Lesson 1 – Infectious Disease

1. Lesson 1 – Infectious Disease Chapter 5 – Fighting Diseases

2. Organisms that cause disease are called pathogens. • Diseases that are caused by pathogens are called infectious diseases. An infectious disease is a disease that is caused by the presence of a living things within the body. • When you have an infectious disease, pathogens have gotten inside your body and caused harm. Understanding infectious diseases

3. The four major groups of human pathogens are bacteria, viruses, fungi, and protists. • Bacteria are one celled microorganisms, which cause a wide variety of diseases such as: ear infections, food poisoning and strep throat. • Some bacterial pathogens damage cells indirectly by producing a poison or toxin. Ex: the bacteria that causes tetanus to get into a wound can cause damage to the nervous system. Kinds of pathogens

4. Viruses are tiny particles, much smaller than bacteria. Viruses cannot reproduce unless they are inside living cells. • Both colds and flu are caused by viruses that invade cells. • There are more than 200 kinds of cold viruses. • Fungi, which includes molds and yeasts, also cause some infectious diseases. Ex: athlete’s foot and ringworm.

5. Protists are also a cause of disease. Malaria, an infection of the blood that is common in tropical areas, is one disease caused by a protist. • Other examples are African Sleeping Sickness and amebic dysentery.

6. Pathogens can spread through contact with an infected person; soil, food, or water; a contaminated object; or an infected animal. How Pathogens are Spread