Emerging Infectious Diseases Test 1

Evolution

The change in inherited traits over successive generations in populations of organisms. 

Genome

The complete set of DNA in an organism

Metabolic (Chemical) Reactions

Enzymes drive metabolic reactions

Cell

The smallest unit of life

Organism

A one-celled bacterium is an organism; Humans are multicellular organisms, composed of billions of cells

Population

Organisms of the same species that live in the same place, at the same time

Outbreak

A sudden rise or increase in the number of cases of a disease in a specific community, location, or season

Endemic

A regularly found, native, or constantly present disease

Epidemic

A sudden, unexpected increase in the number of disease cases in a region

Pandemic

A sudden, unexpected increase in the number of disease cases in a specific community, population, or region

Pathogen

Living or nonliving agent causing disease to its host

Virulence

Severity of disease

Susceptible

Infectious agent is novel or the host is immunocompromised

Resistant

The host has immunity (from a vaccine or from active immunity)

Reservoir

The reservoir of an infectious agent is the habitat in which the agent normally lives — humans, animals, or the environment

Vector

A vector is a living organism that transmits an infectious agent from an infected animal to a human or another animal

MIASMA Theory

Illness spread from “bad” air

Germ Theory of Disease

Theory that infectious diseases are caused by pathogenic microorganisms (“germs”). Four Postulates: 1) Association, 2)  Isolation, 3) Causation, 4) Reisolation

Association (Germ Theory)

The suspected pathogen is in all sick individuals

Isolation (Germy Theory)

The pathogen is isolated from all other potential causes

Causation (Germ Theory)

The isolated pathogen is introduced into a healthy host and symptoms occur

Reisolation (Germ Theory)

The same pathogen is re-isolated from the host

Antibiotic

A chemical or drug that inhibits bacteria growth

Sanitation

Provision of clean water and waste disposal (sewage)

Hygiene

Personal practices that help to maintain health and prevent the spread of infectious diseases

Morbidity

The rate of disease in a population

Mortality

The death rate from a disease

R naught

The number of healthy people a sick person will infect, on average

Humoral model of disease

Illnesses (like cholera) = an imbalance of the 4 hormones

When was germ theory proposed?

In the late 1800s, because of tiny molecules observed on microscopes that we now know as germs

What evidence suggested bats are a Nipah virus reservoir?

They had antibodies for it in their blood but a low morbidity rate

3 methods used to monitor bats (animal reservoir)

1. monitoring symptoms

2. Sequencing viral genomes

3. Detecting antibodies

Spill-over-event

A pathogen overcomes the species barrier (“jumps”)

Cell Theory

Cells are the basic unit of life:

1. All organisms are made of 1+ cell

2. Cells are the basic unit of structure and function

3. All cells come from cells

Metabolism

All the chemical processes that occur within a living organism in order to maintain life

Prokaryotic Cell

NO membrane-bound nucleus (one chromosome)

Eukaryotic Cell

Has a membrane-bound nucleus

Mutations and Natural Selection

Processes that contribute to evolution

Epidemiology

The study of the distribution and determinants of health-related states or events (including disease), and the application of this study to the control of diseases and other health problems

Microbiome

The collection of all microorganisms that naturally live on and inside the human body

Antigen

A structure (usually protein) that raises an immune reaction

Innate Immune System

A nonspecific response and immediate; white blood cells, physical barriers, and chemical barriers

Adaptive Immunity

Built in response to an antigen; Lymphocytes (T-cells, B-cells, memory cells)

Saliva & Tears

Contain lysozyme (an enzyme that breaks down the bacterial cell wall)

Antibody-Mediated Adaptive Immunity

Immunity built by B-cell antibodies

Lymphocytes

Specialized White Blood Cells involved in Adaptive Immunity

Antibodies

Specific to each pathogen. It blocks the receptor from binding to the host.

Memory B-Cells

On call for re-exposure

Primary Immune Response

From a first exposure: fast innate response, slow adaptive response

Secondary Immune Response

From a re-exposure: larger and faster immune response from memory immune cells

Immunity

Resistance created by response to an antigen

Commensalism

Only benefit the bacteria BUT the human host is not harmed

Mutualism

Both the host and the bacteria benefit

Parisitism

The bacteria benefits and harms the human host

Cell Tropism

The specific affinity of a virus or other pathogen for a particular cell type or tissue within a host organism

Microbial antagonism

Competition in the microbiome

Endogenous infections

Caused by opportunistic pathogens within the host

Residential (Microbiata)

Stable and predictable

Transient (Microbiata)

Influenced by hygiene

3 Tenets of the Germ Theory

1. Microbes can cause illnesses in the body

2. Microbes can be spread from one person to another

3. A specific microbe exists for each illness

Communicable disease

Can be spread from person to person

Non-communicable disease

Cannot be spread from person to person

Primary Disease

Cannot live outside of humans

Accidental Disease

Not associated with humans but can cause disease

Opportunistic Disease

Causes disease when host defenses are compromised

Pathogenicity

The ability to cause disease

Capsule

Virulence factor, protects the cell

Infective Dose (n)

The amount of microbes it takes to get sick

Adhesins

Virulence factor, helps the cell attach to the host

Exotoxins

Virulence factor, interferes with vital host functions

Antiphagocytic Factors

Virulence factors that help pathogens evade phagocytes

Phagocytosis

“Cell eating” by white blood cells

4 Stages of Microbial Disease

1. Incubation

2. Prodromal

3. Invasion

4. Convalescent

Incubation

Initial contact with disease

Prodromal Stage

Vague discomfort

Period of Invasion

Height of infectious disease

Convalescent Period

Symptoms decline

SIR Model

Susceptible, Infected, Recovered

Infectious Agent

Pathogen

Host

Infected organism

Vehicle

Food or water

Fomite

Inanimate objects that carry disease

Natural Host

A living organism that normally harbors a pathogen

Intermediate Host

Amplifying host (ex: birds with bird flu)

Common Source Epidemic

Many people are exposed to the same infectious agent at the same time (ex: food poisoning)

Propogated Epidemic

Spread of disease from person to person

Anthroponotic Reservoir

Humans

Zoonotic Reservoir

Animals

Sapronoses Reservoirs

Non-living; soil, water

Horizontal Disease Transmission

From individual to individual in a population

Vertical Disease Transmission

From parent to offspring

Enogenous Infections

From outside of the host

Hospital vs. Community Acquired Infection

Infected in the hospital or not

Microbe

Microscopic Organism

Apoptosis

A process where a cell kills itself (used to destroy abnormal cells)