GUIDELINES

In order to formulate a policy for day-to-day general home hygiene which achieves maximum benefit it is necessary to identify those sites and surfaces which are most frequently contaminated with potentially infectious organisms and which are most likely to spread contamination, as compared with other sites and surfaces where the hazards are less. It is important that these areas are given priority in the application of hygiene procedures. In some cases, cleaning is sufficient whilst in others (most particularly those most likely to represent a cross contamination hazard), hygienic cleaning or the application of heat or a disinfectant is required to achieve a satisfactory level of decontamination.

A policy for general home hygiene, based on risk assessment, can best be identified if sites and surfaces are grouped under different headings: reservoirs; reservoir/disseminators; hand and food contact surfaces; other surfaces (Table 1).

Table 1. Categorisation of sites and surfaces in the home based on risk assessment

When the frequency of occurrence of significant contamination for each of these categories of sites/surfaces is combined with the risk of contamination transfer, it is possible to assess the relative need for decontamination and suggest a suitable approach to achieving this (Bloomfield and Scott 1997; Jones 1998). A general approach to home hygiene based on risk assessment is summarised in Table 2.

Table 2. The infection hazard associated with the four categories of environmental site.

1.1. Reservoir sites

Although the probability of contamination at these sites is high, indications are that the risk of transfer under normal conditions in the home is relatively low. Transfer from reservoirs may occur through direct contact with contaminated reservoir site surfaces e.g. by directly touching toilet bowl surfaces. Although there is some evidence of cross contamination from toilets and sink U-tubes by splashing or aerosol formation, the evidence for this is conflicting and further studies are required. For reservoir sites, therefore, the following procedures should be applied:

Reservoir sites must be regularly cleaned and well maintained. The frequency of the cleaning and maintenance procedures depends on the usage of the site, such as the number of occupants in the home and on the ambient conditions.
Hygienic cleaning or the use of a chemical disinfectant may be beneficial particularly in specific circumstances e.g. in certain high risk situations as outlined in Section 4 (Anon 1991).
Although chemical disinfectants are effective at these sites and surfaces it is important to be aware that contaminating organisms can grow quite rapidly in the aqueous environment which these sites provide, and that in order to achieve maximum benefit, a continuous release or sustained action disinfectant product should ideally be used.

1.2. Reservoir/disseminators

For items which act as reservoir/disseminators a high risk of contamination is combined with a constant risk of transfer of contamination. In the home, reservoir/disseminators represent a situation which has the highest risk of transfer. If cleaning cloths or other cleaning utensils in the kitchen or bathroom are left in damp conditions they can support the growth of microorganisms which can then be spread to other objects or surfaces. Where possible, the use of disposable cloths should be encouraged. However, for re-usable wet-cleaning items such as dishcloths, floor cloths/mops, washing-up brushes and scouring pads the following procedures should be rigorously applied:

All items which can serve as reservoir/disseminators, such as wet-cleaning cloths, must be decontaminated every time after contact with any contaminated surface or material (e.g. after wiping raw food, after wiping up spills, cleaning nappy buckets). At minimum, used wet-cleaning cloths should be decontaminated at least once a day even if they have not come into contact with a contaminating source.
Ensure that all cloths are hygienically clean, not just visibly clean, before use in risk handling procedures (e.g. for cleaning surfaces used in the preparation of cooked food or food to be eaten raw - see Section 2.1).
Cloths and other wet cleaning utensils can be decontaminated by hot machine washing (at least 60°C), by boiling or by use of a chemical disinfectant. Soap and water washing is relatively ineffective for decontamination of cloths (Scott and Bloomfield 1990b).
After decontamination, cloths must be dried as rapidly as possible. If cloths are left in a damp condition residual contamination not destroyed by the decontamination process will rapidly multiply at ambient temperatures.
Mops used to clean up heavily contaminated areas, such as spills of faeces or vomit, should be cleaned, rinsed with a disinfecting solution, wrung as dry as possible and then dried as rapidly as possible, preferably at elevated temperatures.
There is some evidence that aerosols generated from showerheads and humidifiers can cause infection, although this is only likely to occur with "at risk" groups. Showerheads should be designed and maintained so as to avoid the accumulation of stagnant water. Humidifiers should regularly be emptied, disinfected and refilled with fresh water.

