<prompt> Tunica reaction is positive in ?R prowazekiiR typhiR tsutsugamushiR akari  <response>: 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. 