Infectious Diseases - bloodhounds Incorporated

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Infectious Diseases

Sexually Transmitted Infection

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What is a Disease?

Disease

= Any interference with the normal functioning of the body organs or systems

Human Disease may be caused by

Environmental factors

Defects of body structures or functions

Activities of infectious microorganisms

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Signs, Symptoms and Syndromes

Signs

A more or less observable and obvious feature of a disease

Includes things like diarrhia, a rash, peeling of the skin

Painless lesion of syphilis called a chancre

Symptom

Any change in a body structure of function that can be observed or felt by the individual

Asymptomatic

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Signs, Symptoms and Syndromes

Syndrome

A combination of signs and symptoms occurring in a typical pattern

Etiology

The cause, set of causes, or manner of causation of a disease or condition

Sequelae

Some diseases leave aftereffects

Viral infections of the liver can result in the loss of functioning liver cells and interference with bloodflow through the organ

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Signs, Symptoms and Syndromes

The outcome of a disease depends on

Genetics

Age

Nutritional status

Prior exposure to the infectious agent

Resulting levels of body protection or immunity

Prognosis

Predict the course and outcome of a disease

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Types of Diseases

Diseases can be placed in descriptive groups:

Hereditary and congenital

Degenerative

Neoplastic

Metabolic

Immunological infectious

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Hereditary and Congenital

Diseases

Hereditary Diseases

Caused by errors in the information present in an abnormal gene or genes

May be abnormalities in

The number and distribution of chromosomes

Interaction of genetic and environmental factors

Down’s Syndrome

Abnormal distribution of chromosomes

Trisomy 21

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Hereditary and Congenital

Diseases

Abnormalities that develop between the time of fertilization

(conception) and birth are divided into two categories

Embryonic Period

First eight weeks of pregnancy

Fetal Period

From the ninth week of pregnancy to birth

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Embryonic Period

Changes occurring produce visible deformities of organs or other body structures

Embryonic or congenital defects

Are present at birth

Drugs, excessive X-ray exposure, or certain infections may disrupt the developing embryo or fetus

The embryo is most vulnerable to injury during the 3 rd week of pregnancy to 8 th

Infections acquired by the mother may injure the developing fetus and cause congenital defects

Mental retardation, blindness, brain injury, even death

German measles (rubella), Syphilis, Genital Herpes

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Degenerative Diseases

The breakdown of various body parts

Aging

Chronic (long lasting) illnesses that can lead to death

Heart attack

Stroke (bleeding and/or blockages in blood vessels of the brain)

Could occur even without aging

Hardening of the arteries

Certain forms of arthritis

Degenerating joints

Diverticulitis

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Neoplastic Diseases

Diseases associated with abnormal cell growth that leads to the formation of various types of tumors

Benign (harmless)

Malignant (cancerous)

One in five persons die in the United States of some form of cancer

Human papilloma viruses cause genital warts

Has been associated with cervical cancer

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Metabolic Diseases

These diseases include a variety of disorders in which the body’s production of chemical products essential to its functioning either are nonexistent or defective

Hormones

A chemical product body a body organ or gland, which is carried by the blood to another body site where it stimulates a particular function

Endocrine

Enzymes

A complex proteins produced by cells, that causes changes in other substances without being changed in the process

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Immunologic Diseases

Diseases that result from the improper or impaired functioning of the body’s immune system

The immune system provides protection against various disease agents and other factors in an individual’s environment

The immune system can destroy or neutralize disease agents and factors considered to be foreign by the immune system

Inflammation

A response to tissue injury

Swelling, redness, local heat, pain, and abnormal functionin of the part involved

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Immunologic Diseases

Immunologic diseases are grouped into two categories:

Primary Immunodeficiencies

Arise from an inherited lack of development of one or more parts of the immune system

Secondary Immunodeficiencies

Occur more frequently than primary

Results from many factors that suppress an individual’s immune responses to events such as infection

