Transcript Trends in Gastrointestinal Infections in England and Wales

Hygiene II
Mark D. Sobsey
ENVR 890
Spring, 2007
Handwashing with soap after
toilet/cleaning child
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Burkina 1% and 13%
Ghana 4% and 2%
Nigeria – and 10%
Brazil – and 16%
Peru 6% and 30%
Kyrgyzstan 18% and
0%
• N. England 80% and
47%
In the last 10-15 years hygiene has
moved up the health agenda
What has brought about the change ?
• Infectious disease tends have increased for some agents
• Food borne disease remains at unacceptably high levels
• Person-to-person tranmsission is now seen a significant
cause of spread of infectious intestinal & respiratory diseases
• Antibiotic resistant strains - need to prevent spread
• Viral agents - not treatable with antibiotics
• Ongoing emergence of new hazardous agents, e.g SARS
• “at risk” groups in the home and community:
– elderly, very young, immune-compromised
– up to 1 in 7 people in US belong to an “at risk” group
Good hygiene practice is key to reducing these risks
- in many cases the first line of defence
Trends in Gastrointestinal Infections in England and Wales
• Increases in the
1990s
• Campylobacter
and Salmonella
• Increases in
rotavirus illness
• Suspected
increases in viral
etiologies like
Noroviruses
What Proportion of Gastrointestinal
Infections Occurs in the Home?
• Estimates of 50-80% in Europe
• Sources and causes:
– Inappropriate hygiene practice
• Failure to wash hands
• Failure clean high-risk areas
– Domestic pets
– Viruses, enteric and respiratory
– Flies and other insect vectors
Infectious Disease Risks in the Home
• Pathogen contamination is highest in the
kitchen, bathroom and in the washing machine
• Routine activities in these areas facilitate
microbial spread and transmission
• Commercial cleaning products vary in their
efficacy in reducing pathogens
• Product misuse undermines efficacy
• Behavior of consumers is a big factor in
pathogen spread and behavior change though
education and communication is a challenge
Environmental Contamination and
Infectious Disease Transmission
• Contact transmission, direct from body
surface to body surface or indirect
transmission via contaminated inanimate
object, are main routes of microorganism
(pathogen) transmission
• Pathogens are on inanimate objects
• They persist for days to weeks
• Pathogens on inanimate objects in the
environment can be transferred to
hands/fingers and other parts of the body
• Pathogens are on inanimate objects in the
environment and are a source of
transmission causing infectious disease
• Environmental (e.g., surface) disinfection
reduces pathogens and disease risks
Dried MS2 virus infectivity at 25oC on
stainless steel  and ceramic tile
Effect of Different Cleaning Methods on
Norovirus Presence on Surfaces
• Melamine surfaces contaminated with
NV in feces, diluted 1:10 or 1:80 in PBS
• Detergent cleaning, even with 2nd wipe
step, failed to decontaminate surfaces
• Virus was spread to a clean surface and
fingers via a wiping cloth in all but one
case (transfer to fingers from most lightly
contaminated surface)
• Surface treated with HDC (5000 ppm
available chlorine) for 1 min reduced NV
completely
• No-cross-contamination, except for one
of the surfaces, which had the heavier
soiling
Evaluation of Hand Hygiene Methods and Agents:
• Contaminate hands with
bacteria and virus
• Clean hands for 10 seconds
by washing, wiping or rubbing
methods
• Test different cleaning agents
• Recover microbes from hands
(glove juice method)
• Repeated challenges and
recoveries
Sickbert-Bennett, E.E., Weber, D.J., GergenTeague, M.F., Sobsey, M.D., Samsa, G.P.,
Rutala, W.A. 2005 “Comparative efficacy of hand
hygiene agents in the reduction of bacteria and
viruses,” Amer. J. of Infection Control 33(2):67;
Your parents were right:
“Wash Your Hands!”
Efficacy of Hand Hygiene Agents:
Log10 Reductions of S. marcescens after 1 and 10 Challenges
(A) 60% ethyl alcohol; (B) 61% ethyl alcohol; (C) 62% ethyl alcohol; (D) 61% ethyl
alcohol/1% CHG; (E) 70% ethyl alcohol/0.005% silver iodide; (F) 0.4% benzalkonium
chloride; (G) 0.5% PCMX/40% SD alcohol; (H) 0.75% chlorhexidine gluconate; (I) 2%
chlorhexidine gluconate; (J) 4% chlorhexidine gluconate; (K) 1% triclosan; (L) 0.2%
benzethonium chloride; (M) nonantimicrobial control; (N) tap water control.
Your parents were right:
“Wash Your Hands!”
