Disease & Epidemiology

• Epidemiology def:


  study of where and when diseases occur and how they are transmitted in populations
• What organization oversees public health at a global level?

  World health organization
• What organization oversees public health at a national level?

  Centers for disease control (CDC)
• Notifiable disease def:


  physicians are required to report, of public health important on a national level
• Mortality def:


  deaths from notifiable disease
• Morbidity def:


  incidence of a specific notifiable disease
• Prevalence of disease def:

  Number of cases of a disease in a specific population at a particular time point or over a specific period of time
• Incidence of disease def:

  number of new cases of a disease occurring in a specific population over a particular period of time
• Characteristics of sporadic disease:

  Uncommon, occur only occasionally, and affect only a relative number of persons
• Characteristics of endemic diseases:

  constantly present in a certain percent of the population
• Characteristics of epidemic diseases:

  acquired by many people in a given area, causing damage to living organisms within a short period of time
• Characteristics of pandemic diseases:

  affects a large geographical area
• Types of epidemiological studies and their importance:

  Observational: data gathered from study participants through measurements, or answers to question in interviews

  -only measures between disease occurrence and possible casusative agents

  -descriptive, analytical, retrospective, case-control, and cross-section study

  Experimental: uses lab or clinical studies, study subjects manipulated to study connections between diseases and potential causative agents or to assess treatments
• Etiology def:


  connects a disease to a pathogen
• What are the common disease reservoirs?

  Human: passive carriers may have apparent infections or latent diseases

  -active carrier is an infected individual who can transmit the disease to others

  Animal: zoonoses are diseases transmitted from animals to humans

  Nonliving: soil and water
• How can diseases be transmitted?

  Contact transmission:

  -direct: requires close association between infected and host

  -indirect: spread to host by a nonliving object called fomite

  -droplet: via airborne droplets less than 1 meter

  Vehicle transmission:

  -transmission by inanimate reservoir

  -waterborne, airborne, foodborne

  Vectors:

  -flees, ticks, mosquitos (arthropods)

  1. Mechanical: arthropod carries pathogens on feet

  2. Biological: pathogen reproduces in vector, transmitted via bites or feces
• Nosocomial infections and importance:

  acquired while receiving treatment in a health care facility
• Compromised host def:


  an individual whose resistance to infection is impaired by disease, therapy, or burns
• What factors contribute to emerging and re-emerging diseases?

  -previously undetected or unknown infectious agents

  -known agents have spread to new geographic locations or new populations

  -previously known agents whose role in specific disease has previously gone unrecognized

  -disease that are new, increasing in incidence, or showing a potential to increase in near future

  -most zoonotic, of viral origin, and likely to be vector-borne