Chapter 11 - Principles of Disease and Epidemiology PathologyStudy of disease EtiologyStudy of the cause of a disease PathogenesisDevelopment of disease InfectionColonization of the body by pathogens DiseaseAn abnormal state in which the body is not functioning normally

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 Normal Microbiota and the Host

In one organism is benefited and the other is unaffected. In both organisms benefit. i.e. E. coli produces vitamin K (and some B) In parasitism, one organism is benefited at the expense of the other. Normal Microbiota and the Host:

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

Some normal microbiota are opportunistic pathogens. (vaginal yeast infection) Normal location: vagina, mouth (urinary tract infections) Normal location: large intestine

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Normal Microbiota and the Host: (hospital acquired diarrhea; may cause pseudomembranous colitis) Normal location: large intestine (a major cause of meningitis) Normal location: nasopharynx

are live microbes applied to or ingested into the body, intended to exert a beneficial effect. are chemicals used to promote growth of beneficial microbiota

Classifying Infectious Diseases SymptomA change in body function that is felt by a patient as a result of disease SignA change in body function that can be measured or observed as a result of disease. SyndromeA specific group of signs and symptoms that accompany a disease.

Classifying Infectious Diseases Communicable diseaseA disease that can be spread from one host to another. Contagious diseaseA disease that is easily spread from one host to another. Noncommunicable diseaseA disease that is not transmitted from one host to another. i.e. Chicken pox, measles, common cold are contagious i.e. Tetanus, Anthrax are noncommunicable

IncidenceNumber of new cases of a disease during a specific time period. PrevalenceTotal number of old and new cases of a disease during a specific time period. Sporadic diseaseDisease that occurs occasionally in a population. i.e. Eastern Equine Encephalitis Occurrence of Disease

Disease constantly present in a population. i.e. common cold Epidemic diseaseDisease acquired by many hosts in a given area in a short time. i.e. influenza, Pandemic diseaseWorldwide epidemic. i.e. influenza; AIDS Immunity in most of a population.

Acute diseaseSymptoms develop rapidly, but last a short time. i.e. influenza, cold Chronic diseaseDisease develops slowly, lasts a long time. i.e. Hepatitis B Subacute diseaseSymptoms between acute and chronic. i.e. gingivitis Latent diseaseDisease with a period of no symptoms when the “microbe” is inactive. i.e. genital herpes, Severity or Duration of a Disease

Local infectionPathogens limited to a specific area of the body. i.e. pulmonary Tuberculosis; Strep throat Systemic infectionAn infection throughout the body. Focal infectionSystemic infection that began as a local infection. i.e. Tuberculosis; Tetanus BacteremiaBacteria in the blood SepticemiaGrowth of bacteria in the blood Extent of Host Involvement

ToxemiaToxins in the blood ViremiaViruses in the blood Primary infectionInfection that causes the initial illness; often acute Secondary infectionOpportunistic infection after a primary (predisposing) infection Extent of Host Involvement

The Stages of a Disease Figure 14.5

Reservoirs of infection are the primary receptacles of the infectious agent. They may or may not be the direct source of the infection. Animal dogs, bats, racoons, foxes, other mammals Rocky Mountain Spotted Fever: ticks soil, infected cows, sheep, other animals may be transmitted to humans Reservoirs of Infection

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Reservoirs of Infection Human — HIV, gonorrhea Carriers may have inapparent infections or latent diseases Nonliving — Soil: Botulism (Clostridium botulinum), Tetanus (Clostridium tetani) Water: Cholera (Vibrio cholerae) Food: Tapeworm

Contact DirectRequires physical contact between infected and susceptible host IndirectSpread by DropletTransmission via airborne droplets; usually travel less than one meter Transmission of Disease

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

VehicleTransmission by an inanimate reservoir (food, water, air) VectorsInsects, especially fleas, ticks, and mosquitoes Insect carries pathogen on feet. Pathogen reproduces in vector. i.e. Malaria, Rocky Mountain Spotted Fever disease Transmission of Disease

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

Figure 14.7, 9 Are acquired as a result of a hospital stay 5-15% of all hospital patients acquire nosocomial infections A leading cause of death in U.S. Nosocomial (Hospital-Acquired) Infections

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

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Common Causes of Nosocomial Infections

Diseases that are new, increasing in incidence, or showing a potential to increase in the near future. Contributing factors: Evolution of new strains Inappropriate use of antibiotics and pesticides Antibiotic/pesticide resistant strains Changes in weather patterns (and global warming?) (and malaria) Emerging Infectious Diseases

Contributing factors: Modern transportation Ecological disaster, war, expanding human settlement Ebola Animal control measures Public Health failure Diphtheria Emerging Infectious Diseases

The study of where and when diseases occur How they’re transmitted How many infected Epidemiology Figure 14.11

Epidemiology John Snow Mapped the occurrence of cholera in London Ignaz Semmelweis Showed that hand washing decreased the incidence of puerperal fever Florence Nightingale1858Showed that improved sanitation decreased the incidence of epidemic typhus; backed by statistics

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DescriptiveCollection and analysis of data regarding occurrence of disease Snow AnalyticalComparison of two different diseased groups OR diseased and healthy groups 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

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 Table 14.7

Collects and analyzes epidemiological information in the U.S. Publishes Morbidity and Mortality Weekly Report (MMWR) Morbidity: incidence of a disease Mortality: death from disease Centers for Disease Control and Prevention (CDC)