[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fN4i255Q1R5CnZCATQXM5ZGyoyMKKpQGv9oS0Xt9T5tI":32,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":47},[4,8,12,16,20,24,28],{"title":5,"slug":6,"path":7},"About Microbeonline.com","about-microbeonline-com","\u002Fabout-microbeonline-com\u002F",{"title":9,"slug":10,"path":11},"About Me","about-me","\u002Fabout-microbeonline-com\u002Fabout-me\u002F",{"title":13,"slug":14,"path":15},"Advertise with Us","advertise-us","\u002Fadvertise-us\u002F",{"title":17,"slug":18,"path":19},"Privacy Policy","privacy-policy","\u002Fprivacy-policy\u002F",{"title":21,"slug":22,"path":23},"Abbreviations","abbreviations","\u002Fabbreviations\u002F",{"title":25,"slug":26,"path":27},"Microbes","microbes","\u002Fmicrobes\u002F",{"title":29,"slug":30,"path":31},"Books","recommended-books","\u002Frecommended-books\u002F",{"type":33,"data":34},"blog",{"slug":35,"title":36,"description":36,"seoTitle":37,"seoDescription":37,"author":38,"createdDate":39,"lastUpdatedDate":40,"draft":41,"category":42,"image":37,"body":43,"faq":44,"tags":45,"related":46},"q-fever-etiology-general-properties-pathogenesis-laboratory-diagnosis","Coxiella burnetii: Properties, Pathogenesis, Lab Diagnosis",null,"Acharya Tankeshwar","2013-10-21","2025-12-18",false,"bacteriology","Q fever is a zoonotic disease with worldwide distribution having both acute and chronic stages. Q fever is caused by the intracellular bacterium *Coxiella burnetii* and is endemic in nearly every country in the world.\n\n**General properties of *Coxiella burnetii***\n\n1. Gram-negative, pleomorphic coccobacilli\n2. Obligate intracellular pathogen\n\n**Mode of transmission**\n\nQ fever is usually transmitted to humans after contact with infected animals or exposure to contaminated environments such as through aerosolization of the bacteria from animal products; person-to-person transmission is rare.  Drinking infected milk can transmit infection. Cattle, sheep, and goats are the primary reservoirs of *Coxiella burnetii* although a variety of species may be infected. Organisms are excreted in milk, urine, and feces of infected animals.\n\n## Laboratory diagnosis of Q Fever\n\nSample: Blood (microscopy and culture), serum (for serological testing)\n\n**Culture:** Isolation of the Coxiella from blood, sputum, or other clinical specimens is possible but not recommended due to the hazards of laboratory infection.  Please remember that *Coxiella burnetii* is a category B bioterrorism\n\n**Polymerase chain reaction (PCR) assay**\n\nDuring the acute phase of illness, a sample of whole blood can be tested by [polymerase chain reaction (PCR) assay](\u002Fpolymerase-chain-reaction-pcr-steps-types-applications\u002F) to determine if a patient has Q fever.  This method is most sensitive in the first week of illness but sensitivity decreases rapidly following the administration of appropriate antibiotics.\n\nAlthough a positive PCR result is helpful, a negative result does not rule out the diagnosis.\n\n**Serological studies**\n\n- Antibodies to *C. burnetii,* with detectable antibody titers usually observed by**7-10 days** after the onset of illness.\n- There are two distinct antigenic phases to which humans develop antibody responses.\n- **Acute infection:** antibody response to *C. burnetii* Phase II antigen is predominant and is higher than Phase I antibody response;\n- Chronic infection the reverse is true in chronic infection which is associated with a rising Phase I IgG titer (according to current U.S. case definitions >1:800) that is often much higher than Phase II IgG.\n\nSerological tests such as microagglutination, complement fixation, immunofluorescence and enzyme linked immunosorbent assay using phase I and phase II antigens are commonly performed.\n\nThe gold standard serologic test for diagnosis of acute Q fever is the indirect immunofluorescence assay (IFA) using *C. burnetii* antigen, performed on paired serum samples to demonstrate a significant (four-fold) rise in antibody titers. The first sample should be taken as early in the disease as possible, preferably in the first week of symptoms, and the second sample should be taken 2 to 4 weeks later.