Animal Categorization Scheme

To support analyses of outbreaks reported through the Animal Contact Outbreak Surveillance System (ACOSS), CDC categorizes animals into three increasingly specific levels: biologic class, major group, and subgroup. This animal categorization scheme helps public health, regulatory, and animal health professionals use ACOSS data to

describe which animal categories are most often linked to enteric (intestinal) disease outbreaks
identify animals that spread the (bacteria, viruses, or parasites) causing the most outbreak-related illnesses
improve understanding of outbreak characteristics linked to specific animal categories
inform recommendations and policies
assess prevention strategies and measure progress in disease prevention

The levels are based on each animal’s biological characteristics, common settings of exposure, or interactions with humans. For example, a wild dog would be classified as:

Level 1 (Biologic Class): Mammal

Very light purple color representing Level 3

Level 2 (Major Group): Canine

Level 3 (Subgroup): Wild canine

Categorizing animals is part of a larger initiative to improve the collection, quality, and usefulness of data from animal contact outbreaks. This work could be expanded to include animals that transmit non-enteric pathogens.

Click on the categories below to see additional levels. More Information 1 All Animals All Animals /acoss/images/faq/transparent.png 1 Mammals Mammals /acoss/images/faq/Mammals.jpg Small Mammals Small Mammals /acoss/images/faq/Small-Mammals.jpg Rodents Rodents /acoss/images/faq/transparent.png Chiroptera (e.g., bats) Chiroptera (e.g., bats) /acoss/images/faq/transparent.png Other Small Mammals (e.g., rabbits) Other Small Mammals (e.g., rabbits) /acoss/images/faq/transparent.png Felines Felines /acoss/images/faq/Felines.jpg House/domestic Cats House/domestic Cats /acoss/images/faq/transparent.png Non-domestic Cats (e.g., mountain lions) Non-domestic Cats (e.g., mountain lions) /acoss/images/faq/transparent.png Canines Canines /acoss/images/faq/Canines.jpg Domestic Dogs Domestic Dogs /acoss/images/faq/transparent.png Wild Canines (e.g., wolves) Wild Canines (e.g., wolves) /acoss/images/faq/transparent.png Ruminants Ruminants /acoss/images/faq/Ruminants.jpg Bovine (e.g., cattle) Bovine (e.g., cattle) /acoss/images/faq/transparent.png Ovine (e.g., sheep) Ovine (e.g., sheep) /acoss/images/faq/transparent.png Caprine (e.g., goats) Caprine (e.g., goats) /acoss/images/faq/transparent.png Cervidae (e.g., deer) Cervidae (e.g., deer) /acoss/images/faq/transparent.png Other Ruminants Other Ruminants /acoss/images/faq/transparent.png Non-ruminant Hooved Mammals Non-ruminant Hooved Mammals /acoss/images/faq/Non-ruminant-hooved-mammals.jpg Swine (e.g., pigs) Swine (e.g., pigs) /acoss/images/faq/transparent.png Equine (e.g., horses) Equine (e.g., horses) /acoss/images/faq/transparent.png Camelid (e.g., camels) Camelid (e.g., camels) /acoss/images/faq/transparent.png Other Non-ruminant Hooved Mammals Other Non-ruminant Hooved Mammals /acoss/images/faq/transparent.png Non-human Primates Non-human Primates /acoss/images/faq/Non-human-primates.jpg Monkeys Monkeys /acoss/images/faq/transparent.png Apes Apes /acoss/images/faq/transparent.png Other Non-human Primates Other Non-human Primates /acoss/images/faq/transparent.png Marine Mammals Marine Mammals /acoss/images/faq/Marine-Mammals.jpg Aquatic Mammals Aquatic Mammals /acoss/images/faq/transparent.png Semi-aquatic Mammals Semi-aquatic Mammals /acoss/images/faq/transparent.png Other Aquatic Mammals Other Aquatic Mammals /acoss/images/faq/transparent.png Other Mammals Other Mammals /acoss/images/faq/transparent.png Birds Birds /acoss/images/faq/Birds.jpg Poultry, Gamebirds, & Waterfowl Poultry, Gamebirds, & Waterfowl /acoss/images/faq/Poultry-Gamebirds-Waterfowl.jpg