Spread of Diseases There have been several diseases that have spread across the world killing many In the middle ages it was the Bubonic Plague In 1981 it was HIV Epidemiology An area of investigation that deals with factors that influence the frequency and distribution of diseases ID: 508275
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Slide1
Factors in the spread of diseaseSlide2
Spread of Diseases
There have been several diseases that have spread across the world killing many
In the middle ages it was the Bubonic Plague
In 1981 it was HIVSlide3
Epidemiology
An area of investigation that deals with factors that influence the frequency and distribution of diseases
Find way to control and to prevent the outbreaks of disease
Look for the source of transmission
Reporting of the control of the disease
Epidemiology relays heavily on numerical information such as statisticsSlide4
Epidemiology
Requires familiarity with
Signs and symptoms
Stages of the disease
Relationships among pathogens and their hosts
Relationships among pathogens and their environmentSlide5
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 periodSlide6
Endemic, Epidemic, Pandemic and Sporadic Disease Patterns
The patterns of occurrence among infectious and other types of diseases are influenced by the frequency of cases in populations, the size of the geographic are affected, and the degree of injury causedSlide7
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 gonorrheaSlide8
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 proportionsSlide9
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 Slide10
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 transmissionSlide11
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 periodsSlide12
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 periodSlide13
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 entrySlide14
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 diesSlide15
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 secretionsSlide16
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 pathogensSlide17
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 utensilsSlide18
Mechanical Transmission
Transmission where situations involving the physical carrying of pathogens on or within contaminated materials such as food, water or
insections
Five
Fs
Food
Fingers
Flies
Feces
FomitesSlide19
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 vectorsSlide20
Biological Tranmission
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
HIVSlide21
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 HIVSlide22
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
insecticidesSlide23
Immunization
Vaccination for the prevention of diseases
Builds resistance to the disease
Large spread controversy today Slide24
The signs of certain sexually transmitted diseases (STDs) such as syphilis and chlamydial infection are not always obvious
True
FalseSlide25
In general, STDs can be acquired through casual contact situations such as shaking hands.
True
FalseSlide26
Diagnostic tests are available for the detection of most STDs.
True
FalseSlide27
Most STDs are treatable if detected early.
True
FalseSlide28
Having an STD such as syphilis,
chancroid
, or genital wars can increase the possibility of human immunodeficiency (HIV) transmission.
True
FalseSlide29
The proper use of latex condoms during sexually related activities, while not foolproof, is effective in preventing STD
tranmission
.
True
FalseSlide30
An infected mother can transmit certain STDs such as syphilis and HIV infection to her newborn.
True
FalseSlide31
With the exception of hepatitis B virus infection, no immunization (vaccines) are available for any STD.
True
FalseSlide32
The use of oil-based lubricants such as Crisco and Vaseline can weaken
condomes
, making them useless as protection
agains
STD transmission
True
FalseSlide33
Sexually transmitted diseases can spread by women as well as men.
True
FalseSlide34
An individual can acquire an STD by donating blood.
True
FalseSlide35
Sexually transmitted diseases such as syphilis and gonorrhea can be
spready
by kissing.
True
False