Sever's disease or calcaneal apophysitis is usually considered to be due to damage or a disturbance in this area of growth. The two growth areas of the calcaneus can be seen on this x-ray. The smaller area to the back of the heel is normal.hat are the long term consequences of heel pain in the child (Severs disease or Calcaneal apophysitis): This condition is self limiting-it will go away when the two parts of bony growth join together-this is natural.
So, a virus must have a host cell (bacteria, plant or animal) in which to live and make more viruses. Outside of a host cell, viruses cannot function. For this reason, viruses tread the fine line that separates living things from nonliving things.
When infected by a virus, a host cell is forced to produce many thousands of identical copies of the original virus, at an extraordinary rate. Unlike most living things, viruses do not have cells that divide; new viruses are assembled in the infected host cell.But unlike still simpler infectious agents, viruses contain genes, which gives them the ability to mutate and evolve. Over 5,000 species of viruses have been discovered.iruses spread in many ways. Just as many viruses are very specific as to which host species or tissue they attack, each species of virus relies on a particular method for propagation. Plant viruses are often spread from plant to plant by insects and other organisms, known as vectors.