Did a presentation on Q fever today. Just take out some points to share:
Q fever is a zoonotic disease caused by Coxiella burnetii, a pleomorphic, obligate intracellular Gram –ve coccobacillus., causing acute or chronic infection worldwide.
It's first recognized in 1935 by Derrick in Queensland, Australia but this is not the reason it's named so. "Q" stands for "Query" as it has been presenting as prolonged fever of ? cause before the organism identified.
Being one of the Rickettsial infections, Q fever appears rather atypical. You can think that it's Queer because it has no rash, has no vector, has negative Weil-Felix, its causative organism can survive outside for a long time and does not have Rickettsia as its genus name!
Q fever's symptoms are mainly prolonged fever, and commonly manifests as atypical pneumonia, granulomatous hepatitis, myocarditis or meningoencephalitis. Chronic infection leads to endocarditis (culture-negative).
Lab diagnosis is by detecting antibody level to phase I or II antigen with IFA/ ELIZA. Rx for acute infection will be T.Doxycycline for 10-21 days; whereas a longer course for chronic infection - Doxy with quinolones for 4 years OR Doxy with hydroxychloroquine for 1.5 to 3 years. Relapse rates of over 50% are seen despite Rx.