Why do we get hpylori?

Person to person: The most likely mode of transmission is from person to person, by either the oral-oral route (through vomitus or possibly saliva) or perhaps the fecal-oral route. Fecal oral means a person touched infected poop, and then touched his mouth, or touched food that gets eaten. The H. pylori DNA has been found in vomitus, saliva, dental plaque, gastric juice, and feces.

You eat it: The bacteria that ends up in your gut arrive there via a standard pathway. Adults have been shown to randomly touch their face 6-8X/hr. Each touch allows contaminants that include germs to eventually enter the mouth or nose. These can then enter the gut or respiratory tract. H. pylori like other germs enters either at random or from foods we eat.