Introduction

Classification

Taxonomy

• Family: Rickettsiaceae.
• Genus: Coxiella.
• Species: burnetii.

Etymology

• Coxiella: named after Herold R Cox who first isolated this organism in the USA in collaboration with G E Davis soon after it was first discovered in Australia.
• Burnetii: named after Frank MacFarlane Burnet who first studied the properties of the organism.

Active Forms

Clinical Effects

Epidemiology

Habitat

• Survives in the environment.
• Natural hosts include many species of mammals and arthropods (ticks, fleas, mites, lice, and flies).

Lifecycle

• The organism is disseminated hematogenously.
• Persists in tissues and multiplies in vacuoles of the host cell.
• Endospore-like growth phase occurs - the "small-cell variant".

Transmission

• In animals via tick bites or aerosols.
• In humans usually via aerosols.
• C. burnetii also occurs in milk of cows and sheep but transmission not so likely to occur via the gastrointestinal tract.
• May be acquired from contaminated wool.
• Occupational disease of farm workers, slaughterhouse workers and textile workers.

Pathological effects

• Ruminants: sporadic abortions, weak neonates.
• Dogs and cats: usually sub-clinical.
• Humans: abrupt onset fever and headache; 50% of cases radiographs show a patchy pneumonia, although physical chest signs are few.
• Illness is largely systemic and complications and death are uncommon, although it may become severe and chronic with myocarditis, pericarditis or endocarditis.

Other Host Effects

• May be latent until the stress associated with parturition; multiplication of the organism occurs in the birth tissue, urine and stool → environmental contamination.

Control

Control via chemotherapies

• Tetracycline Tetracycline.

Vaccination

• Not successful.

Diagnosis

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Nguyen S V, To H, Minamoto N et al (1997) Evaluation of the high-density agglutination test for Coxiella burnetii antibodies in animals. Clin Diag Lab Immunol 4 (6), 676-680 PubMed.
• Buhariwalla F, Cann B & Marrie T J (1996) A dog-related outbreak of Q fever. Clin Infect Diseases 23 (4), 753-755 PubMed.
• Kelly P J, Matthewman L A, Mason P R et al (1993) Q fever in Zimbabwe. A review of the disease and the results of a serosurvey of humans, cattle, goats and dogs. South African Med J 83 (1), 21-25 PubMed.
• Willeberg P, Ruppanner R, Behymer D E et al (1980) Environmental exposure to Coxiella burnetii - a sero-epidemiologic survey among domestic animals. Am J Epidemiol 111 (4), 437-443 PubMed.