Viral disease overview
Some viruses are pathogenic, meaning that they cause disease in the organisms they infect.
A viral disease is any viral infection that harms the host.
Many well-known diseases are caused by viruses, such as influenza, AIDS, chicken pox and glandular fever.
Viruses cause disease by damaging and killing a large number of cells in the host organism.
Disease symptoms can also be caused by an auto-immune response. Inflammation of infected and neighbouring cells occurs due to the organism's immune response.
Some viruses can remain dormant within cells for years, and only cause disease under certain conditions.
The varicella zoster virus, which causes chicken pox, remains dormant in the spinal cord even after the disease is cured. The virus can reactivate and cause the disease shingles.