Research shows the impact of incarceration on the tuberculosis epidemic in Latin America

The incidence of tuberculosis has been increasing in Latin America, where the incarcerated population has nearly quadrupled since 1990. An unprecedented study conducted by Fiocruz in partnership with institutions from Argentina, Brazil, Colombia, Peru, and the United States assessed the total impact of the tuberculosis epidemic on the incarcerated population, accounting for effects beyond incarcerations – further considering transmission chains that also affect the general population. The analysis found that incarceration is the main risk factor for tuberculosis in this region.

Published on Tuesday (10/15) in The Lancet Public Health, the study (titled Mass Incarceration as a driver of the tuberculosis epidemic in latin america and projected effects of policy alternatives: a mathematical modeling study) was conducted using data collected from 1990 to 2023 in the countries participating in the research. The aim was to understand the impact of the increase in incarcerations on public health. By simulating what would have happened if incarcerations had not increased as much, the researchers were able to estimate how many cases of tuberculosis could have been avoided.

Worldwide, 10.6 million people developed tuberculosis in 2022. Although the global incidence of tuberculosis has decreased by 8.7% since 2015, the occurrence of tuberculosis cases in Latin America has increased by 19% during the same period. In Latin America, the incarcerated population has nearly quadrupled in the past 30 years, the fastest growth of any region in the world. Incarcerated individuals, who may already be at high risk of tuberculosis before incarceration, are further exposed to prison conditions that promote the transmission and progression of the disease, including overcrowding, poor ventilation, malnutrition and limited access to healthcare. Together, these factors contribute to tuberculosis rates being 26 times higher among incarcerated individuals than in the general population in South America.

The methodology used dynamic transmission models, adjusted to historical and contemporary data on incarceration and tuberculosis in the countries analyzed. Together, they represent approximately 80% of the incarcerated population and the "burden" of tuberculosis in Latin America. The analysis further used a projection of the impact of various incarceration scenarios on the future incidence of tuberculosis in the general population. The research found that the increase in incarcerations since 1990 has resulted in an estimated 34,393 excess cases of incident tuberculosis in 2019 in the six countries. In 2019, 27.2% of new cases were related to incarceration, more than the percentage attributable to any other risk factor, including HIV and malnutrition.

The research concluded that, compared to the current scenario of incarceration policies, interventions in this area could reduce the future incidence of tuberculosis in the general population in Brazil, Colombia, Argentina, El Salvador and Peru by more than 10%. To control the disease in the region, the researchers argue that international health agencies, ministries of justice and national tuberculosis programs must work together to tackle this health crisis with comprehensive strategies that include decarceration.

The study projected what could happen by 2034 under different scenarios where incarceration rates decrease in a controlled manner. Three scenarios were simulated. In the first, the number of incarcerated individuals and the length of time they are incarcerated would remain constant. In the second, prison entry rates and time spent in prison would continue to rise, as has been the case for the last 10 years. In the third, the number of people entering and the time they spend in prison would be reduced by 25% or 50%, which, according to the study, could reduce cases of tuberculosis in the future.

These simulations showed that fewer incarcerated individuals would mean fewer tuberculosis cases by 2034, suggesting that policies aimed at reducing incarceration could have a positive impact on public health.

Transmission chains

Previous studies have identified a high risk of tuberculosis in Latin American prisons, concluding that notifications within prisons have been increasing and account for an increasingly larger proportion of all cases in the region. Other national or subnational research has found a high risk of tuberculosis transmission, with "repercussions" in communities due to individuals who were previously incarcerated.

However, according to the study, the total contribution of incarceration to the broader tuberculosis epidemic in Latin America, due to underreporting in prisons and the "repercussions" in communities, has never been quantified. The regional impact of alternative incarceration policies on the future incidence of tuberculosis in the population is unknown.

Methodology

The researchers created an imagined scenario in which the number of incarcerated individuals remained the same as in 1990, and compared it to the actual situation, where the number of incarcerated individuals has increased significantly. This comparison showed that the more individuals are incarcerated, the higher the number of tuberculosis cases.

The research analyzed what percentage of tuberculosis is related to incarceration, primarily in individuals aged 15 and older. Calculations were made to see what would happen if the number of incarcerated individuals were gradually reduced over the years, simulating a scenario where incarceration would be zero by 2009. After 10 years without new incarcerations, the researchers calculated how many cases of tuberculosis would still occur in 2019.

These estimates were compared with data from the World Health Organization (WHO), which shows the five major risk factors for tuberculosis: malnutrition, HIV, alcoholism, smoking and diabetes. Although these factors vary by age and can overlap, the research highlighted that the incarcerated population is a very significant risk factor.

Based on the dynamics of incarceration, the research incorporated historical and contemporary data sources to explain the different turnover rates in prisons and the mechanisms underlying the historical growth of incarceration.

The methodology identified areas with an excess of cases and compared the results with estimates based on notifications from prisons. In six countries with various incarceration contexts, studies on the distribution and determinants of health issues, phenomena and associated processes show that incarceration is one of the main risk factors for tuberculosis, a scenario that has been under-recognized to date. The potential impact of alternative incarceration policies on reducing the future burden of tuberculosis in correctional environments and in the general population was also demonstrated.

According to the study, to date, the true impact of incarceration on the tuberculosis epidemic across the region has been underestimated due to a "narrow focus" on diseases that occur during incarceration. The analysis found that interventions aimed at incarceration could have "enormous" effects on the broader tuberculosis epidemic in Latin America – much greater than previously observed The researchers stress that these interventions should include not only strategies to reduce the risk of tuberculosis among currently and formerly incarcerated individuals, but also efforts to end mass incarceration.