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Chapter 14

Chapter 14. Principles of Disease and Epidemiology. Principles of Disease and Epidemiology. Pathology Study of disease Etiology Study of the cause of a disease Pathogenesis Development of disease Infection Colonization of the body by pathogens

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Chapter 14

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  1. Chapter 14 Principles of Disease and Epidemiology

  2. Principles of Disease and Epidemiology • Pathology Study of disease • Etiology Study of the cause of a disease • Pathogenesis Development of disease • Infection Colonization of the body by pathogens • Disease An abnormal state in which the body is not functioning normally

  3. Normal Microbiota and the Host: • In commensalism, one organism is benefited and the other is unaffected. • In mutualism, both organisms benefit. • In parasitism, one organism is benefited at the expense of the other. • Some normal microbiota are opportunistic pathogens.

  4. Normal Microbiota and the Host: • Locations of normal microbiota on and in the human body Figure 14.2

  5. Normal Microbiota and the Host: • Microbial antagonism is competition between microbes. • Normal microbiota protect the host by: • occupying niches that pathogens might occupy • producing acids • producing bacteriocins • Probiotics are live microbes applied to or ingested into the body, intended to exert a beneficial effect.

  6. Koch’s Postulates • Koch's Postulates are used to prove the cause of an infectious disease. Figure 14.3.1

  7. Koch’s Postulates • Koch's Postulates are used to prove the cause of an infectious disease. Figure 14.3.2

  8. Problems with Koch’s Postulates • Culturing requirements do not allow isolation of pure culture -ex Legionnaires disease: Used tissue from infected patients to infect guinea pigs, which came down with similar symptoms. Guinea pig tissue used to innoculate yolk sac of eggs. Electron microscopy ultimately showed that the very small rod shaped bacteria present in both patient samples and guinea pigs.

  9. Nosocomial (Hospital-Acquired) Infections • Are acquired as a result of a hospital stay • 5-15% of all hospital patients acquire nosocomial infections • Concern because many are drug resistant Figure 14.7, 9

  10. Transmission of Disease • Vehicle Transmission by an inanimate reservoir (food, water) • Vectors Arthropods, especially fleas, ticks, and mosquitoes • Mechanical Arthropod carries pathogen on feet • Biological Pathogen reproduces in vector

  11. Emerging Infectious Diseases • Diseases that are new, increasing in incidence, or showing a potential to increase in the near future. • Contributing factors: • Evolution of new strains • V. cholerae O139 • Inappropriate use of antibiotics and pesticides • Antibiotic resistant strains • Changes in weather patterns • Hantavirus

  12. Emerging Infectious Diseases • Contributing factors: • Modern transportation • West Nile virus • Ecological disaster, war, expanding human settlement • Coccidioidomycosis • Animal control measures • Lyme disease • Public Health failure • Diphtheria

  13. Epidemiology • The study of where and when diseases occur Figure 14.11

  14. PPT of Epidemiology • Person • Place • Time Epidemiologists determine the etiology of a disease and important factors and patterns that may contribute to disease transmission

  15. Epidemiology

  16. Centers for Disease Control and Prevention (CDC) • Collects and analyzes epidemiological information in the U.S. • Publishes Morbidity and Mortality Weekly Report (MMWR) www.cdc.gov Morbidity: incidence of a specific notifiable disease Mortality: deaths from notifiable diseases CDC, along with the National Institutes of Health (NIH), World Health Organization (WHO) work to monitor and understand emerging infectious diseases

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