Zoonotic Diseases

Zoonotic Viruses

Sars-CoV-2, the virus that causes COVID-19, is an example of a virus that "spilled over" from animals to infect people, and is just the most recent and impactful of many viruses that have this capacity.  Diseases that primarily affect non-human animals but can jump to people are known as zoonotic diseases, and can be caused by viruses or bacteria.

Some viruses may be increasing in frequency as people come into closer contact with those animals which have long harbored the virus.  In other cases, viruses may gain the ability to switch hosts through mutation or recombination. In this video, I will include: 

• review of viruses and infection
• review of mutations, natural selection and evolution using viruses as our example 
• how this relates to spill over

Full transcript of Evolution, Natural Selection, Mutations and Viruses video (Word doc)

Tracing the Origins of Zoonotic Diseases

Tracing the origins of zoonotic diseases take a lot of time.  It involves searching large areas and sampling many, many wild animals for traces of the virus or antibodies to that virus (indicating the animal has been infected in the past).  These videos will help you answer study guide question

6. How do zoonotic diseases jump from animals to humans? What are zoonotic diseases? What ways that a human can contract a disease from animals? What are the stages of a successful viruses life cycle? What type of changes would there need to be for each stage in order to infect a new host (such as a human)?  What is the role of mutations in the spillover of diseases from animals to humans? What types of animals are most likely to have viruses that spill over  into humans?

Watch the 4-minute video below to learn about the zoonotic origins of some familiar zoonotic diseases, some of the animals hypothesized to be linked to the COVID-19 pandemic , and how researchers ultimately, after 10 years, linked the 2003 SARS outbreak to Horseshoe Bats.    

You can also find this video and an accompanying article on this NPR Website.  This video is from May 2020.  You'll see more recent updates on the COVID-19 origin on the next page, but this video serves as a good introduction to linking zoonoses to animals more generally.

This TED-Ed cartoon on how viruses jump from non-human animal to human hosts is excellent.  Among other things, it highlights a 2017 outbreak of Swine Flu at a Maryland country fair in which sick pigs may have transferred a virus to human fair-goers.