Scientists say identifying TB hotspots could reduce transmission

Researchers at the Johns Hopkins Bloomberg School of Public Health determined that reducing tuberculosis in high-transmission hotspots could significantly reduce the spread of the disease on a broader scale.

The researchers analyzed data from Rio de Janeiro and found that reducing TB in three such hotspots could reduce transmission 9.8 percent over five years and as much as 29 percent within 50 years.

"Targeting treatment of 'core groups' as a way to reduce community-wide transmission is common with diseases like HIV and malaria, but is less accepted as a mantra for TB control," David Dowdy, the lead author of the study, said. "Our findings suggest that hotspots containing six percent of a city's population can be responsible for 35 percent or more of its ongoing TB transmission. Controlling TB in these hotspots may have a similar impact on long-term, community-wide TB incidence as achieving the same targets in the remaining 94 percent of the population."

Dowdy and his team used mathematical models for TB transmission that were developed from Rio de Janeiro surveillance data. The study suggested a 62.8 percent reduction in TB incidence in the hotspot and a 23.1 percent decrease in the remaining community. While TB may not be as heterogeneous as other illnesses like HIV, the researchers think that targeting hotspots may still make a major impact.

"TB may not follow the same '80/20' rule that we see in parasitic or sexually transmitted diseases, but the '35/6' rule seen in our study suggests that targeting hotspots is still the best way to control TB in a community," Dowdy said.

TB infects more than 8.8 million people worldwide and causes 1.4 million deaths each year.