This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
[{'content': 'Which is true of typhoid- \nSelect and explain. \nA. Female carriers are less common, B. Male carriers though less are more dangerous, C. Gall bladder usually not involved in carrier state, D. Tetracycline is the DOC for carriers', 'role': 'user'}, {'content': 'Answer: B \nExplanation: <p> Typhoid fever:- Typical continuous fever for 3-4 weeks,relative bradycardia with involvement of lymphoid tissue. Without effective treatment, typhoid kills over 10% of those infected. Causative agent- Salmonella typhi. S.paraA and S.paraB are infrequent. Reservoir- man Case - a case is infectious as long as bacilli appear in stools /urine. Carriers:- 1. Convalescent carriers-excrete bacilli for 6-8 weeks,after which their number dimnishes rapidly. 2. Chronic carriers- persons who excrete bacilli for more than a year after a clinical attack. In most chronic carriers,the organism persists in gall bladder and in biliary tract. Source of infection- faeces and urine of cases/carriers. Age group involved mostly is 5-19 yrs old. Males affected more than females. Incubation period- 10-14 days. Mode of transmission: faecal oral route/ urine oral routes. Treatment of carriers:- Intensive course of ampicillin/ amoxycillin (4-6g/day) together with probenecid for 6 weeks. {Reference: park&;s textbook of preventive and social medicine, 23rd edition, pg no.235}</p>', 'role': 'assistant'}]