R2 Talk
Zoonotic Diseases
Ian Kidder, MD
Mentor: Poorani Sekar, MD
Zoonoses Handout
· Zoonoses are infections acquired by direct or indirect contact with animals
· 6 out of 10 infections are zoonotic
Household pets (cats and dogs)
· Pasteurella
o Normal part of feline oral flora = contract from cat bites
o Cellulitis + purulent drainage + lymphangitis
o Treat with amoxicillin-clavulanate
· Rabies
o Bites from infected animals
o Negri bodies on histology
o CNS infection w/ hydrophobia and aerophobia
o Exposure treatment = rabies immunoglobulin + vaccination
· Capnocytophaga
o From dog bites/licks
o Asplenia or liver disease = risk of cellulitis –> sepsis + DIC, loss of limbs
o Treat with ampicillin-sulbactam
· Bartonella (“cat-scratch disease”)
o Due to cat scratch or bite
o Painless papule/pustule at inoculation site + subacute regional lymphadenopathy
o Treatment = drainage of LN purulence + azithromycin (if extensive)
Farm animals
· Coxiella (“Q fever”)
o Infection from aerosolized amniotic fluids of livestock
o Acute presentation = flu-like, pneumonia, and hepatitis
o Persistent localized infection = endocarditis, bone/joint or vascular infections
o Treat with doxycycline (add hydroxychloroquine for persistent localized infxn)
· Brucella (“undulant fever”)
o Infection from unpasteurized dairy products or birth product aerosols
o Undulating pattern of fevers + non-specific systemic symptoms (often MSK pain)
o Associated with culture-negative infections (including endocarditis)
o Treat with doxycycline + rifampin or streptomycin
Other exposures
· Leprosy (Mycobacterium leprae)
o Route of transmission uncertain (but not typically skin-to-skin contact)
o Tuberculoid leprosy (Th1 response) = hypopigmented + numb macules/plaques
o Lepromatous leprosy (Th2 response) = skin nodules/plaques + leonine facies
o Treat with dapsone + rifampin
· Tularemia
o Found in rodents and ticks
o Portals of entry = inhalation, mucous membranes, skin (think bites)
o 3 primary presentations:
§ Ulceroglandular/glandular = +/- ulcer w/ regional lymphadenopathy
§ Oropharyngeal/oculoglandular = pharyngitis, cervical lymphadenopathy, conjunctivitis
§ Pneumonic = imaging shows infiltrates, hilar lymphadenopathy, pleural effusions
o Treat with streptomycin, doxycycline, or tetracycline
· Yersinia (plague)
o Transmission from rodents to humans via fleas
o In US, mostly western states and “Four Corners” area
o Three forms: bubonic, septicemic, and pneumonic
o Treat with streptomycin
· Leptospira
o Source = rodent urogenital tract
o Contract from contaminated water (e.g. via a cut or scrape)
o Usually presents as mild flu-like illness
o Severe cases = hemorrhagic diathesis, jaundice, and AKI (aka Weil’s syndrome)
o Treatment = IV penicillin
