Tuberculosis as a reflection of inequality

PUBHLTH 405
Social Epidemiology of Infectious Disease
University of Michigan School of Public Health

Jon Zelner
[email protected]
epibayes.io

What does studying historical TB teach us about the present?

As “new” immigrants arrive in the United States (a demographic shift that is not unique to this country), we must ask new questions, questions not asked a century ago, to understand the historical connections between class and racial formation, biopolitical contests regarding citizenship rights (the pitiable sick versus the incorrigibly unhygienic), and the concrete (geographic, economic, historical) processes of statecraft, surveillance, and bureaucratic expansion that public health automatically implies. This is not insignificant, for clues to future solutions may be found in past failures.” (Roberts 2009)

Agenda

• Brief reflection on Infectious Fear

• Some basics of TB epidemiology

• Digging into Chapters 1 & 2 of Infectious Fear

• Next Time

Some potentially useful context around Infectious Fear

The Great Migration(s)

What were TB Sanitoria?

TB patients being treated by getting fresh air outside of a TB sanitorium in Los Angeles

Dutch students attending school outside to avoid TB infection

Children at the Meriden State TB Sanitarium in Connecticut undergoing ‘sunlight therapy’ in the winter

⏲️ 5m reflection

• What was your biggest takeaway from these initial chapters?

• What surprised 😲 you most?

• What were you confused 😵‍💫 by and would like to discuss/clarify?

05:00

TB!

Respiratory infection with transmission facilitated by close contact

Anti-TB poster from the American Lung Association

Repeat exposure plays an important role in TB epidemiology

• Primary Infection: On first infection, individuals are more likely to have rapid onset of severe disease and are at higher immediate risk of death.

• Secondary Infection: On subsequent exposures, individuals are less likely to develop disease quickly and those that do may have longer-term, chronic infections.

• Why is this distinction important in the first two chapters of Infectious Fear?

TB can become latent or dormant in the body and re-emerge

Individuals can transition from latent to active TB and back

Latent TB involves the forming of a protective granuloma which prevents spread but also allows the bacteria to hide out and re-emerge. (Image from (Ehlers and Schaible 2013))

TB Diagnosis

Active TB

Chest x-ray of primary TB

Latent TB

Tuberculin skin test for latent TB

What do these different measures tell us about burden in the population?

In the U.S., TB declined dramatically over the course of the 20th century

What happened at the time where the red line is?

But: Availability of effective TB treatments followed these declines

A brief history of TB science and treatment

Present-day TB incidence is highest in Sub-Saharan Africa

Global TB incidence from the 2021 WHO Global TB Report

TB incidence and mortality is now strongly correlated with HIV prevalence

Proportion of new and relapse TB cases that are HIV+ in 2020

TB is the most common cause of death from infectious disease worldwide

And: It is likely that COVID-19 has slowed or reversed the decline of TB in the U.S.

What are the likely implications of this backsliding for health equity? (Image from CDC)

Discussing Chapters 1 & 2

• Break into small groups to work through the questions in this document. (~10m)

• Rotate 1 or 2 times with first group members acting as experts/facilitators (~5m each)

• Back to big group to review additional questions.

Introduction/Ch. 1

The rough thesis of the whole book

How individuals, institutions, black and white leaders, and public officials mediated the demands and politics of tuberculosis-is the subject of this book… Infectious Fear argues that integral to the project of modern urban public health were theoretical and practical compromises that moved the politics of black health from absolute neglect to qualified inclusion based on specific notions of care, expertise, public utility, citizenship, social control, and responsibility. (Roberts 2009)

Why is the book called Infectious Fear?

This book is primarily concerned with two overlapping and mutually informative periods in U.S. urban history: the era of infectious fear all but vanquished by the discovery of antimicrobial therapies, and a period, before the Second World War, when health policy and social policy were, comparatively speaking, overwhelmingly dominated by politics derived from local rather than federal mandates. (Roberts 2009, 20)

How has this statement aged into the COVID era?

