Animals can pass many infections to people, although this route of infection is rare. The medical name for these infections is zoonoses. These infections can be passed on in various ways, and different animals can pass on different infections.

Infections caused by parasites, insects and fungi

Animals can pass infections on through parasites, infected insects and fungi.

Examples are:

  • toxocariasis (toxocarosis) – caused by swallowing soil contaminated with roundworm parasite eggs passed into the soil through infected dogs’ and cats’ poo
  • toxoplasmosis – caused by a parasite found in infected cats’ poo, undercooked or raw meat (mainly pork or lamb) and raw cured meat, such as parma ham or salami
  • giardiasis – most commonly caused by drinking water contaminated with poo containing the Giardia intestinalis parasites
  • Lyme disease – passed on by a bite from a tick that’s bitten an infected animal or bird
  • ringworm – a fungal skin infection sometimes passed on from infected pets such as dogs and cats

Infections caused by food and water contaminated with bacteria

Infections can also be passed from animals to people through contaminated food and water.

Food poisoning can be caused by campylobacter bacteria found in:

  • undercooked and raw meat, particularly poultry (such as chicken)
  • unpasteurised milk
  • untreated water

Salmonella bacteria also cause food poisoning and can be found in:

  • raw meat and poultry
  • unpasteurised milk
  • eggs and raw egg products

Salmonella can also be passed on through contact with poo from infected animals such as reptiles.

Bacteria that less commonly cause food poisoning include:

  • E.coli (Escherichia coli) – found in undercooked meat (particularly beef) and unpasteurised milk
  • Listeria – causes listeriosis and is found in unpasteurised cheeses, such as brie, camembert and blue cheese; cooked sliced meats; pâté; smoked fish; and chilled ready meals

Infections rarely or not found in the UK

Some human infections from animals are rarely found in the UK, including:

  • chlamydiosis – thought to be transmitted by inhalation of aerosols and dusts heavily contaminated with the organism C. abortus from infected sheep during the lambing season
  • leptospirosis – caused by contact with urine from infected animals, such as rats and cattle, or contaminated water
  • Q fever – caused by contact with animals, most commonly sheep, cattle and goats, or contaminated soil, dust, hay or straw
  • tapeworm infections – caused by swallowing tapeworm eggs or larvae in food or water contaminated by human or animal poo
  • tetanus – caused by bacteria in contaminated soil or manure entering a wound, and by animal bites

These infections are not currently found in the UK:

  • bird flu (avian flu) – caused by close or direct contact with infected birds
  • rabies – caused by a bite from an infected animal, usually a dog


If you’re pregnant, it’s important to know that some infections from animals can damage your unborn baby or make you ill. For more information, see:

Read the answers to more questions about infections.

Further information:

Choices, N. H. S. (2016) What infections can animals pass to people? - 
Health questions - NHS Choices [online]. 
Available from: 
(Accessed 22 September 2016).
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