Epidemiology
The natural reservoir of Coxiella
burnetii is not limited to farm
animals. Infection has also been noted
in many other domesticated animals.
Many hosts do not display a visible illness, with the exception of
spontaneous abortions in infected goats.
The bacteria have been isolated from urine, milk, feces, and, in
high concentrations, from amniotic fluid and placenta. Amniotic fluid represents the most common
transmission route to humans. Barn
workers can inhale dust contaminated by dried placenta. Contaminated unpasteurized milk is a less
common infection route. (CDC) Vectors (ticks) can pass
the disease to animals but not humans.
Person to person transmission is rare. (MSDS)
The disease is almost completely limited to rural communities
because commercial milk is pasteurized and transmission from livestock requires
close contact. Contraction is most
often work related. Numerical
epidemiology is difficult because reporting Q-fever to the Centers for Disease
Control and Prevention was not required until 1999. (CDC)
References:
*CDC: www.cdc.gov
*MSDS: http://www.hc-sc.gc.ca/pphb-dgspsp/msds-ftss/msds43e.html
*picture courtesy of: http://www.millennium-ark.net/News_Files/UN_Images/Q.Fever.gif
