COMMENTARY

Q Fever: New Guidelines for Patient Management

Alicia Anderson, DVM, MPH

Disclosures

May 13, 2013

Editorial Collaboration

Medscape &

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Hello. I'm Dr. Alicia Anderson the Centers for Disease Control and Prevention's (CDC) Rickettsial Zoonoses Branch. I'm speaking with you as part of the CDC Expert Commentary series on Medscape about the new guidelines just released by CDC and the Q Fever Working Group. These recommendations address the clinical presentation, appropriate diagnostic testing, laboratory interpretation, and treatment of acute and chronic phases of Q fever in children, adults, and pregnant women. Guidelines for the management of occupational exposure to Q fever are also included.

Q fever is a nationally notifiable disease caused by the bacterium Coxiella burnetii. CDC receives approximately 150 reports of this illness in the United States each year. Although Q fever has been historically considered an occupational disease of those working with livestock, such as veterinarians, farmers, and slaughterhouse workers, most cases reported to CDC each year involve individuals who do not report livestock contact and do not work with animals. These exposures are likely due to airborne transmission of the bacteria after environmental contamination by infected animals. Because wind currents can potentially carry the bacteria for miles and cause large outbreaks, Q fever infection has been documented in people living several miles from a source farm.

Q fever is associated with both acute and chronic infection, and 2 distinct types of antibody response.[1] In acute infection, a phase II IgG antibody response is dominant and higher than the antibody response to phase I. The reverse is true in chronic infection.

Frequently underreported and misdiagnosed, acute Q fever often resembles a nonspecific viral illness. If acute Q fever is suspected, physicians should order IgG IFA (indirect immunofluorescence assay) testing for both phase I and phase II antibodies in paired serum specimens, taken 3-6 weeks apart. The acute specimen is usually negative pending production of measurable antibodies.

Chronic Q fever most commonly manifests as culture-negative endocarditis. The diagnosis of chronic Q fever requires both laboratory confirmation and evidence of clinical infection. This is because many acute Q fever patients with resolved symptoms will have increased phase I titers for several months. These levels may subsequently decrease without the infection ever progressing to chronic disease.

Treatment for acute illness should begin immediately and not be delayed while awaiting laboratory results. The treatment of choice for acute illness is a 2-week course of doxycycline. Alternative regimens for specific groups of patients (for example, pregnant women) and for chronic infection are discussed in detail within the complete guidelines. Management of chronic Q fever requires long-term treatment with multiple antibiotics and intensive patient monitoring for years for possible relapse. Surgical intervention may be required, and consultation with an infectious disease specialist is recommended.

Patients at highest risk for progression to chronic disease, such as those with heart valve or vascular defects, or women who are diagnosed during pregnancy, should be serologically and clinically monitored at intervals of 3, 6, 12, 18, and 24 months after diagnosis of acute Q fever. Patients without obvious risk factors for chronic Q fever should receive a clinical and serologic follow-up approximately 6 months after diagnosis of acute illness to identify potential progression to chronic disease.

To review the complete guidelines and the full recommendations, and for more information on Q fever diagnosis, treatment, and management, please review the resources listed on this page. Thank you.

Web Resources

CDC: Q Fever

CDC: Q Fever: Information and Guidance for Clinicians

Anderson A, Bijlmer H, Fournier PE, et al. Diagnosis and management of Q fever -- United States, 2013: Recommendations from CDC and the Q Fever Working Group. MMWR Recomm Rep. 2013;62:1-23.

Dr. Alicia Anderson serves as a senior epidemiologist in the Rickettsial Zoonoses Branch at the CDC's National Center for Emerging and Zoonotic Infectious Diseases. Dr. Anderson attended Mississippi State University College of Veterinary Medicine, where she received a doctor of veterinary medicine degree in 1993. She received her master's degree in public health in 1999 from Emory University. She joined CDC in 1999 as an Epidemic Intelligence Service Officer, conducting research and the investigation of outbreaks related to zoonotic diseases. She has worked extensively on epidemiologic research, outbreak response and national surveillance related to Q fever.

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