Infectious Disease 40-1

What is Disease? Disease –Any change in the body, other than injury, that disrupts the normal functions of the body –Disease has many causes Bacteria Viruses Environmental Factors (cigarette smoke, pollution) Genetics

Koch’s Postulate Koch said: –Disease is caused by microorganisms and NOT by curses, evil spirits or night vapors –Yes, for thousands of years, people believed that diseases were caused by those things.

Infectious Disease Infectious = can be passed from person to person Pathogens –Cause disease –EX: Bacteria Viruses Protists Worms

Bacteria Single Celled living organisms –Asexual reproduction –Multiply by themselves Can easily be seen with a microscope!! Live & breed in warm, moist environments Prokaryotes: no nucleus

Bacteria and Humans Most bacteria = harmless Good for humans! –many places on our bodies –Intestines…digestion

Bacteria as Pathogens –Break down tissues –Release toxins –EX: Streptococcus (Strep Throat) Diptheria Botulism Anthrax E. coli (found in food)

Bacteria

Treatments for Bacterial Infection Antibiotics –Kill bacteria, but not body cells –Interfere with the cellular processes of the bacteria –One antibiotic will kill many different kinds of bacteria –Examples: Penicillin, Amoxicillin

Virus 1000 times smaller than bacteria!! –Cannot be seen with a microscope Cannot live or reproduce on their own –Must invade a host cell –Contain RNA or DNA but none of the equipment to reproduce

Virus Pathogenic Mutate often Examples: –Common cold –Influenza –Smallpox –Warts –HIV

Virus

Treatments for Viral Infection Best treatment : –Rest –Water –No help from Doc! Antibiotics are NOT effective against viruses because the virus live within your own body’s cells.

Why you feel sick when you have an infection Symptoms caused by your body’s response to the infection –Fever kill the pathogen –Vomiting, Runny nose, coughing physically remove the pathogen –You feel tired because your body is working overtime fighting the infection

In Review An Infectious Disease is –Disease that can be passed from person to person A Pathogen is –A disease causing agent Bacteria –Single-celled living organisms –Killed by Antibiotics Virus –Tiny particles, need host cell in order to replicate –Antibiotics are INEFFECTIVE