In spite of the fact that he was vaccinated against typhoid fever, he does in fact have the disease.  Immunization is only about 85-90% effective against infection.  The “rose spots” that appeared and disappeared, the very high fever following the initial group of symptoms, the oval ulcers oriented in the direction of fecal flow, and the presence of bradycardia make typhoid fever the most likely diagnosis.  This is a systemic infection and can cause a pneumonia.  Diarrhea may occur but enlargement of the Peyer’s patches may block the enterocecal valve and cause constipation.  The bacteria reside and multiply within monocytes.