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.
Section 6.3 Viruses: Structure, Function, and Uses. A virus is a small parasite that cannot reproduce by itself. Once it infects a susceptible cell, however, a virus can direct the cell machinery to produce more viruses. Most viruses have either RNA or DNA as their genetic material.The nucleic acid may be single-or double-stranded. virus is a small parasite that cannot reproduce by itself. Once it infects a susceptible cell, however, a virus can direct the cell machinery to produce more viruses. Most viruses have either RNA or DNA as their genetic material. The nucleic acid may be single-or double-stranded.