Zoonotic diseases

Last updated: June 18, 2021

Summary

Zoonotic diseases are infections that are transmitted from animals to humans. While animals may transmit infection directly (e.g., via saliva) or indirectly (e.g., via contaminated objects), they usually serve as hosts for a pathogen that is then transmitted to humans by a vector (e.g., ticks, fleas) or via contaminated water or food. Zoonoses are usually endemic to certain geographical regions; peaks in incidence often correlate with the life cycle of the transmitting vector. Some examples of zoonotic diseases in the US are zoonotic influenza, salmonellosis, West Nile virus, plague, coronavirus infection, rabies, brucellosis, and Lyme disease. Although these conditions differ in their exact presentation, symptomatic cases typically present with fever, flulike symptoms, and possibly skin rashes. In some cases of fulminant disease, there may be complications such as disseminated intravascular coagulation, shock, and organ failure. Most zoonoses are treated with antibiotics and respond well to treatment.

Overview

Definition

Zoonotic diseases are infections that are transmitted from animals to humans.

Epidemiology

About 6 out of 10 infectious diseases are zoonotic. ^[1]
Zoonotic diseases are usually endemic to a certain geographical region
Peaks in incidence often correlate with the life cycle of the transmitting vector.

Etiology

Transmission occurs via
- Contact with an animal directly (e.g., saliva, feces) or indirectly (contaminated objects such as cages)
- Vector-borne (e.g., fleas, ticks)
- Foodborne
- Waterborne

Etiology of common zoonotic diseases transmitted via animals
	Disease	More information
Farm animals (e.g., cattle, sheep, goats)	Q fever	See “Q fever.”
Farm animals (e.g., cattle, sheep, goats)	Brucellosis	See “Brucellosis.”
Swine	Swine flu	See “Zoonotic influenza.”
Birds	Avian flu	See “Zoonotic influenza.”
Birds	Crimean-Congo hemorrhagic fever	See “Viral hemorrhagic fevers.”
Dromedary camels	Middle East respiratory syndrome (MERS)	See “General virology.”
Rodents	Cowpox Lymphocytic choriomeningitis	See “General virology.”
	Hemorrhagic fever (Hantavirus)	See “Viral hemorrhagic fevers.”
	Lassa fever	See “Viral hemorrhagic fevers.”
Dogs, raccoons, skunks, foxes, bats	Rabies	See “Rabies.”
Potentially bats	Coronavirus disease (e.g., COVID-19)	See “COVID 19.”
Fruit bats, monkeys	Hemorrhagic fever (Ebolavirus, Marburgvirus)	See “Viral hemorrhagic fevers.”

Etiology of common vector-borne diseases
	Disease	More information
Louse-borne	Trench fever Louse-borne relapsing fever	See “Louse- and flea-borne diseases.”
Louse-borne	Epidemic typhus	See “Typhus.”
Flea-borne	Endemic typhus	See “Typhus.”
Flea-borne	Plague	See “Louse- and flea-borne diseases.”
Tick-borne	Lyme disease	See “Lyme disease.”
	Ehrlichiosis Babesiosis Rocky Mountain spotted fever (RMSF) Anaplasmosis Tularemia Colorado tick fever (CTF) Tick-borne relapsing fever Southern tick‑associated rash illness (STARI)	See “Tick-borne diseases.”
	Tick-borne encephalitis Colorado tick fever	See “General virology.”
Mosquito-borne	Malaria	See “Malaria.”
	Yellow fever virus	See “Yellow fever.”
	Dengue fever	See “Dengue.”
	Zika	See “Zika virus infection.”
	West Nile encephalitis St. Louis encephalitis Chikungunya fever Western Equine encephalitis Eastern Equine encephalitis La Crosse encephalitis Rift valley fever	See “Miscellaneous mosquito-borne diseases.”
	California encephalitis virus	See “General virology.”
Chiggars	Scrub typhus	See “Typhus.”
Black fly	Onchocerciasis	See “Helminth infections.”

Etiology of common foodborne/waterborne diseases
	Disease	More information
Bacteria	Salmonellosis Campylobacteriosis Listeriosis Yersiniosis	See “Bacterial gastroenteritis.”
	Brucellosis	See “Brucellosis.”
	E. coli gastroenteritis	See “Diarrheagenic E. coli.”
Bacterial toxins	Heat-stable enterotoxin by S. aureus Heat-labile enterotoxin of Clostridium perfringens Botulinum toxin of C. botulinum Enterotoxin of Bacillus cereus Heat-labile enterotoxin of ETEC	See “Food poisoning.”
Viruses	Rotavirus infection	See “Rotavirus infection.”
	Norovirus infection	See “Norovirus infection.”
	Hepatitis A Hepatitis E	See “Hepatitis A.”
Protozoa	Toxoplasmosis	See “Toxoplasmosis.”
	Cryptosporidiosis Cyclospora	See “Food poisoning.”
	Giardiasis	See “Giardiasis.”
Helminths	Trichinellosis Diphyllobothriasis Taeniasis Clonorchiasis Paragonimiasis Hymenolepiasis Fascioliasis	See “Helminth infections.”
Helminths	Schistosomiasis Cercarial dermatitis	See “Schistosomiasis.”

Prevention

General measures
- Wash hands with soap or alcohol-based hand sanitizer right after being near animals: See “Infection prevention” and “Disinfection.”
- Prevent bites from mosquitoes, ticks, fleas, etc.
  - See “Mosquito bite prevention”
  - See “Prevention of tick bites”
- Handle food/freshwater safely: See “Food and water safety.”
- Be aware of zoonotic diseases both at home (e.g., pets) and away from home (e.g., petting zoo, travel to foreign countries).
- Avoid bites/scratches from animals.

References

Zoonotic Diseases. https://www.cdc.gov/onehealth/basics/zoonotic-diseases.html. Updated: July 14, 2017. Accessed: June 2, 2021.

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