Abstract

Infectious diseases (ID) circulating in the home and community remain a significant concern. Several demographic, environmental, and health care trends, as reviewed in this report, are combining to make it likely that the threat of ID will increase in coming years. Two factors are largely responsible for this trend: first, the constantly changing nature and range of pathogens to which we are exposed and, secondly, the demographic changes occurring in the community, which affect our resistance to infection. This report reviews the evidence base related to the impact of hand hygiene in reducing transmission of ID in the home and community. The report focuses on developed countries, most particularly North America and Europe. It also evaluates the use of alcohol-based hygiene procedures as an alternative to, or in conjunction with, handwashing. The report compiles data from intervention studies and considers it alongside risk modeling approaches (both qualitative and quantitative) based on microbiologic data. The main conclusions are as follows: (1) Hand hygiene is a key component of good hygiene practice in the home and community and can produce significant benefits in terms of reducing the incidence of infection, most particularly gastrointestinal infections but also respiratory tract and skin infections. (2) Decontamination of hands can be carried out either by handwashing with soap or by use of waterless hand sanitizers, which reduce contamination on hands by removal or by killing the organisms in situ. The health impact of hand hygiene within a given community can be increased by using products and procedures, either alone or in sequence, that maximize the log reduction of both bacteria and viruses on hands. (3) The impact of hand hygiene in reducing ID risks could be increased by convincing people to apply hand hygiene procedures correctly (eg, wash their hands correctly) and at the correct time. (4) To optimize health benefits, promotion of hand hygiene should be accompanied by hygiene education and should also involve promotion of other aspects of hygiene. Infectious diseases (ID) circulating in the home and community remain a significant concern. Several demographic, environmental, and health care trends, as reviewed in this report, are combining to make it likely that the threat of ID will increase in coming years. Two factors are largely responsible for this trend: first, the constantly changing nature and range of pathogens to which we are exposed and, secondly, the demographic changes occurring in the community, which affect our resistance to infection. This report reviews the evidence base related to the impact of hand hygiene in reducing transmission of ID in the home and community. The report focuses on developed countries, most particularly North America and Europe. It also evaluates the use of alcohol-based hygiene procedures as an alternative to, or in conjunction with, handwashing. The report compiles data from intervention studies and considers it alongside risk modeling approaches (both qualitative and quantitative) based on microbiologic data. The main conclusions are as follows: (1) Hand hygiene is a key component of good hygiene practice in the home and community and can produce significant benefits in terms of reducing the incidence of infection, most particularly gastrointestinal infections but also respiratory tract and skin infections. (2) Decontamination of hands can be carried out either by handwashing with soap or by use of waterless hand sanitizers, which reduce contamination on hands by removal or by killing the organisms in situ. The health impact of hand hygiene within a given community can be increased by using products and procedures, either alone or in sequence, that maximize the log reduction of both bacteria and viruses on hands. (3) The impact of hand hygiene in reducing ID risks could be increased by convincing people to apply hand hygiene procedures correctly (eg, wash their hands correctly) and at the correct time. (4) To optimize health benefits, promotion of hand hygiene should be accompanied by hygiene education and should also involve promotion of other aspects of hygiene. There can be no doubt that advances in hygiene during the 19th and 20th centuries, along with other aspects of modern medicine, have combined to improve both the length and quality of our lives. However, since the middle of the 20th century, following the development of vaccines