• 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

Table to show some examples of? human only and zoonotic diseases