Immunology: Chapter 35 p. 1010 35.1: Infectious Disease

Infectious disease When microorganisms cause physiological changes that disrupt normal body functions

Causes? Virus Bacteria Fungi Protists Parasites *remember…a pathogen is a disease causing microorganism* Look at p. 1010-1011 and read characteristics of each

Koch’s postulates 1. Pathogen must always be found in the body of a SICK organism and should not be found in a healthy one 2. The pathogen must be isolated and grown in the laboratory in pure culture 3. When the cultured pathogens are introduced into a healthy host, they should cause the same disease that infected the original host. 4. The injected pathogen must be isolated from the second host…it should be identical to the original pathogen

Won the Nobel Prize in 1905! Postulates are guidelines that help identify causes of new and emerging disease

Write… What is a symbiont? How is a different from a pathogen?

How diseases spread Coughing Sneezing Physical contact Exchange of body fluids Contaminated water or food To humans from infected animals

Cool fact! “Pathogens are often spread by symptoms of disease, such as sneezing, coughing or diarrhea  In many cases, these symptoms are changes in host behavior that help pathogens spread and infect new hosts.” p. 1012

Zoonoses: The Animal Connection Any disease that can be transmitted from animals to humans is called a ZOONOSIS i.e. mad cow disease, west nile, lyme disease

Vectors Carriers that transport the pathogen but usually do not get sick themselves This includes: 1. bitten by an infected animal 2. consumes the met of an infected animal 3. comes in close contact with an infected animal’s wastes or secretions