BSC 438 Chapter 1

Disease

a condition of the living animal or plant body or one of its parts that impair normal functioning and is typically manifested by distinguishing signs and symptoms

Outbreak

localized area of a disease

Epidemic

regional area of a disease

Pandemic

worldwide area of a disease

What paleopathological evidence do we have that shows that we have suffered from infections for millions of years?

brucellosis in a male skeleton that lived over 2 million years ago

Pathogen

microbial agent of disease (may be used synonymously with parasite)

Ectoparasite

lives on the surface of the host

Endoparasite

lives inside the host's body

When does an infection occur?

a pathogen or parasite enters or begins to grow on a host

Primary Pathogens

cause disease in healthy hosts

Opportunistic pathogens

cause disease only in immunocompromised patients

Pathogenicity

refers to an organisms ability to cause disease

defined in terms of infectivity and virulence

Infectivity

how easily an organism causes disease

Virulence

measure of the degree or severity of a disease

What are the reasons for increases in emerging and reemerging infectious diseases?

Decrease in vaccination rates, antibiotic resistance, climate change, increased population density, habitat destruction, medication. Practices that lead to immunosuppression, rapid global transportation, and lack of funding

Epidemiology

science that evaluates the occurrence, determinants, distribution, and control of health and disease in a defined human population

study of disease determinants and distribution

Health

condition in which organism (and all its parts) performs its vital functions normally

What is the primary goals of the CDC

Works to protect public health and safety by:

developing and applying disease prevention and control, environmental health, and health promotion and health education activities to improve the health of the people

Worldwide counterpart: World Health Organization

Purpose of NIAID

funds research to understand, treat, and prevent infectious, immunologic, and allergic diseases

What’s the difference between the NIAID and the CDC?

CDC- prevention and control of disease

NIAID- research into understanding of disease that may leaad to prevention and control

Index Case

first case of a particular disease which can be used to identify everyone who has had contact

Index Case for the SARS outbreak in Singapore

woman who stayed in a hotel in Hong Kong who was infected by a physician who had stayed in the room prior to this woman

What did John Snow investigate?

An outbreak of cholera

What did John Snow originally think was the source of cholera?

He believed it was in the water and not miasma in the air

What did John Snow discover and what was his solution?

He found that the broad street pump was contaminated and when they removed the handle, it stopped

Sporadic disease

occurs occasionally and at irregular intervals

endemic disease

maintains a relatively steady low-level frequency at a moderately regular interval

Hyperendemic disease

a disease that is constantly present at a high incidence and/or prevalence rate

outbreak

sudden, unexpected occurence of disease; usually focal or in a limited segment of population

Epidemic

a sudden increase in frequency above expected number

index case-first case in an epidemic

Pandemic

increase in disease occurrence within a large population over a wide region (usually worldwide)

worldwide disease with significant public health implications

What is the purpose of epidemiology?

to obtain necessary data to prevent and control disease through Community Health Intervention

Distribution

frequency and pattern of health events

determinants

variables that directly or indirectly influence the frequency or distribution of a disease, not just the causative agent

a determinant can be anything that meets the criterion of altering one’s risk of disease: behaviors, demographics, genetics, environmental contaminants

Etiology

all determinants of a particular disease

What comprises determinants

causative agent, host susceptibility, opportunity for exposure, vectors, transmissibilty

What are intrinsic determinants?

infectivity, virulence, pathogenicity, age, gender

What are extrinsic determinants?

climate, affects of man (building dams, mass transit)

Frequency

Number of cases and rate or risk

Used to describe how common an illness is with reference to the size of the population and a measure of time

two main measures: prevalence and incidence

Rate (risk)

number of cases divided by population size

What is the importance of spatial arrangement?

can help identify determinants

Incidence

the number of new cases of an infection within a specified period

number of cases per thousand or million individuals per time period

Prevalence

percentage of total cases of currently infected individuals in a particular population