Peptic Ulcer Vaccine May Be Possible
A new scientific assault on one of nature’s nastiest bacteria may lead to an oral vaccine that could prevent the vast majority of peptic ulcers, a painful chronic condition that affects one out of 10 Americans at some time in their lives.
A team of Italian researchers has, for the first time, successfully immunized mice against infection by Helicobacter pylori - an enigmatic, human-loving bacterium believed to cause 70 percent of stomach ulcers, nearly all ulcers of the duodenum and a substantial fraction of stomach cancers.
Approximately half the world’s population is infected with the microbe, which burrows into the stomach lining and causes symptoms ranging from burning irritation called gastritis to bleeding holes to stomach cancer - the second most common cause of cancer death worldwide.
The Italian group’s findings, reported in Friday’s issue of the journal Science, are “a breakthrough” and “a terrific model for an oral vaccine,” said University of Virginia physician Barry Marshall, who first isolated the corkscrew-shaped organism 13 years ago.
A vaccine might be ready for clinical trials within five years, estimated Martin J. Blaser, director of the division of infectious diseases at Vanderbilt University School of Medicine, who with colleagues has identified and cloned the bacterium’s most virulent toxin.
Initial testing, Marshall and Blaser said, would probably be conducted in the Third World, where infection rates reach 80 percent in some countries and children usually acquire the microbe by age 10 due to unsanitary conditions.
Although H. pylori probably has been around as long as the human stomach, it was discovered only recently. Until the mid-1980s, physicians thought ulcers were caused by the effects of stomach acid, and drugs developed to suppress acid production racked up billions of dollars a year in sales. But a troubling puzzle remained: Ulcers tended to recur frequently despite medication.
Even after Marshall and J. Robin Warren fingered H. pylori as the chief culprit in 1983, most researchers remained skeptical.
But as evidence accumulated (including a shocking demonstration in which Marshall swallowed a homemade cocktail of the bacteria and promptly developed an ulcer, as he had predicted), emphasis shifted toward antibiotic treatments.
Researchers around the globe scrambled to investigate the hardy pathogen, which is spread by contact with saliva or fecal matter and somehow thrives in the stomach’s acid climate.