A bacterium that’s known to cause ulcers and stomach cancers, may also provide protection against the worldwide killer tuberculosis, according to researchers at the University of California, Davis; Stanford University, and the University of Pittsburgh. In an article appearing online in PloS ONE, the researchers report that the bacterium Helicobacter pylori or H. pylori infection may enhance immunity against tuberculosis, a disease endemic in many parts of the world, and for which there is no effective vaccine.

 

“Here is a bacterium that we know is sometimes harmful and that is clearly associated with cancer,” says Jay Solnick, UC Davis professor of medicine and microbiology at the Center for Comparative Medicine. “But it’s not that simple.”

 

Solnick says that up until the 20th century, when public health improved and antibiotic use was widespread, virtually everyone was infected with H. pylori. That remains the case today in most developing countries, implying that H. pylori may have evolved with its human host because it confers some selective benefit.

 

“These new findings suggest that one such benefit may be that H. pylori provides protection against tuberculosis, and perhaps other infectious diseases as well,” he says.

 

Tuberculosis is second only to HIV as a cause of death due to a single infectious agent. One-third of the world's population is estimated to be infected with Mycobacterium tuberculosis. However, most individuals do not show clinical symptoms of the disease, a form of infection commonly known as latency. Only one in 10 latent infections will progress to active tuberculosis disease.

 

“One explanation may be the presence of chronic infection of the stomach with H. pylori,” Solnick says. The findings also may eventually aid in managing TB, since H. pylori infection may help determine whether someone infected with TB gets a latent, asymptomatic infection or active disease.