Diseases and Disorders Unit 8 Chapters Unit 8 Chapters

Causes of Infectious Diseases Pathogens-invade the body and attack its cells and tissues. Most pathogens are parasites. Parasites live in or on another organism and derive nourishment from it. EX: BACTERIA, VIRUSES, RICKETTSIAS, PROTOZOANS, AND FUNGI

BACTERIA Single cell organism Classified in 3 categories: spherical, rod-shaped, and spiral-shaped EX: Streptococcus, Staphylococcus, and E. coli

Streptococcus Strep throat - a sore, red throat, sometimes with white spots on the tonsils Scarlet fever - red rash on the body Impetigo - a skin infection Cellulitis and necrotizing fasciitis (flesh-eating disease)

Staphylococcus Skin infections Pneumonia Food poisoning Toxic shock syndrome Blood poisoning (bacteremia)

E. Coli Intestinal bacteria Symptoms: diarrhea, food poisoning Goes away untreated in 5-10 days.

Treatment for Bacterial Infections Antibiotics-kill bacteria or stop it from reproducing Antibiotics DO NOT kill viruses: ColdsFlu Most coughs and bronchitis Sore throats, unless caused by strep

Viruses Smallest known type of infectious agent 1/2 to 1/100 the size of the very smallest bacterium Consist of an inner core of genetic material surrounded by a protective protein shell and are entirely dependent on living cells for survival and reproduction.

HOW A VIRUS WORKS

Examples of Viruses? Human Immunodeficiency Virus (HIV), which is the virus that causes AIDS. herpes simplex virus, which causes cold sores, smallpox, and the human papilloma virus, now believed to be a leading cause of cervical cancer in adult women.

Rickettsias Resemble small bacteria but work like a virus, they must invade the cell of another life form. Usually invade the intestinal tracts of fleas, mice, ticks, and mites When humans are bitten they can contract the rickettsias and contract typhus and Rocky Mountain spotted fever.

What is Typhus/Rocky Mountain Spotted Fever Typhus occurs throughout the world where people and rats occupy the same living area or building. Infection occurs when rat fleas bite humans Rocky Mountain spotted fever occurs most commonly in the mountains of the US and Mexico It is spread by ticks, carrying rickettsias

Protozoans Single-Cell Organisms, larger than bacteria with a more complex cell structure. Most are harmless Most common in tropical areas with poor sanitation Water supplies and contaminated animals

Fungi Simple organisms that cannot make their own food Most are saprophytes or organisms that feed off dead animals, insects, and leaves. The most common are athlete’s foot and ringworm

Athlete’s Foot

Ringworm

How Infectious Diseases are Spread Direct Contact-Human to Human Indirect Contact-bacteria and viruses can both enter the body through the lungs if droplets are exhaled, coughed, or sneezed out.

Animals Spread Infectious Diseases Mad cow disease MalariaRabies West Nile Typhus

The Immune System It’s a network of cells, tissues, organs, and chemicals that fight off pathogens.

Inflammatory Response A reaction to tissue damage caused by injury or infection.

What Happens? Tissue damaged, blood vessels near injury expand Fluid and cells from bloodstream cause swelling Phagocytes attack invading pathogens Pathogens killed, tissue damage under control, body begins to repair

Specific Defenses The inflammatory response is different than the immune response.

How the “Immune System” Responds An antigen enters the body and causes the immune system to respond. Lymphocytes are specialized white blood cells that coordinate and perform many specific functions of immunity. T cells and B cells

Immune System Memory Your immune system has a memory of every antigen it has encountered. Active Immunity develops naturally and artificially. Vaccinations are prepared dead or weakened pathogens that are introduced into the body to stimulate an immune response.

Passive Immunity You acquire passive immunity when your body receives antibodies from another person or animal. This immunity is temporary.

Emerging Diseases and Pandemics These are emerging diseases whose occurrence in humans has increased within the past two decades or threatens to increase in the near future.

Avian Influenza H1N1 Virus Salmonella and E. Coli Recreational Water Illness HIV/AIDS

How Diseases Affect the World Pandemic-global outbreak of an infectious disease.

5 Deadliest Pandemics in History The Peloponnesian War Pestilence (430 BC) The Antonine Plague (165 AD) The Plague of Justinian ( AD) The Black Death (14 th Century) The Spanish Flu (1918)