Diagnosis and Management of Q Fever — United States, 2013
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Diagnosis and Management of Q Fever — United States, 2013: Recommendations from CDC and the Q Fever Working Group
Recommendations and Reports
March 29, 2013 / 62(RR03);1-23
The material in this report originated in the National Center for Emerging and Zoonotic Infectious Diseases, Beth P. Bell, MD, Director; and the Division of Vector-Borne Diseases, Lyle R. Petersen, MD, Director.
Corresponding preparer: Alicia Anderson, DVM, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, CDC, 1600 Clifton Road, MS A-30, Atlanta, GA 30333. Telephone: 404-639-4499; Fax: 404-639-2778; E-mail: aha5@cdc.gov.
Summary
Q fever, a zoonotic disease caused by the bacterium Coxiella burnetii, can cause acute or chronic illness in humans. Transmission occurs primarily through inhalation of aerosols from contaminated soil or animal waste. No licensed vaccine is available in the United States. Because many human infections result in nonspecific or benign constitutional symptoms, establishing a diagnosis of Q fever often is challenging for clinicians. This report provides the first national recommendations issued by CDC for Q fever recognition, clinical and laboratory diagnosis, treatment, management, and reporting for health-care personnel and public health professionals. The guidelines address treatment of acute and chronic phases of Q fever illness in children, adults, and pregnant women, as well as management of occupational exposures. These recommendations will be reviewed approximately every 5 years and updated to include new published evidence.Introduction
Q fever, first described in 1937, is a worldwide zoonosis that has long been considered an underreported and underdiagnosed illness because symptoms frequently are nonspecific, making diagnosis challenging (1–3). The causative organism, Coxiella burnetii, is an intracellular bacterium that tends to infect mononuclear phagocytes but can infect other cell types as well. Infection in humans usually occurs by inhalation of bacteria from air that is contaminated by excreta of infected animals. Other modes of transmission to humans, including tick bites, ingestion of unpasteurized milk or dairy products, and human-to-human transmission, are rare (1). Laboratory diagnosis relies mainly on serology, and doxycycline is the most effective treatment for acute illness. No vaccine is available commercially in the United States.Q fever was designated a nationally notifiable disease in the United States in 1999. Since then, reports of Q fever have increased, with 167 cases reported in 2008, an increase greater than ninefold compared with 2000, in which 17 cases were reported (4). The national seroprevalence of Q fever is estimated to be 3.1% based on data from the National Health and Nutrition Examination Survey (2003–2004), and human infections have been reported from every state in the United States (5). Q fever infections in humans and animals have been reported from every world region except Antarctica (6).
Q fever has acute and chronic stages that correspond to two distinct antigenic phases of antibody response. During an acute infection, an antibody response to C. burnetii phase II antigen is predominant and is higher than the response to the phase I antigen, whereas a chronic infection is associated with a rising phase I immunoglobulin G (IgG) titer. Although acute Q fever symptoms in humans vary, the condition typically is characterized by a nonspecific febrile illness, hepatitis, or pneumonia. Asymptomatic infections followed by seroconversion have been reported in up to 60% of cases identified during outbreak investigations (6–8). Onset of symptoms usually occurs within 2–3 weeks of exposure, and symptomatic patients might be ill for weeks or months if untreated.
Chronic Q fever can manifest within a few months or several years after acute infection and can follow symptomatic or asymptomatic infections. Chronic disease is rare (<5 acute="" and="" as="" by="" characterized="" defects="" endocarditis="" factors="" i="" in="" infections="" is="" of="" or="" patients="" preexisting="" risk="" such="" typically="" valvular="" vascular="" with="">9
). Unlike acute Q fever, which has a low mortality rate (<2 always="" chronic="" endocarditis="" fatal="" fever="" i="" if="" is="" q="" untreated="">10). Routine blood cultures are negative in patients with chronic Q fever endocarditis. Diagnosis of chronic Q fever endocarditis can be extremely difficult because vegetative lesions are visualized by echocardiography in approximately 12% of patients (6).Q fever is an occupational disease in persons whose work involves contact with animals, such as slaughterhouse workers, veterinarians, and farmers, although infection is not limited to these groups. Urban outbreaks and cases with no known exposure or close proximity to livestock have been reported, as have nonoccupational exposures such as through a hobby farm (a small farm that is not a primary source of income) (11). Data collected from Q fever case report forms submitted to CDC during 2000–2010 indicate that 320 of 405 (79%) cases in patients who reported occupational status are recognized in patients who are not in previously defined high-risk occupations, and 243 of 405 (60%) cases are in patients who do not report livestock contact (CDC, unpublished data, 2010). These findings underscore the need for health-care professionals to consider Q fever in the differential diagnosis in patients with a compatible illness, even in the absence of occupational risk or history of direct contact with animal reservoirs. Approximately 200 cases of acute Q fever were reported in U.S. military personnel who had been deployed to Iraq since 2003. Investigations of these cases linked illness to tick bites, sleeping in barns, and living near helicopter zones with environmental exposure resulting from helicopter-generated aerosols (12,13).
The largest known reported Q fever outbreak involved approximately 4,000 human cases and occurred during 2007–2010 in the Netherlands. This outbreak was linked to dairy goat farms near densely populated areas and presumably involved human exposure via a windborne route (14).
Prompt diagnosis and appropriate treatment shortens the illness and reduces the risk for severe complications (15,16). In patients with chronic Q fever illness, early treatment might be lifesaving. Physician awareness of the epidemiologic and clinical characteristics of Q fever is required to make a prompt and correct diagnosis. Information in this report is designed to assist U.S. clinicians with the following:
- Recognize common epidemiologic features and clinical manifestations of Q fever.
- Consider Q fever as the cause of a patient's illness if appropriate.
- Obtain relevant history (e.g., medical history and exposure) and diagnostic tests for Q fever.
- Identify the limitations and utility of laboratory diagnostic testing.
- Make treatment decisions based on epidemiologic and clinical evidence.
- Recognize that doxycycline is the treatment of choice for patients of any age with severe illness.
- Recognize potential severe manifestations of acute and chronic Q fever and understand appropriate strategies to monitor and manage these patients.
- Manage infected children and pregnant women appropriately.
- Provide effective risk communication for persons at high risk for Q fever exposure.
- Report suspect and confirmed cases to appropriate public health officials.
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