 The phenomenon is important for understanding and controlling emerging infectious diseases in humans, especially those caused by viruses , where one reservoir species transfers the virus to a vector species, which in turn transfers the virus to humans . Most viral diseases of humans are zoonotic in origin, having been historically transmitted to human populations from various animal species;
<coherence>  The phenomenon is important for understanding and controlling emerging infectious diseases in humans, especially those caused by viruses , where one reservoir species transfers the virus to a vector species, which in turn transfers the virus to humans . Most viral diseases of humans are zoonotic in origin, having been historically transmitted to human populations from various animal species;
 The phenomenon is important for understanding and controlling emerging infectious diseases in humans, especially those caused by viruses . Most viral diseases of humans are zoonotic in origin, having been historically transmitted to human populations from various animal species;