1. Occurrence of infectious diseases
Biomedical Technology
Part two
Public Health Organizations

2. Epidemiology
The study of the “occurrence of disease” in populations. (General populations, all males, all females, age groups, etc.)
Epidemiologists are concerned not only with infectious diseases, but also with noninfectious diseases such as cancer and atherosclerosis, and with environmental diseases such as lead poisoning.

3. Disease reservoirs
The reservoir for a disease is the site where the infectious agent survives. Colonization and reproduction take place here.
Common reservoirs are humans, animals, environment and fomites.
Animals often serve as reservoirs for
diseases that infect humans.
Example: Yersinis pestis (plague)
Reservoir is rodents or rats!
Example: Clostridium tetani (tetanus)
Reservoir is soil

4. Portal of Exit
The route by which the infectious agent leaves the reservoir to be transferred to a susceptible HOST.
The agent leaves the body “catches a ride” through body secretions such as:
Saliva sputum
Blood draining wounds
Semen vaginal secretions
Urine feces

5. Modes of Transmission
The process that bridges the gap between the portal of exit from the HOST, to the Portal of Entry to the susceptible “new” HOST.
Horizontal transmission and vertical transmission
Horizontal transmission includes direct and indirect contact

6. Direct Contact Transmission
Occurs when an individual is infected by contact with the reservoir
Examples: touching an infected person, being bitten by an infected animal or insect, STD’s, colds, flu

7. Direct Contact examples:
Ringworm
AIDS
Trichinosis
Influenza
Rabies
Malaria

8. Indirect Contact
Occurs when a pathogen can withstand the environment outside its host for a long period of time before infecting another individual.
Inanimate objects that are contaminated by direct contact with the reservoir (ex: a tissue used to wipe someone’s nose) and may be the indirect contact for a susceptible individual.
Examples: door handles, faucets, desks, clothing, dressings, bed linens, medical instruments

9. Indirect Contact cont.
Ingesting food and beverages contaminated by contact with a disease reservoir.
Fecal-oral route of transmission.
Sewage, contaminated water that is used for drinking, washing, or preparing foods.
Soil contaminated from water, spills, toxins, etc.
Hurricaine or flooding- munincipalities
Are damaged or destroyed
Concerns about safe water

10. Vertical Transmission
Transmission of disease from parent to child during the processes of reproduction, fetal development, or birth.
Examples of diseases:
AIDS
herpes→

11. HOST DEFENSES AGAINST INFECTIOUS DISEASES

12. Nonspecific Mechanisms
Nonspecific mechanisms are the body’s primary defense against disease.
They include anatomical barriers ( skin, nasal opening, skull, vertebral column) to invading pathogens,
physiological deterrents (tears, vaginal secretions, saliva, blood, sweat, tissue fluids) to pathogens,
and the presence of normal flora
(“good bacteria”)

13. Anatomical Barriers
Nasal openings to respiratory system – traps airborne particles before reaching the lungs
Skull and vertebral column protect the central nervous system.
SKIN- major anatomical barrier to microorganisms

14. Physiological deterrents
Protect natural openings.
Tears flush debris from eyes
Vaginal secretions are acidic to discourage the growth of pathogens (ph level ?)
Eye, mouth, and nasal openings are protected by secretions that contain lysozyme, an enzyme that breaks down bacterial cell walls.

15. Protective Normal Flora
Microorganisms present on and in the body.
They survive and grow on the skin and in the mouth, GI tract, and other areas of the body.
They don’t cause disease because their growth is kept under control by the body’s natural defenses.
When the growth of the normal flora is suppressed (antibiotics), other opportunistic infections may occur. (Example?)

16. Immunity When a host encounters an antigen
(foreign body) that triggers a specific immune response for the second or later time, the memory lymphocyte recognize it and quickly begin multiplying. (Remembers it)
Memory cells allow the pathogen to be fought off more quickly with each new exposure.
This same response explains the effectiveness of vaccination for preventing even the first occurrence of many diseases.

17. Vaccination
Vaccines contain either a killed or weakened strain (attenuated) of a particular pathogen, OR solution containing antigens from the pathogens.
The body’s immune system will respond to these vaccines as if they contain the actual pathogen, even though the vaccine is NOT capable of causing disease.
As a result, memory lymphocytes will be present and respond rapidly when the actual pathogen is encountered.

18. Vaccinations continued
The ultimate effectiveness of vaccination is eradication
( remove/eliminate or destroy)
of the infectious agent.
Some pathogens mutate (change) quickly producing variants of their antigens not recognized by the host’s immune system.
Cold and influenza are examples of rapidly mutating pathogens. Flu vaccine is different every year.
Vaccinations continued

19. Age- as a person gets older, immunity declines. Why?
Who is at risk?
Age- as a person gets older, immunity declines. Why?
Concurrent disease- other disorders or diseases
Stress- a compromised emotional state has lower defense mechanisms
Immune/vaccine status-
Lifestyle choices-
Occupation-
Nutritional status
Hereditary

20. As a healthcare worker, we strive to “Break the Chain” of infection.
Who’s responsible?
As a healthcare worker, we strive to “Break the Chain” of infection.
Processes to break links in the chain are important to prevent the occurrance and spread of infection.
“Standard Precautions” are guidelines to be used during patient care and cleaning . They must be used when anticipation of contact with blood, body fluids, mucous membranes and nonintact skin.
PPE-
Personal
Protective Equipment
Gloves, gowns, masks,goggles, face shields, shoe covers
Patient may have to be placed in Isolation to protect them, staff and other patients

21. BT06.02PUBLIC HEALTH MEASURES TO PREVENT INFECTIOUS DISEASES
Safe water
Sewage treatment
Food safety
Animal control programs
Vaccination programs
Pesticides to block vector-borne diseases

22. SAFE WATER
Many pathogens that cause GI diseases are transmitted via water.
US water is purified through
*** settling, filtration, and chlorination.***
Some diseases transmitted through contaminated water include cholera and typhoid fever.
Public water must be guarded against contamination from sewage (feces).

23. Sewage treatment and disposal
Sewage includes wash water, water from toilets, and storm run-off.
These fluids may carry the pathogens for many waterborne disease, including giardiasis and Hepatitis A.
The US govt mandates that sewage be treated to eliminate pathogens.
How is sewage treated?

24. Food safety programs The US has many standards, inspection
plans, and regulations about food prep, handling, and distribution.
Milk is pasteurized and dated for sale and is analyzed periodically for contamination.
Restaurants and supermarkets are inspected.

25. Animal Control Programs
Animals are carriers of many diseases that also affect humans.
Domestic herds are inspected
Rabid animals are destroyed
Rat control programs in place in urban areas – major component in public health efforts

26. Vaccination Programs
Programs mandate that children be vaccinated prior to school.
Exemptions are allowed for certain religious beliefs.

27. Pesticides
Block vector-borne diseases – those carried by mosquitoes and ticks
Examples:
Lyme disease
West Nile virus
Yellow fever
Dengue fever

28. Public Health Organizations
Enforce regulation, provide public health services
NIH (National Institutes of Health) supports health related RESEARCH
CDC (Centers for Disease Control & Prevention) INVESTIGATES disease outbreaks
FDA ( Food & Drug Administration) monitors safety of food, medicines and other products
WHO (World Health Organization) provides INTERNATIONAL surveillance and control of disease