate scientific discourse; but words are very exacting. Ideally, they communicate our thoughts precisely and concisely, but they can obfuscate, mislead and confuse, often unintentionally. That is why technical dictionaries are so necessary. Good scientists do not want to be like Humpty-Dumpty, who said to Alice “When I use a word it means exactly what I choose it to mean, nothing more, nothing less.” One incentive to compile the Dictionary of Epidemiology was the insistence by an eminent clinician-epidemiologist that “case-control study” described what everyone else called a randomised controlled trial.

Words arranged in particular ways become more than the sum of their parts. They can arouse strong feelings because of emotional overtones or cultural associations. Several kinds of imagery, especially metaphor, can enliven otherwise bland statements. A metaphor is a figure of speech in which a word or phrase is applied to an object or action to which it is not literally applicable; it is representative or symbolic of something else, but as a metaphor it can evoke emotions. For example, when a famous film star or a favourite aunt dies of cancer, we commonly say she died “after a long battle with cancer.”
Some metaphors are inept. When faced with a troubling problem like poverty, drug abuse or terrorism, American presidents are apt to declare war on it. Lyndon Johnson declared war on poverty in 1964; Richard Nixon declared war on drugs in 1971; and in 2001, George W Bush declared war on terror. The war on poverty was lost through indifference. As for drugs and terror, the “war” metaphor signifies attitudes linked to flawed policies and failed strategies. Despite vast expenditure of money and lives, the wars on drugs and terror are unwinnable with current policies, no matter how much money, how many human lives, are expended. A recent important convert to this view is the Pentagon, which may portend a transformation in policies and strategies not only by the USA but also by other nations. A trial balloon was launched in the influential Washington-based magazine, Foreign Policy in May/June 2009:

Americans are a can-do people. They believe that if something does not work, it needs to be fixed. Unless they are talking about the war on drugs. On this politically fraught issue, Washington’s elites and the majority of the population, believe two contradictory things. First, 76% of Americans think the war on drugs has failed. Yet only 19% believe the central focus of antidrug efforts should be shifted from interdiction and incarceration to treatment and education; 73% of Americans are against legalising any kind of drugs, and 60% oppose legalising marijuana. As a result of this utter failure to think, the USA today is the world’s largest importer of illicit drugs and the world’s largest exporter of bad drug policy. The US government expects, indeed demands, that its allies adopt its goals and methods and actively collaborate with US drug-fighting agencies. This expectation is one of the few areas of rigorous continuity in US foreign policy over the last three decades. A second, and more damaging, effect comes from the US emphasis on curtailing the supply abroad rather than lowering the demand at home. The consequence: a transfer of power from governments to criminals in a growing number of countries. In many places, [drug] traffickers are the major source of jobs, economic opportunity, and money for elections. Fortunately, there are some signs that the blind support for prohibition is beginning to wane among key Washington elites. One surprising new convert? The Pentagon. Senior US military officers know that the war on drugs is bankrupt and that it is undermining their ability to succeed in other important missions, such as winning the war in Afghanistan.1
Among those holding this view is General James L Jones, Barack Obama's national security adviser.

Most health and social problems associated with illicit drug use would disappear if all illicit drugs were legalised. They could be sold to licenced users in government-run stores akin to liquor stores, where drug users could be identified and get counselling, and treatment could be offered. This would eliminate much hazardous conduct associated with drug abuse. It would augment government revenues, eliminate a lucrative source of income for the criminal purveyors and perhaps cleanse society of a great deal of crime. The only nation that has decriminalised illicit drug use, Portugal, is the only one where drug use has declined, along with HIV infections and other drug-related diseases, since the policy was introduced in 2001;2 the Portuguese government missed an opportunity to generate revenue: they do not sell drugs in government outlets and did not decriminalise sales, only the personal use. That is a bit daft, but at least Portugal took one step in the right direction.

Declaring war on drugs that may be abused by susceptible youth is a hopelessly flawed policy. It leads society to criminalise victims who need compassionate treatment and prevention of dangerous complications, notably HIV infection. I am over- simplifying a convoluted problem, but many young people take mood-modifying substances to soften the harsh realities of their lives which they perceive as miserable, offering no hope of better things to come. The war on drugs is complicated by the ideological prejudices of some policy makers. They regard illicit drug use as worse than criminal: it is sinful. Purveyors and users of illicit drugs are all sinners; all must be punished. The lessons of the disastrous American experiment with Prohibition have been forgotten by these zealots.

