A new Stanford-led study reveals that the rise in incarceration rates across Latin America over the past three decades has significantly contributed to the region’s tuberculosis (TB) epidemic in the general population.

The researchers noted that 10.6 million people developed tuberculosis worldwide in 2022. While the global tuberculosis incidence has decreased by 8.7% since 2015, in Latin America the tuberculosis incidence increased by 19% over the same period, highlighting the urgent need to address key tuberculosis drivers in the region.

In Latin America, the incarcerated population has nearly quadrupled over the last 30 years, the most rapid growth of any region in the world.

“We found that more than a quarter of all tuberculosis cases in Latin America are due to incarceration—a figure far higher than previously appreciated. Incarceration is now the leading driver of tuberculosis in the region,” said Jason Andrews, MD, a professor of infectious disease at Stanford Medicine and senior author of the study published in The Lancet Public Health.

The research team used a mathematical model based on real-world data from 1990 to 2023 to assess how TB spreads both within and beyond prisons. Models were tailored for each country and tested alternative scenarios to explore how different incarceration policies could affect TB rates. 

Past research, the authors note, has focused too narrowly on TB cases diagnosed within prisons, missing the full impact of incarceration on the epidemic.

“Overcrowding, poor ventilation, and limited health care in prisons allow TB to spread easily inside prisons,” said Yiran Liu, PhD, an infectious diseases researcher at Stanford Medicine and lead author of the paper. “However, because most people are released from prison within a few years, TB cases often go undiagnosed in prisons or develop only after release, contributing to community transmission.”

The researchers estimate that more than 34,000 additional TB cases in 2019 were linked to the growth of prison populations in six countries: Argentina, Brazil, Colombia, El Salvador, Mexico, and Peru. Nearly 30% of new TB cases among individuals over 15 in these countries were attributed to incarceration, a higher share than other risk factors such as HIV and malnutrition.

The authors recommend expanding public health strategies beyond diagnosing and treating TB in prisons to reforming the criminal justice system. Simulations suggest that policies aimed at reducing the prison population—such as decreasing admissions or shortening sentences—could substantially lower TB rates across the region.

The researchers conclude that reducing incarceration rates, along with improving TB care in prisons, is essential for Latin America to meet its goals for TB control and elimination.

“Our study demonstrates how important criminal justice policies are as determinants of public health,” said Jeremy Goldhaber-Fiebert, PhD, a professor of health policy and one of the study’s authors. “It adds yet another compelling reason to the empirical social science evidence and moral and ethical rationales for why long-term, mass incarceration is bad policy."