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Emerging Diseases

Emerging Diseases . BIOL 119 Spring 2011. The Germ Theory explains infectious diseases. They pass from person to person- directly or through the environment. How does this happen?. Disease Transmission. The “ route of infection ” is the way the disease moves from one individual to another

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Emerging Diseases

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  1. Emerging Diseases BIOL 119 Spring 2011

  2. The Germ Theory explains infectious diseases. They pass from person to person- directly or through the environment. How does this happen?

  3. Disease Transmission • The “route of infection” is the way the disease moves from one individual to another • The disease enters the body through a “portal of entry”. • Different diseases are characterized by different routes of infection • Some pathogens utilize more than one route • To attack your body, the pathogen must attach to a molecule on the surface of your cells called a “disease receptor”

  4. To stop a pathogen you have to block its route of transmission.

  5. Routes of Transmission • Gastrointestinal • Respiratory • Direct Contact • Body fluids • Vector They are not always clear-cut: sometimes they overlap

  6. Gastrointestinal Route • Also known as: fecal-oral, food-borne or water-borne, alimentary • Examples: typhoid, polio, Salmonella, E. coli O157:H7, many parasitic diseases • Raw food is usually the problem

  7. Hepatitis A Outbreak Beaver Valley Mall • 660 cases and 4 deaths Oct-Nov. 2003 • Largest Hepatitis Outbreak in State History • Health officials issued an alert yesterday, warning the estimated 11,000 customers who ate at the Beaver Valley Mall Chi-Chi's between October 22nd and November 2nd that they may have been exposed to Hepatitis A, and should get immunized as a precaution. January 9, 2004 Bill Vidonic, Times Staff Writer BEAVER - Richard Miller will be on anti-rejection medication for the rest of his life to keep his new liver functioning properly. The 57-year-old said he is struggling to regain the stamina he lost after a liver transplant on Nov. 8, a life-saving procedure made necessary when he contracted hepatitis A after eating at the Chi-Chi's Mexican restaurant in Center Township. "I lost my liver for no reason at all," Miller said from his Beaver home Thursday.

  8. Respiratory Route • Pathogen enters via breathing or via contact with the respiratory system • Smallpox, influenza, measles, many bacterial pathogens • Inhalation of dust or aerosols • Irritation of respiratory system leads to sneezing-droplets carry germs

  9. Direct Contact

  10. Fomites Pathogens may contaminate inanimate objects from which a healthy person gets the disease: fomites.

  11. Transmission via Body Fluids(not inhaled) • “blood-borne”: Hepatitis B, HIV-1 and HIV-2 • “sexually-transmitted” or “STDs” or “urogenital”: Hepatitis B, HIV-1 and HIV-2, syphilis, gonorrhea, chlamydia • Herpes viruses like Epstein-Barr Virus can be transmitted through saliva (“mono”)

  12. Vector Transmission The disease is carried from person to person by an animal: Usually an insect or close relative such as a tick. The carrier animal is called a “vector”. Often, there are host species in addition to humans. These are called “reservoir” species or “reservoir” hosts. Malaria is the best example of a vector-borne disease. In Pennsylvania, two Important vector-borne diseases are West Nile (virus) and Lyme Disease (bacterial-caused by Borreliaburgdorferi).

  13. More terms • Some pathogens live peacefully on or in your body until it weakens-then they attack. These are called “opportunistic” pathogens. • Diseases acquired from animals are called “zoonotic”. • Diseases acquired as a result of a medical procedure are “iatrogenic”. • Diseases acquired in a hospital are “nosocomial”.

  14. Summary • Gastrointestinal • Respiratory • Direct Contact • Body fluids • Vector

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