Viruses are by far the most abundant biological entities on Earth and they outnumber all the others put together. There are millions of different types of viruses, although only about 5,000 have been described in detail. They infect all types of cellular life, including animals, plants, bacteria and fungi. Viruses are considered by some to be a life form because they carry genetic material, reproduce, and evolve through natural selection; even though they lack cell structure, which is necessary to count as life, although most scientists regard viruses as non-living.
In this eBook, the first half focuses on what is a virus, history of viral research, replication cycle and more. The second half of the book focuses on pandemics (mass disease) past and present such as HIV aids, Influenza, Ebola, and West Nile Virus.