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Sexually Transmitted Infection

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Disease = Any interference with the normal functioning of the body organs or systems
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Human Disease may be caused by
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Environmental factors
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Defects of body structures or functions
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Activities of infectious microorganisms

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Signs
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A more or less observable and obvious feature of a disease
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Includes things like diarrhia, a rash, peeling of the skin
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Painless lesion of syphilis called a chancre
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Symptom
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Any change in a body structure of function that can be observed or felt by the individual
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Asymptomatic

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Syndrome
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A combination of signs and symptoms occurring in a typical pattern
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Etiology
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The cause, set of causes, or manner of causation of a disease or condition
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Sequelae
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Some diseases leave aftereffects
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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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The outcome of a disease depends on
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Genetics
Age
Nutritional status
Prior exposure to the infectious agent
Resulting levels of body protection or immunity
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Prognosis
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Predict the course and outcome of a disease

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Diseases can be placed in descriptive groups:
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Hereditary and congenital
Degenerative
Neoplastic
Metabolic
Immunological infectious

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Hereditary Diseases
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Caused by errors in the information present in an abnormal gene or genes
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May be abnormalities in
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The number and distribution of chromosomes
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Interaction of genetic and environmental factors
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Down’s Syndrome
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Abnormal distribution of chromosomes
Trisomy 21

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Abnormalities that develop between the time of fertilization
(conception) and birth are divided into two categories
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Embryonic Period
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First eight weeks of pregnancy
Fetal Period
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From the ninth week of pregnancy to birth

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Changes occurring produce visible deformities of organs or other body structures
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Embryonic or congenital defects
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Are present at birth
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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 to 8 th week of pregnancy
Infections acquired by the mother may injure the developing fetus and cause congenital defects
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Mental retardation, blindness, brain injury, even death
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German measles (rubella), Syphilis, Genital Herpes

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The breakdown of various body parts
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Aging
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Chronic (long lasting) illnesses that can lead to death
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Heart attack
Stroke (bleeding and/or blockages in blood vessels of the brain)
Could occur even without aging
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Hardening of the arteries
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Certain forms of arthritis
Degenerating joints
Diverticulitis

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Diseases associated with abnormal cell growth that leads to the formation of various types of tumors
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Benign (harmless)
Malignant (cancerous)
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One in five persons die in the United States of some form of cancer
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Human papilloma viruses cause genital warts
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Has been associated with cervical cancer

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

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Diseases that result from the improper or impaired functioning of the body’s immune system
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The immune system provides protection against various disease agents and other factors in an individual’s environment
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The immune system can destroy or neutralize disease agents and factors considered to be foreign by the immune system
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Inflammation
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A response to tissue injury
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Swelling, redness, local heat, pain, and abnormal functionin of the part involved

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Immunologic diseases are grouped into two categories:
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Primary Immunodeficiencies
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Arise from an inherited lack of development of one or more parts of the immune system
Secondary Immunodeficiencies
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Occur more frequently than primary
Results from many factors that suppress an individual’s immune responses to events such as infection
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AIDS

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Microbiota
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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
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These are known as opportunists
Can lead to opportunistic infections
Pathogens
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Microorganisms that cause severe problems upon gaining entrance to the host tissues
Pathogenesis
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Eventual development of a diseases

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Pathogenicity
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The disease producing capability of a pathogen
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Virulence
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The degree or intensity of pathogenicity
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Infectious Diseases are caused by infectious agents
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Bacteria
Fungi
Protozoa
Viruses
Helminths (worms)

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Communicable or Contagious
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Certain infectious diseases can spread from person to person
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Flu or measles
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Gonorrhea or syphilis
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Noncommunicable or not contagious
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Caused by an infectious agent but does not spread from person to person
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Tetanus

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Incubation Period
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The time between the multiplication of the pathogen and the appearance of signs and symptoms
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Prodromal Phase
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The early stage of some diseases in which nonspecific symptoms such as headache and general weakness appear

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Invasive Phase
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The period during which pathogens invade and cause tissue damage
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Signs and symptoms of the disease appear at the same time
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Convalescence Phase
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The time period during which recovery occurs and includes healing and regaining strength
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Even if signs and symptoms disappear individuals may still be able to spread an infectious diseases

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Acute
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Disease occurs rapidly and sometimes with intense symptoms
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Chronic
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Disease develops more slowly and lasts for a longer, indefinite, period of time

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Girolamo Fracastorius , a Franciscan monk in 1546
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Distinguished several ways an infectious disease was able to spread
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Contact with the skin
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Contact with objects close to a sick person
The air in a sickroom
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Anton Van Leeuwenhoek, late 1600s
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Created the first real microscope
Discovered microorganisms with his microscope
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Rober Koch1876
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Koch’s Postulate - “Germ theory of disease”
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Demonstrated a specific bacterium caused anthrax

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Pathogens act in certain ways to cause diseases
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Gaining access to the host
Attaching to and reproducing on the cell surface
Invading body tissues
Producing poisonous substances known as toxins to breakdown the body’s defenses
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Toxins may also cause allergic responses in some people

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Bacteria
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Single-celled microorganisms
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May be beneficial or harmful to the host
Bacteria are differentiated from one another by several factors:
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Shape
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Color reactions
Chemical composition
Growth
Responses to chemicals such as antibiotics

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Coccus
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Spherical form
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Bacillus
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Rod
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Spirillum
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Twisted or bent
Tight corkscrew known as a spirochete

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Coccus Bacillus

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Medium –
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Nutrient used to grow bacteria
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Made from broth or liquid, and solid or agar
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Contains nutrients
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Sugar
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Protein
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Vitamins
Minerals

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Single- and multi-cellular forms of life
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Yeast
Molds
Mushrooms
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The majority of fungi are involved natural decomposition of rotting and decaying plant and related material
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Commercial production of some bakery goods, cheeses, antibiotics, alcoholic beverages and other chemicals
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Some fungi can attack the
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Skin, nails and hair
Causes different forms of ringworm
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Athlete’s foot
Some can form STD’s like a yeast infection
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Fungi are opportunistic

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Single-celled animal-like microorganisms
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Most are harmless and found in the soil and water
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Some causes diseases such as malaria, African sleeping sickness and Amebic dysentery
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Protozoa are opportunistic and cause STD’s

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Cannot be seen by an ordinary light microscope
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Must use an electron microscope
Viruses are therefore called submicroscopic
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Chicken pox
HIV
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Viruses are not cells
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Viruses vary in shape

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Virions
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Individual virus particles
Contain a single type of nucleic acid
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Either DNA or RNA but never both
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Capsid
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Protein coat encloses the nucleic acid component
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Culvitation
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Viruses can only replicate in living cells

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Helminths that cause most of human disease are
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Flatworms
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Roundworms