Perhaps it was inevitable that our computers would eventually get infected and sick also. Just like the real thing they make copies of themselves at the expense of their woeful host. Computer viruses come in many forms. Pseudovirus worms , which like their animal counterparts replicate themselves endlessly until they die, hoarding and competing for precious memory. Trojans are based on the Trojan horse of mythology, and masquerade as programs when in reality they are malicious intruders.
Time bombs lie in waiting until a particular time or date.
In 1989 thousands of computers were infected with over 350 viruses. On a recent drive through upper New York state I saw a sign for Coxsackie, New York. Thus, perhaps understandably, towns, colleges and companies do not like to be associated with computer viruses and will go to great lengths to avoid being the name of a virus. One of the programs advertised to remove this virus actually infected the host computer with a second, separate virus. Unfortunately some people believe that the publicity garnished by this software author has motivated copycats to write more destructive codes.