Download keynote_1997 - International Scientific Forum on Home Hygiene

The need for a home hygiene policy and guidelines on home
hygiene
An Ad Hoc Meeting of the International Scientific Forum on
Home Hygiene*
Date 1997
*The International Scientific Forum on Home Hygiene currently comprises:
Dr Rijkelt Beumer
Vakgroep Levensmiddlentechnologie, Universitaet van Wageningen, Wageningen, The
Netherlands
Professor Sally Bloomfield
International Hygiene Research and Liaison Manager, Unilever Research, Port Sunlight, UK and
Professor of Environmental Health, Division of Life Sciences, King’s College London, London,
UK
Professor Dr Martin Exner
Direktor, Hygiene-Institut, Rheinische Friedrich-Wilhelms-Universität, Bonn, Germany
Professor Gaetano Fara
Direttore dell’Istituto di Igiene “G. Sanarelli”, Università “La Sapienza” di Roma, Rome, Italy
Dr Elizabeth Scott
Consultant in Food and Environmental Hygiene, Newton, Massachusetts, USA
CONTENTS
Introduction
What do we mean by home hygiene?
The need for a home hygiene policy
The increasing incidence of food-borne diseases acquired in the home environment
The emergence of new pathogens and their significance in the home
Implications of the risk of domestically acquired infections in susceptible groups
The home healthcare environment
The threat posed by the continuing increase in resistance to antibiotics in clinical practice
Education and public awareness
A proposal for establishing guidelines on home hygiene
The development of home hygiene guidelines based on risk assessment
1.
2.
3.
4.
Infection potential of sites and surface in the home
Infection and cross contamination routes within the domestic environment
Home environment factors
Groups who may particularly benefit from hygiene guidelines and education Infection
prevention and improving hygiene in the home Advice on appropriate decontamination
processes in the home Summary and conclusions References
INTRODUCTION
Currently there would appear to be relatively little concern amongst government authorities
regarding the importance of home hygiene in the prevention of community-based infections. This
may be for a number of reasons, including prevailing attitudes to infection control, a focus on
hospital, institutional and food manufacturing hygiene, and the relative lack of epidemiological data
and under-reporting of infections related to the home environment. Furthermore, there is currently
no recognised organisation that takes responsibility for this area of concern.
However, there are a number of reasons to suggest that awareness of home hygiene and its
contribution to family health should, as a matter of urgency, be given higher priority in the
development of national and global healthcare policies. For example, there is considerable evidence
that the incidence of food-borne illnesses in Europe is increasing, with many of these infections
now recognised to be acquired in the home. The emergence of new pathogens such as E. coli
H7:O157 and of antibiotic resistant bacteria has recently received considerable attention, although
the significance of E. coli H7:O157 in relation to domestic food preparation, and the potential risk
from methicillin resistant Staphylococcus aureus (MRSA) in the home environment, has to date
been given little consideration. It has been cited that public education on preventing the spread of
E. coli H7:O157 within the home would reduce the burden of this infection (Parry et al. 1998).
Furthermore, changing trends in healthcare mean that more people, including the elderly, are now
being nursed or cared for in a home healthcare environment. These factors, combined with
evidence showing that the public have a poor understanding of microbiological risk, proper food
storage and preparation procedures and awareness of home health hazards, suggest that raised
awareness of the need for good home hygiene and better education of the public on good hygiene
practice could contribute to a more healthy home environment.
At an international meeting of experts with an interest in hygiene, various issues were reviewed. A
strategy was agreed for the development of “Guidelines for Home Hygiene” which would give a
comprehensive and cohesive approach to all aspects of hygiene in the home. The consensus view
from this meeting is summarised in the following paper.
What do we mean by Home Hygiene?
At the present time, if we talk about “home hygiene”, we tend to be referring to the general day to
day cleaning of the home. In practice, home hygiene encompasses something much wider.
Micro-organisms are introduced continually into the home in a number of ways - on people, food,
pets, insects and via water. In addition certain areas or sites in the home environment where
stagnant water and organic residues accumulate such as sinks, sink and basin U-tubes, toilets, wet
cleaning cloths and facecloths, readily support the growth of potentially pathogenic species and can
thus become a primary source or reservoir of infection.
Many of the types of organisms which enter or reside in the home are of little consequence and
some can be actually beneficial. Some organisms, however, have the potential to cause infectious
disease, although even for these species contact with small numbers of organisms is known to be
important in maintaining the immune system of the normal healthy adult. The fact that potentially
harmful organisms can cause an infection in one person within the household (most usually
someone within a vulnerable group e.g. a neonate) but not others is a further complication. Some
people may also carry highly pathogenic organisms and bring them into the home, without
themselves being affected so that other family members are entirely unaware of the hazard.
Home hygiene is the sum total of the measures used to prevent infection and the transfer of
infection within the home environment. These measures may be categorised into four main areas,
namely food hygiene, personal hygiene, general home hygiene, and home “healthcare”. Home
healthcare (i.e. infection control in the home as opposed to hospital infection control) includes
specific situations of perceived or increased risk such as care of neonates and geriatrics, infection
control measures associated with home nursing of immune-compromised family members, and
infection control measures associated with family members who are carriers of HIV or MRSA. It
also includes situations where decontamination of faecal or other “spillage” material from neonates
or pets, for example, is required. Procedures such as disinfection of contact lenses must also be
regarded as routine home healthcare.
THE NEED FOR A HOME HYGIENE POLICY
As stated at the outset there are a number of issues, supported by epidemiological and
microbiological data, which suggest the need for an improvement in home hygiene awareness and
home hygiene practices:
The increasing incidence of food-borne diseases acquired in
the home environment
There is considerable evidence that the incidence of food-borne disease is increasing in Europe.
The most accurate data available are provided by the UK and the Netherlands, which have effective
surveillance and data collection systems. In the UK there has been a significant increase over 10
years to almost 100,000 cases in England and Wales in 1997, compared with 70,000 cases in 1992.