Efficacy of Hand Hygiene Agents:
Log10 Reductions of Coliphage MS2 after 1 and 10 Challenges
(A) 60% ethyl alcohol; (B) 61% ethyl alcohol; (C) 62% ethyl alcohol; (D) 61% ethyl
alcohol/1% CHG; (E) 70% ethyl alcohol/0.005% silver iodide; (F) 0.4% benzalkonium
chloride; (G) 0.5% PCMX/40% SD alcohol; (H) 0.75% chlorhexidine gluconate; (I) 2%
chlorhexidine gluconate; (J) 4% chlorhexidine gluconate; (K) 1% triclosan; (L) 0.2%
benzethonium chloride; (M) nonantimicrobial control; (N) tap water control.
Summary of Hand Hygiene Results
• At a short time (10 sec.), all agents but handwipes and 60% ethyl
alcohol handrub were similar to non-antimicrobial and tap water controls
• Reductions of 1.15 to 2.0 log10 of Serratia marcescens
• After 10 episodes (multiple episodes of contamination) handwashing
agents with 0.75-4% CHG, 1% triclosan, 0.2% benzethonium chloride,
nonantimicrobial soap handwash, and tap water alone were efficacious
(>1.5 log10) in reducing bacteria
• Only some effectively reduced viruses: water, soap, benzethonium Cl,
and CHG, and CHG effectiveness declined greatly by 10 challenges
• Alcohol-based handrubs and wipes were ineffective for virus reduction
• Short contact times are effective in reducing transient hand flora
– So, focus hand hygiene on improving compliance rather than
increasing the duration of hand hygiene.
– If shorter duration of hand hygiene improves compliance, greater
compliance should lead to reduced infections.
Hand Hygiene at the Community Level
• Minimum effect of a single handwash
with either plain or antimicrobial soap
on the quantity of hand microflora
• After 1 year, significant reduction of
hand microflora counts by use of
either soap
• Sustained and consistent hand
hygiene significantly microbial loads
over time
• Effects of handwashing on hand
microflora may not be predictive of
the effects on pathogen reduction or
disease reduction
Aiello AE, Marshall B, Levy SB, Della-Latta P, Larson E. (2004)
Relationship between triclosan and susceptibilities of
bacteria isolated from hands in the community. Antimicrob
Agents Chemother. 2004 Aug;48(8):2973-9
Comparison of mean preand post- handwash CFU
counts between groups
using antimicrobial (AM) or
plain soap. N = about 200
Developing a rational approach to home
hygiene
- a risk-based approach
Based on material from a Powerpoint by
Sally Bloomfield
London School of Hygiene and Tropical
Medicine
A risk assessment approach to home
hygiene
• In recent years the concept of HACCP (Hazard Analysis
Critical Control Point) - identifying critical points and
targeting hygiene at these risk points has successfully
controlled microbial risks in food and other
manufacturing environments
• To devise a hygiene policy which has real health benefits
it is accepted that a risk-based approach must also be
developed for the home
IFH approach to home hygiene
– For IFH the “risk assessment” or HACCP
approach to home hygiene has come to be
known as the “targeted hygiene”
– “Targeted hygiene” mean identifying situations
where there is a significant risk of spread of
harmful microbes, and intervening at the
appropriate time to prevent spread
Developing a risk assessment approach to
home hygiene
 Pathogens (or potential pathogens) are introduced
continually into the home via:
people, food, pets, water, insects
 Also - sinks, sink and basin U-tubes, toilets, wet
cleaning cloths can support growth of harmful
microbes (mainly opportunist but also some primary
pathogens) and become a primary source of infection.
Developing a risk assessment approach to
home hygiene
 To be effective home hygiene policy based on risk
assessment must consider:
 Hazard identification including dose response
assessment
- probability of contamination c. harmful microbes
- infective dose
 Exposure assessment
- probability of transfer/cross contamination- such that
human exposure could result
Risk approach to hygiene in the domestic setting
Site(s)
Chance of
germs being
present
Risk of
Assessment of need for a
spread of
hygiene procedure
germs
 Reservoirs
(Toilets, U-tubes,
etc)
Highest
variable
Relatively little except
where known high risk
(e.g. Shigella outbreak)
 Reservoir/dissemi
n-ators (wet cloths
& cleaning
utensils)
Highest
Constant
Always
 Hands
Sometimes
Constant
Always`
 Hand, food, water
contact surfaces
Sometimes
Constant
Always
 laundry
Sometimes Occasional
 Floors, walls, etc
Low
Occasional
Known high risk
Relatively little except
where known risk
spillage)
• Good hygiene is not about “creating a germ
free home” but about identifying high risk
sites and situations and targeting hygiene
measures appropriately (i.e as and where
necessary) to reduce exposure to microbes
which could be harmful
Hygiene procedures in the home
- reducing the risks
What do we mean by “hygienic cleaning”
• The purpose of a hygiene procedure (hygienic
cleaning) is to reduce microbial contamination on a
surface (hands or other surface or site) to a level
which is not harmful to health
What do we mean by “hygienically clean”
“a level of germs which is not harmful to health”
But
• infectious dose varies:
– viruses: 1-100 particles
– bacteria: may be 10 --> as high as 106
– Salmonella: amplified following transfer to food
• depends on the susceptibility - may be lower for “at
risk” groups
• Without precise data it seems reasonable that :
– where there is significant risk of germs spreading
(e.g. during food preparation)
– aim should be to get rid of as many germs as possible
What methods are available for “hygiene cleaning”
• A hygienically (as opposed to visibly) clean surface is
achieved either by removal of microbes or application
of a disinfection process or a combination of both:
What methods are available for “hygiene cleaning”
Detergent-based hygienic cleaning
• In many situations - hands, cooking/ eating utensils, hygiene
achievable using detergent-based cleaning.