\n\nPaired samples taken 2-3 weeks apart demonstrating a significant (four-fold) rise in antibody titer provides the best evidence for a correct diagnosis of acute Q fever.\n\n**References**\n\n1. Kazar J. (2005). Coxiella burnetii infection. *Annals of the New York Academy of Sciences*, *1063*, 105–114. \u003Chttps:\u002F\u002Fdoi.org\u002F10.1196\u002Fannals.1355.018>\n2. Maurin, M., & Raoult, D. (1999). Q fever. *Clinical microbiology reviews*, *12*(4), 518–553. \u003Chttps:\u002F\u002Fdoi.org\u002F10.1128\u002FCMR.12.4.518>\n3. Capuano, F., Parisi, A., Cafiero, M. A., Pitaro, L., & Fenizia, D. (2004). Coxiella burnetii: quale realtà? \\[Coxiella burnetii: what is the reality?\\]. *Parassitologia*, *46*(1-2), 131–134.",[],[],[],[48,54,61,66,70,74,79,84,88,92],{"slug":49,"name":38,"description":50,"image":51,"body":52,"postCount":53},"acharya-tankeshwar","Editor-in-chief","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Ftankeshwar-acharya-author-microbeonline.jpg","***Tankeshwar Acharya, MSc (Medical Microbiology)***\n\n*Tankeshwar Acharya is an Assistant Professor in the Department of Microbiology at Patan Academy of Health Sciences (PAHS), Nepal, where he has been teaching and practicing clinical microbiology for over 14 years. He is the founder of Microbe Online, one of the leading free microbiology education resources on the web, covering bacteriology, mycology, parasitology, immunology, and clinical laboratory diagnostics written from direct experience in both the classroom and the diagnostic laboratory.*",433,{"slug":55,"name":56,"description":57,"image":58,"body":59,"postCount":60},"ashma-shrestha","Ashma Shrestha","SEO Copywriter and Science Communicator\nKathmandu, Nepal","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fashma-shrestha.png","Ashma Shrestha holds a Master of Science in Medical Microbiology from the Institute of Science and Technology (IOST), Tribhuvan University, Nepal, where she developed a strong foundation in virology, molecular biology, and diagnostic microbiology.\n\nShe now works as an SEO Copywriter at Resolution Digital, where she combines her scientific training with research-driven content strategy. She is certified in Google Analytics and Google Business Profile (GBP), and brings a data-informed approach to science communication writing content that is not only accurate but structured to reach and serve the students who need it most.\n\nAt microbeonline, Ashma contributes articles primarily in virology and molecular biology, areas she finds most compelling for their mechanistic depth and their growing clinical relevance. Her writing reflects the same standard the site is built on: factual rigor, clear explanation of the *why* behind microbiology concepts, and content that helps students move from memorization to genuine understanding.\n\nShe is passionate about making complex microbiological concepts accessible without sacrificing accuracy; a skill that sits at the intersection of her scientific training and her professional work in content and SEO.",81,{"slug":62,"name":63,"description":64,"image":37,"body":37,"postCount":65},"sushmita-baniya","Sushmita Baniya","Author \u002F Contributor",32,{"slug":67,"name":68,"description":64,"image":37,"body":37,"postCount":69},"samikshya-acharya","Samikshya Acharya",20,{"slug":71,"name":72,"description":64,"image":37,"body":37,"postCount":73},"alisha-tripathi","Alisha Tripathi",6,{"slug":75,"name":76,"description":77,"image":37,"body":37,"postCount":78},"aastha-shrestha","Aastha Shrestha"," Author \u002F Contributor",10,{"slug":80,"name":81,"description":82,"image":37,"body":37,"postCount":83},"guest-author","Guest Author","Guest Author \u002F Contributor",2,{"slug":85,"name":86,"description":64,"image":37,"body":37,"postCount":87},"srijana-khanal","Srijana Khanal",18,{"slug":89,"name":90,"description":82,"image":37,"body":37,"postCount":91},"dr-poonam-acharya","Dr. Poonam Acharya",1,{"slug":93,"name":94,"description":64,"image":37,"body":95,"postCount":96},"nisha-rijal","Nisha Rijal","**Nisha Rijal** is a microbiologist and quality assurance specialist. She served for nearly 12 years as a microbiologist at the National Public Health Laboratory (NPHL), Nepal's national reference laboratory, and continues to work as a consultant microbiologist in international public health organization. ",51]