This figure is considered to be an underestimate since only a fraction of cases are reported to a
doctor. Surveys completed in the Netherlands are thought to give a more accurate figure of 2.5
million gastroenteritis cases per year in contrast to the 300 per year identified by the data collection
system (Hoogenboom-Verdegaal 1994). Data from surveillance programmes in various European
countries and the USA, as reviewed by Scott (1996), is variable in quality but indicates that in most
countries there is a significant problem.
In contrast to the prevailing view of the public that food-borne infections are acquired in
establishments such as restaurants, data from a number of countries indicate that many outbreaks of
food-borne disease originate in the home. This misconception may arise because large outbreaks of
food-borne illness due to problems in food manufacturing and food service facilities are more likely
to be reported to public health authorities and to receive subsequent attention by the media and the
public than smaller outbreaks resulting from poor hygiene in the home (Knabel et al. 1995).
Estimates from the UK by Sheard (1986) covering the period 1980 to 1986 suggest that private
homes account for more outbreaks than the sum total of other reported locations. A more recent
study (Ryan et al. 1996) covering the period 1992 to 1994 indicated that 16% of food poisoning
outbreaks occurred in the domestic setting, although it was suggested that this figure is an
underestimate. Data from the Netherlands indicates that as much as 80% of sporadic Salmonella
and Campylobacter infections arise in the home (Hoogenboom-Vergdegal and Postema 1990)
whilst data from Spain shows the private home as the location of up to 50% of all outbreaks. A
recent study in Italy (Scuderi et al. 1996) showed that 74% of Salmonella outbreaks were
associated with the home. A similar survey in the US (Aserkoff et al. 1970) indicates that the
largest proportion of food poisoning outbreaks originate in the home.
There are a number of reasons that may explain the increasing incidence of gastrointestinal
infections associated with the home environment, including changes in technology/husbandry of
commercial food production, deficiencies in slaughterhouse practices, changes in domestic
practices of food preparation and eating habits, and increasing preference for fresh rather than
preserved foods.
The emergence of new pathogens and their significance in the
home
The ongoing emergence of new pathogens represents a serious global problem (Anon 1996). Many
emerging infections are caused by species which are normally present in the environment but which
hitherto have had little clinical impact on man. The increased clinical significance of these species
relates to a number of factors such as changing environmental conditions and deficiencies in the
prevention and control of infectious diseases (Morse 1995). Several of these species are now
emerging as important foodborne pathogens such as E. coli O157:H7, Campylobacter jejuni,
Listeria monocytogenes, Vibrio cholera O139, Norwalk virus and Yersinia enterocolitica
(Lederberg, Shope and Oaks 1992; Doyle 1991) all of which may have an impact on home health
unless emphasis on preventive practices is highlighted.
Certain pathogens (e.g. HBV, Helicobacter pylori) are also now implicated as the cause of or as cofactors in cancer and possibly of chronic degenerative diseases (Anon 1996).
Implications of the risk of domestically acquired infections in susceptible groups
Alternatively, a microbial species may emerge as a pathogen because of changes in host
susceptibility to infection (Morris 1997). Factors which lead to increased susceptibility to infection
within a population include increased numbers of immune-compromised patients, increased use of
immunosuppresssive agents, ageing of the population and use of drugs such as antibiotics, all of
which have an impact in the home.
As the population structure of Europe ages, infection risk in the home and its consequences can be
expected to increase. It has been estimated that approximately 20% of the population (neonates,
geriatrics, pregnant mothers, immune-compromised patients discharged into the community) may
be classified within a high-risk or “at risk” group, whose immune defences against infection can be
expected to be less than that associated with the normal healthy adult and who therefore require
additional guidance on hygiene and hygiene precautions (Gerba, Rose and Haas 1996). For most
people the quality of their life (their health expectancy) is at least as important as their life
expectancy.
It is generally accepted that the infection risk in the general community is less than that associated
with patients in hospitals. Although the levels of pathogenic organisms found at some sites within
the home may be relatively low, it has been suggested that, for susceptible groups, these levels may
still represent a particular risk in susceptible groups (Scott 1996). For people such as the elderly,
with high susceptibility to infection, the clinical sequelae of food-borne disease in these groups can
have severe consequences.
The home healthcare environment
Due to changing trends in healthcare, increasing numbers of sick people are now being cared for at
home. These, as mentioned above, may be patients with immune compromising conditions. This
can be associated with a range of conditions including not only patients using immunosuppressant
drugs but also those using invasive systems (indwelling catheters) or inhalation systems or devices.
The number of otherwise healthy family members with asthma or allergies, another condition
associated with increased susceptibility to infection, is increasing. Other patients now frequently
cared for in the community include those suffering from communicable diseases such as HIV or
carrying an antibiotic resistant pathogen such as MRSA, which represent a threat to other family
members. A recent investigation of the domestic environment occupied by a nurse known to be
colonised with MRSA revealed contamination on door handles, a computer desk shelf and
computer joystick (Masterton et al. 1995).
Family members involved in home healthcare often do not understand basic infection prevention
measures and require education on correct procedures. By providing home caregivers and other
healthcare providers who work in the home with hygiene guidance it should be possible to reduce
the risk of infection to both patients and caregivers (Simmons et al. 1990).
The threat posed by the continuing increase in resistance to antibiotics in clinical practice
Antibiotic resistance is now considered as a major health threat (Anon 1997). The implication from
this is that greater emphasis must now be placed on preventive hygiene practices rather than
reliance on antibiotic therapy. Although antibiotic resistance has largely been considered as a
hospital-based problem, control of resistant strains such as MRSA is now a community as well as a
hospital problem (Wagenvoort et al. 1997). Experience is now showing that rigorous
implementation of infection control measures (i.e. good hygiene) with reduced antibiotic usage can
have a significant impact in reducing antibiotic resistance (Anon 1997).
