Viruses
Viruses are capsules that contain genetic material, are smaller than cells, and contain protein and lipid molecules that protect them. Host cells are needed to reproduce in the body, taking control of the cells to multiply the virus and infecting new cells. Often, host cells are destroyed during the process. Stronger strains of the virus can unfortunately change the function of the cell, causing diseases. Chickenpox, AIDS, SARS are all due to viruses. Certain age groups are more prone to contracting viruses, especially those with compromised immune systems. Usually only the symptoms are treated letting the immune system fight the virus naturally without medication.