Contains the full lesson along with a supporting toolkit, including teachers’ notes.
What is an infectious disease?
In this lesson we will look at the causes and treatment of infectious diseases as a result of viruses. Disease is an unhealthy condition of the body due to disruption of its normal functioning. Diseases may be genetic or acquired through accidents at birth, through malnutrition or injury. At the present time we still don’t know the cause of many diseases. About one third of all deaths each year are due to pathogenic diseases.
What is a pathogen?
A pathogen is an infectious disease-causing organism. Pathogens can be viruses, bacteria or fungi. All viruses are pathogenic as they are obligate intracellular parasites. A parasiteis an organism that lives with, and gains nourishment from, another organism causing it harm. Intracellular means that it lives within thecell. Obligate means that the virus must be with its host to gain nourishment and to reproduce. Although many human diseases are caused by viruses most viruses are harmless to us.
Is a virus a living organism?
An organism is a living structure composed of one or more cells - based on this definition a virus is not a living organism. Viruses are non-cellular and the typical virus structure is a surrounding wall of protein protecting the genetic material that can be DNA or RNA.