Procedures to prevent infection and the transmission of infection are used in a variety of domestic situations, and collectively may be termed home hygiene procedures. For the purposes of these guidelines, the practices which are used in home hygiene are categorised into four main areas, namely:

• General home hygiene

• Food hygiene

• Personal hygiene

• Home healthcare

The term general home hygiene is used here to define the routine (daily or weekly) procedures employed in the home to prevent cross contamination and cross infection via domestic sites and surfaces. Food hygiene and personal hygiene procedures are also routine home hygiene measures performed on a daily basis to reduce the risk of infection and cross infection.

Home healthcare includes specific situations of increased risk such as the care in the home of neonates and geriatrics. Procedures such as decontamination of areas of faecal contamination or other spillage material, and procedures such as the disinfection of contact lenses, can also be considered as home healthcare. Increasingly, home healthcare also includes infection control measures associated with the use of inhalation or catheterisation equipment, home nursing of immunocompromised family members, and family members who are carriers of infectious diseases, such as the human immunodeficiency virus, hepatitis viruses, methicillin resistant Staphylococcus aureus (MRSA) and people suffering from a foodborne disease.

At the present time these various components of home hygiene tend to be regarded as separate issues rather than a series of interrelated procedures based on the same underlying microbiological principles. Since all of these aspects of home hygiene may be under the control of a single person, the home manager, it is reasonable to expect that an integrated approach to the understanding of these issues, and the implementation of suitable procedures, is likely to be beneficial in achieving and improving standards of home hygiene (Bloomfield and Scott 1997; Jones 1998). It is also essential that the home, and home hygiene, is not viewed in isolation. The home and family are central elements of a community, since there is a dynamic interaction between the home, its occupants, and the community-wide structures such as day-care centres, schools, work places, eating establishments and healthcare facilities.

The aim of this document is to provide current guidelines on the most appropriate procedures to be used in preventing infection and cross infection in the domestic environment. It is anticipated that these guidelines will be continually updated to take account of new research in the area of home hygiene. The objective of this document is to give guidance to doctors, pharmacists, veterinary surgeons, community nurses, midwives, health visitors, environmental health officers, teachers of home economics and other healthcare professionals who are involved in advising the public on all aspects of hygiene in their daily lives.

Where appropriate, these guidelines will refer to other published guidelines for healthcare professionals which provide more detailed information on specific infection control measures which are either not within the scope of this document or are dealt with only briefly. Definitions of terms used in this document (e.g. cleaning, hygienic cleaning, disinfection etc.) are given in Appendix I.

There is a growing list of infections associated with the domestic environment, the occurrence of which may be reduced or prevented by good hygiene practice (Scott 1996).

There is substantial evidence in the literature to establish that foodborne infections represent a significant social and economic problem (Guthrie 1992; Sockett et al. 1993; Scott 1996). 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. Data from The Netherlands, Germany and Spain indicates that more than 50% of reported outbreaks occur in the home (Hoogenboom-Verdegaal 1992; Anon 1992a; Kusch and Klare 1992; Sockett 1993). In the UK during the period 1989-1991, 86% of Salmonella outbreaks and 97% of Campylobacter outbreaks were classed as family outbreaks where only members of a single household were affected (Sockett et al. 1993). A recent survey in Italy showed that 74% of Salmonella outbreaks were associated with home prepared foods (Scuderi et al. 1996).

Other infections specifically reported to be associated with the domestic environment include Shigella sonnei. Outbreaks are often centred on nursery schools and child day-care centres but there is also evidence for subsequent spread within the home (Scott 1996; Bloomfield and Scott 1997). Rotavirus is a frequent cause of diarrhoeal outbreaks in the community and institutions (Sattar 1986), and reports of foodborne outbreaks of viral gastroenteritis have increased in the UK over recent years (Wall et al. 1996a). Survival of rhinovirus on environmental surfaces at ambient temperatures has also been demonstrated (Sattar et al. 1993). Studies indicate a link between airborne bacteria and fungi, associated with poor housing, and the incidence of respiratory allergies such as asthma (Flannigan et al. 1991). Care of HIV and HBV carriers also has important implications for 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, immunocompromised patients discharged into the community) can 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 (Gerba, Rose and Haas 1996; Anon 1998). This percentage is expected to increase significantly by the beginning of the next century. For most people the quality of their life (their health expectancy) is at least as important as their life expectancy.