Terrorism is more complex. It is a health problem because it causes many deaths, much maiming and mutilation of innocent bystanders. Terrorism is multifaceted. Its existence depends upon who views it: one man’s terrorist is another’s freedom fighter. Terrorism is essentially a political problem with economic, social and cultural components, and its peaceful resolution requires strategies and tactics designed by a consortium with expertise and experience in all these domains.3 The most futile, counterproductive tactics are those that rely primarily on military force, which is the worst of all possible tactics if deployed alone: the “collateral damage,” death, dismemberment, mutilation of non-combatant women, children and infants inevitably lead to vengeful retaliation. Comprehensive evidence-based policies and strategies, based in part on epidemiological and sociocultural research, are essential to overcome terrorism.

Now consider another metaphor. In 2007, I was asked in an interview about the contribution of epidemiology to society. I said:

Epidemiology connects the dots, the isolated bits of information that begin to form a coherent pattern when connected in the right way . What we learn is passed on to society through concerned citizens, media, and eventually, often lagging far behind, policy- makers, our elected leaders .. Epidemiology has been a powerful lever for important shifts in societal values, has led to social and behavioural change and improvements in the human condition. There are five ingredients in this process: awareness that a problem exists; understanding what causes it; ability to deal with the cause; a sense of values that the problem matters, and political will. These five ingredients have led in my lifetime to improved control of tobacco smoking, impaired driving, child abuse, domestic violence, environmental lead poisoning and several occupational diseases. We urgently need to apply these five ingredients to control the dangerous problem of global climate change.

The dots can come from anywhere. Identifying them demands a broad perspective, the ability to see the Big Picture. It also requires what John Ashton4 called the “epidemiological imagination,” a particular way of thinking. Sometimes the way the dots are connected is instantly apparent. Sometimes painstaking investigation and analysis are required, for instance when the problem is a common but ill-defined condition (mild mental retardation) caused by trace amounts of a highly reactive environmental toxin (lead salts in soil, food or drinking-water).

Some recent problems and how they were solved demonstrate how human behaviour, including customs, culture, level of economic development, trade, commerce and technical innovations, can influence health hazards - the diversity of the dots we must connect. These examples illustrate another interesting truth: epidemiology is the most eclectic science, using information from wherever intelligence, intuition and imagination suggest that insights and understanding may be found.

A culturally induced disease due to disruption of women’s bodily micro-environment occurred in the middle 1970s: super- absorbent vaginal tampons enabled women to keep working while menstruating, without stopping to insert a fresh tampon. But a tampon soaked in menstrual fluid and retained for hours in the warm, moist environment of the vagina is a perfect culture medium for staphylococcal enterotoxin. When this sequence was identified the nature of toxic shock syndrome was clarified, and the problem was solved.5 The epidemiological evidence (the connected dots) came from gynaecology, microbiology, toxicology, sociology and the fashion and pharmaceutical industries.

If a hot indoor environment is cooled with a dilapidated air conditioning system, the elusive pathogen, Legionella pneumo- philia can breed and is disseminated in the cool moist air. The pneumonia epidemic among members of the American Legion who attended a convention in Philadelphia in 1976, then went home to sicken and die elsewhere, was clarified when this had been worked out.6 The evidence came from clinical medicine, pathology, microbiology, vital statistics and record linkage, and from engineers who make and service air conditioners. All combined and connected the dots to solve that puzzle.

Asiatic cholera in the early 1990s in Peru, Ecuador and Colombia involved a complex causal chain. Ships trading from India discharged ballast water contaminated with a virulent strain of Vibrio cholerae in coastal waters and river estuaries. This coincided with an El Niño Southern Oscillation that warmed those usually cold waters. The warmer seas fostered an algal bloom of zooplankton, which are symbiotic with cholera vibrio; so these proliferated in seaports along the Pacific coast of South America.7 The resulting cholera epidemic lasted several years, causing half a million cases and several thousand deaths. The evidence that unravelled this sequence came from oceanography, marine biology, microbiology, international trade, anecdotes about maritime practices, all united by epidemiological insight: seemingly unrelated dots formed a coherent pattern when they were connected.

