This document discusses disease transmission and infection control. It covers the following key points: 1. Microorganisms like bacteria, viruses, fungi and protozoa can cause illness in humans. The chain of infection requires a microorganism, a mode of transmission to a susceptible host, and a portal of entry. 2. Common modes of disease transmission include airborne via aerosols or droplets, direct contact, fecal-oral, and blood or body fluids. Standard precautions like hand hygiene and barriers are used to prevent transmission. 3. Proper sterilization, disinfection and barriers are critical for infection control. Sterilization kills all microbes using steam, dry heat or chemicals

1. Disease Transmission
&
Infection Control

2. Disease Transmission
Microorganisms

3. Microbiology
• Microbiology is the study of microorganisms
• micro means microscopically small
• bio means living organisms
• The existence of microorganisms is not
usually noticed unless they cause illness
• Most microorganisms do not produce human
illness
• Beneficial microorganisms are used in the
production of cheese and yogurt

4. Disease Transmission
• Five major groups of microorganisms
2. Bacteria
3. Rickettsiae
4. Viruses
5. Protozoa
6. Fungi

5. Bacteria
• One celled microorganisms
• Humans host a variety of bacteria at all
times
• The skin, respiratory tract and
gastrointestinal tract are inhabited by
harmless bacteria

6. Diseases Caused by Bacteria
• Dental Decay
• Periodontal Disease
• Pneumonia
• Rheumatic Fever
• Syphilis
• Tuberculosis

7. Rickettsiae
• Transmitted to humans by bite of an
infected insect ( lice , fleas, ticks, and
mosquitoes)
• Rocky Mountain spotted fever
• Typhus
• Not of concern in dentistry

8. Protozoa
• Found in freshwater and marine
habitats and in moist soil
• May be responsible for intestinal
infections in humans
• Not of concern in dentistry

9. Viruses
• Require an electron microscope to see them
• Much smaller than bacteria
• Parasitic – live and multiply only inside an
appropriate host cell
• Not affected by antibiotics
• Diseases caused by viruses include: AIDS,
Hepatitis, Herpes, Polio, West Nile, SARS

10. Fungi
• Plants such as mushrooms, yeasts and
moulds that lack chlorophyll
• Fungi are not green
• Two divisions: yeasts and moulds
• Oral Candidiasis is a common yeast
found in the oral cavity of about ½ the
patient population

11. The Chain of Infection
• Virulence – refers to the degree of strength of
that organism in its ability to produce disease
• Numbers – there must be a high enough
number of microorganisms present to
overwhelm the body’s defenses
• Susceptible host – is a person who is unable
to resist infection
• Portal of Entry – means of entering the body
such as a needlestick

12. Universal Precautions
• The basis of Universal Precautions is
acceptance that blood and certain body
fluids of all patients are considered
potentially infectious for HIV, Hepatitis B
and all other Bloodborne pathogens.
• Not all patients with infectious diseases
can be identified by obtaining a medical
history.

13. Routes of Transmission

14. Airborne transmission
• Aerosol spray – dental handpiece
• Mists – ultrasonic scaler
• Spatter – from saliva

15. Cross Contamination
• Food Transmission
• Many diseases are transmitted by
contaminated food that has not been cooked
or refrigerated properly
• Water may have been contaminated with
human or animal fecal material
• TB, botulism and staphylococcal and
streptococcal infections are spread this way

16. Fecal –Oral
• Occurs most often among healthcare
workers , day care workers, and by
careless food handlers
• Prevented by proper handwashing after
using the toilet
• May be transmitted by touching another
person or contact with contaminated
surfaces or food

17. Dental Office
• Improperly sterilized instruments and
equipment can transfer all bloodborne
diseases
• Dental treatment often involves contact
with blood and always with saliva,
bloodborne diseases are of major
concern
• HCV, HBC, HIV

18. Tuberculosis
• Bacteria
• No immunization
• Requires high level of sterilization &
disinfection

19. HAV
• Acute Infective Hepatitis A
• Liver disease
• Found in stool
• No carrier state
• Transmission is fecal/oral route
• Prevented by good personal hygiene
• Instrument sterilization
• Vaccination

20. HBV
• Hepatitis B
• Serious liver disease
• May have a chronic carrier state
• Transmission by contact of infectious body
fluids
• Requires Percutaneous or permucosal
• Prevented by universal precautions, barriers,
PPE, aseptic techniques, obtaining
immunizations

21. HCV
• Hepatitis C
• Transmitted through blood, blood
products or IV drug use
( Percutaneous)
• No vaccine
• Treatments to control the effects of the
disease

22. HSV Type I
• Viral infection
• Causes recurrent sores on lips
• Highly contagious first appearance in
very young children ages 1-3
• Transmission through direct contact
with lesions or with infectious saliva

