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FACTORS IN THE SPREAD OF DISEASE 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 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 statistics Epidemiology Requires familiarity with Signs and symptoms Stages of the disease Relationships among pathogens and their hosts Relationships among pathogens and their environment 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 Refers Rate to the number of individuals that died as a result of a specific disease in a specific time period 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 caused 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 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 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 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 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 Factors in the Spread of Infectious Diseases Carrier Healthy Carrier The individual who is in an incubating state, undergoing the initial stages of a disease without exhibiting symptoms Intermittent Carrier A carrier with no apparent ill effects Incubatory Carrier Individuals who harbor pathogens transmissible to others Periodically releases disease agents Convalescent Carrier Serves as a source of pathogens during the recovery period 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 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 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 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 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 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 Fomites Mechanical Transmission Vector Forms of life that transmit disease to humans Mechanical Vectors Flies Ticks Cockroaches Mosquitoes 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 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 HIV 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 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 Immunization Vaccination for the prevention of diseases Builds resistance to the disease Large spread controversy today The signs of certain sexually transmitted diseases (STDs) such as syphilis and chlamydial infection are not always obvious A. B. True False In general, STDs can be acquired through casual contact situations such as shaking hands. A. B. True False Diagnostic tests are available for the detection of most STDs. A. B. True False Most STDs are treatable if detected early. A. B. True False Having an STD such as syphilis, chancroid, or genital wars can increase the possibility of human immunodeficiency (HIV) transmission. A. B. True False The proper use of latex condoms during sexually related activities, while not foolproof, is effective in preventing STD tranmission. A. B. True False An infected mother can transmit certain STDs such as syphilis and HIV infection to her newborn. A. B. True False With the exception of hepatitis B virus infection, no immunization (vaccines) are available for any STD. A. B. True False The use of oil-based lubricants such as Crisco and Vaseline can weaken condomes, making them useless as protection agains STD transmission A. B. True False Sexually transmitted diseases can spread by women as well as men. A. B. True False An individual can acquire an STD by donating blood. A. B. True False Sexually transmitted diseases such as syphilis and gonorrhea can be spready by kissing. A. B. True False
