Modes of Disease Transmission

1. Modes of Disease Transmission Infection Control, DA116

2. Main goal of infection control program in a dental office: • To break the cycle of transmission of disease by lowering the number of possible pathogens present in the environment

3. Terms to know: • Microbiology: the study of living organisms that are so small they cannot be seen without the use of a microscope • Health: physical, mental and social well-being • Disease: an abnormality in body function that threatens well-being • Epidemiology: study of the spread of transmission of disease • Etiology: cause of the disease

4. Many causes of diseases: • Genetic: mutated genes • Cancer: abnormal tissue growth • Physical and chemical agents: toxic or destructive chemicals/mechanical injury • Malnutrition: deficiencies lead to disease • Autoimmunity: immune system attacks the body • One cause that we fight with infection control measures: • Pathogenic: disease causing organisms; virus, bacteria and fungus

5. Types of Pathogens: • Microorganism: living creature so small it can only be seen with a microscope • Pathogen: microorganism that causes disease; (microbe) thrive in warm, dark, moist environments. Many microbes are found in the mouth. Can be present in blood, saliva or mucous membranes that may be contacted during dental treatment • Bacteria and Viruses: of most concern to the dental office

6. Disease producing capabilities of the pathogen depend on: • 1) Virulence: resistance to efforts to kill it (disinfection or sterilization) • 2) Host resistance: health of the individual being affected (keep in good health!) • 3) Concentration: the more pathogens, the more chance of contracting the disease; dental office infection control program aims at reducing the amount of pathogens present

7. How do diseases pass from person to person? • 1) Source of the microbe • 2) Escape from the source • 3) Spread of the microbe to a new person • 4) Entry of a microbe into a new person goal of infection control = break that chain!

8. Steps in the development of an infectious disease

9. 1) Source of the microbe: • Patient’s mouths • Saliva, blood, respiratory secretions • Can also be found on surfaces; dust, water, air, dental team • Cannot tell who has the disease, therefore, use Standard Precautions • Treat all patients as if they have an infectious disease

10. 2) Escape from the source: • Natural mechanism, such as coughing, sneezing or talking. • Artificial Mechanisms, such as found in dental care: • A) Anything that is removed from the patients mouth is contaminated • B) Spatter: larger droplets that may contain several microbes; hit skin, eyes, nostrils, lips and mouth of dental team; settle rapidly from air and contaminate nearby surfaces droplets • C) Aerosol: mostly invisible, contain a few microbes that may be inhaled or remain airborne for some time airborne

11. 3) Spread of the microbe to a new person: • CONTACT • Direct • aka contact transmission • Indirect • Vehicle transmission: touch contaminated instruments • Vectorborne transmission: transferred by animate means, such as Lyme disease • Droplet infection • AIRBORNE

12. Direct Contact • Spread by direct contact with infected skin, mucus membranes, or body fluids • eg. Touching open wound

13. Indirect Contact • Spread from one person to an object and on to another person • eg. injuries from contaminated sharps or contact with contaminated instruments, equipment, surfaces and hands. These can carry a variety of pathogens, usually in the presence of blood, saliva, or other secretions from patient • Anything touched during treatment is considered to be cross contaminated • An explorer tip dipped into saliva can carry up to 50,000 organisms of infection! • 1 gm (1/4 tsp) of dental plaque has 200 billion bacteria!

14. Droplet Infection • Caused from aerosols and spatter, talking, breathing, sneezing and coughing • An uninfected person can become infected by inhaling the droplets • When someone sneezes, contaminated particles travel about eight feet out and four feet up • Mist from the handpiece with water spray is like having someone sneeze in your face from twelve inches away

15. Airborne • Spread through the air. An organism spread in this way can be suspended in air. eg. Chicken pox and TB • Uninfected person can enter the area and inhale these suspended organisms.

16. Droplet vs. Airborne: • Droplet spread and airborne transmission are different in a very important way: • Droplet spread organisms can only contaminate nearby air while airborne organisms can spread infection over a much wider area.

17. 4) Entry of Microbe into a new person • Microbe causes no damage unless it enters the person • Four Routes of Entry into new person • Inhalation or breathing • Ingestion or swallowing • Mucous membranes (spatter in eyes, nose and mouth) • Breaks in skin (direct contact, spatter, or puncture with sharps)