23. HSV Type II
• Genital Herpes
• Most common STD in the U.S.
• Transmitted only during occurrences of
the lesions

24. HIV
• Human Immunodeficiency Virus
• Bloodborne viral disease
• Spread by sexual contact with an
infected person
• Needle sharing

25. Preventing Disease Transmission
• Immunization – Hepatitis B, MMR &
influenza
• Handwashing Protocols
• Office Hygiene
• Pre cleaning – remove bioburden that
could inactivate disinfectant

26. Infection Control
• Sterilization: process that kills all
microorganisms
• If a surface is not clean, it cannot be
disinfected.
• If a surface cannot be easily &
thoroughly cleaned & disinfected it
should have barrier protection

27. Infection Control

28. Sterilization Techniques
• Asepsis = the product of sterilization
• Sterilization destroys all microbial forms
including bacterial spores
• All reusable items must be heat
sterilized

29. Terminology
• Sterilize: process where all forms of life
are COMPLETELY destroyed
• Disinfect: process where some forms of
life are destroyed
• Sanitize: process that few forms of life
are destroyed

30. Sterilization
1. Steam Autoclave
2. Chemical Vapor Sterilization
3. Dry Heat Oven
4. Chemical Immersion

31. Steam Autoclave Sterilization
• Sterilizes dental instruments by means
of steam under pressure
• Rapidly kills all microorganisms
• Disadvantage is that the moisture may
cause corrosion on some high carbon
steel instruments

32. Chemical Vapor Sterilization
• Similar to autoclaving except a
combination of chemicals is used
instead of water
• Does not rust, dull, or corrode
instruments if absolutely dry
• Chemical vapors can be irritating

33. Dry Heat Sterilization
• Operate by heating up air and
transferring that heat from the air to the
instruments
• Requires higher temperatures than
steam or chemical vapor sterilization
• Instruments will not rust
• Static air and forced air
• Toaster oven is NOT adequate

34. Chemical Liquid Sterilization
• For items that will be damaged by heat
• Requires a 10 hour contact time
• Post sterilization procedures are
essential
• Must be used full strength
• Replace solutions as recommended by
the manufacturer

35. Disinfection
• Process that kills disease causing
microorganisms, but not necessarily all
microbial life
• Disinfectant: chemical used to reduce
or lower the number of microorganisms
on inanimate objects
• Applied to countertops and dental chair

36. Disinfectant Solutions
• Glutaraldehydes • Iodophors
• High level • Intermediate level
disinfectant/sterilant disinfectant
• Times for disinfection • Effective within 5 – 10
range from 10 – 90 minutes
minutes • Contain iodine
• Generally used as an • May discolor clothing or
immersion disinfectant other surfaces

37. Disinfectants
• Synthetic Phenol • Sodium Hypochlorite
• Broad spectrum activity • Intermediate level
• Surfaces must be disinfectant
cleaned first • Main ingredient in
• Can be used on metal bleach
glass rubber or plastic • Not EPA registered so
is NO longer a
recommended product
for use as a disinfectant
in a dental setting

38. Performing Treatment Room
Cleaning & Disinfection
1. Personal Protective Equipment
2. Preclean with the appropriate product
3. Spray the paper towel or gauze
4. Vigorously wipe the surface to be cleaned
5. Spray a fresh paper towel or gauze and this
time let the surface remain moist for the
recommended time for tuberculocidal action
6. Usually 10 minutes

39. Barriers
• Useful to cover equipment and
surfaces that are difficult to clean and
disinfect
• Should be resistant to fluids
• Prevents contamination when properly
placed
• Changed for each patient ( mask,
gloves)

40. Instrument Processing
• Protective clothing, mask, eyewear and
utility gloves
• Soiled instruments are processed in a
single loop or workflow pattern
• From dirty to clean to sterile to storage
without ever doubling back

42. Ultrasonic Cleaning
• Used to loosen and remove debris from instruments
• Reduces hand injuries from cuts and punctures
• Produces sound waves which can travel through
metal & glass
• Causes cavitation ( formation of bubbles in liquid)
• Implosion = mechanical cleaning action of bursting
bubbles
• Combined with chemical action of the solution
removes the debris from the instruments
• 16 times more effective than scrubbing by hand

43. Biologic Monitoring
• Spore testing
• Only way to determine if sterilization has
occurred
• Strips of paper contain harmless bacterial
spores ( heat resistant)
• Placed inside instrument packs during normal
operation
• Sent to UBC for culturing and a report is sent
back

44. Maintaining Infection Control
While Gloved
• During dental procedures it may be
necessary to touch surfaces or objects
• Use a barrier or cotton forceps to
minimize the possibility of cross-
contamination
• Limit operatory contamination by being
prepared for treatment

45. Mini - paper
Break into pairs and choose one topic
• Explain Universal Precautions
• Explain Biologic monitoring
• Explain Ultrasonic cleaning
• Explain Disinfection

46. Conclusion
• Discuss your mini – paper with the
class
How much could you recall?
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47. Thank you