1.3. Hand and food contact surfaces

Although microorganisms will not grow in the absence of water, there is evidence to show that bacteria and viruses can survive on a dry surface for relatively long periods of time (from 2-4 hours up to 24 hours or more for some species) in sufficient numbers to represent a cross infection hazard (Hendley et al. 1973; Scott and Bloomfield 1990a, 1990b; Sattar et al. 1993). Surfaces which represent the greatest hazard in the home are hand and food contact surfaces For these surfaces there is a constant risk of infection transfer, indicating the need for regular and rigorous decontamination.

The following procedures should be applied:

Hand and food contact surfaces must be decontaminated after contact with contaminated material (e.g. after contact with raw meat or processing of nappies).
Ensure that all hand and food contact surfaces are hygienically clean, not just physically clean, most particularly before use in risk handling procedures (e.g. before using surfaces, including utensils, for preparation of cooked food or food to be eaten raw).
Hand and food contact surfaces can be decontaminated by washing with hot water and detergent followed by rinsing (e.g. for cutting boards or cooking and feeding utensils). Where this is not feasible (e.g. for large surfaces where rinsing cannot be applied) surfaces should be decontaminated using a hygienic cleaner or by wiping to remove soil followed by application of a chemical disinfectant. Wiping with a cloth impregnated with only a cleaning product will not decontaminate surfaces.
Hand contact surfaces such as taps, toilet seats, toilet flush handles and door and refrigerator handles should be regularly decontaminated either with a hygienic cleaner or with a disinfectant. This is particularly important after touching contaminated surfaces e.g. when washing hands after raw meat preparation, especially poultry, tap handles may become contaminated.
Hands must be washed after contact with contaminated material and before risk handling procedures. Hand washing is reviewed in Section 3, Personal Hygiene.
After decontamination of surfaces, where possible they should be rapidly dried and maintained in a dry condition.
Contact surfaces that apply particularly to children are reviewed in Section 1.6.

1.4. Other surfaces

These surfaces generally combine a low risk of contamination with low risk of transfer.

All other surfaces should be regularly cleaned, kept dry to prevent the growth of microorganisms, and well maintained.
Disinfection or hygienic cleaning is only necessary where there is a known high risk (e.g. MRSA contamination) or where there is known contamination such as vomit or faecal material.
Hygienic cleaning may, however, be beneficial for floors in hotter, more humid climates where the possible rates of growth of microorganisms (and potential transfer by, for example, insects) are considerably greater.

1.5. Laundry hygiene

The laundering of clothing and other fabrics is strongly related to well-being and comfort, alongside its function of reducing microbial contamination, particularly where the ill, disabled or infants are concerned. Clothing, bedlinens, towels and other items which are in constant or intermittent contact with the body may form an important route of transmission of infection for "at risk" groups (see Section 4.1). The following procedures should ensure effective laundry hygiene:

Fabrics which may be contaminated with microorganisms can be decontaminated using soap/detergent and hot water washing (60°C).
During laundering, modern cleaning products effectively remove substrates from soiled fabrics which may support the growth of microorganisms.
If lower temperature washes are used (<45°C), the addition of hypochlorite bleach will promote decontamination.
Laundering of cloths, towels etc. which are used in association with food preparation should be carried out separately from laundering of clothes and bedlinens.
Hands should be washed after contact with soiled laundry.

1.6. Hygiene issues for homes with young children

When there are young children in a home, such as crawling toddlers, a number of surfaces with which they come into close contact may become contaminated. These may include toys that children put in their mouths, cot/crib rails, food preparation surfaces, nappy changing areas, nappy changing mats, toilet training equipment, floor surfaces and carpets. Nappy hygiene is as important for young children as for neonates.

