What You Need To Know About Zoonotic Diseases

A zoonotic disease (or zoonosis) is a type of disease that passes from an animal or insect to a human. Zoonotic diseases are caused by a pathogen such as a virus, bacterium or parasite and transmitted through a ‘vector’ (e.g. mosquito, tick) in order to infect a human.

Some zoonoses don’t make the animal sick, but will sicken a human. The infected human typically transmits the infectious agent to at least one other human, who, in turn, infects others. It may range from a minor to short-term illness or to a major life-changing illness.

Zoonoses have different modes of transmission:

• Enteric zoonoses are generally transmitted through contaminated food or water and cause gastrointestinal illness such as Salmonellosis, Campylobacter and Giardia infections.
• Non-enteric zoonoses is a grouping of vector-borne diseases and infections transmitted between animals and humans and may be a bacterium, a virus, a fungus or other communicable disease agent, such as Lyme disease, West Nile virus (WNV) and plague.
• Direct zoonoses the disease is directly transmitted from animals to humans through bites and saliva (rabies) or through media, such as air (influenza).
• Environmentally mediated zoonoses (such as Anthrax, Echinococcosis, Leptospirosis), are important re-emerging infectious diseases that affect humans worldwide.
• Humans can suffer from several food-borne helminth zoonotic diseases, (such as Toxoplasmosis, Trichinellosis). The route of infection is normally consumption of the parasite’s natural host as a human food item (e.g. meat). Inadequate knowledge of infection and hygiene, and unsafe management and disposal of animal waste products facilitate transmission.

Types of zoonosis include those caused by:

• a virus
• bacteria
• fungus
• parasites

Some of the most serious zoonoses are spread by mosquitos and ticks.

Examples of zoonotic diseases and how they are contracted:

Leptospirosis: Contact with contaminated water

Bordetella: Interacting with other infected pets

Lyme Disease: Transmitted through tick bites

Rabies: Passed on from bats and raccoons

Leptospirosis is considered the most widespread zoonotic disease in the world. It is a bacterial disease that can pass from animals to humans when an unhealed break in the skin comes into contact with water or soil where an infected animal’s urine is present. Cases usually occur during the summer and fall.

Bordetella the main bacteria Bordetella Bronchiseptica is a respiratory pathogen commonly found in companion animals and can cause infectious bronchitis in dogs and other animals. It can infect humans and is only a risk factor for people with weakened immune systems.

Lyme Disease is an infectious disease caused by the bacteria Borrelia burgdorferi and transmitted to humans by a bite from an infected blacklegged or deer tick, after feeding on infected deer, birds or mice.

Rabies is the best-known zoonosis in Canada, and the most deadly. Rabies is usually spread through an animal bite, saliva contamination of wounds or entrance into damaged skin, and infects warm-blooded mammals. Wildlife animals most likely to spread rabies include skunks, raccoons and bats. Unvaccinated feral cats and dogs are a concern in remote areas of Canada. Vaccination can prevent infection and is mandatory for pets in many areas.