Zoonosis

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.

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

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.  The rat is the host of the disease, and the flea is the vector.

Types of zoonotic diseases
Foodborne illnesses
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.

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. Cholera  Vibrio cholerae bacteria  Shellfish  Eating under-cooked shellfish. Creutzfeldt-Jakob disease  Prions  Cattle  Eating meat from cattle who had mad cow disease. Listeriosis  Listeria bacteria  Cattle, fish  Having unpasteurized milk or cheese; Eating under-cooked meat or seafood. Toxoplasmosis  Toxoplasma gondii parasite  Pigs, lambs, deer, cattle  Eating under-cooked meat.

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

Direct zoonoses
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. Influenza  Influenza A virus  Horses, pigs, birds, seals, whales, and more  Exhaled air from infected animals. Lassa fever  Lassa virus  Rodents  Contact with rodent feces. Rabies  Rabies virus  Dogs, bats, cattle, monkeys, wolves, and more  Infected saliva from being bitten, or by being scratched. Toxoplasmosis  Toxoplasma gondii parasite  Cats  Cat feces (in cat litter boxes or dirt). Tuberculosis  Mycobacterium bovis bacteria  Cattle, deer, llamas, pigs, cats, and more  Exhaled air, sputum, urine, feces, or pus from infected animals.

Vector-borne zoonotic diseases
 Disease Pathogen Host Vector African sleeping sickness  Trypanosoma brucei rhodesiense parasite  Many wild and farm animals  Tsetse fly. Bubonic plague  Yersinia pestis bacteria  Rodents  Fleas. Dengue fever  Flaviviruses  Humans and primates  Aedes mosquitoes. Lyme disease  Borrellia bacteria  Rodents  Ticks. Malaria  Plasmodium parasites  Humans  Mosquitoes. West Nile fever  West Nile virus  Mostly birds  Mosquitoes.

Related pages
 Infectious disease
 Vector (biology)
 2019 novel coronavirus

References


Category:Diseases caused by bacteria
Category:Diseases caused by protozoa
Category:Diseases caused by viruses
Category:Diseases spread by insects