factors in the spread of disease. spread of diseases there have been several diseases that have...
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FACTORS IN THE SPREAD OF DISEASE
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Spread of Diseases
There have been several diseases that have spread across the world killing many
In the middle ages it was the Bubonic or Black Plague
In 1981 it was HIV
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Epidemiology
An area of investigation that deals with factors that influence the frequency and distribution of diseases Find ways to control and prevent the
outbreak of disease Look for the source of transmission Reporting of the control of the disease
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Patterns of Disease Occurrence Incidence or Prevalence
The number of new cases seen in a specific time period
Morbidity Rate The number of new cases per 10,000 in the
population per year Mortality Rate
Refers to the number of individuals that died as a result of a specific disease in a specific time period
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Endemic, Epidemic, Pandemic and Sporadic Disease Patterns
Endemic Disease A disease that is constantly present in the
population of a particular geographic area, but involves relative few individuals Severity of the disease is low Does not present as a major public health
problem Tuberculosis, mumps, the STD chancroid and
gonorrhea
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Endemic, Epidemic, Pandemic and Sporadic Disease Patterns
Epidemic An unusual occurrence of a disease
involving large segments of a population for a limited period of time
An endemic disease can develop into an epidemic if a harmful form of the pathogen appears Influenza and measles are good examples Genital Herpes and Genital Warps are in
epidemic proportions
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Endemic, Epidemic, Pandemic and Sporadic Disease Patterns
Pandemic A series of
epidemics affecting several countries, or even major portions of the world Influenza of 1918-
1919 HIV and AIDs are
following a similar pattern
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Endemic, Epidemic, Pandemic and Sporadic Disease Patterns
Sporadic Diseases Are uncommon,
occur irregularly and affect only a relatively few persons Diptheria Whooping Cough –
although this is on the rise in the US
Transmission Factors include: Sources and
reservoirs of disease agents
Portals by which the agents leave and enter the body
The mechanisms or means of transmission
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Factors in the Spread of Infectious Diseases
Reservoirs of Infection A host or local environment that supports
the survival and multiplication of pathogens is referred to as a reservoir of infection
Living reservoirs include infected humans and other animals
Nonliving reservoirs include air, food, soil, water, eating utensils and toothbrushes
Provides the disease agent a suitable environment to survive for prolonged periods
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Factors in the Spread of Infectious Diseases
Carrier Individuals who harbor pathogens transmissible to others
Healthy Carrier A carrier with no apparent ill effects
Incubatory Carrier The individual who is in an incubating state, undergoing
the initial stages of a disease without exhibiting symptoms Intermittent Carrier
Periodically releases disease agents Convalescent Carrier
Serves as a source of pathogens during the recovery period
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How do Pathogens Get Into and Out of the Body?
Portals of Entry Pathogens enter the body through a small
number or routes Skin Respiratory system Gastrointestinal system Genitourinary system Wounds Animal bites
Particular pathogens are generally restricted to a specific portal of entry
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Portal of Entry
Infectious Dose The number of pathogens needed to
initiate a disease process May be as low of one organism or may need
hundreds of thousands HIV infection requires large doses of disease agent
The pathogen must overcome the hosts defenses in order to enter If it cannot overcome the defenses the
pathogen dies
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Portals of Exit
The site at which the organisms leave the body Pathogens are typically discharged with
body fluids and wastes. Respiratory pathogens exit by
Coughing Sneezing Speaking
STDs such as gonorrhea and HIV discharge through semen and vaginal secretions
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Mechanisms of Disease Transmission
Transmission may occur by: Direct contact with
infected person or carrier Indirect contact with
nonliving objects, or food or water contaminated by infected individuals
Inhalation of airborne dust or droplets of saliva, or other body fluids containing pathogens
Injection of body fluids containing disease agents
Insects and related forms carrying pathogens
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Contact Transmission
Direct Contact Refers to the
transmission of pathogens from person to person through close personal association Coughing Sneezing Handshaking Kissing Sneezing
Indirect Contact Infectious agents are
carried form one individual to another on contaminated, living or nonliving objects
Fomites Contaminated
nonliving objects other than food and water Hypodermic needle Toothbrush Eating utensils
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Mechanical Transmission
Transmission where situations involving the physical carrying of pathogens on or within contaminated materials such as food, water or insects Five F’s
Food Fingers Flies Feces Fomites
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Mechanical Transmission
Vector Forms of life that transmit disease to humans
Flies Ticks Cockroaches Mosquitoes
Mechanical Vectors Transmitters that carry infectious agents on their bodies and are
not used by the agents for multiplication Biological Vectors
Serves as reservoirs and are at times required by disease agents for their development Ticks Mosquitoes There are no known STDs transmitted by arthropod vectors
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Biological Transmission
A portion of the pathogen’s development occurs in the form of life that serves to transmit the disease agent Injection of blood Blood products Bites of warm-blooded animals Arthropods
Malaria Rabies Hepatitis HIV
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Horizontal and Vertical Transmission Horizontal Transmission
Transfer of disease agents in the population by air, physical contact, food, water or vectors
Vertical Transmission Transfer of infectious agents from parent to
offspring by means of male and female sex cells or breast milk or during pregnancy Syphilis and HIV
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General Approaches to the Control of Contagious Diseases
Isolation and Quarantine Prevents contact with the general
population Minimizes the spread of the disease Protects infected individual from exposure to
other diseases Elimination of Vectors and Sources of
Disease Agents Hand washing Disinfectant Insecticides
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Immunization
Vaccination for the prevention of diseases
Builds resistance to the disease Large spread controversy today
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The signs of certain sexually transmitted diseases (STDs) such as syphilis and chlamydial infection are not always obviousA. TrueB. False
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In general, STDs can be acquired through casual contact situations such as shaking hands.
A. TrueB. False
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Diagnostic tests are available for the detection of most STDs.
A. TrueB. False
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Most STDs are treatable if detected early.
A. TrueB. False
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Having an STD such as syphilis, chancroid, or genital wars can increase the possibility of human immunodeficiency (HIV) transmission.A. TrueB. False
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The proper use of latex condoms during sexually related activities, while not foolproof, is effective in preventing STD transmission.A. TrueB. False
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An infected mother can transmit certain STDs such as syphilis and HIV infection to her newborn.
A. TrueB. False
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With the exception of hepatitis B virus infection, no immunization (vaccines) are available for any STD.
A. TrueB. False
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The use of oil-based lubricants such as Crisco and Vaseline can weaken condoms, making them useless as protection against STD transmission
A. TrueB. False
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Sexually transmitted diseases can spread by women as well as men.
A. TrueB. False
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An individual can acquire an STD by donating blood.
A. TrueB. False
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Sexually transmitted diseases such as syphilis and gonorrhea can be spread by kissing.
A. TrueB. False