Q fever
Q fever is a zoonosis caused by Coxiella burnetii, but cases can occur without evidence of exposure to animals. Q fever can present as cholestatic hepatitis or, occasionally, atypical pneumonia; however, symptoms can be nonspecific so Q fever should be considered in any undiagnosed febrile illness. Q fever endocarditis, bone and joint infection, and infection of aneurysms and vascular grafts are rare and can be difficult to diagnose. Diagnosis of Q fever relies on serology and nucleic acid amplification testing (eg polymerase chain reaction [PCR])1.
Acute Q fever usually resolves spontaneously within 2 to 6 weeks. There is no value in treating nonpregnant patients after spontaneous recovery; however, patients with cardiac valve disease or vascular grafts require careful investigation and follow-up to exclude the development of endocarditis or graft infection.
For acute infection in adults, use:
doxycycline 100 mg orally, 12-hourly for 14 days. q fever doxycycline
For acute infection in children of all ages, use:
doxycycline 2.2 mg/kg up to 100 mg orally, 12-hourly for up to 14 days2. doxycycline
For children 8 years or younger who have mild or uncomplicated disease, treat with doxycycline for 5 days only. If fever does not resolve within 5 days, complete the 14-day course of doxycycline.
Doxycycline is recommended to treat Q fever in children of all ages because it is the most effective treatment. The risk of dental adverse effects in young children is minimal, particularly when a single short course of doxycycline is used.
Doxycycline is contraindicated in pregnancy. Trimethoprim+sulfamethoxazole (TGA pregnancy category C) is recommended instead for the treatment of Q fever in pregnant women; although it has been associated with congenital abnormalities when used during pregnancy, the benefit of treatment for Q fever outweighs the potential harms. Concomitant use of folic acid reduces the risk of congenital abnormalities. In pregnant women, use:
trimethoprim+sulfamethoxazole 160+800 mg orally, 12-hourly. For dosage adjustment in adults with kidney impairment, see trimethoprim+sulfamethoxazole dosage adjustment q fever trimethoprim + sulfamethoxazole
PLUS
folic acid 5 mg orally, daily. q fever folic acid
Treatment is recommended until 32 weeks’ gestation, even if the patient has spontaneously recovered, to prevent fetal and maternal complications. Seek expert advice for the management of pregnant women beyond 32 weeks’ gestation.
For chronic infection, prolonged therapy may be required. For Q fever endocarditis (see Culture-negative endocarditis), bone and joint infection and infection of aneurysms and vascular grafts, seek expert advice. Valve surgery may be required.