Zoonoses (SL IB Biology)

• Some diseases are species specific whilst others can cross species barriers to infect multiple different species
• Species-specific disease may be unable to cross the species barrier for many reasons:
  • If a species does not possess the necessary receptors to be at risk of infection
  • If the body temperature of the organism doesn't reach temperatures required for the development of the disease
• Zoonotic diseases are those which can cross the species barrier from animal to human
• This is a growing global concern due to the close relationships between humans and animals meaning the disease may be difficult to control and eradicate
• This may potentially lead to pandemics such as that caused by COVID-19
• Animal products may also be affected by zoonotic disease which poses a further issue
• Some zoonotic diseases can initially emerge from animal populations before developing into human only strains e.g. HIV

Human & zoonotic diseases table