• To be effective it must be applied in conjunction with a thorough
rinsing process - to wash germs away from the surface
Disinfection
• Alternatively “germ kill” can be used
- chemical disinfectant products
- heat (e.g boiling or >60°C)
or: Combined removal and kill
- laundry - removal, heat and bleach kill
- dishwashing - removal, heat kill
In deciding whether “soap and water” is the
appropriate hygiene procedure or whether a
disinfectant is needed - need to consider:
•Can you “wash” the germs away?
– Large surface, taps, biofilms ?
•Have you washed the germs away?
– “In homes” studies suggest that this is sometimes not the
case - in some situations e.g food hygiene the extra margin
of safety from use of disinfectants is advisable
•Where have the germs gone ?
– Contaminated water, particularly c. a cloth is highly effective
means of spreading pathogens
Food hygiene - risks associated with preparation of a meal using a
chicken contaminated with Salmonella or Campylobacter
Percentage of sites contaminated with
Salmonella and/or Campylobacter
After Meal
No of
Preparation
participants
in each group
= 20
Chopping bd
60
Utensils
5
Hands
35
Dishcloth
25
Taps
5
Sink
30
Sink
Rim
10
Surround
Fridge Door
10
Cupboard
10
Oven
Door
10
Door dr
Kitchen Door
10
Condiments
5
TOTAL
17.3
After Cleaning Soap and
with Soap and
water +
Water
hypochlorite
15
25
20
25
25
30
15
10
5
10
10
5
15.3
0
5
0
5
0
0
5
0
5
0
0
0
2.3
Cogan, Bloomfield and Humphries, Letters in Appl.Microbiology 1999, 29,354-358
UK data indicates:
• 25% and 83% of raw chickens contaminated
c.Salmonella and Campylobacter
(Jorgensen et al. 2002).
• Every day 1 in 25 homes prepare a meal with
a Salmonella and/or Campylobactercontaminated chicken
• 0.4% and 0.8% of beef & lamb products from
retail butchers are +ve for E. coli O157
(Chapman et al. 2001)
General hygiene - effectiveness of hygiene procedures in
eliminating norovirus from surfaces (N = 14)
Barker, Vipond and Bloomfield, J. Hospital Infection 2004, 58, 42-49
Surfaces soiled with
faeces/norovirus
Contaminated cloth used to
wipe a clean surface
Key concepts of targeted hygiene
• Current concept of home hygiene:
– People still largely see home hygiene as a
process of "getting rid of household germs" believing that this is the appropriate means to
protect their family against infection.
• we need to promote the concept of “targeted
hygiene”
– identifying a microbes, and intervening at the
appropriate time in appropriate manner to prevent
spread
Key concepts of targeted hygiene
• In the places and at the times that matter it is
important to not just clean but “hygienically clean”
– can be achieved by detergent based cleaning,
provided this is through and accompanied by
adequate “rinsing” process
– within a targeted hygiene approach - in some
situations it is advisable to disinfect
Targeted hygiene is simpler - and
healthier
• “Targeted” hygiene offers the means to
deliver messages which make sense to
consumers
• It offers the means to maximise protection
against infection whilst reducing the
impact on our human and natural
environment to the least extent
Education is the key factor
IFH guidelines on
home hygiene
IFH teaching/selflearning materials
on home hygiene
Targeted
hygiene
www.ifh-homehygiene.org
Further Reading - IFH reviews, consensus
views, Guidelines, training resources etc
Biocides and resistance
•
Microbial resistance and biocides: a review and consensus statement
http://www.ifh-homehygiene.org/2003/2public/2pub03.asp
Hygiene Hypothesis
•
The Hygiene hypothesis and its implications for hygiene. http://www.ifhhomehygiene.org/2003/2hypothesis/hh.htm
Targeted approach to home hygiene
•
Bloomfield, S.F. (2002) Home hygiene: a risk based approach. International
Journal of Hygiene and Environmental Health, 205, 1-8
IFH guidelines and teaching materials
•
•
•
Guidelines for prevention of infection and cross infection the domestic
environment. http://www.ifh-homehygiene.org/2public/2pubgu00.htm
Recommendations for selection of suitable hygiene procedures for use in
the domestic environment.
http://www.ifh-homehygiene.org/2public/2pub04.htm
Home Hygiene - prevention of infection at home: a training resource for
carers and their trainers
http://www.ifh-homehygiene.org/2003/2public/2pub06.asp