and antimicrobial therapy, and with serious epidemics of the "old" infectious enemies such as diphtheria, tuberculosis, and others apparently under control, hygiene has tended to lose its prominent position, and the focus of concern has shifted to degenerative and other chronic diseases. Nowhere has the decline in concern about hygiene been more evident than in the home and community. However, whereas advances in medicine and public health seemed, at one time, to offer the possibility that infectious diseases (ID) might soon be a thing of the past, it is now clear that this is not the case. In the past 20 years, concern about ID and the need for prevention through home and community hygiene has moved steadily back up the health agenda. Between 1980 and 1992, deaths attributable to ID increased by 22% in the United States alone, representing the third leading cause of death among US residents.1Pinner R.W. Teutsch S.M. Simonson L. Klug L.A. Graber J.M. Clarke M.J. et al.Trends in infectious disease mortality in the United States.JAMA. 1996; 275: 189-193Crossref PubMed Google Scholar Two factors are largely responsible for this trend: first, the constantly changing nature and range of pathogens to which we are exposed and, secondly, the changes occurring in the community, which affect our resistance to infection. To what extent our more relaxed attitudes to hygiene practice have contributed to these trends is not known, but poor hygiene is a significant factor for a large proportion of the gastrointestinal (GI), skin, and respiratory tract (RT) infections, which make up the greatest part of the ID burden. Prior to approximately 1980, common pathogens such as rotavirus, campylobacter, Legionella, Escherichia coli (E coli) O157, and norovirus were largely unheard of. Whereas methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile (C difficile) were once considered largely hospital-related problems, this is no longer the case. Now, community-associated MRSA (CA-MRSA) strains are a major public health concern in North America and, increasingly, in Europe. Most recently, the severe acute respiratory syndrome (SARS) outbreak and concerns about avian flu have raised awareness of the potential for transmission of respiratory viruses via hands and surfaces. Demographic trends mean that the proportion of the population in the community who are more vulnerable to infection is increasing, whereas trends toward shorter hospital stays and care in the community also demand increased emphasis on care of "at-risk" groups in the home who require protection from infection. In assessing the potential for reducing ID transmission through hygiene practice, it is recognized that contaminated hands and failure to practice hand hygiene are primary contributors. In this report, we review the evidence base related to the impact of hand hygiene in reducing transmission of ID in the home and community. This report focuses on developed countries, most particularly North America and Europe, within the context of renewed public health concerns about IDs and their impact on health and well-being. The review also evaluates the use of alcohol-based hand hygiene procedures as an alternative to, or in conjunction with, handwashing. These products are defined by a number of different terms in Europe and North America (hand sanitizers, handrubs, and others). For the purposes of this report, we will refer to them as alcohol-based hand sanitizers (ABHS). Although this report focuses primarily on the home, it is recognized that the home forms a continuum with public settings such as schools, offices, and public transport and cannot be considered totally in isolation. Nevertheless, the hand hygiene practice framework proposed in this review is largely also applicable to "out of home" settings. This report compiles data from intervention studies and considers it alongside risk modeling approaches based on microbiologic data. Currently, there is a tendency to demand that, in formulating evidence-based policies and guidelines, data from intervention studies should take precedence over data from other approaches. Although there are those who still adhere to this, it is accepted increasingly that, as far as hygiene is concerned, because transmission of pathogens is highly complex and involves many different pathogens each with multiple routes of spread, decisions regarding infection control must be based on the totality of evidence including microbiologic