Education and public awareness
Two recent questionnaire studies in the United States have raised concern over the inadequate
consumer knowledge of foodborne microbial hazards, food-handling practices and their
misconceptions regarding the sources and consequences of foodborne illness (Fein, Lin and Levy
1995; Altekruse et al. 1995).
Patterns of home food preparation are also changing in Europe and the United States. It is no longer
the case that one person is responsible for food preparation. Now children and other adult
household members are all involved in food preparation or food handling - more food handlers
need to be educated and the information to be conveyed is increasingly complex (Wolf 1995).
A PROPOSAL FOR ESTABLISHING GUIDELINES ON HOME HYGIENE
Overall the evidence suggests that comprehensive guidelines on all aspects of home hygiene would
be a valuable aid in educating hygiene professionals (i.e. those people whose job or profession
involves advising the public on hygiene and healthcare), and ultimately the public, on
microbiological risk in the home environment and the way in which this risk might be reduced
through improvements in home hygiene.
As stated previously micro-organisms are introduced continually into the home - in a number of
ways - on people, food, pets and via water. These must be considered as the primary sources of
potentially harmful micro-organisms in the home. In addition certain areas or sites in the home
environment where stagnant water and organic residues accumulate, such as sinks, sink and basin
U-tubes, toilets, wet cleaning cloths and facecloths, will readily support the growth of potentially
pathogenic species and thus also become a primary source or reservoir of infection.
Currently, many aspects of hygiene which relate to the domestic environment tend to be
compartmentalised into recognised areas such as advice on food hygiene, advice on personal
hygiene, or what to do if there is a young baby in the home. Since all of the appropriate hygiene
activities are based on the same underlying microbiological principles, it is more appropriate that
they are discussed together and advice on all areas of hygiene relevant to the home provided.
Although a significant proportion of infections occur as the result of person to person contact and
can only be controlled by changes in social behaviour, indications are that many infections relate to
poor hygiene and could be prevented by proper infection control procedures.
The main principles for optimising infection control in any environment are concerned with:
the reduction or elimination, where feasible, of sources/reservoirs of infection
preventing transfer of contamination from these sources
In the home, as far as food is concerned, the main emphasis is on elimination of the contaminating
organisms to a safe level by application of a cooking process. However, preventing transfer of
contamination during the cooking and food preparation processes is also extremely important. As
far as other primary sources are concerned, namely people and pets, elimination is not an option!
Thus, the major emphasis is on prevention of transfer which involves good surface hygiene (mainly
hands and hand contact surfaces). For environmental reservoirs of infection, experience has shown
that, since in many situations there is continual recontamination of surfaces or sites either due to
recontamination or re-growth of residual survivors, elimination of risk organisms is not a feasible
proposition (Scott, Bloomfield and Barlow 1984). The emphasis for controlling infection from
these sites is again on managing these risks through appropriate hygiene practices which prevent
infection transfer.
The implied purpose of applying a hygiene procedure anywhere in the home, as elsewhere e.g. in
hospitals, is to achieve a reduction in the number of viable organisms to a level where there is no
longer a threat to health. One of the problems of drawing up guidelines for good hygiene however
is that the level of risk from exposure to micro-organisms is variable according to specific
circumstances. Cross infection in the domestic environment does not always result in an infectious
disease; the risk of infectious disease arising from transfer of infection in the domestic environment
is highly variable and depends on a number of factors:
The presence and pathogenicity of the organism
The infective dose - there is a direct correlation between the size of the infecting dose and the risk
of infection
The susceptibility of the host. Neonates, geriatrics, pregnant mothers and other
immunocompromised people are at increased risk of infection. Even for healthy adults,
susceptibility to infection can be altered by various factors e.g. stress, alcohol use, and even the use
of medications such as antacids which reduce the effectiveness of the acid barrier
The route by which the organism enters the body e.g. oral, topical etc.
The degree of occupancy of the home and the climatic conditions.
This variability demands that a “flexible approach” is adopted according to each specific situation
or problem. This can only be achieved by a proper awareness of these interdependent factors (Scott
1996) which in turn depends on sound education; as with any educational programme, members of
the public are unlikely to achieve improvements in home hygiene unless they understand which
practices in the home are most likely to contribute to the infection risk and the factors which
increase or decrease the risk. Such information must be incorporated into the guidelines and, ideally
also, explained.
In order to identify potential health hazards, it is proposed that guideline advice should be based on
identifying critical control points in the home using risk analysis approaches. The use of hazard
analysis and critical control point (HACCP) evaluation in identifying areas of potential risk in
certain food manufacturing processes is well documented and a recognised tool for analysing
critical factors which may lead to food contamination or infection risk and for introducing control
measures. Griffith and Worsfold (1994) suggested that HACCP has a role in the preparation of food
in the domestic environment, with potential applications in forming the basis of health-education
programmes to improve consumer awareness of food-borne disease and its prevention. The
application of HACCP to other aspects of home, apart from not only food preparation procedures,
is also proposed as a valuable way of identifying risks associated with particular home situations,
for example, when there is a young child, an elderly person or someone with an infection resident
in the home (Jones 1997).
THE Development of HOME HYGIENE GUIDELINES BASED ON
RISK ASSESSMENT
In developing guidelines for home hygiene based on a risk assessment approach a number of
factors need to be taken into account:
1.
Infection potential of sites and surface in the home
A review of microbial contamination of the home enables us to identify sites and surfaces most
likely to contribute to infection risk.
Several published studies have shown that a wide range of potentially pathogenic micro-organisms
are commonly found at sites in the home (Finch et al. 1978; Scott, Bloomfield and Barlow 1982),
with the most commonly identified sites being the kitchen and bathroom. A microbiological survey
of the home by Scott et al. (1982) reported the presence of pathogenic bacteria and opportunistic
pathogens in reservoir sites such as kitchen sinks and at contact transfer sites in the kitchen and
bathroom. A similar pattern was reported by Finch et al. (1978), and more recently by Josephson et
al. (1997). In a survey of 213 homes, Listeria species were found in about 15% of homes and were
recovered from wet sites such as the kitchen sink, dishcloths and washing up brushes, the
refrigerator and the toothbrush (Beumer et al. 1996).
