Unexpected Anthrax Cases Among Metalworkers

In 2022, researchers from the CDC identified a surprising trend. Since 1997, there have been seven documented cases of infections linked to Bacillus bacteria that produce anthrax toxins, all occurring in metalworkers. Among these, six individuals were welders, leading to the term “welder’s anthrax,” while the seventh case involved someone grinding metal in a foundry. In six of these cases, the specific bacteria identified was B. tropicus, which was also the cause in the latest reported incident.

Understanding the Risks

The reasons behind the heightened susceptibility of metalworkers, especially welders, to this infection remain unclear. In their 2022 analysis, CDC experts proposed that this vulnerability might stem from a combination of compromised immune responses in the lungs due to inhaling toxic fumes and heightened exposure to harmful bacteria in their work environments.

In the recent case, a teenager worked as a welder for four hours a day, four days a week, in poorly ventilated, sometimes cramped conditions. Often, he did not wear personal protective gear, including respirators. Environmental tests at his workplace revealed the presence of anthrax-toxin-producing Bacillus in 28 out of 254 samples. Similar findings have emerged from other investigations into welder’s anthrax.

Up to now, all nine known cases have been reported in Louisiana or Texas. However, experts caution that these instances are probably underreported, with models indicating that these hazardous bacteria could also be proliferating in various Southern states.

Additionally, there’s speculation that exposure to iron might contribute to the problem. Bacillus bacteria require iron to survive, and metalworkers can accumulate excess iron in their respiratory systems due to their work. This iron overload might provide an ideal condition for bacterial infections. In the case of the teenager, he worked with carbon steel and low-hydrogen carbon steel electrodes.

At this point, the exact risk factors remain a mystery, particularly why this healthy teen became ill while others in the same workplace did not. In response, CDC and state officials have suggested improvements in workplace safety, which include better use of respirators, increased ventilation, and enhanced dust control measures.

There is an anthrax vaccine recommended for individuals classified as high-risk, such as specific military personnel, lab workers, and livestock handlers. It remains uncertain whether metalworkers will be considered part of this high-risk group in the future.