and other data. This document is intended for infection control and public health professionals who are involved in developing hygiene policies and promoting hygiene practice for home and community settings, including those involved with food and water hygiene, care of domestic animals, pediatric care, care of elderly adults, and care of those in the home who may be at increased risk for acquiring or transmitting infection. The purpose of the review is to provide support for those who work at the interface between theory and practice, particularly those involved in developing policies for the home and community, by providing a practical framework for hand hygiene practice together with a comprehensive review of the evidence base. In recent years, a significant amount of research has been done to identify strategies for changing hygiene behavior. Whereas those who manage hygiene improvements often choose to promote hygiene by educating people on the links between hygiene and health, one of the lessons that has been learned is that traditional (cognitive) approaches can raise awareness but do not necessarily achieve the desired effects. If practices such as handwashing are to become a universal norm, a multidimensional promotion that engages the public is needed to persuade people to change their behavior. Although we recognize that this aspect is fundamental, it is outside the scope of this report and is reviewed elsewhere.2Griffith C. Redmond E. Evaluating hygiene behaviour in the domestic setting and the impact of hygiene behaviour.J Infect. 2001; 43: 70-74Abstract Full Text PDF PubMed Scopus (11) Google Scholar, 3Pittet D. Improving adherence to hygiene practice: a multidisciplinary approach.Emerg Infect Dis. 2001; 7: 234-240Crossref PubMed Google Scholar, 4Curtis V. Talking dirty: how to save a million lives.Int J Environ Health Res. 2003; 13: S73-S80Crossref PubMed Scopus (16) Google Scholar, 5Kretzer E.K. Larson E.L. Behavioural interventions to improve infection control practices.Am J Infect Control. 1998; 26: 245-253Abstract Full Text PDF PubMed Scopus (155) Google Scholar, 6Whitby M. Pessoa-Silva C.L. McLaws M.L. Allegranzi B. Sax H. Larson E. et al.Behavioural considerations for hand hygiene practices: the basic building blocks.J Hosp Infect. 2007; 65: 1-8Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar Whereas, in the past, research and surveillance largely focused on health care-associated and foodborne illnesses, increasing resource is now being allocated to generating data that give a better view of the extent to which infections are circulating in the community; how they are being transmitted; and how this varies from one region, country, or community to another. Although the data in the following section represent a useful overview, we note that the data collection methods differed significantly from one study to another, which means that comparisons from different geographic locations must be interpreted with care. Current trends in communicable IDs in Europe are described in more detail in the recent (2007) European Communicable Disease Epidemiological Report from the European Centre for Disease Prevention and Control (ECDC).7Amato-Gauci A, Ammon A, eds. The First European Communicable Disease Epidemiological Report. European Centre for Disease Prevention and Control. Available at: http://www.ecdc.eu.int/pdf/Epi_report_2007.pdf. Accessed 2007.Google Scholar Rates of foodborne illness remain at unacceptably high levels, despite the efforts of food producers to ensure the safety of the food supply. Raw meat and poultry and fruits and vegetables bought at retail premises may be contaminated with pathogens. Good hygiene practices during food preparation in the home are therefore essential in preventing cross contamination of prepared foods from raw foods and preventing contamination of food by infected household members or domestic animals. The European Food Standards Agency (EFSA) 2005 report8Campylobacteriosis overtakes salmonellosis as the most reported animal infection transmitted to humans in the EU European Food Standards Agency. Available at: http://www.efsa.europa.eu/en/press_room/press_release/press_releases_2006/pr_zoonoses_report2005.html. Accessed 2006.Google Scholar and the 2007 ECDC report7Amato-Gauci A, Ammon A, eds. The First European Communicable Disease Epidemiological Report. European Centre for Disease Prevention and Control. Available at: