Simplify the following text for a Grade 13 native English-speaking person.
Original: Chronic causes are infection with bacteria , primarily Helicobacter pylori , chronic bile reflux , stress and certain autoimmune disorders can cause gastritis as well .
Simplified: Long term causes are infection with bacteria , mainly Helicobacter pylori . Certain diseases , such as pernicious anemia , chronic bile reflux , stress and certain autoimmune disorders can cause gastritis as well .