AIDS

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Infectious Diseases

Microbiota

Microscopic forms that live on the skin, in the mouth and the large intestine

Most are harmless

Some, if given the opportunity can cause a disease

These are known as

opportunists

Can lead to opportunistic infections

Pathogens

Microorganisms that cause severe problems upon gaining entrance to the host tissues

Pathogenesis

Eventual development of a diseases

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Infectious Diseases

Pathogenicity

The disease producing capability of a pathogen

Virulence

The degree or intensity of pathogenicity

Infectious Diseases are caused by infectious agents

Bacteria

Fungi

Protozoa

Viruses

Helminths (worms)

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Infectious Diseases

Communicable or Contagious

Certain infectious diseases can spread from person to person

Flu or measles

Gonorrhea or syphilis

Noncommunicable or not contagious

Caused by an infectious agent but does not spread from person to person

Tetanus

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The Course of an Infectious

Disease

Incubation Period

The time between the multiplication of the pathogen and the appearance of signs and symptoms

Prodromal Phase

The early stage of some diseases in which nonspecific symptoms such as headache and general weakness appear

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The Course of an Infectious

Disease

Invasive Phase

The period during which pathogens invade and cause tissue damage

Signs and symptoms of the disease appear at the same time

Convalescence Phase

The time period during which recovery occurs and includes healing and regaining strength

Even if signs and symptoms disappear individuals may still be able to spread an infectious diseases

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The Course of an Infectious

Disease

Acute

Disease occurs rapidly and sometimes with intense symptoms

Chronic

Disease develops more slowly and lasts for a longer, indefinite, period of time

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The Concept of Infectious Disease

Girolamo Fracastorius , a Franciscan monk in 1546

Distinguished several ways an infectious disease was able to spread

Contact with the skin

Contact with objects close to a sick person

The air in a sickroom

Anton Van Leeuwenhoek, late 1600s

Created the first real microscope

Discovered microorganisms with his microscope

Rober Koch1876

Koch’s Postulate - “Germ theory of disease”

Demonstrated a specific bacterium caused anthrax

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Factors Contributing to the Success of an Infectious Disease

Pathogens act in certain ways to cause diseases

Gaining access to the host

Attaching to and reproducing on the cell surface

Invading body tissues

Producing poisonous substances known as

toxins

the body’s defenses to breakdown

Toxins may also cause allergic responses in some people

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The Microbial World

Bacteria

Single-celled microorganisms

May be beneficial or harmful to the host

Bacteria are differentiated from one another by several factors:

Shape

Color reactions

Chemical composition

Growth

Responses to chemicals such as antibiotics

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Shape of Bacteria

Coccus

Spherical form

Bacillus

Rod

Spirillum

Twisted or bent

Tight corkscrew known as a spirochete

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Coccus Bacillus

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Isolating and Growing (Culturing)

Bacteria

Medium –

Nutrient used to grow bacteria

Made from broth or liquid, and solid or agar

Contains nutrients

Sugar

Protein

Vitamins

Minerals

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Fungi

Fungi

Single- and multi-cellular forms of life

Yeast

Molds

Mushrooms

The majority of fungi are involved natural decomposition of rotting and decaying plant and related material

Commercial production of some bakery goods, cheeses, antibiotics, alcoholic beverages and other chemicals

Some fungi can attack the

Skin, nails and hair

Causes different forms of ringworm

Athlete’s foot

Some can form STD’s like a yeast infection

Fungi are opportunistic

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Fungi

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Protozoa

Single-celled animal-like microorganisms

Most are harmless and found in the soil and water

Some causes diseases such as malaria, African sleeping sickness and Amebic dysentery

Protozoa are opportunistic and cause STD’s

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Viruses

Cannot be seen by an ordinary light microscope

Must use an electron microscope

Viruses are therefore called submicroscopic

Chicken pox

HIV

Viruses are not cells

Viruses vary in shape

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Viruses

Virions

Individual virus particles

Contain a single type of nucleic acid

Either DNA or RNA but never both

Capsid

Protein coat encloses the nucleic acid component

Culvitation

Viruses can only replicate in living cells

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Helminths or Worms

Helminths that cause most of human disease are

Flatworms

Roundworms

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