Zoonosis are diseases caused or spread by contact with animals. Every year, tens of thousands of Americans will get sick from diseases spread between animals and people. These are known as zoonotic diseases. Zoonotic means infectious diseases that are spread between animals and people.
Some animals, even those that look perfectly healthy, can carry harmful organisms that can make people sick. Those organisms that originate in animals can cause diseases in humans. Sometimes this process works the other way also, and organisms from humans can cause diseases in animals.
Zoonoses are common in the United States and around the world. In fact, as many as 60% of all communicable diseases and 75% of emerging infectious diseases of people originated with animals.
Causes of Zoonoses
The zoonotic diseases can be transmitted from the animals to humans by many ways.
- Direct contact: Contact with an animal’s body fluids, such as saliva, blood, urine, mucus, or feces, that can occur when petting or touching animals or being bitten or scratched.
- Foodborne: Eating or drinking something unsafe (such as unpasteurized milk, undercooked meat or eggs, or raw fruits and vegetables) that are contaminated with feces from an infected animal.
- Indirect contact: Contact with items in areas where animals live and roam or with objects or surfaces contaminated with germs. Examples include aquarium tank water; pet living areas, food bowls, and water dishes; chicken coops; plants, and soil.
- Inhalation: Breathing in airborne organisms or spores.
- Vectorborne: Being bitten by an infected tick or an insect (such as a mosquito or flea).
Examples of Zoonoses
Myriad zoonoses are known to exist. Here a few examples.
- Rabies, which you can get from the bite of a rabid infected animal, often a raccoon, skunk, bat, or fox.
- Anthrax, which you can get from contact with an infected animal or animal products (e.g., hides); sources include domestic and wild animals such as cattle, sheep, goats, antelope, and deer.
- Dengue, malaria, Zika virus infection, and Lyme disease, which you can get from the bite of an infected mosquito in areas where those diseases are common.
- Salmonella infection, which you can get after handling an infected baby chick, chicken, duck, turtle, or snake, or by eating contaminated food.
- Escherichia coli infection, which you can catch by touching surfaces in areas such as petting zoos or dairy farms where some of the animals may be infected, or by eating contaminated food.
Who is at risk?
Anyone can become sick from a zoonotic disease, including healthy people. However, some people may be more at risk than others and should take steps to protect themselves or family members. These people are more likely than others to get really sick, and even die, from infection with certain diseases. These groups of people include:
- Children younger than 5
- Adults older than 65
- People with weakened immune systems
Prevention of zoonosis
People can come into contact with animals in many places. This includes at home and away from home, in places like petting zoos, fairs, schools, stores, and parks. Insects, like mosquitoes and fleas, and ticks bite people and animals day and night. Thankfully, there are things you can do to protect yourself and your family from zoonotic diseases.
- Keep hands clean. Washing your hands right after being around animals, even if you didn’t touch any animals, is one of the most important steps you can take to avoid getting sick and spreading germs to others.
- Always wash your hands after being around animals, even if you didn’t touch the animals.
Many germs are spread by not washing hands with soap and clean, running water. If clean, running water is not accessible, use soap and available water. If soap and water are unavailable, use an alcohol-based hand sanitizer that contains at least 60% alcohol to clean hands. Because hand sanitizers do not eliminate all types of germs, it is important to wash your hands as soon as soap and water are available.
- Know the simple things you can do to stay safe around your pets.
Prevent bites from mosquitoes, ticks, and fleas.
- Avoid bites and scratches from animals.
