Natural ecosystem is made up of both living and non-living entities coexisting with one another in a well structured environment.
Living systems constitute the biological community; human beings, animals, birds, microbes and plants. Humans, being the most advanced class, exercise control and influence over other living classes. The interaction between humans and the other living systems, especially animals, has contributed remarkable benefits to mankind. Conversely, the relationship has also subjected humans to untold suffering, with zoonoses, a group of diseases caused by germs that spread from animals to persons, at the centre stage. To lay it bare, zooneses account for 60 per cent of infectious diseases afflicting humans.