Zoonoses

Vet examining kitten

Zoonoses are biological agents originating from animals or from products of animal origin which are able to cause disease in humans. A zoonotic disease is a disease that can be transmitted from animals to humans.

More than three quarters of human diseases are zoonotic. Zoonotic diseases may be occupationally-acquired, but are not exclusively occupational diseases. Some zoonoses can cause serious disease in humans but have little or no effect on animals (e.g. verocytotoxin producing Escherichia coli O157), whereas others such as Rabies virus can cause serious disease in both humans and animals.

Transmission

Transmission from animals to humans may occur via:

direct contact with infected animals, such as in a farm or veterinary setting or
indirect contact involving contact with infected animal secretions (e.g. saliva, blood, urine, mucous, faeces, or other body fluids) or products.

Zoonoses have different modes of transmission. The main routes of exposure are via:

inhalation e.g. breathing in an airborne zoonose;
ingestion e.g. consumption of food or drink contaminated with the zoonose;
absorption e.g. entry of the zoonose through broken skin; or
injection e.g. bite or scratch from an infected animal or via an intermediate species (known as a vector e.g. ticks or mosquitoes which carry the zoonose without getting infected). Lyme disease is an example of a vector borne disease.

Who May be at Risk?

Workers who may be at risk of zoonotic infections include those who work in:

contact with live or dead infected animals e.g. farmers, veterinarians, animal removal services, local authority workers, zoo keepers, pet shop workers;
contact with aerosols, dust or surfaces contaminated with animal secretions;
animal trade, breeding or slaughtering facilities;
contact with contaminated water or land e.g. outdoor leisure workers, wastewater treatment workers, construction workers, forestry workers, landscapers/gardeners;
cleaning or disinfection jobs in contaminated areas;
research laboratories; or
customs officials.

Anyone can become sick from a zoonotic disease, including healthy people. However, some people may be more at risk than others e.g. older workers or workers with weakened immune systems. Some infections during pregnancy such as listeriosis, toxoplasmosis or Q fever, can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.

Precautions

Good occupational hygiene and animal practices will help reduce the risk of infection.

Although the risk of infection is low, pregnant women should still avoid contact with certain animals and their products during pregnancy. For example, if pregnancy is suspected or confirmed, do not help deliver calves, kids or lambs and avoid contact with new born lambs, birthing by-products and contaminated bedding etc. Avoid handling and washing other people's clothing worn during lambing. Ensure such clothing is washed separately from other washing.