Zoonosis

infectious disease that can be transmitted from one animal species to another (or human)

Zoonosis or a zoonotic disease is an infectious disease which an animal can give to a human. These diseases may be caused by bacteria, viruses, fungi, or parasites.[1]

The bubonic plague, a zoonotic disease, killed one-third of Europe's population in the 1300s. This painting from The Chronicles of Gilles Li Muisis show people burying plague victims

Zoonotic diseases are very common. About 60% of all infectious diseases in humans are spread by animals.[2]

Zoonotic diseases can be spread in different ways. They may be spread from a sick animal directly to a human – for example, through bites and infected saliva (like with rabies), or through the air. This is called direct zoonosis.

Zoonotic diseases can also be spread through a vector. This is an animal that carries the pathogen that causes the disease without getting infected. Diseases like this are called vector-borne diseases.

Sometimes the vector picks up the disease from another animal. For example, rats who have the bubonic plague do not directly infect humans. Instead, fleas bite the rats and pick up the bacteria that causes plague without getting sick. Then, if the flea bites a human, they can pass the bacteria on to the human, and the human can get the plague.[3] The rat is the host of the disease, and the flea is the vector.

Types of zoonotic diseases

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Foodborne illnesses

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Many foodborne illnesses are zoonotic diseases. In these cases, a human gets infected by eating food that came from a sick animal, or one which had picked up a parasite.

The most common pathogens that cause foodborne illnesses are Salmonella, Campylobacter, and Escherichia coli (E. coli) bacteria. Eggs, seafood, meat, poultry, and dairy products can all carry these bacteria and cause foodborne illnesses, like food poisoning, in humans.[4][5]

Other zoonotic illnesses that humans can get from eating or drinking include:

Disease Pathogen Host Spread by...
Brucellosis Brucella bacteria Cattle, goats, sheep, camels Having unpasteurized milk or cheese; Eating under-cooked meat.[6]
Cholera Vibrio cholerae bacteria Shellfish Eating under-cooked shellfish.[7]
Creutzfeldt-Jakob disease Prions Cattle Eating meat from cattle who had mad cow disease.[8]
Listeriosis Listeria bacteria Cattle, fish Having unpasteurized milk or cheese; Eating under-cooked meat or seafood.[9]
Toxoplasmosis Toxoplasma gondii parasite Pigs, lambs, deer, cattle Eating under-cooked meat.[10]

Often, people can avoid foodborne illnesses by cooking meat, seafood, and eggs well enough to kill the bacteria or parasites in them.[1]

Direct zoonoses

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Below are some examples of zoonotic diseases that humans can get directly from sick, live animals.

Disease Pathogen Host Spread by...
Anthrax Bacillus anthracis bacteria Cattle, sheep, goats, camels, horses, pigs Breathing in anthrax spores or getting them on the skin.[11]
Influenza Influenza A virus Horses, pigs, birds, seals, whales, and more Exhaled air from infected animals.[12]
Lassa fever Lassa virus Rodents Contact with rodent feces.[13]
Rabies Rabies virus Dogs, bats, cattle, monkeys, wolves, and more Infected saliva from being bitten, or by being scratched.[14]
Toxoplasmosis Toxoplasma gondii parasite Cats Cat feces (in cat litter boxes or dirt).[10]
Tuberculosis Mycobacterium bovis bacteria Cattle, deer, llamas, pigs, cats, and more Exhaled air, sputum, urine, feces, or pus from infected animals.[15]

Vector-borne zoonotic diseases

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Disease Pathogen Host Vector
African sleeping sickness Trypanosoma brucei rhodesiense parasite Many wild and farm animals Tsetse fly.[16]
Bubonic plague Yersinia pestis bacteria Rodents Fleas.[3]
Dengue fever Flaviviruses Humans and primates Aedes mosquitoes.[17]
Lyme disease Borrellia bacteria Rodents Ticks.[18]
Malaria Plasmodium parasites Humans Mosquitoes.[19]
West Nile fever West Nile virus Mostly birds Mosquitoes.[20]
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References

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  1. 1.0 1.1 "Toxoplasmosis". One Health. United States Centers for Disease Control and Prevention. October 18, 2013. Retrieved February 11, 2016.
  2. Taylor L.H; Latham S.M. & Woolhouse M.E.J. 2001. Risk factors for human disease emergence. Philosophical Transactions of the Royal Society B: Biological Sciences 356 (1411): 983–989. [1]
  3. 3.0 3.1 "Plague". WHO.int. World Health Organization. November 2014. Retrieved February 11, 2016.
  4. Humphrey T; O'Brien S; et al. (2007). "Campylobacters as zoonotic pathogens: A food production perspective". International Journal of Food Microbiology. 117 (3): 237–257. doi:10.1016/j.ijfoodmicro.2007.01.006. PMID 17368847.
  5. Cloeckaert A 2006 (2006). "Introduction: emerging antimicrobial resistance mechanisms in the zoonotic foodborne pathogens Salmonella and Campylobacter". Microbes and Infection. 8 (7): 1889–1890. doi:10.1016/j.micinf.2005.12.024. PMID 16714136.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  6. "Brucellosis: Transmission". CDC.gov. United States Centers for Disease Control and Prevention. November 12, 2012. Retrieved February 11, 2016.
  7. Sack DA; Sack RB; et al. (2004). "Cholera". Lancet. 363 (9404): 223–33. doi:10.1016/S0140-6736(03)15328-7. PMID 14738797. S2CID 208793200.
  8. Ironside JW; Sutherland K; et al. (1996). "A new variant of Creutzfeldt–Jakob disease: neuropathological and clinical features". Cold Spring Harbor Symposia on Quantitative Biology. 61: 523–30. doi:10.1101/SQB.1996.061.01.052. PMID 9246478.
  9. Ryan, K.J.; Ray, C.G., eds. (2003). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 0-8385-8529-9.
  10. 10.0 10.1 "Toxoplasmosis". DPDx – Laboratory Identification of Parasitic Diseases of Public Health Concern. United States Centers for Disease Control and Prevention. July 6, 2015. Retrieved February 11, 2016.
  11. "Anthrax". WHO.int. World Health Organization. 2016. Retrieved February 11, 2016.
  12. "Zoonoses – Animal influenza: Human and animal influenza". WHO.int. World Health Organization. 2016. Archived from the original on April 13, 2016. Retrieved February 11, 2016.
  13. Fraser, Victoria J.; et al. (2007). Diseases and disorders. Marshall Cavendish Corp. p. 502. ISBN 978-0761477709.
  14. "Rabies". WHO.int. World Health Organization. 2016. Retrieved February 11, 2016.
  15. Abalos P; Retamal P (2004). "Tuberculosis: a re-emerging zoonosis?". Revue Scientifique et Technique. 23 (2): 583–94. doi:10.20506/rst.23.2.1502. PMID 15702721.
  16. "Trypanosomiasis, human African (sleeping sickness)". WHO.int. World Health Organization. 2015. Retrieved February 11, 2016.
  17. "Vector-borne viral infections". World Health Organization. 2016. Retrieved February 11, 2016.
  18. Tilly K; Rosa PA.; et al. (June 2008). "Biology of infection with Borrelia burgdorferi". Infectious Disease Clinics of North America. 22 (2): 217–34, v. doi:10.1016/j.idc.2007.12.013. PMC 2440571. PMID 18452798.
  19. "Malaria". WHO.int. World Health Organization. 2016. Retrieved February 11, 2016.
  20. "West Nile virus". WHO.int. World Health Organization. July 2011. Retrieved February 11, 2016.