Preventing%20Disease

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Chapter 20Preventing Disease
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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

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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)
• Statistics
• Incidence rate
• rate of acquiring a disease during certain period
• Prevalence rate
• rate of having certain disease at specific time

Figure 20.2
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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

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Descriptive Epidemiology

• geographical distribution of tuberculosis

• Ethnic distribution of tuberculosis

Figure 20.3
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Surveillance Epidemiology

• Example
• tracking smallpox outbreaks
• use of vaccination programs to limit spread of
  disease
• result in eradication of smallpox worldwide

Figure 20.4
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Field Epidemiology

• Investigative work
• gather information
• collecting samples
• infected vectors or animals
• interviewing individuals
• interpreting the data

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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

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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

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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
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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

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Acellular vaccine

• Anti-toxin
• Toxoid
• purified exotoxin
• inactivated by heat or chemical
• Tetanus
• Diphtheria

Figure 20.7
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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

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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