Why is Tuberculosis (TB) more prevalent in poorly ventilated, crowded areas?

From the Guidelines

Tuberculosis is more prevalent in poorly ventilated, crowded areas because these environments allow airborne tuberculosis bacteria to remain suspended in the air for hours, increasing the likelihood of transmission to others. The most recent and highest quality study on this topic is from 2005, which highlights the importance of ventilation in preventing the transmission of tuberculosis 1.

Key Factors Contributing to TB Prevalence

• Poor ventilation: allows infectious droplet nuclei to remain suspended in the air
• Crowding: increases the proximity of individuals to each other, making it more likely for them to inhale infectious droplets
• Lack of natural sunlight: preserves the viability of the pathogen, allowing it to remain infectious for longer periods

High-Risk Environments

• Homes and institutions with poor ventilation
• Crowded indoor spaces such as prisons, homeless shelters, and impoverished housing
• Areas with limited access to sunlight, such as basements or rooms with limited windows

Preventing TB Transmission

• Improving ventilation in high-risk areas, such as installing HEPA filters or using ultraviolet germicidal irradiation (UVGI) 1
• Reducing crowding and increasing distance between individuals
• Increasing access to natural sunlight and using UVGI to kill tuberculosis bacteria It is essential to prioritize ventilation and crowd control in high-risk areas to prevent the transmission of tuberculosis, as highlighted in the 2005 study 1. By understanding the key factors contributing to TB prevalence and taking steps to prevent transmission, we can reduce the risk of infection and improve public health outcomes.

From the Research

Factors Contributing to TB Prevalence

• Overcrowding and poor ventilation in congregate settings, such as hospitals, clinics, prisons, and refugee camps, facilitate TB transmission 2
• The risk of TB in an institution is assessed by factors including entrance-point prevalence of infection, potential for reactivation, and the role of transmission within the institution 3
• Poorly ventilated social gathering places, such as informal alcohol drinking places and clinic waiting rooms, are potential transmission hot spots in areas where TB is hyperendemic 4

Environmental Control Measures

• Natural ventilation is a main means of air disinfection, but may not be effective in all climates or situations 2
• Mechanical ventilation can provide adequate air disinfection, but is expensive to install and maintain 2
• Upper room germicidal irradiation is a cost-effective way to achieve high levels of air disinfection 2
• Ultraviolet air disinfection is a suggested control strategy for high-risk areas in hospitals, nursing homes, and prisons 3

Transmission and Prevention

• TB transmission is facilitated in overcrowded, poorly ventilated areas, and can be controlled through source control, environmental control measures, and personal respiratory protection 2, 5
• The control and prevention of TB in hospitals is best achieved by administrative, engineering, and personal respiratory protection approaches 5
• Reducing the number of infectious people in a community can lead to a decrease in the annual risk of infection, but the relationship between these factors is nonlinear 4