http://www.ecdc.eu.int/pdf/Epi_report_2007.pdf. Accessed 2007.Google Scholar cite campylobacteriosis as the most reported animal infection transmitted to humans. In 2005, reported campylobacter infections increased by 7.8% compared with the previous year, rising to an incidence rate of 51.6 cases per 100,000 people. The EFSA states that the source of most human campylobacter infections is related to fresh poultry meat. On the other hand, Salmonella infections fell by 9.5% in 2005 to an incidence of 38.2 cases per 100,000 (176,395 reported cases). The 2003 World Health Organization (WHO) report9WHO assesses that up to 40% of food poisoning outbreaks occur in the home. Several foodborne diseases are increasing in Europe. WHO's "five keys to safer food" for winter holidays. 2003 Press Release EURO/16/03. Available at: http://www.euro.who.int/eprise/main/who/mediacentre/PR/2003/20031212_2.Google Scholar concluded that approximately 40% of reported foodborne outbreaks in the WHO European Region over the past decade were caused by food consumed in private homes. The report cites several factors as "critical for a large proportion of foodborne diseases" including use of contaminated raw food ingredients, contact between raw and cooked foods, and poor personal hygiene by food handlers. United Kingdom data show that food poisoning notifications reached a peak in 1997-1998 and has since declined but remains in excess of 70,000 per year.10Food Poisoning Notifications—annual totals England and Wales, 1982–2005. Available at: www.hpa.org.uk/infections/topics_az/noids/food_poisoning.htm.Google Scholar In reality, the burden of food poisoning is much higher because most cases go unreported; according to the UK Food Standards Agency,11Food Standards Agency. A report of the study of infectious intestinal disease in England. The Stationary Office, London2000Google Scholar the true number of cases is approximately 4.7 million per year. In 1999, Mead et al12Mead P.S. Slutsker L. Dietz V. McCaig L.F. Bresee J.S. Shapiro C. et al.Food-related illness and death in the United States.Emerg Infect Dis. 1999; 5: 607-625Crossref PubMed Google Scholar reported on food-related illness in the United States, using data from a range of sources including national surveillance and community-based studies. They estimated that foodborne illness in the United States causes 76 million illnesses, 500,000 hospital admissions, and 9000 deaths each year. Most frequently recorded pathogens were campylobacter, Salmonella, and norovirus, which accounted for 14.2%, 9.7%, and 66.5%, respectively, of estimated foodborne illnesses. Data suggest that the total number of reported outbreaks has not declined substantially in recent years, ranging from 980 to 1400 outbreaks and between 20,000 and 80,000 cases per year for the years 2000 to 2005.13Centers For Disease Control and Surveillance. Outbreak Response and Surveillance Team. Available at: http://www.cdc.gov/foodborneoutbreaks/outbreak_data.htm.Google Scholar From recent investigations, it is now recognized that a substantial proportion of the total infectious GI disease burden in the community is because of person-to-person spread within households, particularly for viral infections, where it is most often the cause. Person-to-person transmission in the home can occur by direct hand-to-mouth transfer, via food prepared in the home by an infected person, or by transmission because of aerosolized particles resulting from vomiting or fluid diarrhea. Apart from transmission by inhalation of airborne particles, these infections are preventable by good hygiene practice. The 2003 WHO report9WHO assesses that up to 40% of food poisoning outbreaks occur in the home. Several foodborne diseases are increasing in Europe. WHO's "five keys to safer food" for winter holidays. 