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IMMUNOLOGY

IMMUNOLOGY. THE NATURE OF INFECTIOUS DISEASE. How Are Diseases Caused?. Infectious diseases are caused by disease-producing agents called Pathogens . Bacteria, Protists, Fungi, and Viruses Not all microorganism are pathogenic

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IMMUNOLOGY

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  1. IMMUNOLOGY THE NATURE OF INFECTIOUS DISEASE

  2. How Are Diseases Caused? • Infectious diseases are caused by disease-producing agents called Pathogens. • Bacteria, Protists, Fungi, and Viruses • Not all microorganism are pathogenic • Infectious disease – Any disease caused by the presence of pathogens in the body.

  3. Where do diseases come from? • The main source of human disease pathogens is the human body itself. • People can be carriers. • They do not have the disease but act as a reservoir and can spread the disease.

  4. Carriers • Carriers can pass on the disease during the incubation period. • Incubation period – A symptom-free period, while cells are multiplying within the body. • Ex. Common cold, HIV

  5. Other Reservoirs • Animals can also serve as reservoirs for microorganisms that cause disease in humans. • Rabies • Soil and Water can be reservoirs for infectious disease. • Soils can contain pathogens such as fungi and a type of bacterium that causes botulism. • Water may be contaminated by feces

  6. Transmission • 4 ways for pathogens can be transmitted from reservoirs to humans. • Direct contact, by an object, through air or by a vector • 1. Direct contact – Common cold, Flu, STDs and HIV • 2. An object – Food poisoning, food is contaminated by a food handler

  7. Transmission • 3. Vectors – An intermediate organism • Insects and ticks: • Malaria is transmitted by mosquitoes • Lyme disease is transmitted by ticks • Fleas helped transmit the bubonic plague from rats to humans.

  8. Causes of Symptoms of Disease • Viruses take over a host cell’s genetic material and may cause death to the cells they invade • Bacteria release toxins, which cause damage to the host. • Toxins can produce fever, inhibit protein synthesis, destroy blood cells, or cause spasms • Some toxins can be deadly. • What makes us FEEL sick (fever, sore throat) are symptoms from our fight against the disease!

  9. Patterns of Disease • Diseases are able to spread rapidly in today’s highly mobile world. • Endemic – a disease that is always present in a population. Ex. Common Cold • Epidemic – occurs when many people in a given area are afflicted with the same disease at the same time. • Ex. Flu, Polio

  10. Treating Disease • Antibiotics are often used to kill or inhibit the growth and reproduction of bacteria • Produced naturally by various species of bacteria and fungi. • Do not affect viruses.

  11. Problems with Antibiotics • Bacteria can often become genetically resistant to antibiotics. (This involves plasmid transfer) • Resistance is caused by continued use of antibiotics. • Penicillin first used in the 1940s but now after about 60 years of use, types of bacteria have evolved a resistance. • The bacteria produce an enzyme that breaks down the antibiotic. Ex. Gonorrhea

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