Download Q fever

Q fever
The disease and Panbio product training
Overview
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“Query” fever
First described in Australia
World wide zoonosis
Caused by the bacterium Coxiella burnetii
Infectious Agent
• Coxiella burnetii
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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
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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
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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
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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
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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.