Q Fever
What is it?
A zoonotic disease mainly affecting mammals including sheep,
goats and cattle. The disease has also been reported in various other mammals,
birds and reptiles. The causative agent of the disease is the bacteria Coxiella burnetii. Q fever is found in
almost every country, and was first discovered in Australia. The “Q” stands for
query because scientists couldn’t determine the root cause of the disease (Coxiella burnetii bacteria) when it was
first discovered.
How is it transmitted?
The majority of infections are believed to come from direct
contact between infected and non-infected animals. Animals inhale or ingest
infected materials or secretions like saliva, milk, urine, feces, birthing
fluids, and afterbirth. Transmission may also be a result of contact with
contaminated objects (fomites). The bacteria have also been found to circulate
between wild animals via ticks, which can transmit the disease through a bite.
What are the clinical signs?
The majority of infected animals do not exhibit significant clinical
signs. The most common indicator of a Q Fever infection in affected animals is
late term abortion, stillbirth or the birth of small or weak offspring.
How is it diagnosed?
Samples can be collected from tissues from sick animals,
aborted fetuses and afterbirth and submitted to a diagnostic laboratory to
identify C. burnettii bacteria. Additionally,
collecting blood samples on whole herds can identify if the disease is, or has
been, present in the group by testing for an antibody response. If tested animals
show a positive antibody response, it means members of the herd were infected
at one point in time.
Is there a risk to people?
Yes, Coxiella burnetii
can become aerosolized and inhaled by people, especially those assisting an
infected animal as it gives birth. Veterinarians and livestock handlers have a
greater chance of exposure than the general public. However, anyone is at risk
through consumption of infected raw milk, and via the bite of an infected tick.
Pasteurization of milk has been proven to kill the organism, and pasteurized
products are safe to consume. Women who are infected during pregnancy may have a
higher risk of complications.
How can it be prevented?
Precautions should be taken to separate pregnant livestock from
the rest of the herd. Animals that have experienced an abortion or a stillbirth
should be isolated and separated from the remaining pregnant animals in the
herd. Livestock handlers should regularly clean and disinfect birthing areas
and properly dispose of afterbirth because C.
burnetii can remain viable for prolonged periods in the environment and is
extremely resistant to heat, drying, and many common disinfectants. The
bacteria can survive on equipment, so routine cleaning should be a standard
precaution. Ticks can carry the bacteria, and minimizing livestock exposure to
tick habitat and routinely examining animals for ticks can reduce risk of this
disease. Vaccines are available in countries where the disease is an ongoing
threat.
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