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FINDINGS: The main syndromes identified are flu-like illness, pneumonia, hepatitis, and endocarditis after chronic infection. About 1% of Q fever cases are complicated by meningoencephalitis, which may be accompanied by cranial nerve palsies, seizures, and coma. Other possible complications are vertebral osteomyelitis, hemolytic anemia, optic neuritis, and erythema nodosum. About 60% of cases in the USA are manifest as hepatitis. The three types of hepatitis are acute hepatitis, persistent fever associated with granulomas of the liver, and incidental hepatitis in patients with pneumonia. Pneumonia may be atypical, rapidly progressive, or incidental. Of patients with lung infiltrates by chest x-ray, only 28% have a cough. Other findings of patients with Q fever pneumonia are headache (75%), sweats (84%), myalgia (68%), nausea (49%), pleural effusions (35%), leukocytosis (33%), pleuritic chest pain (28%), diarrhea (21%), and splenomegaly (5%). Almost all patients with pneumonia have slight elevation of liver enzymes (2-3 times). [PPID, p. 2296-2301] Endocarditis is the most common complication of chronic Q fever. Other complications are pericarditis and myocarditis. [ID, p. 163, 1482-5] EPIDEMIOLOGY: The organism has a spore form that can survive on meat in cold storage for 1 month and in infected tissue stored in formaldehyde for 4-5 months. There are case reports of infections transmitted by handling contaminated laundry or living next to a road used by farm vehicles hauling contaminated dust and straw. [PPID] Q fever is an occupational hazard for laboratory workers, veterinarians, meat packers, and sheep handlers. "Infected animals, including sheep and house cats, are usually asymptomatic, but shed massive numbers of organisms in placental tissues at parturition." Contaminated clothing may transmit the infection from person to person. Use of vaccine is recommended for laboratory workers handling the pathogen. The case-mortality rate may be as high as 2% to 3% in untreated cases. The natural reservoirs are sheep, cattle, goats, cats, dogs, wild ungulates, birds, bandicoots, feral rodents, birds, and ticks. Some cases may be transmitted by milk from infected cows. [CCDM, p. 434-8] |
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