ABSTRACT
Coxiella burnetii occasionally persists in humans following acute Q fever and may subsequently cause life-threatening chronic disease. Chronic disease manifestations frequently include endocarditis and hepatosplenomegaly. This chapter examines the biological bases for persistence and chronic disease. It discusses the present state of knowledge of chronic Q fever in humans and in in vitro model systems. Diagnosis of Q fever endocarditis is based on clinical patterns and serology; occasionally it involves isolation and cultivation of the agent from infected valves. It should be suspected in patients presenting clinical evidence of endocarditis and whose blood cultures are negative for routine bacterial pathogens commonly implicated in its etiology. Antibiotic treatment of chronic Q fever has not been consistently effective and has been directed towards elimination of the parasites from the valve leaflets. The in vitro model system of C. burnetii persistent infection has yielded some important observations and clues regarding the parasite’s persistence.
