Enteric Fever

Which Salmonella species is the most common cause of enteric fever in India?

A 35-year-old man from rural Uttar Pradesh presents with a 3-week history of intermittent fever, headache, and abdominal distension. On examination, he is febrile (38.8°C), has a palpable spleen (3 cm below costal margin), and a faint rose-coloured rash on the trunk. Laboratory investigations reveal: Hb 10.2 g/dL, WBC 3,200/μL (normal differential), platelets 95,000/μL, and elevated transaminases (AST 120 U/L, ALT 95 U/L). Blood culture is negative after 48 hours. Widal test: O antigen 1:160, H antigen 1:80, both IgM and IgG positive. What is the most likely diagnosis?

A 35-year-old woman from Kolkata with a 3-week history of undulating fever, headache, and abdominal distension is admitted. She has hepatosplenomegaly and a faint rash on the trunk. Widal test shows O antigen titre 1:320 and H antigen titre 1:640. Blood culture is negative. Which finding best distinguishes this presentation of enteric fever (S. typhi) from a relapsing fever (Borrelia recurrentis) in the same endemic region?

Which of the following is the most reliable diagnostic test for enteric fever during the third week of illness?

A 35-year-old woman from Chennai with a 5-day history of fever and abdominal pain is suspected to have enteric fever. Blood culture has been sent. Which is the most appropriate next investigation if blood culture remains negative after 48 hours?