Microbiology Ch14: Pathology, Infection, Disease

pathology

study of disease

etiology

cause of disease

Pathogenesis

development of disease

infection

invasion/colonization of the body by pathogens

infectious disease

infection results in any change in the state of health

Human microbiome project

analyzes relationship between microbial communities on the body & human health

Normal microbiota (normal flora)

permanently colonize the host & dont cause disease under normal conditions

When do normal microbiota being to develop

in utero

factors influencing normal microbiota (5)

- nutrients

- physical & chem factors

- mechanical factors

- body's defense against microbes

- personal lifestyle (hygiene, diet, age, geography, etc.

symbiosis

relationship between normal microbiota & host

commensalism

1 organism benefits & the other is unaffected

mutualism

both organisms benefit

parasitism

1 organism benefits at the expense of the other

koch's postulate

4 criteria used to determine if a specific microbe is the cause of a disease

koch's postulate criteria (4)

- The same pathogen must be present in every case of the disease

- The pathogen must be isolated from the diseased host and grown in pure culture

- The pathogen from the pure culture must cause the disease when it's inoculated into a healthy, susceptible laboratory animal

- The pathogen must be isolated from the inoculated animal and must be shown to be the original organism

3 ways of classifying infectious disease

- symptoms

- signs

- syndrome

symptoms

changes in body function that are felt by a patient as a result of disease

signs

changes in a body that can be measured or observed as a result of disease

syndrome

a specific group of signs and symptoms that accompany a disease

communicable disease

a disease that is spread from 1 host to another

contagious disease

diseases that are easily and rapidly spread from one host to another

noncommunicable disease

a disease that is not spread from one host to another

incidence

a number of people who develop a disease during a particular time period for first time

prevalence

number of people who develop a disease at a specified time, regardless of when it first disappeared (old and new cases)

Types of diseases indicated by dif levels of incidence/prevalence (4)

- sporadic

- endemic

- epidemic

- pandemic

sporadic disease

disease that occurs only occasionally

endemic disease

disease constantly present in a population

epidemic disease

disease acquired by many people in a given area in a short time

pandemic disease

worldwide epidemic

duration

avg. time that individuals have a disease from diagnosis until they are either cured or die

Types of diseases based on duration (5)

- acute

- chronic

- subacute

- latent

- herd immunity

acute disease

symptoms develop rapidly but has a short duration

chronic disease

symptoms develop slowly, likely to last for a long period

subacute disease

intermediate between acute & chronic

latent disease

causative agent is inactive for a time but then activates and produced symptoms

herd immunity

immunity in most of a population

types of extent of host involvement (3)

- local infection

- systemic (generalized) infection

- focal infection

local infection

pathogens are limited to a small area of the body

systemic infection

infection throughout the body

focal infection

systemic infection that began as a local infection

sepsis

toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins from a focus of infection

bacteremia

bacteria in the blood

septicemia

aka blood poisoning; growth of bacteria in the blood

toxemia

toxins in the blood

viremia

viruses in the blood

primary infection

acute infection that causes the initial illness

secondary infection

infection after a primary (predisposing) infection

subclinical disease

no noticeable signs or symptoms (inapparent infection)

stages of disease

- period of illness (most severe)

- acme (peak illness)

- period of decline (signs & symptoms)

types of reservoirs of infections (3)

- human

- animal

- nonliving

human reservoirs

Carries may have inapparent infections or latent diseases

animal reservoirs

Zoonoses are diseases transmitted from animals to humans

nonliving reservoirs

Soil and water

types of contact transmission (4)

- direct contact

- congenital

- indirect contact

- droplet

direct contact transmission

requires close associated between the infected and a susceptible host

congenital transmission

transmission from mother to fetus or newborn at birth

indirect contact transmission

spreads to a host by a nonliving object called a fomite

droplet transmission

transmission via airborne droplets less than 1 meter

vehicle transmission (3)

transmission by an inanimate reservoir (airborne, waterborne, foodborne)

vectors

transmission by Arthropods, especially fleas, ticks, and mosquitoes

mechanical transmission of vectors

arthropod carries pathogen on its feets

biological transmission of vectors

pathogen reproduces in the vector; transmitted via bites or feces

healthcare-associated infections (HAIs) (nosocomial infections)

Acquired while receiving treatment in health care facility (can be highly resistant)

types of control of associated infections

- universal precautions

- standard precautions

universal precautions

- Designed to reduce the transmission of microbes in health care and long-term care settings

- Protect patients, residents, staff, visitors from contact with pathogens

standard precautions

- Applied to every person, every time, all levels of healthcare

- Include hand hygiene, personal protective equipment, respiratory hygiene, cough etiquette, disinfection of equipment, environment cleaning & disinfection, safe injection practices, patient placement

emerging infectious diseases

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

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

contributing factors of emerging infectious diseases (7)

- Genetic recombination

- evolution of new strains

- widespread use of antibiotics and pesticides

- changes in weather patterns

- modern transportation

- insect vectors

- ecological disaster, war, expanding human settlement

epidemiology

Study of where & when diseases occur and how they are transmitted in populations

epidemiologists (4)

- Determine etiology of a disease

- Identify other important factors concerning the spread of disease

- Develop methods for controlling a disease

- Assemble data and graphs to outline incidence of disease

descriptive epidemiology

collection and analysis of data

analytical epidemiology

analyzes a particular disease to determine its probable cause

experimental epidemiology

involves a hypothesis and controlled experiments

clinical trial

test and control group

centers for disease control & prevention (CDC)

- Collects and analyzes epidemiological info in the US

- Publishes morbidity and mortality weekly report (MMWR)

morbidity

incidence of a specific notifiable disease

mortality

deaths from notifiable diseases

notifiable infectious diseases

diseases in which physicians are required to report occurrence

morbidity rate

# of people affected in relation to the total population in a given time period

mortality rate

# of deaths from a disease in relation to the population in a given time