The species of Enterobacteriacae isolated in these various studies included Klebsiella, Enterobacter,
Citrobacter, Proteus and E. coli. Although these species are not normally pathogenic to the healthy
adult, they must be regarded as indicators of poor hygiene. Species of Pseudomonas (including Ps.
aeruginosa) and Staph. aureus were also isolated. The fact that in all of these studies primary
pathogens such as Salmonella was isolated only once and Campylobacter only twice (Josephson et
al. 1997) should not be taken as an indication that environmental transfer of these pathogens is not
a problem; it must be borne in mind that the number of homes surveyed was relatively small in
global terms, and the homes were evaluated under “normal” conditions i.e. not specifically during
or immediately after food preparation, or where there was a known carrier. Van Schothurst et al.
(1978) demonstrated that, in 73 homes where a case of salmonellosis had occurred, in over half of
these homes, isolates of the same serotype were isolated from environmental sites including
worktops, sinks, towels etc. De Wit et al. (1979) demonstrated the potential for cross-contamination
via inanimate surfaces in the home during preparation of raw chickens, whilst Humphrey et al.
(1994) showed recovery of Salmonella enteritidis PT4 from fingers and utensils, sometimes after
washing, following preparation of egg dishes using artificially contaminated eggs. In the latter
study the organisms could be recovered from dry films of batter or eggs on work-surfaces up to 24h
after contamination.
Most usually pathogens found in the home are brought in on raw or processed food contaminated,
with the micro-organisms most commonly implicated in food-poisoning cases including
Salmonella, Campylobacter and Listeria. Micro-organisms are ubiquitous throughout nature and
can often contaminate raw agricultural food products. Levels of contamination in raw products are
reduced by treatment and preservation processes, but will survive, and humans may re-contaminate
foods during production, processing, distribution or preparation. Any food, therefore, whether raw
or processed may carry some level of risk for foodborne illness if not properly handled in the home
before consumption (Knabel et al. 1995).
During and after viral infections, virus particles may be shed in large numbers in many body fluids
including blood, faeces, saliva, urine and nasal secretions. There are a number of laboratory
investigations which indicate that viral species including rotavirus, rhinovirus, adenovirus,
poliovirus, herpes simplex virus and hepatitis A virus can survive for significant periods on dry
surfaces (Mahl and Sadler 1975; Nerukar et al. 1983; Sattar 1986; Ansari et al. 1988; Ward et al.
1991; Mbithi et al. 1991) but no studies have been carried out to investigate the prevalence of viral
species at environmental sites and surface in the home environment.
The risk of young pets bringing potentially infectious organisms into the home is also recognised.
High levels of contamination on the paws of dogs and cats have been found and it has been
concluded for example that dogs may serve as a source of salmonellosis, especially in children
(Morse et al. 1976; Wall et al. 1996).
2.
Infection and cross contamination routes within the domestic
environment
Another factor which needs to be taken into account is the fact that the risks associated with
environmental contamination depend not only on whether the site is contaminated, but also the
probability of transfer - either to food, to other surfaces, or directly from hand to mouth. For
example, a surface contaminated with Salmonella may be a hazard but only becomes a health risk if
those micro-organisms are transferred from that surface either to the person or to food, and if the
numbers transferred, or eaten, exceed an infective dose.
The majority of food poisoning cases result from the consumption of contaminated food.
Considerable research has been performed on identifying the actual causes for food-borne disease
outbreaks. Identified steps include preparation of food too far in advance which enables
contamination of products and the growth of micro-organisms to levels responsible for clinical
disease (Roberts 1982). An interval of more than 12 hours between preparation and eating,
improper cooling and inadequate re-heating have been identified as the most important causes of
contaminated food outbreaks (Bryan 1988). Guidelines on home hygiene must therefore give clear
guidance on methods for cooking and storage of foods and need to be communicated to the
consumer in health education campaigns. The importance of good food hygiene in the home cannot
be underestimated.
Cross-contamination during food preparation has been identified as a common cause of food
poisoning and can occur at any stage in food preparation (Foulger 1980). Sources of contact
transfer sites include food preparation surfaces and the occurrence and survival of bacteria and
viruses on such surfaces has been well documented. Wet cloths, cleaning utensils, together with
hand and food contact surfaces are important elements in cross-contamination (Scott and
Bloomfield 1990). Where contaminated surfaces or cloths containing even relatively low levels of
bacteria come into contact with fingers or surfaces, organisms may be transferred in sufficient
numbers to represent a potential infection hazard (Scott and Bloomfield 1990).
Reviewing the mechanisms of transmission of food-borne infection Roberts (1990) concluded that,
although most outbreaks result from poor temperature control of raw and cooked foods, a
significant number are directly or indirectly associated with cross-contamination, although crosscontamination via surfaces is relatively less frequent. Data suggest that cross-contamination is
implicated in about 6%, and poor hand hygiene in about 4%, of outbreaks. Roberts (1986) reported
that cross-contamination was a contributory factor in 14% of UK outbreaks of human
salmonellosis. A more recent UK study of food poisoning (1992-1994) outbreaks in the domestic
setting suggested that cross contamination was a contributory factor in 28% of the outbreaks
investigated.
The importance of the hands as a means of transfer not only of food poisoning bacteria but also
other pathogenic species, is well accepted, such that the need for good hand hygiene is usually well
emphasised in hygiene education literature and hygiene education campaigns. There are a number
of reports in the literature in which the circumstantial evidence strongly suggests direct hand to
mouth transfer as the cause of food poisoning. Although consumption of contaminated,
undercooked beef products accounts for most outbreaks of E. coli O157:H7, other food vehicles are
also responsible for transmission and improper hygiene with secondary spread from person-toperson contact is another well-documented route of infection (Feng 1996; Griffin and Tauxe 1991).
