This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'Tunica reaction is positive in ? \nSelect and explain. \nA. R prowazekii, B. R typhi, C. R tsutsugamushi, D. R akari', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., R typhi Neill - Mooser (Tunica) reaction When male guinea pigs are inoculated intraperitoneally with blood from a case of endemic typhus or with a culture of R. typhi (R. mooseri) they develop fever and a characteristic scrotal inflammation. This reaction is used to differentiate R. typhi and R. prowazekii.", 'role': 'assistant'}]