The World Health Organization defines zoonotic infections as those diseases and infections that are naturally transmitted from vertebrate animals to or from humans. Zoonotic infections are often encountered in emergency care. Ticks are one of the most important vectors of human infectious diseases in the world.
A zoonotic infection has presenting symptoms similar to many acute infections: fever, headache, myalgias, malaise, and weakness. Given this, a specific diagnosis is often difficult. Particular exposures or occupations that involve animal contact carry an increased risk of disease (Table 1). Recent travel, particularly in spring, summer, and early fall, or history of habitation in an underdeveloped country, are also risk factors. Zoonoses can occur at any time of the year, but in temperate climates, most zoonoses happen in the spring and summer.
Table 1 Risk Factors for Zoonotic Infection |Favorite Table|Download (.pdf)
Table 1 Risk Factors for Zoonotic Infection
Farmers, cattle ranchers, sheep ranchers, and migrant workers
Animal processing workers
Slaughterhouse workers, animal hide processors, and workers in manufacturing who deal with animal products
Forestry workers, lumbermen, surveyors, park rangers, hunters, spelunkers, and fishermen
Those living alongside a dog, cat, bird, rodent, rabbit, reptile, or fish
Veterinarians, animal researchers, and animal handlers
Those with congenital immunodeficiencies, diabetes mellitus, alcoholism, renal failure, liver failure, cancer, splenectomy, or human immunodeficiency virus
Zoonoses that can present as an undifferentiated febrile illness are listed in Table 2.
Table 2 Common Systemic Zoonotic Infections |Favorite Table|Download (.pdf)
Table 2 Common Systemic Zoonotic Infections
Nonspecific fever, severe crepitant cellulitis with systemic toxicity, gastroenteritis
See chapter titled "Foodborne and Waterborne Diseases"
Serologic testing, blood culture
Doxycycline plus gentamicin or rifampin. TMP-SMX plus gentamicin in children
Dogs and cats
Fever, septic shock, and
meningitis from infected bite
Culture of bite wound
Amoxicillin-clavulanate or clindamycin.
Pip-Tazo or a carbapenem plus clindamycin/vancomycin for shock
Fever, flulike illness, pneumonia, endocarditis, sepsis
Serologic testing and sputum culture
Doxycycline. Azithromycin and levofloxacin are alternatives
Cattle, sheep, goats. Occasionally cats
Fever, pneumonia, hepatitis, meningitis, endocarditis
Serologic testing, PCR
Doxycycline, with the possible alternative of a fluoroquinolone or macrolide
Nonspecific fever, sepsis, meningitis, hepatitis
Clinical diagnosis, serologic
testing, peripheral blood smear, immunocytologic testing, PCR
Doxycycline recommended for all patients (even children and pregnancy). Rifampin is alternative.
Birds, dogs, rodents
Fever, pneumonia, conjunctivitis, lymphadenopathy
Darkfield microscopic examination of body fluids, serologic testing
Penicillin G IV. Ceftriaxone IV alternative. Mild disease: oral doxycycline or amoxicillin or azithromycin
Rabbits, cats, wild animals, biting insects
Fever, sepsis, meningitis, pneumonia, hepatitis, rash
Serologic testing (poses hazards to laboratory staff)
IV aminoglycosides. Alternative: Doxycycline ...