The CDC report that many unrecognised, sporadic outbreaks of E. coli O157:H7 probably occur in
the US due to undercooking of meat products, such as hamburgers, in the home (Anon 1994a;
Knabel et al. 1995).
Although hand transfer of infection is well accepted, there is some reluctance to accept that
inanimate surfaces may can represent the route of transfer for a range of different infectious
diseases, not only in the hospital environment but also in the home. During the 1970s and 1980s
Maki et al. (1980) and McGowan (1981) reported microbiological surveillance studies of hospitals
showing that, although control procedures could be used to reduce the incidence of contamination
in the hospital environment, there was no evidence of any reduction in the incidence of infection.
These results have encouraged the belief that general environmental sites and surfaces do not
represent a hazard, which is not the case. From time to time infection outbreaks (hospital,
institutional and domestic) involving a variety of bacteria and fungal species are reported in the
literature in which environmental sites and surfaces are cited as the source or means of transfer
(Bloomfield and Scott 1997). Although such reports are infrequent they illustrate the potential for
infection transfer involving direct contact with inanimate surfaces.
Indications are that Shigella sonnei infection usually spreads from person to person and is
associated with poor personal hygiene/toilet facilities. Shigella infection is also facilitated in
schools and day-care centres by handling contaminated toys and other inanimate objects. The
infectious dose is very small and young children are implicated in the spread of shigellosis to their
families (Evans and Maguire 1996). Rotaviruses are the primary cause of severe diarrhoeal disease
in infants and young children and faecal-oral transmission may occur via hand contact with
contaminated surfaces (Ward et al. 1991). Evidence has shown that rotavirus can be readily
transmitted from environmental surfaces either directly from surface-to-finger or from surface-tomouth (Ward et al. 1991). Its survival on environmental surfaces and hands has also been
demonstrated (Sattar 1986; Ansari et al. 1988; Ward et al. 1991). In a study of two infant day care
centres, Butz et al. (1993) showed that moist surfaces such as telephones, water fountains and water
play tables were common sources of rotavirus contamination. Ward et al. (1991) demonstrated that
13 out of 14 adult subjects who consumed rotavirus (103 focus forming units) in a controlled
laboratory experiment became infected. It was also found that rhinoviruses can survive for several
hours on the hands, and that self-inoculation by rubbing of the nasal mucosa or conjunctivae with
virus-contaminated hands can lead to infection in susceptible hosts (Hendley et al. 1973).
The possibility that infection can result from direct contact with contaminated surfaces is supported
by evidence showing that ingestion or contact with relatively small numbers of pathogenic
organisms can be sufficient to cause infection. Investigations with healthy adults indicate that the
infective dose of species such as Salmonella and E. coli may be as high as 106 to 107 colony
forming units (cfu) but may be as low as 102 to 103 or even less depending on the strain involved
(McCullough and Eisele 1951; Ferguson and June 1952; Lipson 1976; Hockin et al. 1989; Craven
et al. 1975; Gill et al. 1983; Greenwood and Hooper 1983; D’Aoust 1985). Infective doses for
Campylobacter and E. coli 0157 are estimated at 100-300 and 500 cfu (Tauxe 1992; Anon 1994b).
For Staph. aureus it was shown that although an inoculum of up to 106 cfu may be required to
produce pus in healthy skin, as little as 102 may be sufficient where the skin is occluded or
traumatised (Marples 1976).
3.
Home environment factors
Although not appropriate for inclusion in guidelines on home hygiene, consideration also needs to
be taken of social and environmental factors in the spread of infection in the domestic environment.
Home design may influence hygiene in the home, such as the ability to clean toilet areas and other
surfaces which may become contaminated within the home. Advice does, however, need to be
included on the control of mould and fungal growth in the home because of the reported link with
respiratory health, particularly in relation to asthma (Flannigan et al. 1991; Martin et al. 1987).
4.
Groups who may particularly benefit from hygiene guidelines and
education
All people are at some risk of food-borne illness, but it must be recognised that certain sub-groups
within the population are more susceptible to food-borne and other pathogens, than healthy young
and middle-aged adults. In a normal healthy population, people are exposed fairly regularly to
Salmonella but very few people become infected carriers and shedders, and only a small proportion
become seriously ill. However, some Salmonella strains may be particularly hazardous to the
elderly population. Guidelines should therefore highlight those groups at increased risk such as
infants, pregnant women, the elderly and the immunocompromised (Wolf 1995).
Although the care at home of infectious family members such as HIV or MRSA carriers returning
from hospital is a specific healthcare issue, the general practices and principles which may be
regarded as home healthcare procedures also apply to some situations which are considered as
everyday matters in the home. This includes the care of babies who may cause faecal contamination
of the home, the care at home of elderly people or of a family member or child with a
gastrointestinal infection.
It is important that both the infected person and those who have to care for them in the home have a
good knowledge of hygiene practices. Such people would particularly benefit from an
understanding of the idea of relative risk, which takes into account the susceptibility of different
subgroups to different pathogen.
INFECTION PREVENTION AND IMPROVING HYGIENE IN THE HOME
Having identified the hazards and relative risks in the home, it is then necessary to give advice on
appropriate hygiene procedures for implementation in each situation. Guidelines must outline
which home hygiene measures for each situation can most effectively be applied to reduce potential
infection risk. This needs to emphasise common sense procedures and provide more detailed
instructions where appropriate.
Preparing guidelines to address these issues must also take into account the best method of
communicating the educational information to the public for maximum effect in order to positively
influence behaviour.
Advice on appropriate decontamination processes in the home
Generally, there are a number of decontamination practices which can be encouraged in the home
to ensure that food is wholesome to eat, and that sites and surfaces which represent a potential for
cross contamination are hygienically clean and not just visibly clean. These include drying,
detergent and hot water washing, heat and disinfection.
