BACKGROUND People have been infected by this bacteria 58,000 years ago. Prevalence of infection varies in different nation. In developing countries infection is acquired in early childhood. The forms of infection are/fecal-oral, oral-oral an gastro oral. In Perú we found same prevalence in the coast, jungle and sierra and described that water is one of the ways of infection.MICROBIOLOGY: Three strains predominant in Spanish, Asiatic and people from India have been identified. DNA has 1.65 million bases. Different factors of virulence, enzymes and toxins have also been described. METHODS Inflamatory response; neutrophiles, lymphocytes T and B, plasma cells, macrophages.METHODS OF DIAGNOSIS: Invasive and non invasive procedures. METHODS Different treatment schemes are described: 1st, 2nd, 3rd lines, rescue therapies. Secondary reactions, alternative schemes, recurrence, reinfection and experience in Perú are also described.