Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture Slide Presentation prepared by Christine L. Case Microbiology B.E Pruitt & Jane J. Stein AN INTRODUCTION EIGHTH EDITION TORTORA FUNKE CASE Chapter 14 Principles of Disease and Epidemiology

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Principles of Disease and Epidemiology PathologyStudy of disease EtiologyStudy of the cause of a disease PathogenesisDevelopment of disease InfectionColonization of the body by pathogens HostOrganism that shelters and supports growth of pathogens DiseaseAn abnormal state in which the body is not functionally normally Define pathogen, etiology, infection, and disease.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Transient microbiota may be present for days, weeks, or months, but then disappear Normal microbiota permanently colonize the host Symbiosis is the relationship between normal microbiota and the host Animals/humans are usually germ-free in utero, but colonization soon begins after birth Normal Microbiota and the Host Define normal and transient microbiota.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Representative normal microbiota Bacteria on skinPlaque on teeth enamelBacteria in large intestine

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings In commensalism, one organism is benefited and the other is unaffected. (+ 0) In mutualism, both organisms benefit. (+ +) In parasitism, one organism is benefited at the expense of the other. (+ -) Some normal microbiota are opportunistic pathogens if they gain access to other parts of the body. Microbial antagonism – normal microbiota can prevent pathogens from causing infections Cooperation among microorganism species can make it possible for one to cause disease or greater symptoms Normal Microbiota and the Host: Compare commensalism, mutualism, and parasitism, and give an example of each.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 14.2 Locations of normal microbiota on and in the human body If E. coli gains access to other body sites than large intestine, it becomes an opportunistic pathogen AIDS often accompanied by opportunistic infections (low immunity) Normal Microbiota and the Host: Contrast normal and transient with opportunistic microbes.

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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. Normal Microbiota and the Host:

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Koch's Postulates are used to prove the cause of an infectious disease. Koch’s Postulates Figure List Koch's postulates.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Koch's Postulates are used to prove the cause of an infectious disease. 1.Same pathogen present in every case of disease 2.Pathogen isolated from diseased host and grown in pure culture 3.Pathogen from pure culture must cause disease when in healthy host animal 4.Pathogen reisolated from inoculated animal is original organism. Koch’s Postulates Figure Exceptions: Etiologies of viruses and some bacteria not grown on artificial media Tetanus which has unequivocal signs Pneumonia caused by variety of microbes Some pathogens causing several diseases HIV causes disease in humans only

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Classifying Infectious Diseases SymptomA subjective change in body function that is felt by a patient as a result of disease SignA change in a body that can be measured or observed as a result of disease. (measurable) SyndromeA specific group of signs and symptoms that accompany a disease.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Classifying Infectious Diseases Communicable diseaseA disease that is easily spread from one host to another. (direct/indirect) Contagious diseaseA disease that is easily spread from one host to another. Noncommunicable diseaseA disease that is not transmitted from one host to another. Differentiate between a communicable and a noncommunicable disease. Categorize diseases according to frequency of occurrence. Define herd immunity.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings IncidenceFraction of a population that contracts a disease during a specific time. PrevalenceFraction of a population having a specific disease at a given time. Sporadic diseaseDisease that occurs occasionally in a population. Endemic diseaseDisease constantly present in a population. Epidemic diseaseDisease acquired by many hosts in a given area in a short time. Pandemic diseaseWorldwide epidemic. Herd immunityImmunity in most of a population. Occurrence of Disease

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Acute diseaseSymptoms develop rapidly Chronic diseaseDisease develops slowly Subacute diseaseSymptoms between acute and chronic Latent diseaseDisease with a period of no symptoms when the patient is inactive Severity or Duration of a Disease Categorize diseases according to severity.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Reported AIDS cases in U.S. Notice 12 years for first 250 K cases, then 3 and 5 years for next 250

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Local infectionPathogens limited to a small area of the body Systemic infectionAn infection throughout the body Focal infectionSystemic infection that began as a local infection BacteremiaBacteria in the blood SepticemiaGrowth of bacteria in the blood Extent of Host Involvement

