Pathogen

• A disease-causing organism

• Harmful – Hurt host cells

• Physically or through a toxin (poison)

• Bacterial diseases– Strep throat, Pneumonia, Lyme’s disease,

Bubonic plague, STD’s (many)

Three types of pathogens

• Bacterium– Examples of diseases: meningitis, strep throat

• Viruses– Ex. Diseases Hepatitis A, B, C

• Fungus– Ex. Disease; Athlete’s foot

Disease Transmission

• Exposed – when you come in contact with a pathogen

• Infected – when the pathogen enters the body AND causes disease

What does infection depend on?

• Dose – amount of organisms that enter the body

• Virulence – strength of the organism

• Host resistance – ability of your immune system to fight infection

Non-living pathogens

• Viruses – – Genes (DNA or RNA) in a protective protein shell -- Ebola,

measles, polio, cancers) 

• Prions – – infectious protein particles

• -- transmissible spongiform encephalopathies (TSEs) • -- Creutzfeld-Jakob disease (kuru), • bovine spongiform encephalopathy  (BSE or mad cow disease) 

• Parasitic DNA -- transposons -- mobile genetic elements -- heritable disorders -- hemophilia, severe combined

immunodeficiency, porphyria, cancer

Transmitting Diseases

• Air

• Water

• Sexual

• Personal Contact

• Animals

Airborne

•Anthrax

•Tuberculosis

Water/Foodborne diseases

Foodborne:SalmonellaListeria

WaterborneCholera

Sexual Contact

ChlamydiaGonorrhea

Herpes SimplexHIV/AIDS

HPVSyphilis

Bloodborne Pathogens

• HBV (hepatitis B)

• AIDs

• Hepatitis (A, B, C)

• Syphilis

• Malaria

• Brucellosis

Personal Contact

• Common colds

• Typhoid

• Shigella

• Norovirus

Rocky Mountain Spotted Fever (ticks)

West Nile Virus (mosquitos)

Lyme Disease (ticks)

Malaria (mosquitos)

Bubonic Plague (transmitted from rats to humans via fleas)

Insect Borne

So…what to do????

Personal Contact and Hygiene

Controlling Diseases

• Sanitation and Hygiene– Washing– Filtering or boiling water– Chlorine

• Antibiotics– Used to kill bacteria that have caused (or

could cause) infection. Can be preventive.

Controlling Diseases - Vaccines

• Used to PREVENT disease– Produces immunity (some temporary, some permanent

• Causes body to produceantibodies

• MMR – 99% effective with booster

• Varicella Zoster– Not as effective

• Smallpox (variola)• Polio (poliovirus)

Controlling Disease - Antibiotics

• Used to TREAT disease– Interfere with cell walls– Stop growth

• Cannot stop viruses like the rhinovirus– Usually given if 2ndary bacterial infections

occur (like bronchitis, pneumonia, etc)

Controlling Disease – antiviral drugs

• Some prevent cell entry

• Some target protein or protein sequences unique to the virus

• Some prevent polymerase binding– HIV– Herpes– Hepatitis B– Influenza