INFECTIOUS DISEASE

What is Infectious Disease? A disease caused by the presence of a living thing in the body.

What are Pathogens? Organisms that cause disease.

Four Types of Pathogens… Bacteria Viruses Fungi Protists

BACTERIA One-celled microorganisms that cause a wide variety of diseases. Some bacteria damage cells directly, however others damage them indirectly by releasing toxins, or poisons, into your body. They are LIVING.

VIRUSES Tiny particles, much smaller than bacteria that cannot reproduce unless they are inside living cells. The cells are damaged or destroyed in the process, releasing new viruses to infect other cells. Viruses are NONLIVING! They are particles- NOT CELLS!

FUNGI Fungi, which include molds and yeasts, also cause some infectious diseases. Fungi grow in warm, dark, moist areas. Two examples are athlete’s foot and ringworm. They are LIVING!

PROTISTS An organism that cannot be classified as an animal, plant, or fungus. One example is Malaria, an infection of the blood. Protists are LIVING!

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

Infected People Direct physical contact (kissing, shaking hands, etc) Indirect contact (sneezing, coughing, etc)

Soil, Food, Water Some pathogens occur naturally in the environment. Some pathogens contaminate food and water, spreading disease when drinking and eating.

Contaminated Objects Some pathogens can survive outside a person’s body. Contact with contaminated objects can infect a person (towels, silverware, etc).

Infected Animals If an animal is infected with a pathogen and bites a person, it can pass the pathogen to the person. Example: Rabies, Lyme Disease, etc.