What are Zoonoses?

What are Zoonoses?

(Excerpts from Preventing the next pandemic - Zoonotic diseases and how to break the chain of transmission, UN Environment Programme, July 6, 2020

We share many of the micro-organism species that live  in and on us, with both wild and domestic animals. Of our infectious diseases 75 per cent “jump species” from (non-human) animals to people. How does this happen?

• direct infection (ex: bacterial infection from a cut that gets infected) 
• insect vectors ( ex: mosquito bite that transmits malaria)
• food borne (ex: eating meat that contains infectious virus, bacteria or parasite)
• domestic animals (ex: virus that jumps from chickens/ducks/turkeys to humans)
• wildlife (ex: viruses that jump from wild animals to humans due to living in close proximity) 
• habitat encroachment ( ex: mining, logging, farming in areas that were previously isolated) 

Emerging vs. Endemic Zoonoses

Endemic Zoonoses (or Neglected Zoonoses)

In poorer parts of the world, there are many diseases that are endemic (constant and chronic) that have devastating impacts on people. Mostly these diseases come from domestic animals. Examples include

• • • • bovine tuberculosis ( jumps from cows to people)
      • Rabies ( from dogs and other mammals) 
      • Brucellosis (from sheep, cows, goats to people) 
      • pig tapeworm
      • tryptanosomiasis ( sleeping sickness) 
      • and many others. 

The root problems are usually a mix of lack of clean water and waste removal services, poverty, low literacy levels, gender inequality and degraded natural resources. These communities usually rely on livestock such as chickens and have a lot of contact with them. This makes it easier for infectious diseases to make the jump from animal to person.

Emerging Zoonoses 

Since the 1970s, about 40 infectious diseases have been discovered, including SARS, MERS, Ebola, chikungunya, avian flu, swine flu, Zika and most recently COVID-19, caused by a new coronavirus, SARS-CoV-2. Here is a timeline of the last century of diseases.  You can see that there has been a big increase in emerging zoonoses. In the next activity we will examine those reasons.