Despite advances in the fight against infectious diseases, the risk posed by old and new pathogens is likely to increase. The emergence of new pathogens, such as E. coli O157:H7, has implications for community and home hygiene (Anon 1996). 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 as opposed to an increasing reliance on antibiotic therapy. This situation in turn demands that complacency about home hygiene is no longer acceptable. Although antibiotic resistance has largely been considered as a hospital-based problem, control of MRSA for example is now a community as well as a hospital problem. This also highlights the dynamic interaction between the community and the home.

Sources of infection

The main sources of infection in the home are people, domestic animals, raw food and water. There is also evidence that 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 become a source or "reservoir" of infection.

The transmission of infection in the domestic environment
Transmission of infection in the home can occur in a number of ways:

1. In many cases infection arises as a result of direct contact with infected people or animals. Prevention of these infections is related to patterns of social behaviour and it is the responsibility of the healthcare professional to ensure family members and the public are aware of the mechanisms of transmission. The importance of measures to prevent the transmission of these infections cannot be overemphasised but are outside the scope of this document.

2. A proportion of infections arise by self-infection from the body's own flora, such as cystitis, and personal hygiene plays a major role in reducing this risk of infection.

3. Gastrointestinal infections most usually arise by ingestion of contaminated food but sometimes also occur as a result of direct hand-to-mouth transmission (Linton et al. 1977). In addition, other infections, such as hepatitis A, can occur through ingestion of contaminated food or through direct hand-to-mouth contact (Hadler 1991).

4. A proportion of infections are transmitted indirectly, for example by transfer via surfaces. Although bacteria do not grow in the absence of water, and will eventually die on a dry surface, most species can survive on surfaces in sufficient numbers for a sufficient period of time to represent an infection hazard (Bloomfield and Scott 1997). Organisms transferred in small numbers via surfaces to cooked foods can multiply rapidly if the food is stored at ambient temperature. This also applies to organisms picked up onto wet cleaning cloths which are then left at ambient temperatures (Scott and Bloomfield 1990a). Viruses and parasites may also survive long enough on inanimate surfaces to cause infections. As far as domestic hygiene is concerned the most important of these surfaces are the hands, hand and food contact surfaces and cleaning utensils. Currently there is insufficient awareness of the potential for cross contamination via, not only hands, but also apparently clean surfaces and apparently clean cloths in the home.

5. Insects, other household pests and also pets can act as the vector for transfer of infection.

6. Airborne transmission of infection can occur, most particularly via contaminated skin scales and aerosol droplets.

The implied purpose of applying a hygiene procedure in the home is to achieve a reduction in the number of viable organisms to a level where there is no longer a threat to health. This level is variable according to specific circumstances and will dictate what acceptable measures are required. 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.

The main principles for achieving high standards of infection control in the domestic environment are concerned with:

• The reduction or elimination, where feasible, of sources/reservoirs of infection (which includes the proper cooking of contaminated raw foods)
• Preventing transfer of contamination from these sources
• Education of the public in good hygiene practices

Since in many situations there is continual recontamination of surfaces or sites, the emphasis in these situations is on managing these risks through high standards of hygiene practices which prevent infection transfer.
A number of procedures can be applied in order to achieve hygienic decontamination of sites and surfaces. These include:

Cleaning.
In many situations, such as for cooking and eating utensils and handwashing, decontamination can be achieved by the use of a cleaning product and water. However, since decontamination in these situations is largely achieved by mechanical removal of the contaminating microorganisms, this method is only effective in achieving a hygienically clean surface if applied in conjunction with mechanical action (i.e. wiping or scrubbing) and a rinsing process. This process is thus not effective on fixed surfaces, such as some food preparation surfaces, which cannot be effectively rinsed.

Heat.
Although heat is an effective method for decontamination of small items such as clothes, cleaning utensils and linens, it is not the most convenient method for decontamination of areas and surfaces in the home and can be unreliable in unskilled hands. Heat is the method used to reduce microbial contamination of foods to a level which is safe for consumption.

Hygienic cleaners and chemical disinfectants.
Hygienic cleaners and chemical disinfectants 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. Information on the choice of a suitable disinfectant or hygienic cleaning product is given in a number of international guideline documents such as the British Standard document BS 7152 Guide to Choice of Chemical Disinfectants (Anon 1991) or the List of Disinfectants published by the Disinfectant Commission of the German Society for Hygiene and Microbiology.

It must be borne in mind 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 the disinfectant) but also on the way in which it is applied i.e. in the right way and at the right time. Effective hygiene in the home requires good hygiene practices, which in turn are dependent on good hygiene education. It is important to raise and maintain the awareness of the need for consistent standards of hygiene. It is important that the home manager understands the fact that a lapse in hygiene practices which does not result in an infection outbreak does not imply that the procedure is not important.