zoonotic
Summary
A zoonotic infection is one transmitted from vertebrate animals to humans, either directly, through animal products, or via an arthropod vector. Identifying the animal exposure is often the fastest route to the diagnosis.
Detail
Exposure history maps to organism with unusual reliability, which is why examiners favour it. Cattle, sheep, goats, and unpasteurized dairy suggest Brucella, Coxiella burnetii, Listeria, and Bacillus anthracis; dogs and cats suggest Pasteurella multocida after a bite, Bartonella henselae after a scratch, Toxocara, and Toxoplasma from cat faeces; rabbits and deerflies suggest Francisella tularensis; rats suggest Leptospira, Streptobacillus moniliformis, and hantavirus via deer mouse droppings; parrots suggest Chlamydophila psittaci; birds and bat guano suggest Histoplasma capsulatum; and reptiles suggest Salmonella. Prairie dogs and squirrels carry Yersinia pestis via fleas. Vector-borne zoonoses include Lyme disease, babesiosis, and anaplasmosis from Ixodes, Rocky Mountain spotted fever from Dermacentor, and plague from the rat flea. Understanding reservoir and vector also drives prevention, since interrupting animal contact or vector exposure is usually more effective than treating human cases.
Sources
- Levinson Medical Microbiology and Immunology
- First Aid for the USMLE Step 1
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