It was Hippocrates, who is famed to have claimed that diseases of the human body are due to physical tangible causes, and not the acts of demons, spirits or capricious gods. He is considered to be the father of modern medicine because; from that point onwards medicine became a quest to find that physical element which caused so much strife. Finally it was Louis Pasteur with the proposition of the germ theory of infectious diseases that brought about a massive change in the field of medicine regarding the causative organism for much of the diseases of that time period. But now, we have several other non communicable diseases which are causing great distress in the populace. The most important aspect regarding these diseases is understanding, the natural history and the causative factor, so that preventive, management wise or rehabilitative actions can be taken to halt further incidences or water down the effects.
A disease is an abnormal state in the human body, psyche or the interpersonal negotiations, which causes greater levels of morbidity and mortality. It is usually associated with symptoms and signs. The disease may be caused by congenital, traumatic, toxic, infectious, inflammatory, neoplastic, metabolic, degenerative, iatrogenic, vascular, etc. One of the most common causes is the infective organisms, which include bacteria, fungi, parasites and viruses. Metabolic causes, give rise to a set of the most common present day diseases, namely diabetes mellitus. As mentioned here, single diseases can occur due to a set of diseases. Thus, coronary artery disease can be due to hypertension, diabetes mellitus and obesity. There are various sets of permutations of the level of contribution, all ultimately lead to CAD. On occasions, complications of a disease can cause greater morbidity than the disease itself.
A virus, as mentioned above is an infectious agent, which contributes to the causation and spread of infectious diseases. These are minute agents, only seen by the electron microscope and require another living cell to proliferate and produce other viral particles. This is due to the lack of self replicating machinery or metabolic functions required to proliferate itself. They spread using various methodologies from direct to vector based spread. And these cause and have caused dangerous epidemics and pandemics like Ebola fever, Lassa fever, and more recently Dengue fever, all the influenzas including swine flu. The most famous in the recent past and currently is HIV. One of the problems faced in dealing with viruses is that, some of them, have a tendency to change their genetic material from generation to generation, thus, a proper anti viral agent cannot be produced to kill off that virus. This is the case with HIV/AIDS. There are other uses in biotechnology with the viruses like gene therapy, phage therapy, etc.
What is the difference between Virus and Disease?
Both of these are medically relevant, but are totally opposite at a single point in time. This is because viruses will ultimately lead to all the characteristics of a disease. But all diseases are not caused by viruses, and all viruses will not invariably cause diseases. Some of them are sub clinical and some are immune to the effects of the virus. So the best analogy that would give justice to this topic is the comparison between the hydrogen atom (as a component of water –H2O) and a giant tsunami.