A 28-year-old male presents with 5 days of fever accompanied by poor appetite, fatigue, abdominal pain, distension, and diarrhea. Despite self-medication with antipyretics, co-trimoxazole, and chloramphenicol, the fever persists. He was hospitalized on day 10 of illness. Examination reveals a temperature of 39.8°C, heart rate of 92 bpm, and spleen palpable 1 cm below the costal margin (soft consistency). Blood culture is negative. Which of the following statements about typhoid fever is incorrect?