InfectiousDiseasesforHighSchool传染性 20school合金材料扎制而成20iseases 20.pptVIP

Infectious Diseases Natural Emerging Dangers Infectious Disease in the News Avian flu and influenza vaccine shortage West Nile outbreaks Severe Acute Respiratory Syndrome Polio eradication efforts Anthrax in postal workers Any current example can be used as teachable moment about biology of infectious disease What is an infectious disease? Illness resulting when a foreign organism lives in/on a person Infection ≠ Infectious Disease Factors involved Organism = Parasite or pathogen Human = Host Method of spread = Transmission Parasite Factors Cooperation is the rule; disease is rare Enlightened self-interest: If host dies, parasite dies Normal colonization with “smaller life” Beneficial Bacteria growing in intestine (“gut flora”) make vitamin K Unnoticed Mites in hair follicles Characteristics related to ability to cause disease: Virulence factors Avoid host control and allow growth Make products that damage host cells Cause host to damage itself as a result of responding to infection Host Factors Barrier to infection Intact skin and mucous membranes Secretions Response to infection Innate immunity: Non-specific and immediate, includes phagocytes and neutrophils Adaptive immunity: Specific to organism, includes antibodies and activated lymphocytes Transmission Direct spread: by contact or airborne particles from infected to uninfected (Contagious disease) Food or environment-borne: water, food, or soil contaminated by infected person and serve as reservoir for spread Zoonotic: infection transmitted to humans from an animal host or reservoir Mother-to-infant: shared blood circulation before birth or exposure during delivery (Vertical ) Reasons for “Outbreaks” Look to three major factors in infectious disease Parasite/Pathogen New or new to population Increased virulence due to genetic change or recombination Drug resistance Host Breakdown in defense (nutrition, infection, cancer, injury) Genetic variation in immune response Transmission Altered environment res