Infectious Diseases. Infectious Diseases

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1 Lesson 5.1 Infectious Diseases By Carone Fitness You have probably been in a situation similar to Corry's. The common cold is a type of infectious disease. Infectious diseases are caused by organisms that multiply within the human body once they have gained entry. 1

2 Every infectious disease is caused by small, microscopic organisms known as pathogens. The pathogens attack the cells and tissues of your body. Most of these pathogens are parasites. Parasites are organisms that live in or on another organism and consume its nourishment. Pathogens Different types of pathogens include: Bacteria Viruses Rickettsias Protozoans Fungi 2

3 Bacteria Bacteria are single-celled organisms that invade the body and then multiply at a rapid rate. Bacteria can be found in the air, soil, and water. Some bacteria harm humans by releasing a poison. Tuberculosis and strep throat are both infectious diseases caused by bacteria. Viruses Viruses are the smallest known type of infectious agent. A virus attacks specific types of cells by attaching itself onto the cell, injecting genetic material into the cell, and then making copies of itself. The common cold and influenza are examples of infectious diseases caused by viruses. 3

4 Rickettsias Rickettsias resemble small bacteria, but like viruses they can only multiply by invading the cells of another life form. Rickettsias are found in the intestinal tracts of insects, mice, ticks, and mites. Typhus and Rocky Mountain Spotted Fever are caused by rickettsias. Protozoans Protozoans are single-celled organisms that are larger and more complex than bacteria. Most protozoans are harmless. Protozoans that harm humans are usually found in tropical areas that have poor sanitation. Malaria is caused by a protozoan. 4

5 Fungi Fungi are simple organisms that cannot make their own food. Fungi prefer dark, damp environments. Examples of disease-causing fungi include ringworm and athlete s foot. Resident Bacteria There are certain types of bacteria that live within your body and aid in biological functions. These types of friendly bacteria are referred to as resident bacteria. 5

6 Resident Bacteria Examples of resident bacteria are: Lactobacilli, which resides in the gastrointestinal tract to aid in digestion. Coliform are found in the intestines and help break down carbohydrates and invading, disease-causing bacteria. Transmission Transmission is the spread of infectious pathogens. Transmission can occur through several different means, namely: People Animals Contaminated objects The environment 6

7 People People serve as a means of transmission, as one can be infected through direct and indirect contact with an infected person. Direct contact is when an uninfected person comes into physical contact with an infected person. Sexually transmitted diseases are spread by means of direct contact. People Both bacteria and viruses can enter the body through the lungs, if droplets containing diseased cells are inhaled. These droplets are formed when an infected person exhales, coughs, or sneezes. This means of transmission is known as indirect contact. 7

8 People Communicable diseases are infectious diseases that are spread by direct or indirect contact. Animals Animals, especially insects, spread many infectious diseases. An infected dog can spread rabies, which can be fatal. Mosquitoes often ingest blood from an infected person and then spread it to an uninfected person. Malaria and dengue fever are spread this way. 8

9 Contaminated Objects Certain pathogens can be spread when an uninfected person comes into contact with a contaminated object. Contaminated objects can include: Eating utensils Glasses Toothbrushes Needles used to inject drugs Environment The environment in which you live can also transmit disease through the food, water, air, and soil. Transmission can result from careless behavior. Toxic dumping and the improper handling of food are examples of this. 9

10 Presented By Carone Fitness 10

Bacteria vs. Virus: What s the Difference? Grade 11-12

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