1. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chapter 14 Principles of Disease and Epidemiology Biology 205 Chandler-Gilbert Community College

2. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Principles of Disease and Epidemiology  Pathology: The study of disease  Etiology: The study of the cause of a disease  Pathogenesis: The development of disease  Infection: Colonization of the body by pathogens  Disease: An abnormal state in which the body is not functioning normally

3. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Normal Microbiota and the Host  Transient microbiota may be present for days, weeks, or months.  Normal microbiota permanently colonize the host.  Symbiosis is the relationship between normal microbiota and the host. Figure 14.1c

4. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Symbiosis  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.

5. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Normal Microbiota and the Host  Locations of normal microbiota on and in the human body. Table 14.1c

6. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Normal Microbiota and the Host  Microbial antagonism is a 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.

7. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Koch’s Postulates  Koch's postulates are used to prove the cause of an infectious disease. Figure 14.3 (1 of 2)

8. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Classifying Infectious Diseases  Symptom: A change in body function that is felt by a patient as a result of disease.  Sign: A change in a body that can be measured or observed as a result of disease.  Syndrome: A specific group of signs and symptoms that accompany a disease.

9. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Classifying Infectious Diseases  Communicable disease: A disease that is spread from one host to another.  Contagious disease: A disease that is easily spread from one host to another.  Noncommunicable disease: A disease that is not transmitted from one host to another.

10. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Occurrence of Disease  Incidence: Fraction of a population that contracts a disease during a specific time.  Prevalence: Fraction of a population having a specific disease at a given time.  Sporadic disease: Disease that occurs occasionally in a population.

11. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Occurrence of Disease  Endemic disease: Disease constantly present in a population.  Epidemic disease: Disease acquired by many hosts in a given area in a short time.  Pandemic disease: Worldwide epidemic.  Herd immunity: Immunity in most of a population.

12. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

14. Figure 14.4

15. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Severity or Duration of a Disease  Acute disease: Symptoms develop rapidly.  Chronic disease: Disease develops slowly.  Subacute disease: Symptoms between acute and chronic.  Latent disease: Disease with a period of no symptoms when the patient is inactive.

16. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Extent of Host Involvement  Local infection: Pathogens are limited to a small area of the body.  Systemic infection: An infection throughout the body.  Focal infection: Systemic infection that began as a local infection.

17. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Extent of Host Involvement  Bacteremia: Bacteria in the blood.  Septicemia: Growth of bacteria in the blood.

18. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Extent of Host Involvement  Toxemia: Toxins in the blood.  Viremia: Viruses in the blood.  Primary infection: Acute infection that causes the initial illness (i.e., Sinus infection).  Secondary infection: Opportunistic infection after a primary (predisposing) infection (i.e., Meningitis).  Subclinical disease: No noticeable signs or symptoms (inapparent infection).

19. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Predisposing Factors  Make the body more susceptible to disease  Short urethra in females  Inherited traits such as the sickle-cell gene  Climate and weather  Fatigue  Age  Lifestyle  Chemotherapy

20. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Stages of a Disease Figure 14.5

21. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Reservoirs of Infection  Reservoirs of infection are continual sources of infection.  Human — AIDS, gonorrhea  Carriers may have inapparent infections or latent diseases.  Animal — Rabies, Lyme disease  Some zoonoses may be transmitted to humans.  Nonliving — Botulism, tetanus  Soil

22. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Transmission of Disease  Contact  Direct: Requires close association between infected and susceptible host.  Indirect: Spread by fomites.  Droplet: Transmission via airborne droplets.

23. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Transmission of Disease  Vehicle: Transmission by an inanimate reservoir (food, water).  Vectors: Arthropods, especially fleas, ticks, and mosquitoes.  Mechanical: Arthropod carries pathogen on feet (fly).  Biological: Pathogen reproduces in vector (Malaria).

24. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Transmission of Disease Figures 14.7b, 14.8

25. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nosocomial (Hospital-Acquired) Infections  Are acquired as a result of a hospital stay.  5-15% of all hospital patients acquire nosocomial infections. Figures 14.6b, 14.9

26. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Relative Frequency of Nosocomial Infections Table 14.5

27. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Percentage of Nosocomial Infections Percentage Resistant to Antibiotics Gram + cocci51%29%-89% Gram – rods30%3-32% Clostridium difficile13% Fungi6% Common Causes of Nosocomial Infections

28. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Emerging Infectious Diseases  Diseases that are new, increasing in incidence, or showing a potential to increase in the near future.  Contributing factors  Genetic recombination  E. coli 0157, Avian influenza (H5N1)  Evolution of new strains  V. cholerae 0139  Inapproriate use of antibiotics and pesticides  Antibiotic resistant strains

29. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Emerging Infectious Diseases  Changes in weather patterns (moisture)  Hantavirus  Modern Transportation (Hitching a ride)  West Nile virus  Ecological disaster, war, and expanding human settlement  Coccidioidomycosis  Animal control measures (Deer)  Lyme disease  Public Health failure (Lack of water treatment)  Diphtheria

30. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Crossing the Species Barrier UN 13.3

31. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epidemiology  The study of where and when diseases occur Figure 14.10

32. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings John Snow1848-1849Mapped the occurrence of cholera in London Ignaz Semmelweis1846-1848Showed that hand washing decreased the incidence of puerperal fever Florence Nightingale1858Showed that improved sanitation decreased the incidence of epidemic typhus Epidemiology

33. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings DescriptiveCollection and analysis of data regarding occurrence of disease Snow AnalyticalComparison of a diseased group and a healthy group Nightingale ExperimentalStudy of a disease using controlled experiments Semmelweis Case reportingHealth care workers report specified disease to local, state, and national offices Nationally notifiable diseases Physicians are required to report occurrence

34. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Table 14.7 (1 of 2) “AIDS” to “Gonorrhea”; “Pertussis” to “Streptococcal Toxic Shock Syndrome”

35. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Table 14.7 (2 of 2) “Haemophilus influenzae” to “Mumps”; “Streptococcus pneumonaie” to “Yellow Fever”

36. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Centers for Disease Control and Prevention (CDC)  Morbidity: Incidence of a specific notifiable disease.  Mortality: Deaths from notifiable diseases.  Morbidity rate: Number of people affected in relation to the total population in a given time period.  Mortality rate: Number of deaths from a disease in relation to the population in a given time.

37. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Collects and analyzes epidemiological information in the United States.  Publishes Morbidity and Mortality Weekly Report (MMWR) www.cdc.gov Centers for Disease Control and Prevention (CDC)

38. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Exam Review  Read Chapter 14  Complete the Chapter 14 Quiz  Study the Chapter 14 Exam Notes  Review the following YouTube video on Malaria for a possible essay question on the Exam. Malaria