|Original map made by John Snow in 1854. Cholera cases are highlighted in black. 2nd Ed by John Snow.|
John Snow is often justly referred to as the father of modern epidemiology: present-day public health still strives toward the upstream approaches, primordial prevention and redress of the social determinants of health that he pioneered. It seems, however, that the core lessons from John Snow’s work back in the mid-nineteenth century have yet to be adequately integrated into public health policy and practice.
Before any scientific knowledge of the existence of pathogenic microorganisms, Snow identified the source of a cholera outbreak afflicting inhabitants of Soho, London in 1854, by associating the contamination of human drinking water—particularly via human feces—with the frequency of cholera disease. This association suggested a solution to the epidemic, which proved swift and effective: the Broad Street pump was shut off.
No superhuman insight was required. Rather, Snow patiently employed a healthy mixture of empiricism, critical thinking, hypothesizing and eventually a dot map (pictured) to prove the merits of a literally upstream approach to combatting infectious disease. He did this at a time when to even posit the existence of something like Vibrio cholerae might draw scorn and ridicule. To the unaided human eye, and without all the benefits of modern knowledge, the rapid diminishment of disease that followed the efforts of John Snow and his contemporary public health pioneers seemed miraculous. The real change, of course, is attributable to the fact that large numbers of people ceased to regularly ingest human feces.
The fundamental lesson here is that it can be highly effective—and certainly more efficient—to address the root causes of human suffering and disease. Because although there are many ways in which the water supplying the Broad Street pump might have been filtered and treated, and although there are many ways in which those ingesting the water might have been treated clinically, an upstream solution ensured that fewer people defecated directly into drinking water supplies.
To take an upstream approach is to simply start at the beginning. Cholera is a disease of poverty. This is also true of tuberculosis and rheumatic fever, which continue to prevail today in contexts where basic necessities are not being met. From an activist perspective, cholera is a symptom of injustice and neglect.
When there are many causes at play, it can be futile to focus on just one. Rather, we can focus on those fundamental determinants of health that are correlated with other important downstream factors. This is why we treat drinking water before consumption, without knowing exactly which health issues have been mitigated in doing so.
Poverty is as important a mechanism of disease transmission and acquisition as the more minute and direct mechanisms by which Vibrio cholerae has its effects. The only difference is whether we approach the issue from the perspective of a biomedical professional or of a civil engineer, sociologist, economist or public health professional. Since all microorganisms need a reservoir or a host environment, focusing solely on microorganisms themselves is myopic.
Many factors threaten human health, including:
- Overcrowded, moldy and inadequate housing and homelessness
- Malnutrition, undernutrition and their attendant effects
- Stressors caused by biopsychosocial phenomena such as relative poverty
- Contaminated air, soil, water supplies, etc.
- Lack of access to quality health services including medicines and vaccines
The World Health Organization’s World Health Statistics 2018 report states:
cholera is a stark indicator of inequality and lack of social and economic development as it disproportionately affects the world’s poorest and most vulnerable populations . . . Cholera transmission is closely linked to inadequate access to clean water and sanitation facilities . . . most of the counties that reported locally transmitted cholera cases to WHO during the period 2011–2015 were those in which only a low proportion of the population had access to basic drinking water and sanitation services.
Although biomedical knowledge and technologies have advanced tremendously since the nineteenth century, optimal solutions remain largely unchanged. Addressing the human suffering caused by diseases like cholera one issue at a time is inefficient. When it comes to budgeting, spending, policy, and practice, emphasis on individual illnesses is reactive, superficial, symptoms-based, inefficient and defensive of the status quo. It is lazy and morally indefensible not to address the infectious diseases at their sources: inadequate housing, hygiene and nutrition.
Cost is no excuse, especially given the astronomical levels of debt that rich western nations continue to accrue. Meanwhile, the cost of inaction is similarly astronomical, and mounting. Productivity is lost when people starve or are incapacitated by preventable disease. With a little bit of forethought, the return on investment from doing the right thing is ours for the taking. Vaccines and antibiotics are critical, but less fundamental than basic human needs.