Chapter 5: Descriptive Epidemiology: Patterns of Disease

Case reports (counts)

only learning about an individual patient, response to a rare disease/unsure of disease experiencing

Ex. rat bacteria causing back pain in 1 woman

Case series

collection of individuals with similar symptoms

Ex. 5 cases of hantavirus pulmonary syndrome

Cross-sectional studies

observational study, analyzing data from a population at a single point in time → done to estimate prevalence of disease through conducting surveys (ask about potential exposure and their outcomes/symptoms of disease)

Reasons for differences in MR/MB due to age

• Strength of immune system

• Accumulation of harmful exposures + protective factors

  • Life style choices

  • Engagement in risk behaviors

Female paradox

females more likely to get sick, males more likely to die

Reasons for differences in MR/MB due to sex

• Socialization of males vs. females

• Hormone levels

• Engagement in risk behaviors

• Occupational exposures

• Lack of certain sex organs

Married people experience ___ (higher/lower) rates of morbidity and mortality

lower

Healthy migrant effect

individuals who are able to migrate tend to be healthier/younger than those who can’t

Social causation explanation

 conditions associated with lower SES produce mental illness

Downward drift hypothesis

persons with severe mental disorders move to impoverished areas (often lack resources to stay in wealthier areas)

Acculturation hypothesis

as immigrants become acculturated to a host country, their health profile becomes for similar to individuals native born to that area

Hispanic/latino paradox

tend to have higher rates of morbidity but lower rates of mortality for those diseases compared to white individuals

Characteristics of a person examined (7)

1. Age

2. Sex

3. Marital status

4. SES

5. Race/ethnicity

6. Native vs. migrant

7. Religion

cyclic fluctuations

over period of a year, seasonal patterns

3 reasons for cyclic variations

• Changes in lifestyle of host (behavioral)

• Seasonal climatic changes (driving behavior changes)

• Virulence of the infectious agent for a comm. Disease

Common source epidemic

focus on time aspect of an epidemic, outbreak due to exposure to noxious influence that is common to the individuals in the group

Identify source/where health event is coming from, determine who got sick, determine if all were exposed to the agent

Point epidemic

1. wrong place at wrong time, group of people share common source of infection

• Can determine what exposed to

• Only last 1 incubation period

ex. food borne illness

Continuous common source epidemic

outbreak lasts longer than single incubation period, common source of exposure harder to determine = more incubation periods

Propagated epidemic

transmission from infected person to person

Curve: long in duration, lasts more than 1 incubation period, no external source identified

Secular time trends

longer than 1 year, reflect public health trends over longer period of time

Case clustering

identifying all clusters/cases of a disease, done based on an event

Temporal clustering

concentration of a disease to a specific time (ex. post partum depression)

spatial clustering

concentration of disease in a specific geographic area (ex. cholera epidemic in London)