infectious diseases
Q Fever
Symptoms and Signs of Q Fever
The incubation period averages 18 to 21 days (range 9 to 28 days). Acute Q fever is often asymptomatic; in other patients, it begins abruptly with influenza-like symptoms: fever, severe headache, chills, severe malaise, myalgia, anorexia, and sweats. Fever may rise to 40°C and persist 1 to>3 weeks. Rarely, acute Q fever manifests as encephalitis or meningoencephalitis. Respiratory symptoms (a dry nonproductive cough, pleuritic chest pain) appear 4 to 5 days after onset of illness. These symptoms may be particularly severe in older patients or patients who are debilitated. During examination, lung crackles are commonly noted, and findings suggesting consolidation may be present. Unlike rickettsial diseases, acute Q fever does not cause a rash. Acute hepatic involvement, occurring in some patients, resembles viral hepatitis, with fever, malaise, hepatomegaly with right upper abdominal pain, and possibly jaundice. Headache and respiratory signs are frequently absent. A post-Q fever fatigue syndrome has been reported to occur in up to 20% of patients with acute Q fever ( Symptoms and signs references ). Patients report severe fatigue, muscle pains, headache, photophobia, and/or mood and sleep changes. may manifest within a few weeks to many years after the initial infection. People with a history of cardiac valvular defects, arterial aneurysms, or vascular grafts are at increased risk of developing chronic Q fever. Pregnancy and immunosuppression have also been linked to the development of chronic Q fever. Hepatitis may manifest as Fever of Unknown Origin (FUO) . Liver biopsy may show granulomas, which should be differentiated from other causes of liver granulomas (eg, tuberculosis, sarcoidosis, histoplasmosis, brucellosis, tularemia, syphilis). resembles culture-negative subacute Infective Endocarditis ; the aortic valve is most commonly affected, but vegetations may occur on any cardiac valve. Marked finger clubbing, arterial emboli, hepatomegaly, splenomegaly, and a purpuric rash may occur. Only 20 to 40 % of patients who develop Q fever endocarditis have symptoms of acute infection. The case-fatality rate of acute Q fever is only about 1% in untreated patients. Untreated chronic Q fever endocarditis is always fatal. Adequate antibiotic treatment reduces the mortality rate for Q fever endocarditis to <5% ( Symptoms and signs references ). Some patients with neurologic involvement have residual impairment. 1.Centers for Disease Control and Prevention: Information for Healthcare Providers, Q Fever 2.Million M, Thuny F, Richet H, et al: Long-term outcome of Q fever endocarditis: a 26-year personal survey.Lancet Infect Dis10(8):527-35, 2010. doi: 10.1016/S1473-3099(10)70135-3 