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The World Health Organization defines zoonotic infections as
those diseases and infections that are naturally transmitted between
vertebrate animals and humans. This broad class of diseases includes
>200 specific diseases and syndromes covering an extremely variable
range of clinical syndromes and medical therapy.1 Zoonotic
infections can be transmitted to humans by direct contact with an
infected animal or infected animal product, by ingestion of contaminated
water or food products, by inhalation, and through arthropod vectors.
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In North America, >4 million people are estimated to be infected
annually. Zoonotic infections represent a significant public health
problem in underdeveloped regions dependent economically on agricultural
animals. The growth and mobility of the world’s population
has resulted in the appearance of new zoonotic infections and the
reemergence of previously eliminated ones. More than 50% of
the newly identified infectious agents since 1976 are associated
with animals.This diversity of presentation, human
mobility, and zoonotic reemergence make the diagnosis and management
of zoonotic infections a challenge for emergency physicians.
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A zoonotic infection should be considered part of the differential
diagnosis of any undifferentiated infectious syndrome: fever, headache,
myalgias, malaise, and weakness. However, diagnosis is difficult. Determining
risk factors for acquiring a zoonotic infection can help focus the
differential diagnosis. Specific avocations and occupations that involve
animal contact and certain medical comorbidities carry an increased
risk (Table 155-1).Tick
exposure carries a significant risk of zoonotic illness transmission,
particularly of rickettsial disease. Also, the type of animal exposure
is an important factor. Dressing, skinning, or handling an animal’s
skin; a history of animal bite or scratch; and ingestion of animal
or dairy products all carry an associated risk of zoonotic infection.
Bush meat hunting is a particularly high-risk exposure activity.
Recent travel, particularly in spring, summer, and early fall months, and
history of habitation, particularly in an underdeveloped country
or rural area, are additional risk factors. Zoonoses can occur at
any time of the year, but in the U.S., most zoonoses show an increased
incidence in the spring and summer.
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Zoonoses that can present as an undifferentiated febrile illness
or sepsis are listed in Table 155-2. The
table lists only some of the more common zoonotic ...