Tuberculosis Spreading in Surprising Ways
The waste facility worker was one of three employees in the same processing plant who all developed TB during the period from May to September 1997. State and federal authorities were called in to investigate the source of the outbreak and to take steps to stop the infection from spreading throughout the community.
Johnson and her colleagues interviewed all three workers and their friends and family members, reviewed their medical records and conducted TB tests on them. Some were found to have a positive skin test, indicating they had been exposed to TB, but none had an active case of infection.
They also conducted sophisticated genetic tests on the type of TB each of the workers had, and found that one was infected with a particularly rare strain that is resistant to drugs that usually kill TB. Then, after checking the type with all the laboratories that sent their used TB tests to this facility for waste processing, the researchers were able to match this worker's TB with that of a person with the same type who was seen at one of the labs.
The other workers may also have contracted TB from the waste they processed, but because they had more common forms of the disease, this could not be proven, Johnson says.
All of the workers were treated with antibiotics. In addition, the waste facility was required to implement additional safeguards to better protect its workers. The investigation for the source of the outbreak had revealed that the workers had been regularly exposed to any number of infections. Equipment was broken, workers often failed to wear the proper protective gear, and they did not shower or decontaminate themselves after exposures, according Johnson.
The tale of the TB bacteria's survival is awe-inspiring to Kent A. Sepkowitz, an infectious disease specialist with Memorial Sloan-Kettering Cancer Center in New York City. Sepkowitz, who wrote an editorial in the same issue of the journal, also notes that not enough is known about how TB is transmitted. He agrees with Johnson that more research is necessary to determine the extent to which medical waste workers might contract TB.
Peter Small, MD, lead researcher at the Stanford Center for Tuberculosis Research in Palo Alto, Calif., tells WebMD this report is a useful warning about the need for vigilance in TB elimination.
"If you take it at face value, it looks like a pretty isolated event," says Small, who was not involved in this report. "But unusual modes of transmission will become more important and more obvious as we move into the elimination phase of TB, and as the rates are declining. I think we need to start paying attention to the more uncommon method of transmisson if we are serious about elimination." Small is also an assistant professor of medicine at Stanford University Medical Center.