Parents must be made aware that toys which children put in their mouths can sometimes act as a means of transfer of infection, particularly where they are shared between different children. Preferably, toys should be washed and disinfected between use by different children (Hale and Polder 1996).
Spills of body fluids from children such as faeces, nasal and eye discharges, saliva, urine and vomit should be cleaned immediately and any contaminated surfaces cleaned and disinfected.
Nappy hygiene is described in Section 4.1.1.

1.7. Hygiene issues for homes with pets

Owners of pets need to be made aware of the potential infection hazards associated with their pets (Wall et al. 1996b). These may include cats, dogs, especially when young, reptiles and birds. There is evidence to show that the presence of pets in the home is associated with increased levels of contamination in the kitchen and bathroom (Scott 1981). Domestic cats, dogs and other types of pets, although apparently healthy, can act as carriers of enteric pathogens such as Salmonella and Campylobacter. Pets such as cats and dogs may also bring pathogens into the home on their paws and contaminate kitchen food preparation surfaces as well as floor surfaces.

In these situations, additional hygiene measures need to be considered:

Pets such as dogs or cats should be appropriately immunised from disease.
Pets are best housed and fed elsewhere than in the kitchen.
Pet living quarters, and items such as cat litter boxes, should be cleaned on a daily basis. Faecal material should be removed from the surface of the litter tray using gloved hands and paper towels and flushed down the toilet.
Avoid cleaning pet cages and tanks in the kitchen sink.
Floor surfaces used by pets and pet feeding areas should be regularly decontaminated using a hygienic cleaner, or by cleaning followed by disinfection.
Pets should not be allowed to come into contact with food preparation surfaces. Any of these surfaces which may have been contacted by a pet should be decontaminated before food preparation (see Section 2.3).
Pet feeding utensils should be decontaminated using a hygienic cleaner or by application of a disinfectant.
Hands should be washed after handling pets, pet cages, pet feeding utensils or other pet objects. Children most particularly must be taught to wash their hands after handling their pets, especially before eating.
Spills from pets such as faeces, urine and vomit should be cleaned immediately and any contaminated surfaces cleaned and disinfected.
If a pet appears unwell, it should be taken to a veterinarian. Veterinarians should also advise parents about pets that are suitable for children.
Pets in the home may be a particular risk in those groups of people whose immune defence systems are less than those of the normal healthy adult. This is reviewed in Section 4.

1.8. Home hygiene to reduce the risk of infection from airborne disease

Indoor bioaerosols generated in the home may include bacteria (including actinomycetes), yeasts, moulds and fungi. Although mould spores can occur in isolation, bacteria and viruses in the air are usually associated with skin scales, or mucous droplets generated by sneezing. Although these airborne microorganisms do not generally represent an infection hazard to the normal healthy individual, the following advice should be given:

Airborne contamination from bacteria, viruses, moulds and fungi can best be avoided by good ventilation and by the use of cleaning procedures that involve vacuum extraction.
Excessive mould in the home should be avoided.
Regular cleaning of surfaces where mould is likely to grow is important to prevent accumulation to levels that may become hazardous.

Allergic reactions from airborne contamination
The relationship between damp housing, mould growth and symptomatic health state has been well established (Strachan and Elton 1986; Martin et al. 1987; Platt et al. 1989; Strachen et al. 1990) and it has been concluded that damp and mouldy living conditions have an adverse effect on health, especially among children. Moulds can exacerbate asthma and other respiratory diseases and allergens from house dust mite faeces are also implicated in respiratory disease such as asthma. Although these are allergic reactions and are outside the scope of this document, the following advice, in addition to published advice for asthmatics, should be considered:

As a temporary measure, moulds should be wiped away with a diluted solution of bleach and areas of mould growth treated with approved products. More severe problems of damp housing and mould growth suggest poor ventilation and may need to be referred to relevant environmental housing departments.
Regularly remove dust from sites where dust mites and dust mite faeces may accumulate to reduce their occurrence.

1.9. Home hygiene in emergency situations

Following emergency situations and natural disasters, such as flooding, the home may become dangerously contaminated and the risk of infection increased. In these situations local authorities will usually provide advice and support for affected homes and make provision in case of loss of power and running water.