Drying of contaminated items and surfaces plays a vital role in maintaining low levels of
contamination. However there is evidence to suggest that many bacterial and viral species can
survive for considerable periods of time even on dry surfaces and, for this reason, drying should not
be considered as an effective means of achieving a hygienically clean surface, but only as a means
of maintaining surfaces in a hygienic state. Studies have shown survival up to 4 hours for Gramnegative species like Salmonella and E. coli, and up to 24 hours at least for Staph. aureus (Scott and
Bloomfield 1990).
In many situations, such as the decontamination of cooking and eating utensils, detergent and hot
water washing is adequate for achieving a hygienically clean surface. However, it must be
emphasised that because the micro-organisms are removed by mechanical removal, detergent and
water washing is only effective if applied with a suitable rinsing process. Since the purpose of the
detergent is to facilitate detachment of the bacteria from the surface, cleaning products should
therefore be formulated to maximise this effect.
Heat is an effective form of disinfection although it may not be applicable to large surface areas
and may be unreliable in unskilled hands. An early survey by Anderson and Gatherer (1970)
showed that, although disinfection of infant feeding utensils can be consistently achieved under
controlled laboratory conditions using either hypochlorite or boiling, disinfection failures were
encountered more frequently with bottled and teats treated by mothers in the home using boiling
(54 and 66%) as compared with hypochlorite (22 and 30%). Set against this however, heat is the
method used to reduce contamination levels in foods to a level which is safe for consumption. The
operating temperature of dishwashers is also generally sufficient for disinfection of contaminated
cooking and eating utensils.
Chemical disinfectants or hygienic cleaners are used for decontamination of sites and surfaces in
situations where the former methods are either impractical or deemed to be inadequate for the
particular situation. Chemical disinfection may also be particularly beneficial in high risk
situations, for example where there are elderly persons, neonates or young pets in the home and
where either the infection risk is increased or the consequences of infection are more significant.
Since chemical disinfectants vary considerably in their properties, it is important that guidelines
give information on the choice of a suitable disinfectant or hygienic cleaning product
It is important to stress that the effectiveness of any hygiene procedure applied in the home depends
not only on the effectiveness of the procedure (e.g. the hygienic cleaner or disinfectant) but also on
the way in which it is applied i.e. in the right way and at the right time. Although the evidence
shows that decontamination procedures will reduce the number of viable organisms to a safe level,
the effects may be relatively short lived and recontamination of these sites may occur quite rapidly
either as a result of recontamination or, for surfaces which remain damp, by the re-growth of
residual survivors not destroyed or removed by the hygienic decontamination process. This clearly
indicates that to achieve benefit, hygiene procedures should be applied for a specific purpose, rather
than as part of a routine cleaning process.
In using chemical disinfectants in the home there are a number of issues which suggest that
inappropriate use or overuse of chemical disinfectants should be avoided. These relate to the
development of resistant microbial strains, a lowering of natural immunity or environmental
factors.
SUMMARY AND CONCLUSIONS
Epidemiological and microbiological data presented in this paper suggest an a priori need for an
improvement in hygiene awareness and hygiene practices in the home. It was agreed that, as a first
step to achieving this, “Home Hygiene Guidelines” , which draw together all aspects of home
hygiene and healthcare related to infectious disease control, and give comprehensive and consistent
information on procedures to prevent infection and the transfer of infection in the home, should be
prepared. It was considered that such guidelines should be written with the specific intention of
educating those hygiene professionals from whom the public receive information and guidance of
home hygiene (i.e. those people whose job or profession involves advising the public on hygiene
and healthcare).
It was agreed that the most cost-effective approach (in terms of time and effort) to achieving
improvements in home hygiene is to identify situations which represent the greatest risk and to
ensure that hygiene advice and hygiene practice focuses on the reduction of the risks in these
situations; a strategy which might aim to reduce the overall levels of microbial contamination in the
home must be regarded as neither practicable nor desirable.
Since the complexity of the various aspects of home demands that a “flexible approach” is adopted
as appropriate to each specific situation or problem, it is recognised that the guidelines should aim
to educate the user on the basic principles which underlie all aspects of home hygiene as well as
provide practical advice on appropriate intervention measures for sites and surfaces etc. where a
need for intervention is considered desirable. As with any educational programme, both hygiene
professionals and members of the public are unlikely to achieve improvements in home hygiene
unless they understand which practices in the home are most likely to contribute to the infection
risk. An additional benefit of a total approach to home hygiene is that it encourages an
understanding of the relative risks for different aspects of home hygiene; hitherto each of the
components of home hygiene have tended to be considered only in isolation e.g. food hygiene and
home healthcare.
As stated by Scott (1996) improved awareness of good home hygiene practice and its importance
would also have the benefit of developing a public better able to apply hygiene principles and
practice in the community in areas such as day-care centres, residential homes, schools, restaurants
and retail outlets. Whatever profession we choose to follow, our basic understanding of hygiene is
developed in the home.
It is recognised that the preparation of home hygiene guidelines represents only the first stage, and
that improved standards of home hygiene can only be achieved by implementation of the guidelines
which requires a concerted programme of interaction with practising hygiene professionals, health
education authorities and other relevant parties. Overall, however, it is concluded that raised
awareness of home hygiene and improved hygiene practice could have a significant impact in
reducing infection risks in the home.
REFERENCES
Altekruse, S.F., Street, D.A., Fein, S.B. and Levy, A.S. (1995) Consumer knowledge of foodborne
microbial hazards and food-handling practices. Journal of Food Protection 59, 287-294.
Anderson, J.A.D. and Gatherer, A. (1970) Hygiene of infant feeding utensils: Practices and
standards in the home. British Medical Journal 2, 20-23.
Anon (1994a) Centers for Disease Control. Escherichia coli O157:H7 outbreak linked to homecooked hamburgers - California. Morbidity and Mortality Weekly 43, 213-215.
Anon (1994b) Foodborne pathogens. Council for Agricultural Science and Technology. Task force
report 122. pp. 11-12. Iowa: Ames.
