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It’s been implicated as(1) the bacterium(2) that causes ulcers(3) and the majority of stomach cancers(4), but studies by researchers(5) at UC Davis, Stanford University and the University of Pittsburgh have found that Helicobacter pylori(6) (H. pylori) also may play a protective(7) role, against the worldwide(8) killer, tuberculosis(9) (TB).

In an article appearing online(10) in PloS ONE, Jay Solnick, UC Davis professor of medicine and microbiology(11) at the Center for Comparative Medicine(12) and his co-authors(13) report that H. pylori infection(14) may enhance(15) immunity(16) against tuberculosis, a disease endemic in(17) many parts of the world, and for which there is no effective vaccine(18).

“Here is a bacterium that we know is sometimes harmful and that is clearly associated with(19) cancer(20),” Solnick said. “But it’s not that simple.”

Solnick explains that up until the 20th century, when public health(21) improved and antibiotic(22) use was widespread(23), virtually(24) everyone was infected with(25) H. pylori. That remains the case today in most developing countries(26), implying(27) that H. pylori may have evolved(28) with its human host(29) because it confers(30) some selective(31) benefit.

“These new findings suggest that one such benefit may be that H. pylori provides protection against(32) tuberculosis, and perhaps other infectious diseases(33) as well,” he said.

Tuberculosis is second only to(34) HIV(35) as a cause of death due to(36) a single infectious agent(37); one-third of the world's population is estimated to be infected with Mycobacterium tuberculosis(38). However, most individuals do not show clinical symptoms(39) of the disease, a form of infection commonly known as latency(40). Only one in 10 latent infections(41) will progress to(42) active(43) tuberculosis disease.