International trade brought the Asian tiger mosquito, Aedes albopictus, to the southern USA in the 1980s as larvae in pools of water in used car tires imported for retreading.8 9 The southern USA provided many ecological niches for this efficient vector for dengue and several kinds of virus encephalitis. The Asian tiger mosquito has proliferated along the eastern seaboard and west to the Mississippi Valley. With the expected global warming of the next century, the range and breeding seasons of these mosquitoes (and of anopheles mosquitoes that transmit malaria) will extend further. This is several epidemics in waiting. Epidemiological and vector surveillance reduce the risks, but tax revolts and the recession have engendered budget-slashing administrations, public health infrastructure has been weakened, and this defensive line may be vulnerable.

These and many other examples illustrate how epidemiology is combined with scientific and technical expertise from many disciplines and varieties of knowledge to investigate and control public health problems. These problems were solved by a combination of intelligent merging of information from diverse sources and disciplines (connecting the dots) and the epidemiological imagination. This approach to problem-solving is a learnt skill, so it can be taught.

From the 1940s onward, biomedical scientists discovered and developed powerful antibacterial drugs to treat and often cure previously lethal infections. I am old enough to remember what medical practice was like before we had antibiotics, and could do little but watch as previously fit young people died, sometimes in hours, from pneumonia or overwhelming septicaemia.

Physicians from that generation can be forgiven for embracing antibiotics so enthusiastically, and using them, we realise belatedly, too often, too uncritically. Antibiotics were weapons in our “war” against pathogenic bacteria. We declared war on them all, even bacteria that live symbiotically in our gut, assisting digestion and manufacturing vitamins.

The medical profession is not the only guilty party. Veterinarians, agricultural scientists, farmers and advisers about animal husbandry were guilty too, advocating addition of antibiotics to animal feed to ensure healthy animals destined for slaughter. These customs and evolutionary rules bred generations of antibiotic-resistant pathogens.

Also, in the 1940s, scientists discovered the insecticidal power of DDT and began using it in the “war ” against malaria and other vector-borne diseases. In 1944, when Naples was liberated from Nazi occupation, a threatened epidemic of louse-borne typhus was aborted by dusting the population with DDT. I recall rejoicing at a cinema newsreel as the story of this public health victory was told, accompanying news of military victories after years of unremitting bad news from war zones in Europe and the Pacific.

Initially, our wars against bacteria and insects succeeded. Pneumonia, septicaemia, meningitis, syphilis and gonorrhoea melted away under bombardment by penicillin and other antibiotics. Malaria was eliminated from south-eastern Europe, the Middle East, China, much of South and East Asia, Mexico and Central and South America, where previously its toll had impeded development. But proclamations of victory over infectious pathogens and insect vectors were premature. The laws of evolutionary biology soon produced antibiotic-resistant pathogens and DDT-resistant insect vectors. In a favourable environment, the generation time of pathogenic bacteria may be only a few minutes: in a few days, the length of a course of treatment, there is time for antibiotic-resistant bacteria to evolve and proliferate. The same rules apply to insect vectors, although generation time is longer. Soon DDT-resistant mosquitoes proliferated. We have had victories against pathogens and insect vectors, but we cannot win the war with these tactics. We need different strategies.

A promising strategy is to find ways to live in harmony with our microbial enemies. Vaccines that confer immunity enable us to coexist alongside pathogens. Sometimes a physical barrierdwindow screens, bed netsdcan shield us, especially vulnerable infants and small children, preventing contact with mosquitoes and other vectors.

Humans are an aggressive species, and our metaphors reflect this. We wage wars against cancer, alcoholism, epidemic diseases and bacterial pathogens. With far-reaching consequences, another metaphor boasts of conquering the environment. But the environment is our essential life-support system. We may harm, even destroy, it when we change it to suit current whims.

Every year, humans withdraw an estimated average $33 trillion of global ecological goods and services, making little or no capital return.10 We cannot go on doing this indefinitely. James Lovelock11 thinks it is already too late; we are on an irreversible path to a hotter world. We behave as though perpetual economic growth and “development” are not only possible but desirable. Perpetual economic growth is no more possible than perpetual motion, the fanciful dream of the scientifically illiterate.

In my lifetime of over 80 years, the world has become a better place for me and others in the tiny, well-educated, affluent minority; but life has not improved for the billion who subsist on a dollar a day or less, and there are increasing signs of irreversible damage. All indicators show evidence of deteriorating life-supporting ecosystems. Thirty years ago, when I first became concerned about global sustainability, we had few indicators and less sensitive models than now of trends in global sustainability, soil productivity, atmospheric and ocean currents. The signs were worrying, but the evidence suggested that serious trouble was hundreds of years away, adequate time to put things right. The evidence in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change in 2007 and recent direct observations of Arctic ice and glacier melt are more urgent. The time for effective action has shrunk to a few decades or less.

