1. © 2004 Wadsworth – Thomson Learning Chapter 20 Preventing Disease

2. © 2004 Wadsworth – Thomson Learning Epidemiology Study of occurrence of disease when where how transmitted –Epidemic disease outbreak –affects many people –Pandemic worldwide epidemic –Endemic always present –Sporadic occur only occasionally

3. © 2004 Wadsworth – Thomson Learning Methods of Epidemiology Sources of information –Public record –Questionnaires –Surveys –Hospital records Notifiable diseases –Physicians required to report certain diseases Local agencies report to state and CDC Morbidity and Mortality Weekly Report (MMWR link)(MMWR link) Statistics –Incidence rate rate of acquiring a disease during certain period –Prevalence rate rate of having certain disease at specific time Figure 20.2

4. © 2004 Wadsworth – Thomson Learning Types of Epidemiological Studies Descriptive –general information about a disease incidence prevalence death rates Surveillance –tracks epidemics monitor potential epidemic situations follow progress of epidemic assist in prevention or eradication Field and Hospital –investigate source and spread of disease outbreaks

5. © 2004 Wadsworth – Thomson Learning Descriptive Epidemiology geographical distribution of tuberculosis Ethnic distribution of tuberculosis Figure 20.3

6. © 2004 Wadsworth – Thomson Learning Surveillance Epidemiology Example –tracking smallpox outbreaks –use of vaccination programs to limit spread of disease –result in eradication of smallpox worldwide Figure 20.4

7. © 2004 Wadsworth – Thomson Learning Field Epidemiology Investigative work –gather information collecting samples –infected vectors or animals interviewing individuals interpreting the data

8. © 2004 Wadsworth – Thomson Learning Hospital Epidemiology Nosocomial infections –hospital acquired infection immunocompromised patients invasive medical procedures development of antibiotic resistance –examples urinary tract infections--catheterizatoin surgical wound infections pneumonia skin infections

9. © 2004 Wadsworth – Thomson Learning Public Health Public health organizations –Local health departments –State health departments –United States Public Health Service (USPHS) Center for Disease Control and Prevention (CDC) –World Health Organization

10. © 2004 Wadsworth – Thomson Learning Public Health Areas of impact –Clean water –Clean food –Personal cleanliness –Insect control –Prevention of sexually transmissible diseases –Prevention of respiratory diseases Figure 20.6

11. © 2004 Wadsworth – Thomson Learning Immunization Active immunization –Develop immunity without disease Vaccinations –attenuated microorganism or virus alive but incapable of causing disease –inactivated killed by chemicals –acellular contain only antigen molecules; toxoids –DNA vaccines contain only DNA which encodes a protein

12. © 2004 Wadsworth – Thomson Learning Acellular vaccine Anti-toxin –Toxoid purified exotoxin inactivated by heat or chemical –Tetanus –Diphtheria Figure 20.7

13. © 2004 Wadsworth – Thomson Learning Attenuated and Inactivated Attenuated –Live organisms –genetically altered –limited infection –advantages organism multiples stimulates strong immunity long-lasting immunity Inactivated –killed organisms chemicals –destroys antigens –immunity not long lasting –require multiple injections

14. © 2004 Wadsworth – Thomson Learning Passive immunization Protection without developing immunity –gamma globulin antibodies from pooled serum –human or animal general or special preparations –advantages protection for immunocompromised immediate protection temporary protection while immunity develops –disadvantages serum sickness (animal preparations) no lasting immunity