Coxiella burnetii is the causative agent of Q fever, an acute systemic infection that primarily affects the lungs.

GENERAL CHARACTERISTICS

C. burnetii is smaller than Rickettsia spp. and is more resistant to various chemical and physical agents. Recent phylogenetic studies of this gram-negative coccobacillus have demonstrated that it is far removed from the rickettsiae and most closely related to Legionella. In contrast to the rickettsiae, C. burnetii can survive extracellularly; however, it can be grown only in lung cells. The organism has a sporelike life cycle and can exist in two antigenic states. When isolated from animals, C. burnetii is in phase I (large-cell variant form) and is highly infectious. In its phase II form (small-cell variant), C. burnetii has been grown in cultured cell lines and is not infectious, but it acts like a spore, assisting in extracellular survival of the organism.

EPIDEMIOLOGY AND PATHOGENESIS

 The most common animal reservoirs for the zoonotic disease caused by C. burnetii are cattle, sheep, and goats. In infected animals, organisms are shed in urine, feces, milk, and birth products. Usually, the infected animals are asymptomatic. Humans are infected by the inhalation of contaminated aerosols. Of significance, because of its resistance to desiccation and sunlight by virtue of forming spores, C. burnetii is able to withstand harsh environmental conditions. Q fever is endemic worldwide except in New Zealand.

Following infection, C. burnetii is passively phagocytized by host cells and multiplies within vacuoles. The incubation period is about 2 weeks to 1 month. After infection and proliferation in the lungs, organisms are picked up by macrophages and carried to the lymph nodes, from which they then reach the bloodstream.

SPECTRUM OF DISEASE

 After the incubation period, initial clinical manifestations of C. burnetii infections are systemic and nonspecific: headache, fever, chills, and myalgias. In contrast to rickettsial infections, a rash does not develop. Both acute and chronic forms of the disease are recognized. Possible clinical manifestations are listed in Box 1.

Box1. Clinical Manifestations of C. burnetii Infection

LABORATORY DIAGNOSIS

 Because laboratory-acquired infections caused by C. burnetii have occurred, cultivation of the organism must be done in a biosafety level 3 containment facility. However, the use of a shell vial assay with human lung fibroblasts to isolate the organism from buffy coat and biopsy specimens has not resulted in any laboratory-acquired infections. Once inoculated, cultures are incubated for 6 to 14 days at 37° C in carbon dioxide. The organism is detected using a direct immunofluorescent assay.

Although organisms can be detected by nucleic acid amplification assays, serology is the most convenient and commonly used diagnostic tool. Three serologic techniques are available: IFA, complement fixation, and EIA. IFA is considered the reference method for both acute and chronic Q fever that is both highly specific and sensitive and is recommended for its reliability, cost effective ness, and ease of performance. Many reference and state health laboratories perform phase I and phase II IgG and IgM serologic assays.

ANTIBIOTIC SUSCEPTIBILITY TESTING AND THERAPY

 Because C. burnetii does not multiply in bacteriologic culture media, susceptibility testing has been performed in only a limited number of laboratories. Tetracyclines are recommended for the treatment of acute and chronic Q fever.

PREVENTION

The best way to prevent infection with C. burnetii is to avoid contact with infected animals. A vaccine is commercially available in Australia and Eastern European countries; a vaccine is being developed in the United States.

اخر الاخبار

اخبار العتبة العباسية المقدسة

وفد العتبة العباسية المقدسة يجري جولة في أروقة معرض بغداد الدولي للكتاب

شعبة التوجيه الديني النسوي تطلق برنامجًا قرآنيًّا لزائرات مرقد أبي الفضل العباس (عليه السلام)

جامعة الكفيل تطلق دورة تدريبية عن تقييم الأداء الجامعي لعدد من ملاكاتها

المجمع العلمي يقيم محفلًا قرآنيًا بذكرى ولادة الصادقين (صلوات الله عليهما)

المزيد

الآخبار الصحية

هل يتنبأ الذكاء الاصطناعي بأمراضنا قبل حدوثها؟

وداعا للنظارات.. قطرة عين واحدة قد تغير كل شيء ؟

دراسة تكشف تأثير "تيك توك" وتطبيقات الفيديو على سلوك الأطفال

"أسرار خفية" في الشاي الأخضر.. تغير قواعد الصحة والوزن

المزيد

الآخبار التكنلوجية

أول قطار يعمل بالهيدروجين في أميركا يدخل الخدمة رسميًا

أجهزة أبل القادمة.. "حصن منيع" في عصر الهجمات الرقمية !

روسيا: تطلق قمرين اصطناعيين بواسطة الصاروخ سويوز 2.1

ميزة ثورية.. أبل تدخل عالم قياس ضغط الدم

المزيد

مواضيع ذات صلة

Rickettsia, Orientia, Anaplasma, and Ehrlichia

Chlamydia pneumonia

Urinary Tract Infections

Actinomyces

Neisseria meningitidis

The Brucellae

Diagnostic Laboratory Tests of Bordetella pertussis

Chlamydia psittaci

Laboratory Diagnosis of Chlamydia trachomatis

Spectrum of Disease of Chlamydia trachomatis

Epidemiology and Pathogenesis of Chlamydia trachomatis

Antigenic Structure, Pathogenesis, and Pathology of Bordetella pertussis