Epidemiology and Infectious Diseases Quiz

Health Statistics and Epidemiology

• This presentation covers health statistics and epidemiology.
• The presenter is Ma. Veronica C. Legaspi, RN, MPH.

Demography

• Demography is the study of population size, composition, and distribution in space.
• Population refers to the number of people in a given place or area, during a specific time.
• Household is a person or group of related or unrelated persons who live together in the same dwelling unit, share the same housekeeping arrangements and who are considered a single unit.
• The head of the household is usually an adult male or female.
• Sources of demographic information:
  • Census: An official and periodic enumeration of the population. It can be De Jure or De Facto.
  • Sample surveys
  • Registration

Population Size

• Information on population changes is important for prioritizing and strategizing health programs and interventions for the community.
• Population size is also helpful for assessing possible health factors.

Measuring Population Changes

• Two methods are used to measure population changes:
  • Comparing the Crude Birth Rate (CBR) and Crude Death Rate (CDR)
  • Comparison by Census

Birth Rate

• The average number of live births in a year for every 1000 people in a total population.
  • Philippines: 22.28
  • Japan: 6.95
  • United States: 12.28
  • Canada: 10.17
  • Somalia: 37.98

Death Rate

• The average number of deaths in a year for every 1000 people in a total population.
  • Philippines: 6.41
  • Japan: 11.59
  • United States: 8.38
  • Canada: 8.12
  • Somalia: 11.62

Natural Increase

• The difference between the number of births and deaths occurring in a population in a specific period of time. -NI = Births – Deaths (Specified Year)

Crude Birth Rate

• A measure of one characteristic of the natural growth or increase of population.
• Example calculations (using Kidapawan City, North Cotabato data):
  • Number of births: 4567
  • Total population: 125,447
  • CBR: 36.4 per 1000 population

Crude Death Rate

• A measure of one characteristic of mortality from all causes which may result in a decrease of population
  • Example calculations (using Balo-i, Lanao Del Norte data):
    • Number of deaths: 5634
    • Total population: 192,310
    • CDR: 29.3 per 1000 population

Rate of Natural Increase

• The difference between the Crude Birth Rate (CBR) and Crude Death Rate (CDR) in a specific period of time
  • NRI = CBR – CDR

Demographic Indicators

• Population statistics
  • Sex ratio
  • Dependency ratio
  • Density.
• Population size
  • Vital Statistics
    • Birth Rate (BR)
    • Death Rate (DR)

Population Composition

• Sex Composition
• Age Composition
• Age and Sex Composition

Sex Ratio

• The number of females per 1000 males in the population.
• Calculation: (Number of Females / Number of Males) x 1000
• Example calculation using Philippines data:
  • Males: 1,996,355
  • Females: 1,930,234
• Result: 967 females per 1000 males

Age Composition

• Median: The age in the middle of a ranked list when the ages are arranged from smallest to largest.
• Example ages: 8, 9, 10, 10, 12, 13, 65. Median = 10

Age and Sex Composition

• Charts visualize Philippines age and sex composition in 2018 (pyramid type)

Population Distribution

• Urban Rural Distribution - proportion of people living in urban or rural areas.
• Crowding Index - describes how easy a communicable disease is to transmit from one host to another.
• Population Density - how congested a place is and implies the adequacy of basic health services

Vital Health Statistics

• Systematic study of vital events such as births, illness, marriages, divorces/separations, and deaths.

Nurse Function

• Collects data
• Tabulates data
• Analyses & interprets data
• Evaluates data
• Recommends redirection and/or strengthening of specific areas of health programs

Rates and Ratios

• RATE: Relationship between a vital event and those exposed in a given area and specific time period.
• RATIO: Describes the relationship between two numerical quantities or measures of events.
• CRUDE/GENERAL RATES: Relates to the total living population.
• SPECIFIC RATES: Relates to a specific population class or group.

Uses of Vital Statistics

• Planning human development
• Dynamics of reproduction
• Life-tables
• Risks of dying
• Population growth dynamics
• Population projections
• Monitoring & evaluating interventions
• Provision of services for vulnerable populations (single mothers & children),
• Regional & urban/rural comparisons,
• Allocation of resources (e.g., health care, education, social security).

Vital Statistics Calculations

• Crude Birth Rate (CBR):
  • CBR = (Number of live births in a year / Estimated mid-year population) × 1000
• Crude Death Rate (CDR):
  • CDR = (Number of deaths in a year / Estimated mid-year population) × 1000
• Infant Mortality Rate (IMR):
  • IMR = (Number of deaths of infants under one year of age / Total live births) × 1000
• Maternal Mortality Rate (MMR):
  • MMR = (Number of maternal deaths from pregnancy-related causes / Number of live births) × 1000
• Fetal Death Rate (FDR):
  • FDR = (Number of fetal deaths / Total live births) × 1000
• Neonatal Death Rate (NDR):
  • NDR = (Number of neonatal deaths / Total live births) × 1000
• Attack Rate (AR):
  • AR = (Number of persons acquiring the disease / Number of persons exposed to the same disease in the same year) × 100

Attack Rate Examples

- Calculations for different scenarios are shown in a table of cases of illness and non-illness grouped by food eaten.

Case Fatality Rate (CFR)

• Killing power of a disease
• CFR = (Number of registered deaths from a specific disease in a given year / Number of registered cases from a specific disease in the same year) × 100

Incidence and Prevalence

• INCIDENCE RATE - Frequency of occurrence during a given period of time. It only deals with new cases.
  • IR = (Number of new cases of a particular disease registered during a specific period of time / Population at risk of developing the disease) × 100
• PREVALENCE RATE - Proportion of a population that exhibits a particular disease at a particular time. It deals with new and old cases.
  • PR = (Number of new and old cases of a certain disease registered at a given time / Number of persons examined at the same time) × 100

Introduction to Basic Epidemiology

• Definition of Epidemiology
• Definition of Field Epidemiology
• Core Epidemiology functions
  • Public Health Surveillance
  • Field Investigation
  • Analytic Studies
  • Evaluation
  • Linkages
  • Policy Development

Descriptive Epidemiology

• Characterizes the occurrence of disease as time, place, and person while looking at risk factors which influences the disease/situation.

The W's of Descriptive Epidemiology

• What: Health issue of concern
• Who: Person
• Where: Place
• When: Time

Epidemic Curve

• Analyzing disease occurrence from different points of view. Example chart of Cholera in Philippines from March 10th to June 28th, 2012.

Epidemiological Triad

• Describes the causation of a disease using an agent, host, and environment triangle.

Infectious Disease Agents

• Infectious microbe: Can be bacteria, viruses, mycoses (fungi), protozoa, and helminths.
• Characteristics of infectious disease agents
  • Infectivity
  • Pathogenicity
  • Virulence
  • Toxigenicity
  • Resistance
  • Antigenicity

Host

• The human who can get the disease. Host factors include age, race, sex, socioeconomic status, behaviors (smoking, drug use, lifestyle), genetic composition, nutritional and immunologic status, anatomic structure, presence of disease, and medications.

Environment

• Extrinsic factors: geology, climate, biological factors (e.g., insects), socioeconomic factors (e.g., crowding, sanitation), and availability of health services. It refers to factors outside the host that impact the agent of infection.

Test your knowledge on key concepts in epidemiology and infectious diseases with this quiz. Questions cover pathogenicity, virulence, intrinsic factors affecting host susceptibility, and the role of vital statistics in public health. Perfect for students and professionals looking to refresh their understanding of infectious disease dynamics.