Poultry* (e.g., chickens) Poultry* (e.g., chickens) /acoss/images/faq/transparent.png Gamebirds Gamebirds /acoss/images/faq/transparent.png Non-domesticated Waterfowl Non-domesticated Waterfowl /acoss/images/faq/transparent.png Seabirds, Shorebirds, and Wading Birds Seabirds, Shorebirds, and Wading Birds /acoss/images/faq/Sea-Shore-Wading-Birds.jpg Seabirds Seabirds /acoss/images/faq/transparent.png Shorebirds Shorebirds /acoss/images/faq/transparent.png Wading Birds Wading Birds /acoss/images/faq/transparent.png Birds of Prey Birds of Prey /acoss/images/faq/Birds-of-Prey.jpg Falconiformes (e.g., hawks) Falconiformes (e.g., hawks) /acoss/images/faq/transparent.png Strigiformes (e.g., owls) Strigiformes (e.g., owls) /acoss/images/faq/transparent.png Flightless Birds Flightless Birds /acoss/images/faq/Flightless-Birds.jpg Ratites (e.g., ostriches) Ratites (e.g., ostriches) /acoss/images/faq/transparent.png Other Flightless Birds Other Flightless Birds /acoss/images/faq/transparent.png Parrots (Psittacine Birds) Parrots (Psittacine Birds) /acoss/images/faq/Parrots.jpg 1 Passerines Passerines /acoss/images/faq/Passerines.jpg Finches Finches /acoss/images/faq/transparent.png Warblers Warblers /acoss/images/faq/transparent.png 1 Other Passerines Other Passerines /acoss/images/faq/transparent.png Other Birds Other Birds /acoss/images/faq/transparent.png Reptiles Reptiles /acoss/images/faq/Reptiles.jpg Testudines (Turtles) Testudines (Turtles) /acoss/images/faq/Testudines.jpg Turtles, smaller than 4 inches Turtles, smaller than 4 inches /acoss/images/faq/transparent.png Turtles, larger than 4 inches Turtles, larger than 4 inches /acoss/images/faq/transparent.png Tortoises Tortoises /acoss/images/faq/transparent.png Squamates Squamates /acoss/images/faq/Squamates.jpg Snakes Snakes /acoss/images/faq/transparent.png Lizards Lizards /acoss/images/faq/transparent.png Crocodilians Crocodilians /acoss/images/faq/Crocodilians.jpg Crocodiles Crocodiles /acoss/images/faq/transparent.png Alligators Alligators /acoss/images/faq/transparent.png Other Reptiles Other Reptiles /acoss/images/faq/transparent.png Amphibians Amphibians /acoss/images/faq/Amphibians.jpg Anura (Tailless Amphibians) Anura (Tailless Amphibians) /acoss/images/faq/Anura.jpg Frogs Frogs /acoss/images/faq/transparent.png Toads Toads /acoss/images/faq/transparent.png Cuadata (Tailed Amphibians) Cuadata (Tailed Amphibians) /acoss/images/faq/Cuadata.jpg Salamanders Salamanders /acoss/images/faq/transparent.png Newts Newts /acoss/images/faq/transparent.png Other Amphibians Other Amphibians /acoss/images/faq/transparent.png Fish Fish /acoss/images/faq/Fish.jpg Freshwater Fish Freshwater Fish /acoss/images/faq/Freshwater-Fish.jpg Saltwater Fish Saltwater Fish /acoss/images/faq/Saltwater-Fish.jpg Other Fish Other Fish /acoss/images/faq/transparent.png Other Other /acoss/images/faq/transparent.png 1 Link One http://www.cdc.gov Turtles, smaller than 4 inches Turtles, less than 4 inches /acoss/images/faq/transparent.png 0 3 4 5

*Domesticated birds kept by humans for their eggs, meat, or feathers.

This animal categorization scheme reflects a collaborative effort among CDC’s Enteric Diseases Epidemiology Branch, One Health Office, and Outbreak Response and Prevention Branch; the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service; and the Food and Drug Administration’s Center for Food Safety and Applied Nutrition. The structure and goals of the scheme align with those of the Interagency Food Safety Analytics Collaboration (IFSAC) Food Categorization Scheme published in 2017, which is used to characterize foods linked to outbreaks.

Page last reviewed: June 27, 2022

Content source: Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Foodborne, Waterborne, and Environmental Diseases (DFWED)