Salmonella may also be divided into 3 groups based on how well the organism is adapted to human hosts: Those highly adapted to humans and having no nonhuman hosts: This group includes S Typhi and S Paratyphi types A, B (also called S Schottmülleri), and C (also called S Hirschfeldii), which are pathogenic only in humans and commonly cause enteric (typhoid) fever.