Transcript Q fever
Q fever The disease and Panbio product training Overview • • • • “Query” fever First described in Australia World wide zoonosis Caused by the bacterium Coxiella burnetii Infectious Agent • Coxiella burnetii – – – – obligate intracellular organism organism very stable in environment resistant to drying, chemicals and may disinfectants. two antigenic phases: phase I and II • phase I (lipopolysaccharide present) - as found in nature, virulent • phase II (partial loss of lipopolysaccharide) - as found after multiple laboratory passages, less infectious Epidemiology • Occurrence – worldwide, endemic in every part of the world except New Zealand. – esp. prevalent in meatworks, dairies and animal farms therefore making Q fever an occupational hazard • Reservoir – cattle, sheep, goats, some wild animals,ticks, domestic cats Clinical Notes • Clinical signs often subclinical or extremely mild • Infection can be acute or chronic • Acute infection – no typical form of acute Q fever, although there are generally 3 major presentations 1) Self-limited flue-like syndrome 2) Pneumonia 3) Hepatitis Clinical Notes cont... • Chronic Q fever – – – – – lasts more than 6 months occurs in approx. 5% of patients infected with C. burnetii C. burnetii multiplies in macrophages heart is the most commonly involved organ of all cases of endocarditis it represents:• 3% in England and Lyon (France) • 15% in Marseille (France) Clinical Notes cont... • Mode of Transmission – airborne dissemination of organisms in dust and direct contact with infected animals – transplacental transmission congenital infection. – blood transmissions – intradermal inoculation – ticks transmit to domestic animals but not to humans. – sexual transmission suspected. • Incubation Period – Usually 2-3 weeks • Treatment – Tetracycline and rifampin Antibody response • Antibodies to phase 1 – indicates chronic infection • Antibodies to phase 2 – IgM & IgA appear shortly after onset of symptoms & may persist for up to 3 months – IgG appears shortly after IgM & remain for life – indicates acute infection but also persist throughout chronic infection. • phase 2 molecules are highly immunogenic compared to phase 1 • phase 1 molecules are masked in acute infection and therefore not exposed to the host’s immune system Diagnosis • • • • Culture Complement fixation test (CFT) Indirect immunofluorescence assay (IFA) ELISA Culture • Hazardous • Not routinely used • Requires specially equipped laboratory CFT • Usually phase II antigen • CF antibodies may not be detectable early in acute infection • CF antibodies may persist for months/years • Usually requires paired sera IFA • Accepted method of diagnosis (“Gold Standard”) • More sensitive than CFT • Can measure individual antibody classes to different phase and can therefore be used to distinguish between acute & chronic infection • Ideal for confirmation and small volume testing ELISA • • • • More sensitive than IFA (IgG studies) Very specific Suitable for large scale screening Diagnosis can be based on single serum specimen when IgM ELISA used • Can measure responses to different classes of antibody Panbio Q fever ELISAs C. burnetii (Q fever) IgG ELISA C. burnetii (Q fever) IgM ELISA • • • • • Cat # E-QFB01G Cat # E-QFB01M Phase II antigen Ideal for laboratory use 1hr 10min assay time IgG and IgM kits available Proven performance 1,2,3 – IgM ELISA sensitivity 99%, specificity 88%1 – IgG ELISA sensitivity 71%, specificity 96% 2; sensitivity 98.4%, specificity 95.7% (compared to IFA using cutoff titre of 1/160) 3 Panbio Q fever Dip-S-Tick C. burnetii Total Ig Dip-S-Tick kit Cat# D-QFB03T • Has dots for both Phase I and Phase II antigens. – Three dots are for Phase II (acute infection) determination and one is for Phase I (chronic infection) determination. • Built in control well indicates test has worked correctly • Convenient for small-volume testing • No special equipment other than a 50°C waterbath required • Semi-quantitative Panbio Q fever Dip-S-Tick: configuration Panbio Q fever IFA C. burnetii (Q fever) IFA Slides Cat#I-QFB01X • Contain both Phase I and Phase II purified organisms as well as a normal yolk sac (NYS) control. • All three are represented on each well of the slides as distinct microdots (figure 1). • Dilutions of the patient's serum are placed in wells on the slide, permitting the antibody to bind specifically to the organisms. Bound antibodies are tagged with a fluorescein labeled anti-human conjugate and observed using a fluorescence microscope. In this format, organisms are readily identified as small coccobacilli. Fluorescent coxiellae are bright yellow against a dull red background (counterstain). Panbio Q fever IFA Figure 1 Dot configuration in slide well as seen through the microscope Promotional Resources • Clinical Sheet • Publications – General – Panbio Q fever ELISAs • Newsletter articles References 1. Field P. et al. (2000) J. Clin. Microbiol. 34(4):1645-47. 2. Field P. et al (2002) J. Clin. Microbiol. 40(9):3526-29. 3. D’Harcourt et al. (1996) Eur. J. Clin. Micro. Infect. Dis. 15:749-52.