New Research Challenges Thinking on the Places Where TB Is Transmitted

7 April 2025

For centuries, it was believed that TB spread primarily when a vulnerable person spends hours in a poorly ventilated space with someone infectious. But new findings suggest that much TB transmission also occurs through casual contact.

Conventional thinking held that enclosed spaces such as households, prisons, and shelters, where people spent long periods of time together, were where most TB transmission took place. But new data suggest that casual contact at social settings like shopping malls, restaurants, bars, and places of worship also account for much TB transmission.

A recent study found that close contact explained only 9% of TB transmission links, while casual contact accounted for 49%. The study, called CONTEXT (Casual Contact and Migration in XDR-TB), was conducted in KwaZulu-Natal.

The study’s lead author, Professor Neel Gandhi of Emory University in Atlanta, recently presented the findings at the Conference on Retroviruses and Opportunistic Infections (CROI) in San Francisco. The work has not yet been published in a peer-reviewed medical journal.

The new findings come in the context of other research (much of which was conducted in Cape Town) that suggest TB could be transmitted through breathing, and growing evidence that people with asymptomatic TB can transmit the infection.

Read the full news story at Spotlight.