List of common Zoonotic diseases
|Disease||Organism||Main reservoirs||Usual mode of transmission to humans|
|Anthrax||Bacillus anthracis||livestock, wild animals, environment||direct contact, ingestion, inhalation|
|Animal influenza||Influenza A viruses||pigs, other livestock, humans||direct contact|
|Avian influenza||Influenza A viruses||poultry, ducks||direct contact|
|Bovine tuberculosis||Mycobacterium bovis||cattle||unpasteurised milk, exposure to tuberculous animals|
|Campylobacteriosis||Campylobacter spp.||poultry, farm animals||direct animal contact, raw meat, milk|
|Cat scratch fever||Bartonella henselae||cats||bite, scratch|
|Cowpox||Cowpox virus||rodents||direct contact (usually with cats)|
|Cryptosporidiosis||Cryptosporidium spp||cattle, sheep, pets||contaminated water, direct contact|
|Cysticercosis / Taeniasis||Taenia spp.||cattle, pigs||raw/undercooked meat|
|Erysipeloid||Erysipelothrix rhusiopathiae||pigs, fish, environment||direct contact, fomites, environment|
|Fish tank / swimming pool granuloma||Mycobacterium marinum||fish||contact with fish or contaminated water|
|Giardiasis||Giardia spp||humans, wildlife||contaminated water, ingestion|
|Haemorrhagic colitis and haemolytic uraemic syndrome (HUS)||Shiga toxin-producing E. coli||ruminants||direct contact, foodborne|
|Hantavirus syndromes||Hantaviruses||rodents||aerosolised excreta|
|Hepatitis E||Hepatitis E virus||pigs, wild boar, deer||undercooked animal meats|
|Hydatid disease||Echinococcus granulosus||dogs, sheep||ingestion of eggs excreted by dog|
|Leptospirosis||Leptospira spp||rodents, ruminants||urine-contaminated water or direct contact|
|Listeriosis||Listeria spp.||cattle, sheep, soil||dairy produce, meat products|
|Louping ill||Louping ill virus||sheep, grouse||direct contact, tick bite|
|Lyme disease||Borrelia burgdorferi||ticks, rodents, deer, sheep, small mammals||tick bite|
|Lymphocytic choriomeningitis||Lymphocytic choriomeningitis virus (LCMV)||rodents||direct contact|
|Orf||Orf virus||sheep, goats||direct contact|
|Ovine chlamydiosis||Chlamydia abortus||sheep, farm animals||direct contact, aerosol|
|Pasteurellosis||Pasteurella spp||dogs, cats, many mammals||bite/scratch, direct contact|
|Psittacosis||Chlamydia psittaci||psittacine birds, poultry, ducks||aerosol, direct contact|
|Q fever||Coxiella burnetii||cattle, sheep, goats, cats||aerosol, direct contact, products of conception, fomites|
|Rabies||Rabies virus and other lyssaviruses||bats only in the UK||Bite or scratch|
|Rat bite fever||Streptobacillus moniliformis||rats||bite/scratch, milk, water|
|Ringworm||Dermatophyte fungi||many animal species||direct contact|
|Salmonellosis||Salmonella spp.||poultry, farm animals||direct animal contact, raw meat, other raw foods|
|Streptococcal sepsis||Streptococcus suis||pigs||direct contact, meat|
|Streptococcal sepsis||Streptococcus zooepidemicus||horses||direct contact|
|Toxocariasis||Toxocara canis/catis||dogs, cats||ingestion|
|Toxoplasmosis||Toxoplasma gondii||cats, ruminants||ingestion of faecal oocysts, meat|
|Zoonotic diphtheria||Corynebacterium ulcerans||cattle, farm animals, dogs||direct contact, milk|
2. Less common zoonotic diseases
|Disease||Organism||Main reservoirs||Usual mode of transmission to humans|
|Alveolar echinococcosis||Echinococcus multilocularis||foxes||ingestion of eggs|
|Brucellosis||Brucella spp.||cattle, goats, sheep, pigs||dairy products, milk|
|Crimean-Congo haemorrhagic fever (CCHF)||CCHF virus||livestock, ticks||tick bite, direct contact animal blood|
|Ebola virus disease||Ebola virus||unknown, possibly bats||wild animals|
|Glanders||Burkholderia mallei||horse, donkey, mule||direct contact, contaminated fomites, food and water|
|Hendra virus infection||Hendra virus||fruit bats, horses||exposure to body fluids|
|Kyasanur Forest disease||Kyasanur Forest virus||rodents, shrews, and monkeys||tick bite, direct animal contact|
|Lassa fever||Lassa virus||multimammate rat||direct or indirect contact with infected rodent excreta|
|Marburg virus disease||Marburg virus||bats||bats|
|MERS||MERS Coronavirus||dromedary camels||direct and indirect contact|
|Monkeypox||Monkeypox virus||rodents||direct contact|
|Nipah virus infection||Nipah virus||fruit bats||contaminated date palm sap, close contact with infected pigs|
|Plague||Yersinia pestis||rats and their fleas||flea bite, scratches or bites from infected cats|
|Rabies||Rabies virus and other lyssaviruses||dogs, foxes, bats, cats||Bite or scratch|
|Rift Valley fever||Rift Valley fever virus||cattle, goats, sheep||direct contact, mosquito bite|
|Tickborne encephalitis||Tickborne encephalitis virus||rodents, small mammals, livestock||tick bite, unpasteurised milk products|
|Trichinellosis||Trichinella spiralis||pigs, wild boar||undercooked or raw meat|
|Tularemia||Francisella tularensis||rabbits, wild animals, ticks,||direct contact, aerosol, ticks, inoculation|
|West Nile virus infection||West Nile virus||wild birds, mosquitoes||mosquito bite|
|Yellow fever||Yellow fever virus||monkeys||mosquito bite|