Chapter 16 (Disease and Epidemiology)

List some nonliving reservoirs for pathogens.

Soil and water in the environment.

Explain the difference between endemic and epidemic disease.

Endemic - diseases that are constantly present (often at a low level) in a population within a particular geographic region (ex. malaria is endemic to some regions of Brazil, but is not endemic to the United States). Epidemic - diseases for which a larger than expected number of cases occurs in a short time within a geographic region (ex. influenza).

Explain the difference between incidence and prevalence.

Incidence of HIV (the number of new cases reported each year) Prevalence (the total number of cases each year) They can be expressed via graph or as a rate/proportion for a given population.

Describe how morbidity and mortality rates are expressed..

Morbidity or total morbidity is expressed in numbers of indviduals without reference to the size of the population. Morbidity rate can be expressed as the number of diseased indivudals out of a standard number of individuals in the population, such as 100,000, or as a percent of the population.

Explain the difference between a passive carrier and an active carrier.

Passive - contaminated with the pathogen and can mechanically transmit it to another host; however, a passive carrier is not infected (ex. health-care professional who fails to wash his hands after treating a patient harboring an infectious agent, thus transmitting the pathogen to another patient who becomes infected). Active - infected individuals who can transmit the disease to others; may or may not exhibit signs or symptoms of infection (ex. active carriers may transmit the disease during the incubation period (before showing signs or symptoms) or period of convalescence (after symptoms have subsided).

Explain the difference between prevalence and incidence of disease.

Prevalence - number, or proportion, of individuals with a particular illness in a given population at a point in time. Incidence - number or proportion of new cases in a period of time.

Describe how the observations of John Snow, Florence Nightingale, and Joseph Lister led to improvements in public health.

Snow - determined the source of a cholera outbreak in London (found the causative agent as a contaminated water source). Nightingale - compiled data on causes of mortality in soldiers, leading to innovations in military medical care. Lister - showed that surgical wound infection rates could be dramatically reduced by using carbolic acid to disinfect surgical tools, bandages, and surgical sites.

Explain the difference between sporadic and endemic disease.

Sporadic - diseases that are seen only occasionally and usually without geographic concentration (ex. tetanus, rabies, and plague). Endemic - diseases that are constantly present (often at a low level) in a population within a particular geographic region (ex. malaria is endemic to some regions of Brazil, but is not endemic to the United States).

Distinguish the characteristics of sporadic, endemic, epidemic, and pandemic diseases.

Sporadic - diseases that are seen only occasionally and usually without geographic concentration (ex. tetanus, rabies, and plague). Endemic - diseases that are constantly present (often at a low level) in a population within a particular geographic region (ex. malaria is endemic to some regions of Brazil, but is not endemic to the United States). Epidemic - diseases for which a larger than expected number of cases occurs in a short time within a geographic region (ex. influenza). Pandemic - epidemic that occurs on a worldwide scale (ex. HIV/AIDS and novel influenza virus strains).