Celtnet Medicine: Infectious Diseases

Infectious Diseases

Welcome to the Celtnet Medicine Infectious Diseases information page. Here you will find information about what constitutes an infectious disease, as well as links to various infectious diseases described in detail on this site.

To be infectious a disease needs to be caused by what's termed a pathogenic (ie disease causing) microbial agent. To be classed as Infectious Diseases the organism or substance causing the infection must also, typically, be contagious (ie, it must potentially be transmittable from one person or one spiecies to another).

What Constitutes and Infectious Disease?

Infctious diseases are caused by organisms such as viruses, bacteria, fungi, protozoa and the class of aberrant proteins known as prions (these are briefly described below).

By definition, to be infectious, an organism must demonstrate infectivity, which is defined as the ability of an organism to enter, survive and then multiply in a host. In contrast, the infectiousness of a disease refers to the relative ease by which a disease can be transmitted from one host to another.

There is some confusion as to what constitutes an infectious disease and I am using a fairly rigid definition here that an infectious disease is one caused by a microorganism that can directly infect the host. As a result other diseases such as malaria, schistosomiasis, even flea and tick infestations are covered in my pages on Parasitic Diseases.

Orhanisms Causing Infectious Diseases

Viruses

Top of the list here are viruses. Viruses are sub-microscopic organisms that cannot survive independently. Viruses are so small that they cannot be seen with ordinary microscopes and you need an electron microscope to see them. Viruses can only survive by infecting living cells before taking-over the molecular machinery of that cell to reproduce themselves. By its very nature, therefore, a virus is infective and can only survive by infecting other organisms.

Many of humanity's commonest and deadliest diseases are cuased by viruses. The list is extensive, but here are some examples: common cold, influneza (flu), HIV/Aids, Polio, Smallpox, Chickenpox, Whoping Cough, Rubella, Mumps, Measles, Herpes, Warts, cancer viruses, dengue fever, yellow fever... the list goes on and on. Because, by some definitions, a virus is not truly alive it's very difficult to cure viruses. Antibiotics do not work agianst viruses, so don't expect a does of antibiotics if you have cold or flu. All infectious viruses are potentially killers and the only way to be protected against them is by immunization.

Bacteria

Bacteria are single-celled organisms that represent the smallest form of what one could loosely call 'true life'. Bacteria have been around longer than any other form of life. As a result they live in and colonize each and every ecosystem and nieche on Earth. They are incredibly successful organisms and the vast majority are either beneficial or cause no harm. Indeed, the healt of the human gut is dependent on its many colonies of baciteria. Only a very few species of bacteria cuase diseas and these are classed as Pathogenic Bacteria.

Fungi

A good example of a fungal disease is Candida Yeast Infection (Thrush)

Protozoa

A good example of a fungal disease is Candida Yeast Infection (Thrush)

Prions

A good example of a fungal disease is Candida Yeast Infection (Thrush)

Celtnet Infectious Diseases Sitemap

Infectious Diseases Links

Candida Infection (Thrush)

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Further Information

Below you will find a selection of books from Amazon to do with medicine and common diseases and their treatments. If you find any of these books of interest please note that you will be buying direct from Amazon so that you can select and purchase these books with confidence: