Q fever

Question 1

—grow intracellularly in eukaryotic cells
—associated with arthropods (e.g., ticks)
—Related to Legionella
—Q (query) fever
◦outbreak in Australian abattoir workers

Question 2

—Two structural forms:
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Answer 2

**1.Small cell variants

2.large cell variants

—**

Question 3

—Phase I

—

Answer 3

◦observed in nature
◦intact LPS
◦Resistant to fusion with lysosomes containing hydrolytic enzymes

Question 4

—Phase II

Answer 4

◦molecule with lipid A and core sugars
◦missing the outermost O-antigen sugars
◦Susceptible to lysosomal fusion

Question 5

–resistant to environmental stress
–Form where organism attaches to macrophages and monocytes
–internalized in a phagocytic vacuole

Answer 5

1.Small cell variants

Question 6

–metabolically active form

Answer 6

1.large cell variants

Question 7

—acute or chronic disease is determined in part by the ______________
—able to regulate the cell signaling pathways in its phagocytic home
—interferon-γ
◦phagosome–lysosome fusion occurs
—interleukin-10
◦chronic infections
◦interferes with fusion

Answer 7

organism’s ability to survive intracellularly

Question 8

—Hosts: mammals, birds, and numerous
—species of ticks
—extremely stable in harsh environmental conditions
—can survive in soil and milk for months to years
—primary reservoirs
◦Farm animals (sheep, cattle, and goats)
◦cats, dogs, and rabbits

Question 9

—Mode of infection:
◦Inhalation of airborne particles from a contaminated environmental source
◦ingestion of contaminated unpasteurized milk or other dairy products
—high concentrations in the placenta of infected livestock
◦Dried placentas left on the ground after parturition and feces, urine, and tick feces
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Question 10

—Human infection
◦ranchers, veterinarians, and food handlers
◦Infectious dose is small (10 or fewer bacteria)
◦most human infections are asymptomatic or mild

Question 11

—asymptomatic infection
—most symptomatic infections are mild
◦nonspecific flulike symptoms
◦abrupt onset, high-grade fever, fatigue, headache, and myalgias
—Less than 5% of infected persons require hospitalization
◦hepatitis, pneumonia, or isolated fevers

Question 12

◦symptoms lasting more than 6 months
◦Can develop months to years after the initial exposure
◦occurs almost exclusively in patients with predisposing conditions
–underlying valvular heart disease
–immunosuppression
◦Subacute endocarditis
–Most common presentation

Answer 12

—Chronic Q fever

Question 13

—Culture
◦tissue culture cells
◦cell-free medium
◦rarely performed
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Question 14

—Serology
◦Most commonly performed diagnostic test
_____________
–weakly antigenic
–the microagglutination tests
–i

Answer 14

◦phase I antigens

Question 15

–Test of choice
–

Answer 15

indirect immuno fluorescence antibody (IFA) test

Question 16

◦Cross reactions with Bartonella

Answer 16

enzyme-linked immunosorbent assay (ELISA)

Question 17

—Acute Q fever
◦
—C

Answer 17

immunoglobulin M (IgM) and IgG antibodies
–phase II antigens
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Question 18

◦Demonstration of antibodies against both phase I and II antigens
◦

Answer 18

chronic Q fever

Question 19

—Treatment of acute and chronic C. burnetii infections is guided by clinical experience
_______________
—
—

Answer 19

◦14 day treatment with doxycycline

Question 20

Treatment for chronic disease?

Answer 20

Chronic disease
◦Doxycycline + hydroxychloroquine
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Question 21

What is the alternative treatment ?

Answer 21

—Fluoroquinolones
◦Alternative treatment
◦contraindicated in children and pregnant women

Question 22

Prevention is by?

Answer 22

—Inactivated whole-cell vaccines
—partially purified antigen vaccines
—vaccines prepared from phase I organisms have been shown to provide the best protection
—does not eradicate Coxiella in infected animals or decrease asymptomatic shedding
—Vaccination of previously infected individuals is contraindicated
◦single-dose vaccine with no booster immunizations is recommended
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