No naive nostalgia for the germ is presumed in imagining, for example, that many of the health problems of post-war inner cities, many of which are not infectious but are nonetheless tied to geography, might have appeared more urgent—as public health problems as opposed to simply social or moral problems—had there still existed a disease that plainly…illustrated the geographical links among class, geography, and health. (Roberts 2009, 40)

Patterns of infection and death by age tell us a lot about TB transmission

Chapter 2

Yet more…predisposition

“By 1895, most trained physicians accepted Koch’s findings, but they reached consensus only on the necessity of the bacillus in the development of tuberculosis. Opinion fell across a broad spectrum whose poles might be considered as having the emerging principles of bacteriology and infection on one end (the seed, metaphorically speaking) and speculations of the body (the soil) on the other.” (Roberts 2009)

“Tuberculization”

“A theoretical compromise between racial determinism and strict environmentalism condensed around the idea of tuberculization- the view, emerging around 1908-10, of physical resistance as having developed through interaction with the disease environment and then passing on genetically to progeny. Tuberculization theory challenged racial essentialism and even natural selection, but without better research, the differences between it and moderate eugenic theory were largely speculative, inferential, and not always clear.” (Roberts 2009)

Some implications of the fundamental cause approach

FCT explains how innovation acts as an engine 🛫 of health inequality

• When new tools and technologies are available for prevention and treatment, they are first available to the most-privileged.

• This introduces or increases inequity in outcomes at first.

• Over time, the tool becomes available to more people and inequity decreases.

• Over time, the innovation saturates the population and inequality stabilizes or disappears.

This leads to a relatively predictable life-cycle of inequity

Example of how inequity rises and falls as an innovation diffuses through the population from (Zapata-Moya, Willems, and Bracke 2019)

We can see the generation of inequality during the first phases of covid

Changes in SARS-CoV-2 mortality by SES of U.S. counties. High SES counties are represented by the short-dashes, all others by long-dash and solid line (from (Clouston, Natale, and Link 2021))

What interventions or policies might explain this pattern?

Next Time

Chs 3 & 4: Connecting residential segregation to infectious disease transmission.

Important to remember: Segregation is not unique to the U.S. and only a reflection of racism

Residential segregation of Muslims and Hindus in Delhi, India (from (Susewind 2017))

How can we apply FCT to infectious disease specifically?

Socio-structural inequities drive unequal outcomes across the entire life-cycle of infection

Flow diagram from Zelner et al. (2022)

What is the distinction between inequity in exposure versus susceptibility?

Mechanisms leading to differential exposure to infection from (Noppert, Hegde, and Kubale 2022)

What is the distinction between inequity in exposure versus susceptibility?

Mechanisms leading to differential vulnerability to infection from (Noppert, Hegde, and Kubale 2022)

Link & Phelan identified structural determinants of infection inequity in their original work

An example of how fundamental causes may be reflected in foodborne infection (Link and Phelan 1995)

References

Clouston, Sean A. P., Ginny Natale, and Bruce G. Link. 2021. “Socioeconomic Inequalities in the Spread of Coronavirus-19 in the United States: A Examination of the Emergence of Social Inequalities.” Social Science & Medicine 268 (January): 113554. https://doi.org/10.1016/j.socscimed.2020.113554.

Ehlers, Stefan, and Ulrich E. Schaible. 2013. “The Granuloma in Tuberculosis: Dynamics of a Host–Pathogen Collusion.” Frontiers in Immunology 3 (January): 411. https://doi.org/10.3389/fimmu.2012.00411.

Link, Bruce G., and Jo Phelan. 1995. “Social Conditions As Fundamental Causes of Disease.” Journal of Health and Social Behavior 35: 80. https://doi.org/10.2307/2626958.

Noppert, Grace A, Sonia T Hegde, and John T Kubale. 2022. “Exposure, Susceptibility, and Recovery: A Framework for Examining the Intersection of the Social and Physical Environment and Infectious Disease Risk.” American Journal of Epidemiology, October, kwac186. https://doi.org/10.1093/aje/kwac186.

Roberts, Samuel K. 2009. Infectious Fear: Politics, Disease, and the Health Effects of Segregation. University of North Carolina Press.

Susewind, Raphael. 2017. “Muslims in Indian Cities: Degrees of Segregation and the Elusive Ghetto.” Environment and Planning A: Economy and Space 49 (6): 1286–1307. https://doi.org/10.1177/0308518X17696071.

Zapata-Moya, Ángel R., Barbara Willems, and Piet Bracke. 2019. “The (Re)production of Health Inequalities Through the Process of Disseminating Preventive Innovations: The Dynamic Influence of Socioeconomic Status.” Health Sociology Review 28 (2): 177–93. https://doi.org/10.1080/14461242.2019.1601027.

Zelner, Jon, Nina B. Masters, Ramya Naraharisetti, Sanyu A. Mojola, Merlin Chowkwanyun, and Ryan Malosh. 2022. “There Are No Equal Opportunity Infectors: Epidemiological Modelers Must Rethink Our Approach to Inequality in Infection Risk.” PLOS Computational Biology 18 (2): e1009795. https://doi.org/10.1371/journal.pcbi.1009795.