Climate change has several direct and indirect adverse effects on human populations.12 It causes extreme weather (severe storms, hurricanes, heat waves, droughts, torrential rainstorms and floods); sea level rise disrupts coastal ecosystems and fisheries, destroys habitat and floods fertile coastal farmland. Storm surges over low-lying coasts drown large numbers, for example in Bangladesh, and endanger everybody in small island states. Heat waves kill vulnerable people, an estimated 50 000 in the European heat wave in 2003. High humidity and increased surface water accompanying high ambient temperatures, favour water-borne diseases, insects and vector-borne diseases: malaria, dengue, virus encephalitis, perhaps newly emerging pathogens. By 2050, an additional billion people may be at risk of malaria. Extremely high temperatures damage germinating rice and grain crops, and floods and droughts can destroy the growing crops, so food shortages, perhaps severe enough to cause hunger, starvation, famine, are another scenario. When a region is afflicted, the people have to move, becoming environmental refugees. Massive population movements and large refugee communities produce challenging public health problems. Conflict is a common sequel, as in Darfur.

Resource depletion is another aspect of global change. The most critical resource is freshwater for drinking and irrigation. The daily requirement varies with environmental conditions, physical activity, metabolic demand and other factors. Freshwater is critically short in the Middle East, South-western USA, North-eastern South America, north China, and Australia south of the “top end” that gets seasonal monsoon rains. Contrary to popular belief, Canada does not have limitless freshwater: the Great Lakes are mostly fossil water, left over from the last ice age. Canada does not have enough spare water to nourish the parched US south-west. Wars have been fought over access to water, and water shortages will probably lead to future conflicts. These and other health-related consequences of climate change are described in the reports of the Intergovernmental Panel on Climate Change (http://www.ipcc.ch) and in many other reports.

Sea levels are rising as polar and alpine ice melts. Arctic sea ice is melting, so there is open water at the North Pole in summer. The water reflects less solar radiation than ice and snow, so the warming and melting accelerate: ice-melt that previously took many decades can happen in a few summers. Regions of concern are the glaciers of Greenland and Antarctica. When these melt, sea levels could rise by 5-7 m, perhaps more. All seaports and many of the world’s most populous cities face inundation. Over a billion people’s habitat and many sources of food supplies are threatened. Food shortages and famines are part of this scenario.

Epidemiologists and front-line healthcare workers have important tasks. It is essential to identify vulnerable groups at highest risk and have plans to protect them from harm in climatic extremes (heat waves, floods, etc). Risk assessment, evaluation of intervention strategies, disease and vector surveillance, water and food security policy and disaster planning are all high priorities. Collaborative research between health scientists and environmental scientists is needed to identify critical environmental “load” limits and to develop amelioration strategies. We know very little about interactions between survival of other species and human survival; this is a field for epidemiologists to cultivate. Many more dots must be identified and connected before all the health and social problems associated with climate change are delineated, classified and solved.

SUMMARY

Words both shape and reflect our sometimes irrational behaviour, as in the unwinnable “wars” on drugs and on terrorism. “Wars” on pathogenic organisms are also irrational and unwinnable with antibiotics and pesticides because they attempt to defy inexorable laws of evolutionary biology. Logic and rational thinking are essential prerequisites in tackling intractable problems such as drug abuse, terrorism and control of diseases caused by pathogenic agents. Logic and rational thought are equally essential and are urgently needed to tackle the problems associated with climate change. These problems transcend traditional disciplinary boundaries and require innovative, eclectic approaches and unconventional solutions.
Epidemiology is the most eclectic health science. It transcends disciplinary boundaries and stretches the imagination. The environmental crisis of climate change provides opportunities for epidemiological research and surveillance, including studies of cause/effect relationships, risk identification and risk assessment, evaluation of adaptation and mitigation strategies. Many more epidemiologists must get engaged in climate change research and surveillance. Epidemiologists need wide horizons to see the big picture. It is very satisfying to see the picture emerging from the connected dots. That satisfaction has kept
me going. I hope it keeps young generations of epidemiologists going, too.

Competing interests None. Provenance and peer review Commissioned; externally peer reviewed.

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