Anon (1996) Memorandum on the threat posed by infectious diseases. Need for reassessment and a
new prevention strategy in Germany. Rudolphe Schulke Foundation. Weisbaden: mph-Verlag
GmbH.
Anon (1997). BMA submission to the Lords Select Committee into antimicrobial resistance.
London: British Medical Association.
Ansari, S.A., Sattar, S.A., Springthorpe, G.A., Wells, G.A. and Tostowaryk, W. (1988) Rotavirus
survival on human hands and transfer of infectious virus to animate and non-porous inanimate
surfaces. Journal of Clinical Microbiology 26, 1513-1518.
Aserkoff, B., Schroeder, S.A. and Breckman, P.S. (1970) Salmonellosis in the United States - A
five year review. American Journal of Epidemiology 92, 13.
Beumer, R.R., teGiffel, M.C., Spoorenberg, L. and Rombouts, F.M. (1996) Listeria species in
domestic environments. Epidemiology and Infection 117, 437-442.
Bloomfield, S.F. and Scott, E. (1997) Cross-contamination and infection in the domestic
environment and the role of chemical disinfectants. Journal of Applied Microbiology 83, 1-9.
Bryan, F.L. (1988) Risks of practices, procedures and processes that lead to outbreaks of foodborne
diseases. Journal of Food Protection 51, 663-673.
Butz, A.M., Fosarelli, P., Dick, J., Cusack, T. and Yolken R. (1993) Prevalence of rotavirus on
high-risk fomites in day-care facilities. Paediatrics 92, 202-205.
Craven, P.C., Mackel, D.C., Baine, W.B. et al. (1975) International outbreak of Salmonella
eastbourne infection traced to contaminated chocolate. Lancet i, 788-793.
De Wit, J.C., Broekhuizen, G. and Kampelmacher, E.H. (1979) Cross-contamination during the
preparation of frozen chickens in the kitchen. Journal of Hygiene, Cambridge 83, 27-32.
D’Aoust, J.Y. (1985) Infective dose of Salmonella typhimurium in Cheddar cheese - brief report.
American Journal of Epidemiology 122, 717-720.
Doyle, M.P. (1991) A new generation of foodborne pathogens. Contemporary Nutrition 16, 6.
Evans, H.S. and Maguire, H. (1996) Outbreaks of infectious intestinal disease in schools and
nurseries in England and Wales 1992 to 1994. Communicable Diseases Report Review 6, R103R108.
Fein, S.B., Lin, C.-T. J. and Levy, A.S. (1995) Foodborne illness: perceptions, experience, and
preventive behaviour in the United States. Journal of Food Protection 58, 1405-411.
Feng, P. (1996) Escherichia coli serotype O157:H7: Novel vehicles of infection and emergence of
phenotypic variants. Emerging Infectious Diseases 1.
Ferguson, W.W. and June, R.C. (1952) Experiments on feeding adult volunteers with Escherichia
coli 111, B4, a coliform organism associated with infant diarrhoea. American Journal of Hygiene
55, 155-169.
Finch, J.E., Prince, J. and Hawksworth, M. (1978) A bacteriological survey of the domestic
environment. Journal of Applied Bacteriology 45, 357-364.
Flannigan, B., McCabe, E.M. and McGarry, F. (1991) Allergenic and toxigenic microbes in houses.
Journal of Applied Bacteriology 70, (suppl) 615-735.
Foulger, R. (1980) The challenge of catering: control measures. Royal Society of Health Journal
100, 183-189.
Gill, O.N., Bartlett, C.L.R., Sockett, P.N. and Vaile, M.S.B. (1983) Outbreak of Salmonella napoli
infection caused by contaminated chocolate bars. Lancet i, 574-575.
Gerba, C.P., Rose, J.B. and Hass, C.N. (1996) Sensitive populations: who is at greatest risk?
International Journal of Food Microbiology 30, 113-123.
Greenwood, M.H. and Hooper, W.L. (1983) Chocolate bars contaminated with Salmonella napoli.
British Medical Journal 286, 1394.
Griffin, P.M. and Tauxe, R.V. (1991) The epidemiology of infections caused by Escherichia coli
O157:H7, other enterohemorrhagic E. coli, and the associated hemolytic uremic syndrome.
Epidemiological Reviews 13, 60-98.
Griffith, C.J. and Worsfold, D. (1994) Application of HACCP to food preparation practices in
domestic kitchens. Food Control 5, 200-204.
Hendley, J.O., Wenzel, R.P. and Gwaltney, J.M. (1973) Transmission of rhinovirus colds by selfinoculation. New England Journal of Medicine 288, 1361-1364.
Hockin, J.C., D’Aoust, J.Y., Bowering, D. et al. (1989) An international outbreak of Salmonella
nima from imported chocolate. Journal of Food Protection 52, 51-59.
Hoogenboom-Verdegaal, A.M.M., de Jong, J.C., During, M., Hoogenveen, R. and Hoekstra, J.A.
(1994) Community-based study of the incidence of gastrointestinal disease in The Netherlands.
Epidemiology and Infection 112, 481-487.
Hoogenboom-Verdegaal, A.M.M. and Postema, C.A. (1990) Voedselinfecties. The Practitioner 5,
549-554.
Humphrey, T.J., Martin, K.W. and Whitehead, A. (1994) Contamination of hands and worksurfaces
with Salmonella enteriditis PT4 during the preparation of egg dishes. Epidemiology and Infection
113, 403-409.
Jones, M. (1998) Application of HACCP to identifying hygiene risks in the home. International
Journal of Biodeterioration and Biodegradation (in press).
Josephson, K.L. et al. (1997) Pathogens in household kitchens. Journal of Applied Microbiology
83, 737-750.
Knabel, S.J. for the Institute of Food Technologists (1995) Foodborne illness: role of home food
handling practices. Scientific Status Summary. Food Technology 49, 119-131.
