Importance and Value of Trees. Since the beginning, trees have furnished us with two of lifeâs essentials, food and oxygen. As we evolved, they provided additional necessities such as shelter, medicine, and tools. Today, their value continues to increase and more benefits of trees are being discovered as their role expands to satisfy the needs created by our modern lifestyles.
However, the most serious is called psittacosis. With this disease, an agent called Chlamydia psittaci causes it, and the disease is also called ornithosis. Birds can be asymptomatic carriers, and may only fall ill when upset, as stress is a major component in all avian diseases.
Diseases such as foot-and-mouth disease and bluetongue are caused by viruses. Companion animals such as cats, dogs, and horses, if not vaccinated, are susceptible to serious viral infections. Canine parvovirus is caused by a small DNA virus and infections are often fatal in pups.ther viruses, such as rabies virus, can infect different species of mammals and are said to have a broad range. The viruses that infect plants are harmless to animals, and most viruses that infect other animals are harmless to humans.