Q Fever

Question 1

What is Q fever?

Answer 1

Zoonosis caused by Coxiella burnetti.

Question 2

Which animals are susceptible to Q fever infection?

Answer 2

Infection is widespread in domestic, farm and other animals, birds and arthropods. Mainly spread by ticks.

Question 3

How is Q fever transmitted to humans?

Answer 3

Modes of transmission to humans: -dust (inhaled) -aerosol -unpasteurised milk from infected cows -tick bites (rare)

Question 4

Is Q fever easily transmissible?

Answer 4

YES! Infective dose is very small; minimal animal contact is required.

Question 5

Who is suscpetible to/frequently associated with Q fever infection?

Answer 5

Farm and abattoir workers.

Question 6

What is the clinical presentation of Q fever?

Answer 6

Symptoms begin insidiously 2-4 weeks post-infection. Suspect in anyone with PUO or atypical pneumonia; -fever -sweats -myalgia -headache -cough - hepatitis (+/- splenomegaly)

Question 7

What is the time course of Q fever?

Answer 7

Symptoms begin insidiously 2-4 weeks post infection > acute illness generally resolves spontaneously BUT -May lead to pneumonia, hepatitis or CNS infection. -May become chronic.

Question 8

What is chronic Q fever?

Answer 8

Q fever may become chronic with: -endocarditis -myocarditis -ueitis -osteomyelitis -other focal infections Also causes miscarriages and CNS infection.

Question 9

What is C. burnetti?

Answer 9

Obligate intracellular organism Does not grow on standard culture medium. Spore forming - survives harsh conditions.

Question 10

How is Q fever diagnosed?

Answer 10

C. burnetti does not grow on standard media. Diagnosis made serologically using immunofluorescent assay. Ab tests for 2 different bacterial Ags allow distinction b/w acute and chronic infection: -Acute = phase II antigens -Chronic = phase I antigens

Question 11

How is Q fever treated?

Answer 11

ACUTE: 100mg doxycycline bd po for 2-3/52 Reduces duration of acute illness; unknown whether eradicates organism. Also used: azithromycin, ciprofloxacin and co-trimoxazole. CHRONIC (including endocarditis): -doxycycline + hydroxychloroquine 600mg daily 18 months +/- valve replacement.

Question 12

What investigations should be done in suspected Q fever?

Answer 12

CXR: may show consolidation (multi lobar or slowly resolving) LFTs: may be hepatitic Liver biopsy: may show granulomata