Lederberg, J., Shope, R.E. and Oaks Jr, S.C. (1992) Emerging infections: Microbial threats to
health in the United States. Institute of Medicine. Washington DC: National Academy Press.
Lipson, A. (1976) Infection dose of Salmonella. Lancet i, 969.
Mahl, M.C. and Sadler, C (1975) Virus survival on inanimate surfaces. Canadian Journal of
Microbiology 21, 819-823.
Maki, D.G., Alvarado, C.J. and Hassemer, C.J. (1980) Prospective study of the role of the
inanimate environment in endemic nosocomial infections. American Journal of Infection Control 8,
87-88.
Marples, R.R. (1976) Local infections experimental aspects. Journal of the Society of Cosmetic
Chemists 27, 449-457.
Martin, C.J., Platt, S.D. and Hunt, S.M. (1987) Housing conditions and ill-health. British Medical
Journal 294, 1125-1127.
Masterton, R., Coia, J., Notman, A. et al. (1995) Refractory MRSA carriage associated with
contamination of the home environment. Journal of Hospital Infection 25, 318-319.
Mbithi, J.N., Springthorpe, S. and Sattar, S.A. (1991) Effect of relative humidity and air
temperature on survival of hepatitis A virus on environmental surfaces. Applied Environmental
Microbiology 57, 1394-1399.
McCullough, N.B. and Eisele, C.W. (1951) Experimental human salmonellosis. Journal of
Infectious Diseases 88, 278-279.
McGowan, J.E. (1981) Environmental factors in nosocomial infection - a selective focus. Review
of Infectious Diseases 3, 760-769.
Morris, G.J. Jr (1997) Emergence of new pathogens as a function of changes in host susceptibility.
Emerging Infectious Diseases 3, 435-440.
Morse, E.V., Duncan, M.A., Estep, D.A., Riggs, W.A. and Blackburn, B.O. (1976) Canine
salmonellosis: a review and report of dog to child transmission of Salmonella enteriditis. Public
Health Briefs 66, 1.
Morse, S.S. (1995) Factors in the emergence of infectious diseases. Emerging Infectious Diseases,
1 (1).
Nerurkar, L.S., West, F., May, M., Madden, D.L. and Sever, J.L. (1983) Survival of herpes simplex
in water specimens collected from hot tubs in spa facilities and on plastic surfaces. Journal of the
American Medical Association 22, 3081-3083.
Parry, S.M., Salmon, R.L., Willshaw, G.A. and Cheasty, T. (1998) Risk factors for and prevention
of sporadic infections with vero cytotoxin (shiga toxin) producing Escherichia coli O157. Lancet
351, 1019-1022.
Roberts, D. (1982) Factors contributing to outbreaks of food poisoning in England and Wales.
Journal of Hygiene, Cambridge 89, 491-498.
Roberts, D. (1986) Factors contributing to outbreaks of food poisoning in England and Wales 19701982. In: Proceedings of the World Congress of Foodborne Infections and Intoxications 1. pp. 157159. Berlin: Institute of Veterinary Medicine.
Roberts, D. (1990) Foodborne illness; sources of infection: food. Lancet 336, 859-861.
Ryan, M.J., Wall, P.G., Gilbert, R.J., Griffin, M. and Rowe, B. (1996) Risk factors for outbreaks of
infectious intestinal disease linked to domestic catering. Communicable Disease Report, 13, R179182.
Sattar, S.A. (1986) Institutional outbreaks of rotavirus diarrhoea: potential role of fomites and
environmental surfaces as vehicles for virus transmission. Journal of Hygiene, Cambridge 96, 277289).
Scott, EA (1996). Foodborne disease and other hygiene issues in the home. Journal of Applied
Bacteriology 80, 5-9.
Scott, E, and Bloomfield, S.F. (1990) The survival and transfer of microbial contamination via
cloths, hands and utensils. Journal of Applied Bacteriology 68, 271-278.
Scott, E., Bloomfield, S.F. and Barlow, C.G. (1982) An investigation of microbial contamination in
the home. Journal of Hygiene, Cambridge 89, 279-293.
Scott, E., Bloomfield, S.F. and Barlow, C.G. (1984) Evaluation of disinfectants in the domestic
environment under “in use “ conditions. Journal of Hygiene, Cambridge 92, 193-203.
Scuderi, G et al. (1996) Foodborne outbreaks caused by Salmonella in Italy, 1991-4. Epidemiology
and Infection 116, 257-265.
Sheard, J.B. (1986) Food poisoning in England and Wales during 1983. Environmental Health 94,
57.
Simmons, B., Trusler, M., Roccaforte, J., Smith, P. and Scott, R. (1990) Infection control for home
health. Infection Control and Hospital Epidemiology 11, 362-370.
Tauxe, R.V. (1992) Epidemiology of Campylobacter jejuni infections in the United States and other
industrial nations. In: Campylobacter jejuni: current status and future trends. Washington DC:
American Society of Microbiology, 9-19.
Van Schothurst, M., Huisman, J. And Van Os, M. (1978) Salmonella-onderzoek in huishoudens
met salmonellose bij zuigelingen. Nederlands Tijdschrift voor Geneeskunde 12, 1121-1124.
Wagenvoort, J.H., Toenbreker, H.M., Nurmohamed, A and Davies, B.I. (1997) Transmission of
methicillin-resistant Staphylococcus aureus within a household. European Journal of Clinical
Microbiology and Infectious Diseases 16, 399-400.
Wall, P.G., Threllfall, E.J., Ward, L.R. and Rowe, B. (1996) Multiresistant Salmonella
typhimurium DT104 in cats: a public health risk. Lancet 348, 471
Ward, R.L., Bernstein, D., Knowlton, D., Sherwood, J., Yung, E., Cusack, T. et al. (1991)
Prevention of surface-to-human transmission of rotaviruses by treatment with disinfectant spray.
Journal of Clinical Microbiology 29, 1991-1996.
Wolf, D. (1995) Home food handling: a timely scientific summary. Food Technology 49, 28.