2003 Press Release EURO/16/03. Available at: http://www.euro.who.int/eprise/main/who/mediacentre/PR/2003/20031212_2.Google Scholar stated that, of the total GI infection outbreaks (including foodborne disease) reported in Europe during 1999 and 2000, 60% and 69%, respectively, were due to person-to-person transmission. In the United Kingdom, it is estimated that up to 50% of GI infection results from person-to-person tranmsission.11Food Standards Agency. A report of the study of infectious intestinal disease in England. The Stationary Office, London2000Google Scholar A study of United Kingdom outbreaks14Le Baigue S, Long S, Adak GK, O'Brien SJ. Infectious intestinal disease—it's not all foodborne! PHLS 25th Annual Scientific Conference, 2000.Google Scholar suggested that 19% of Salmonella outbreaks and more than half of E coli O157 outbreaks are transmitted by nonfoodborne routes. National surveillance systems vary in their methods of data collection but mostly focus on foodborne disease. Inevitably, this means that data on GI illnesses relate mainly to large foodborne outbreaks in restaurants, hospitals, and others, whereas sporadic nonfoodborne cases in the general community go largely unreported. In the United Kingdom, even when "household" outbreaks are reported, they mostly involve home catering for parties and other functions and are therefore mainly foodborne outbreaks.15Gillespie I.A. O'Brien S.J. Adak G.K. General outbreaks of infectious intestinal diseases linked with private residences in England and Wales, 1992-1999: questionnaire study.BMJ. 2001; 323: 1097-1098Crossref PubMed Google Scholar Because milder cases of GI illness often go unreported, this means that the overall GI infection burden, particularly that which is not foodborne, is unknown; the most informative data on the overall burden of infectious GI illness (both foodborne and non-foodborne) in the community come from various community-based studies, which have been carried out in Europe and the United States and are reviewed below. Two large community studies have been carried out in Europe: one in the United Kingdom and the other in The Netherlands. The UK study, carried out from 1993 to 1996 involving 460,000 participants in the community presenting to general practice, estimated that only 1 of 136 cases of GI illness is detected by surveillance. The study indicated that as many as 1 in 5 people in the general UK population develop GI illness each year, with an estimated 9.4 million cases occurring annually of which about 50% are nonfoodborne.11Food Standards Agency. A report of the study of infectious intestinal disease in England. The Stationary Office, London2000Google Scholar, 16Wheeler J.G. Sethi D. Cowden J.M. Wall P.G. Rodrigues L.C. Tompkins D.S. et al.Study of infectious intestinal disease in England: rates in the community, presenting to general practice and reported to national surveillance.BMJ. 1999; 318: 1046-1050Crossref PubMed Google Scholar It was estimated that, for every 1 reported case of campylobacter, Salmonella, rotavirus, and norovirus, another 7.6, 3.2, 35, and 1562 cases, respectively, occur in the community; based on the number of laboratory reports, it is possible to estimate the true number of infections occurring in the community (Table 1).Table 1Estimated number of cases of infectious gastrointestinal disease in England and Wales associated with campylobacter, Salmonella, rotavirus, and norovirusOrganismNumber of laboratory reports from fecal isolates in 2005Ratio of actual reported casesEstimated number of cases in the communityCampylobacter42,6797.6324,360Salmonella11,1913.247,763Rotavirus13,30635567,790Norovirus260715624,072,734 Open table in a new tab From the community study carried out in The Netherlands between 1996 and 1999,17de Wit M.A. Koopmans M.P. Kortbeek L.M. van Leeuwen N.J. Bartelds A.I. van Duynhoven Y.T. Gastroenteritis in sentinel general practices in The Netherlands.Emerg Infect Dis. 2001; 7: 82-91Crossref PubMed Google Scholar it was estimated that approximately 1 in 3.5 people experience a bout of infectious GI disease each year. Campylobacter was detected most frequently (10% of cases), followed by Ghiardia lamblia (5%), rotavirus (5%), norovirus (5%), and Salmonella (4%). Relative to the population of The Netherlands (16 million), 650,000 norovirus gastroenteritis cases occur annually.18de Wit M.A. Koopmans M.P. van Duynhoven Y.T. Risk factors for norovirus, Sapporo-like virus and group A rotavirus gastroenteritis.Emerg Infect Dis. 2003; 9: 1563-1569Crossref PubMed Google Scholar The US study of Mead et al,12Mead P.S. Slutsker L. Dietz V. McCaig L.F. Bresee J.S. Shapiro C. et al.Food-related illness and death in the United States.Emerg Infect Dis. 1999; 5: 607-625Crossref PubMed Google Scholar which also included data from community-based studies, indicated that the total number of cases of infectious GI illness annually is approximately 210 million (of which approximately 64% are nonfoodborne). They estimated that the number of episodes of acute gastroenteritis per person per year is approximately 0.79. From the available data, the