Coxiella burnetii: Habitat, mode of transmission, pathogenesis, clinical diseases, lab diagnosis and treatment

Coxiella burnetii

Coxiella burnetii is the smaller than other Rickettsia and passes through porcelain filter.
Formally Coxiella burnetii is classified as Rickettsia burneti.
It causes Q- fever
C. burnetii is pleomorphic, small rod ( 0.4-1.4 µm long and 0.2 -0.4µm wide) or sphere (0.3-0.4µm) in diameter.
The organism is generally considered to be gram negative although it appears to be gram positive when alcoholic iodine is used as mordant.
C. burnetii is the only Rickettsia that shows phase variation.
It contains two distinct plasmids.

Natural reservoir hosts are cows, goats, sheeps, rodents, wild mammalss and several species of birds.
C. burnetii also inhabitat several species of ticks

Human get infected with Coxiella burnetii by inhalation of contaminated aerosols.
By the bite of infected ticks
By direct contact; by handling infected animals and birds
By consuming contaminated raw milk.

Coxiella burnetii causes Q-fever which is also known as Red River Fever and Nine mile fever.
Human get infected to C. burnetii by inhalation of contaminated aerosol. The organism parasitizes and remains viable inside alveolar macrophage. It also infects histiocytes of spleen and kupffer cell of liver and causes the enlargement of the organs.
Most of time Infection may be asymptomatic or sub clinical.
Incubation period: about 2 weeks.

Fever, and influenza like syndrome which lasts for 4-7 days.
In some patients bronchopneumonia, thrombophlebitis, pulmonary embolism and endocarditis may occurs.

Q fever: it is characterized by influenza like syndrome, high fever, headache, body pain and occasionally slight rashes on body.
Serious complication of Q-fever: pneumonitis, chronic infective endocarditis and liver disease

Specimen: blood, sputum and urine