Q Fever
Section snippets
Microbiology
C burnetii is a short (0.3 to 1.0 μm) gram-negative bacterium stained by the Gimenez method. Previously classified in the order Rickettsiales, C burnetii has been placed with Legionella and Francisella into the gamma subdivision of the Proteobacteria on the basis of sequences of the 16S rDNA encoding gene [3]. Coxiella burnetii is a strict intracellular bacterium and can be cultivated in embryonated eggs, laboratory animals, and cell cultures from clinical or animal specimens [1]. C burnetii
Epidemiology
Q fever is a worldwide zoonosis. Humans are incidental hosts in the zoonotic infection caused by C burnetii. The reservoir is large and includes mammals, birds, and arthropods, mainly ticks [1]. The most commonly identified sources of human infection are cattle, goats, and sheep; however, pets, including cats, rabbits, pigeons [7], and dogs, can serve as sources of infection [1]. Infected mammals shed C burnetii in urine, feces, milk, and birth products. High concentrations of C burnetii (up to
Clinical features
Primary infection with C burnetii is commonly asymptomatic. During an outbreak of 415 cases of Q fever in Switzerland, 224 patients (54%) were asymptomatic and only 2% were hospitalized [23]. The factors that determine whether symptoms will develop are unknown. Symptomatic infection is more likely in adults when compared with children and in men when compared with women [25]. The genotype of the organism also may be important [26]. Symptomatic illness can be divided into acute and chronic
Diagnosis
The laboratory findings during acute Q fever are nonspecific, and the diagnosis is usually made by serology. The leukocyte count is generally normal but may be elevated or decreased [21]. The erythrocyte sedimentation rate might also be high. Thrombocytopenia is noted in 25% of cases. Liver enzymes are commonly moderately elevated. Autoantibodies are commonly found, including antimitochondrial antibodies, anti–smooth muscle antibodies, and antibodies to phospholipids [1]. Anticardiolipin
Treatment
Acute Q fever is usually a mild disease that resolves spontaneously within 2 weeks. Therapy is warranted only in symptomatic patients. Tetracycline reduces fever duration significantly more than placebo [46]. Doxycycline is now recommended [46]. In children, doxycycline is recommended when the disease is established. Fluoroquinolones such as ofloxacin (200 mg three times a day) and pefloxacin (400 mg twice a day) have been used successfully. The efficacy of erythromycin is disputed, but newer
Prevention
An effective whole-cell vaccine for Q fever has been developed in Australia and has protected humans in occupational settings [1]. To prevent and control Q fever, it is useful for persons at high risk (eg, those who have cardiac valvular disease, those with vascular grafts, pregnant women) to avoid high-risk situations unless they are immune [25].
References (50)
- et al.
Natural history and pathophysiology of Q fever
Lancet Infect Dis
(2005) - et al.
Phylogenic homogeneity of Coxiella burnetii strains as determinated by 16S ribosomal RNA sequencing
FEMS Microbiol Lett
(1993) - et al.
Q fever–a review and issues for the next century
Int J Antimicrob Agents
(1997) - et al.
Q fever
Clin Microbiol Rev
(1999) - et al.
Complete genome sequence of the Q-fever pathogen Coxiella burnetii
Proc Natl Acad Sci U S A
(2003) - et al.
Q fever pneumonia: virulence of Coxiella burnetii pathovars in a murine model of aerosol infection
Infect Immun
(2005) - et al.
Genetic diversity of the Q fever agent, Coxiella burnetii, assessed by microarray-based whole-genome comparisons
J Bacteriol
(2006) - et al.
Pigeon pneumonia in Provence: a bird borne Q fever outbreak
Clin Infect Dis
(1999) - et al.
Epidemiologic features and clinical presentation of acute Q fever in hospitalized patients: 323 French cases
Am J Med
(1992) Rapport sur le bioterrorisme
Ministère de la Santé, de la Famille et des personnes handicapées
(2003)
Q fever during pregnancy–a risk for women, fetuses, and obstetricians
N Engl J Med
Tick-borne diseases in transfusion medicine
Transfus Med
Sexually transmitted Q fever
Clin Infect Dis
Bacteriostatic and bactericidal activities of moxifloxacin against Coxiella burnetii
Antimicrob Agents Chemother
Q fever and the US military
Emerg Infect Dis
Q fever in members of the United States armed forces returning from Iraq
Clin Infect Dis
Summary of notifiable diseases–United States, 2004
MMWR Morb Mortal Wkly Rep
Clinical features, diagnosis, treatment, and prevention of Q fever
Up to Date
Q fever endocarditis
Up to Date
Microbiology and epidemiology of Q fever
Up to Date
Changing clinical presentation of Q fever endocarditis
Clin Infect Dis
Q fever 1985–1998: clinical and epidemiologic features of 1383 infections
Medicine (Baltimore)
Q fever and HIV infection
AIDS
An important outbreak of human Q fever in a Swiss Alpine valley
Int J Epidemiol
Chronic Q fever. Ninety-two cases from France, including 27 cases without endocarditis
Arch Intern Med
Cited by (145)
Automated sample-to-answer system for rapid and accurate diagnosis of emerging infectious diseases
2023, Sensors and Actuators B: ChemicalCoxiella and Q fever
2023, Molecular Medical Microbiology, Third EditionDetection of Coxiella burnetii DNA in sheep and goat milk and dairy products by droplet digital PCR in south Italy
2022, International Journal of Food MicrobiologyQ Fever: A Troubling Disease and a Challenging Diagnosis
2021, Clinical Microbiology NewsletterCitation Excerpt :Q fever infection can manifest as acute (primary) or chronic (localized) infections. While up to 50% of primary infections are thought to be asymptomatic, symptomatic acute infections typically present as a nondescript febrile illness following a 2- to 3-week incubation period [45]. Acute infections may present as a severe headache that is often retro-orbital and includes photophobia [46].