Q Fever is caused by an obligate intracellular bacterium Coxiella burnetii. The primary reservoirs of infection are cattle, goats and sheep and is mainly an occupational disease of meat and livestock workers. This is a disease of public healh concern.
There are approximately 500 Australian notifications each year of which over half are in Queensland. The notification rate for the south-west region far exceeds any other area, followed the Central West and the Darling Downs. There is a male to female ratio of approximately 7:1 and 70% of notifications are aged between 36 and 65 years. Most notifications are from people who live on a farm or near an abattoir.
The clinical features of acute disease are a flu-like illness with fatigue, headache, rigors, excessive sweating, myalgias, atypical pneumonia and hepatitis.
Chronic Q Fever is more likely to occur in patients who are pregnant, immunocompromised, have underlying vascular disease, or a prosthetic joint. Patients with underlying valvular disease are at high risk of developing endocarditis, which is the predominant manifestation of chronic Q fever. Bone and joint infections are not uncommon, particularly in children.
Laboratory findings are non-specific with transaminitis, leucocytosis with reactive lymphocytes, thrombocytopenia and raised ESR. Laboratory diagnosis is by serology or PCR. Patients are screened with enzyme immunoassay for IgG and IgM, with further testing with immunofluorescence assay for IgG and IgM against Phase 1 and Phase 2 antigens.
A number of case studies will be described, including variations of acute Q Fever presentation, and an unusual case of chronic Q Fever with osteomyelitis of the vertebrae with an epidural abscess. Also, a case of recurrent osteomyelitis infection in a young child occurring over several years.