Parasites are organisms that need a host to survive and reproduce. Without a host, there is simply no way for parasites to live. One very interesting example of a parasite is the Dicrocoelium dendriticum or most commonly called …show more content…
Viruses “rely on their hosts to carry them around and introduce them to new hosts” (Survival of the Sickest, paperback, p. 119). The cold virus knows that its host has to be relatively healthy so its ride can be mobile (Survival of the Sickest, paperback, p.119). The virus has evolved with humans to allow it to reproduce faster and survive more efficiently. If you take the host out of the picture, the cold virus could never survive or reproduce. The rabies virus is another manipulative virus. The rabies virus is a type of virus that would die out immediately in isolation. The virus has to have a host to survive and reproduce. The virus first “colonizes the salivary glands of its host, making it difficult to swallow” (Survival of the Sickest, paperback, p.104) Next, the virus makes its way into the host’s brain where it “chemically induces the animal to feel higher and higher levels of agitation and aggression” (Survival of the Sickest, paperback, p.104). With a mouth full of rabies-filled saliva, every bite is infectious. “Angry bite plus infected saliva equals new host” (Survival of the Sickest, paperback, p.104) which means survival and reproduction for the virus. Without the host doing the work for the virus, survival for the rabies virus would be close to