Final answer:
The described symptoms with the triad of fever, rash, and eosinophiluria suggest a diagnosis of a rickettsial disease such as murine typhus, Rocky Mountain spotted fever, or epidemic typhus. Tests like IFA, PCR, and serologic testing can confirm the diagnosis, with doxycycline being the primary treatment.
Step-by-step explanation:
The triad of fever, rash, and eosinophiluria, combined with initial cold-like symptoms and a high fever followed by a macular or papular rash three to five days later, is indicative of a rickettsial infection, which is a group of diseases caused by the genus Rickettsia. When considering the diagnostic tests mentioned, such as indirect immunofluorescent antibody (IFA) staining, PCR for R. typhi or R. rickettsii, and acute and convalescent serologic testing, a few potential diagnoses arise. Murine typhus, Rocky Mountain spotted fever (RMSF), and epidemic typhus are among the conditions that present with such symptoms and require these diagnostic methods. The primary treatment for these rickettsial infections is doxycycline, with chloramphenicol as the second choice.
A patient presenting with these symptoms should be evaluated for rickettsial diseases, and healthcare providers should also consider travel history, potential exposure to vectors like ticks or fleas, and onset and progression of symptoms.