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings ToxemiaToxins in the blood ViremiaViruses in the blood Primary infectionAcute infection that causes the initial illness Secondary infectionOpportunistic infection after a primary (predisposing) infection Subclinical diseaseNo noticeable signs or symptoms (inapparent infection) Extent of Host Involvement

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Make the body more susceptible to disease Gender Short urethra in females Inherited traits such as the sickle-cell gene Climate and weather Fatigue Age Lifestyle Chemotherapy Predisposing Factors Identify four predisposing factors for disease. Put the following terms in proper sequence in terms of the pattern of disease: period of decline, period of convalescence, period of illness, prodromal period, incubation period.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 1.Incubation period: time interval between initial infection and first appearance of signs/symptoms 2.Prodromal period: appearance of first mild signs/symptoms 3.Illness period: disease at height and all signs/symptoms apparent 4.Decline period: signs and symptoms subsiding 5.Convalescence period: body returns to prediseased state Development of a Disease

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The Stages of a Disease Figure 14.5

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 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 or water Reservoirs of Infection Define reservoir of infection. Contrast human, animal, and nonliving reservoirs, and give one example of each.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Contact DirectRequires close association between infected and susceptible host IndirectSpread by fomites (inanimate objects) DropletTransmission via airborne droplets Vehicle By medium like water, food, air AirborneCarried on water droplets or dust > 1 m ArthropodVectors carry pathogens between hosts Transmission of Disease Explain four methods of disease transmission.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Transmission of Disease Figure 14.6a & 8 ContactDroplet transmission

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Zoonoses are diseases that affect wild and domestic animals and can be transmitted to humans. Zoonoses

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VehicleTransmission by an inanimate reservoir (food, water) VectorsArthropods, especially fleas, ticks, and mosquitoes MechanicalArthropod carries pathogen on feet BiologicalPathogen reproduces in vector Transmission of Disease

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Transmission of Disease Figure 14.6b, c VehiclesVectors

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Figure 14.7, 9 Are acquired as a result of a hospital stay 5-15% of all hospital patients acquire nosocomial infections Nosocomial (Hospital-Acquired) Infections Define nosocomial infections and explain their importance.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Relative frequency of nosocomial infections

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Common Causes of Nosocomial Infections Percentage of nosocomial infections Percentage resistant to antibiotics Gram + cocci34%28%-87% Gram – rods32%3-34% Clostridium difficile17% Fungi10%

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List several methods of disease transmission in hospitals.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Compromised host is one whose resistance to infection is impaired by disease, therapy, or burns. Two principal conditions can compromise the host: 1.broken skin or mucous membranes 2.Suppressed immune system. Chain of transmission 1.Direct contact between staff and patients 2.Fomites (inanimate) like catheters, syringes, respiratory devices Compromised Host Define compromised host.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 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 Emerging Infectious Diseases (EIDs) List five probable reasons for emerging infectious diseases, and name one example for each reason.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Contributing factors: Modern transportation West Nile virus Ecological disaster, war, expanding human settlement Coccidioidomycosis Animal control measures Lyme disease Public Health failure Diphtheria Emerging Infectious Diseases

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The study of where and when diseases occur (transmission, incidence, frequency) Epidemiology Figure 14.11

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Epidemiology History John Snow Mapped the occurrence of cholera in London Ignaz Semmelweis Showed the hand washing decreased the incidence of puerperal fever Florence Nightingale1858Showed that improved sanitation decreased the incidence of epidemic typhus

Copyright © 2004 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 Define epidemiology and describe three types of epidemiologic investigation. Epidemiology

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Collects and analyzes epidemiological information in the U.S. Publishes Morbidity and Mortality Weekly Report (MMWR) Morbidity: incidence of a specific notifiable disease Mortality: deaths from notifiable diseases Morbidity rate = number of people affected/total population in a given time period Mortality rate - number of deaths from a disease/total population in a given time Centers for Disease Control and Prevention (CDC) Identify the function of the CDC. Define the following terms: morbidity, mortality, and notifiable disease.