Infectious Disease Compendium

Coxiella burnetti aka Q fever


Gram negative pleomorphic coccobacillus; lives in phagolysosomes. And you think your apartment is located in a bad neighborhood.

Epidemiologic Risks

Exposures to cows, sheep, and goats, European rabbits and many other animals as well. Especially if the patient is exposed to placentas; it can survive in soil for a long period of time. Being seen by the (few) troops returning from Iraq (along with Leishmania and very resistant Acinetobacter). It can also be found in filth flies (PubMed). Time flies like an arrow, filth flies like a dung pile. So don't be eating a filth fly.

It is carried on the wind from sheep and goats (but not cows): "Coxiella burnetii travels up to 18 km (11 miles) on gale force winds. In rural areas, highest infection risk occurs within 5 km (3 miles) of sources (PubMed)."

Incubation period can be up to 40 days. I would how much was seen on the ark.

Common in veterinarians (22% of those tested are seropositive). Risk factors included age > 46 years, routine contact with ponds, and treatment of cattle, swine, or wildlife (PubMed).

"Coxiella burnetii specific antibodies were detected in 40.7% of camels, 19.3% of cattle, 11.2% of buffaloes, 8.9% of sheep and 6.8% of goats (PubMed)."

May even be in seals in Greenland.  And don't stand under 3-toed sloths, the may be excreting Coxiella on you (PubMed).

There have been outbreaks of Q fever by fools drinking raw milk (PubMed).

And even weirder?  This is a wack-a-loon therapy whereby people get injected with "fetal sheep cells" and with the fetal sheep cells comes Q fever (PubMed) as part of live cell therapy.  Why anyone would think injection embryonic cells from cows, sheep or sharks is a good idea is beyond me. See my SBM essay on the topic (SBM).

Only New Zealand lacks Q fever.


Fever (self limited), pneumonia with headaches (in a series from New Zealand, headache was the predominant presenting symptom, leading to a meningitis evaluation rather than a pneumonia work-up) and hepatitis (has a donut cell on histopathology. Plain, not Krispy Kreme), endocarditis (culture negative).

Pneumonia is unusual, with 10% symptomatic and 30 with abnormal x-rays in acute Q fever (PubMed). Oddly, 25% of cases of community acquired pneumonia in French Guiana are due to this bug; they do not speculate as to why (PubMed).

Chronic Q fever is usually endocarditis; risks include valvular surgery, vascular prosthesis, aneurysm, renal insufficiency, and older age (PubMed) (PubMed).

Patients who are older or who have valvulopathy are at high risk for endocarditis and will benefit from a year of doxycycline and hydroxychloroquine prophylaxis (PubMed).

Immunoglobulin G anticardiolipin antibodies predicts progression to Q fever endocarditis (PubMed) and is common (PubMed).

The diagnosis of endocarditis is often made serologically as serology goes from phase II to phase I (yes, its backwards) and this can take three months so patients with acute Q fever need long term serologic follow up (PubMed). Chronic Q fever is confirmed by a phase I IgG antibody > 1:1024.

Multilevel disc infection associated with infected AAA or graft (PubMed).

One breast implant infection whose removal led to 6 exposures in the OR and 3 seroconversions (PubMed).

There is a post infectious fatigue after Q fever (as with many infections) that does NOT respond to doxycycline but does get better with cognitive-behavioral therapy (PubMed).


Doxycycline is the treatment of choice followed by quinolones or macrolides. Add rifampin for synergy.

From CDC: Diagnosis and Management of Q Fever — United States, 2013

Acute Q fever: Doxycycline 100 bid x 14 d.

Endocarditis/Chronic Q fever: Doxycycline 100 mg twice a day and hydroxychloroquine 200 mg three times a day ≥18 months. Doxycycline plus a quinolone is just as good (PubMed). Don't give monotherapy.

Endocarditis therapy is perhaps forever.

Noncardiac organ disease: Doxycycline 100 mg twice a day and hydroxychloroquine 200 mg three times a day.

Postpartum with serologic profile for chronic Q fever: Doxycycline 100 mg twice a day and hydroxychloroquine 200 mg three times a day ≥12 months.


There was a cool case of four guys playing poker in a garage where a cat was giving birth. Three of the 4 came down with Q fever.

The Q comes from “query” fever from the 1930's instead of abattoir fever or Queensland rickettsial fever. Me? I like abattoir fever.

"An early mention of Q fever was important in one of the early Dr. Kildare films (1939, Calling Dr. Kildare). Kildare’s mentor Dr. Gillespie (Lionel Barrymore) tires of his protégé working fruitlessly on "exotic diagnoses" (“I think it’s Q fever!”) and sends him to work in a neighborhood clinic, instead (Wikipedia)."

I live to work fruitlessly trying to diagnose exotic diseases. It is what defines and ID doc.

Curious Cases

Relevant links to my Medscape blog

Word History

Last update: 05/05/18