Host

is an organism that shelters and supports the growth of pathogens

Disease

A normal state in which part or all of the body is not properly adjusted or is incapable of performing normal functions

Pathogens

Disease causing microorganisms

Infection

the invasion and growth of pathogens in the body

Pathology

the scientific study of disease

PATHOLOGY is concerned with

eitiology (cause), pathogens (development) and effects of disease.

Animals including humans

are usually germfree in utero

Microorganisms begin colonization

in and on the surface of the body soon after birth

Transmission of formites

involve close physical contact between the host

and source of the disease

Transient Microbiota

 are microbes that are present for various periods

and then disappear

The phenomenom called

Microbial antagonism

is where

Normal microbiota can prevent pathogens

from causing and infection

Symbiosis

Normal Microbiota and the host living together

what are the three types of Symbiosis

commensalism (one organism benefits and the other is unaffected)

mutualism (both organisms benefit)

Parasitism (one organism benefits and one is harmed)

Oppurtunistic Pathogens

Do not cause disease under normal conditions

but

can cause disease under special conditions

In some situations,

one microorganism makes it possible for another to

cause a disease or produce more severe symptoms

are criteria for establishing that specific microbes cause specific diseases.

what are the 4 requirements under Koch's postulates?

1.  the same pathogen must  be present in every case of the disease.

2. the pathogen must be isolated in pure culture.

3. the pathogen isolated from pure culture must cause the same diseasein healthy, susceptible laboratory animal

4. The pathogen must be reisolated from the inoculated laboratory animal.

What are the 5 exceptions to Koch's Postulates?

1.  modified to establish etiologies of diseases caused by viruses and some bacteria, which cannot be grown on artificial media

2.  Some diseases, such as tetanus, have unequivocal signs and symptoms.

3.  Some diseases, such as pneumonia and nephritis, may be caused by a variety of microbes

4.  Some pathogens, such as S. pyogenes, cause several different diseases.

5.  Certain pathofens, such as HIV, cause disease in humans only

Symptoms

A patient exhibiting subjective changes in body functions

Signs

Measurable changes in a patients body functions

Diagnosis

Identification of the disease

made by a physician

Syndrome

A group of symptoms or signs

that always accompanies a specific disease

Communicable

diseases

Are transmitted directly or indirectly

from

one host to another

A

Contagious Disease

is one that is easily spread

from

one person to another

Noncommunicable

Diseases

Are cause  by microorganisms that normally grow outside

the human body

and are not transmitted

from one host to another.

Disease occurence is reported by

incidence (number of people contracting the disease)

and

prevalence (number of cases at a particular time)

Diseases are classified by

4 types of

frequency occurence

1.  sporadic

(disease occurs occasionally i.e. typhoid fever)

2.  endemic 

(disease is constantly present i.e. common cold)

3.  epidemic 

(a given area, acquire disease in a relative short period of time i.e. AIDS, ghonerrhea)   

4.  pandemic

(An epedemic disease that occurs worldwide i.e. influenza/AIDS)

The scope of a disease can be defined as

1.Acute

2.chronic

3.subacute

or

4.latent

Acute disease

One that develops rapidly but lasts only a short time (influenza)

Chronic Disease

develops more slowly

bodys reactions may be less severe

disease likely to continue or recur for long periods

(hepatitis B)

Subacute disease

A disease that is between acute and chronic

(sclerosing panencephalitis)

a continual source of infection

Latent disease

one in which the causitive agent remains inactive for a time,

then becomes active to produce symptoms of the disease

(shingles - caused by varicella virus)

Herd community

presence of immunity to a disease in a most of the population in a community. 

(example vaccination)

affects a small area of the body

Local infection

affects a small area of the body

Systemic infection

is spread throughout the body via

the circulatory system

Primary infection

is an acute infection that causes the initial illness

Secondary infection

can occur after the host is weakened

 from a primary infection

(Pneumocystic pneumonia as a consequence of AIDS)

Inapparent or Subclinical Infection

does not cause any signs of disease in the host

(poliovirus or hepatitis A virus)

Sepsis

a toxic inflammatory condition arising

from the spread of microbes,

especially bacteria or their toxins

from a focus of infections

Septicimia

blood poisoning, is a systemic infection

arising from the multiplication of pathogens in the blood.

Bacteremia toxemia

presence of toxins in the blood (as occurs in tetanus)

Viremia

refers to the presence of viruses in the blood

What is the sequence of disease

1.there must be a reservoir for infections as a source of pathogen

2.the pathogen must be transmitted to a susceptible host by direct contact, by indirect contact or vectors

3.  transmission is followed by invasion, in which the  microorganism enters the host and multiplies

4. following invasion the microorganism injures the host through a process called pathogenesis

5. extent of injury depends on the degree to which host cells are damaged, either directly or by toxins

6. The occurence of disease ultimately depends on the resistance of the host to the activities of the pathogen

people that have a disease or

are carriers of a disease

are diseases that affect wild and domestic animals and

can be transmitted to humans

(west nile virus)

Soil and water

can occur after the host is weakened from primary infection

transmission by

fomites (inanimate objects)

constitutes indirect contact

Vehicle transmission

Transmission by medium

by water, food or air

Droplet transmission

transmission via saliva, mucus in coughing or sneezing

any infection that is acquired during the course of a hospital stay.

Percentage of hospitalized patients that acquire Noscomial infections

5 - 15%

EID's

emerging infectious diseases

are new diseases with increasing incidences

Who is responsible for survelliance and response to new diseases

the use of antibiotics,

 pesticides,

climactic changes,

travel,

the lack of vaccinations

and improved case reporting

Descriptive epidemiology

Analytical epidemiology

analyzes a particular disease to determine probable cause

or

group of infected people is compared with and

uninfected group of people

Experimental epidemiology

controlled experiments designed

to test hypotheses are performed

CDC

Center for disease control

provides data on incidence and prevalence to local, state and national health officials.

Mechanical transmission

transmission of pathogens by incests feet or body parts

biological transmission

athropod bites and infected person or animal

makes the body more susceptible to disease

(gender is sometimes a predisposing factor - ie. bladder infections)

the need of bacteria to cause disease