authors were also able to estimate the proportion of total episodes that were nonfoodborne. As shown in Table 2, by far the most frequently reported causes of GI illness were norovirus, rotavirus, and campylobacter. For campylobacter, E coli, and norovirus, a significant proportion of cases was estimated as nonfoodborne, whereas, for hepatitis A (HAV), Shigella, and rotavirus, almost all cases were estimated as nonfoodborne. For Salmonella on the other hand, only 5% of cases were considered as nonfoodborne. Davis et al reviewed outbreaks of E coli O157 related to family visits to animal exhibits.19Davis M.A. Sheng1 H. Newman J. Hancock D. Hovde J. Comparison of a waterless hand-hygiene preparation and soap-and-water hand washing to reduce coliforms on hands in animal exhibit settings.Epidemiol Infect. 2006; 134: 1024-1028Crossref PubMed Scopus (9) Google ScholarTable 2Estimated annual infectious gastrointestinal illnesses in the United StatesTotal infectious GI illnessesInfectious illnesses (%) that are nonfoodborneNorovirus23,000,00013,800,000 (60)Rotavirus3,900,0003,861,000 (99)Campylobacter2,453,926490,785 (20)Salmonella1,412,49870,624 (5)Shigella448,240358,952 (80)Hepatitis A83,39179,221 (95)E coli O15773,48011,022 (15) Open table in a new tab Indications are that norovirus is now the most significant cause of infectious GI illness in the developed world, both outbreak related and endemic.20Widdowson M.A. Monroe S.S. Glass R.I. Are noroviruses emerging?.Emerg Infect Dis. 2005; 11: 735-737Crossref PubMed Google Scholar, 21Carter M.J. Enterically infecting viruses: pathogenicity, transmission and significance for food and waterborne infection.J Appl Microbiol. 2005; 98: 1354-1380Crossref PubMed Scopus (104) Google Scholar Currently, we are seeing increased outbreaks of norovirus, a major concern in Japan22Japan: largest norovirus since 1981. Available at: http://depts.washington.edu/einet/?a=printArticle&print=284.Google Scholar and also in Europe.23Kroneman A. Vennema H. Harris J. Reuter G. von Bonsdorff C.-H. Hedlund K.-O. et al.Increase in norovirus activity reported in Europe.Eurosurveillance. 2006; 11 (Available at:)http://www.eurosurveillance.org/ew/2006/061214.asp#1/Google Scholar Expert opinion is that norovirus strains now circulating are more "virulent" and more easily spread from person to person via hands and surfaces or during food handling.20Widdowson M.A. Monroe S.S. Glass R.I. Are noroviruses emerging?.Emerg Infect Dis. 2005; 11: 735-737Crossref PubMed Google Scholar Infection with HAV is common worldwide,24Shapiro C.N. Shaw F.E. Mendel E.J. Hadler S.C. Epidemiology of hepatitis A in the United States.in: Hollinger F.B. Lemon S.M. Margolis H.S. Viral hepatitis and liver disease. Williams and Wilkins, Baltimore1991: 214Google Scholar and adenovirus is also a frequent cause of gastroenteritis. C difficile-associated disease now occurs with increasing frequency in the community, in which it usually affects persons receiving antibiotic therapy but also healthy individuals.25Bloomfield SF, Cookson BD, Falkiner FR, Griffith C, Cleary V. Methicillin-resistant Staphylococcus aureus (MRSA), Clostridium difficile, and ESBL-producing Escherichia coli in the home and community: assessing the problem, controlling the spread. International Scientific Forum on Home Hygiene 2006. Available at: http://www.ifh-homehygiene.org/2003/2library/MRSA_expert_report.pdf.Google Scholar Recently, a new strain (027) of C difficile has emerged in North America, causing infections in the community among individuals with no predisposing factors.25Bloomfield SF, Cookson BD, Falkiner FR, Griffith C, Cleary V. Methicillin-resistant Staphylococcus aureus (MRSA), Clostridium difficile, and ESBL-producing Escherichia coli in the home and community: assessing the problem, controlling the spread. International Scientific Forum on Home Hygiene 2006. Available at: http://www.ifh-homehygiene.org/2003/2library/MRSA_expert_report.pdf.Google Scholar A recent study26Perry S. de la Luz Sanchez M. Yang S. Haggerty T.D. Philip Hurst P. Perez-Perez G. et al.Gastroenteritis and transmission of Helicobacter pylori infection in households.Emerg Infect Dis. 2006; 12: 1701-1708Crossref PubMed Google Scholar indicated that exposure to a family member with Helicobacter pylori gastroenteritis was associated with a 4.8-fold increased risk of infection in another family member and that infection most usually involved person-to-person transmission, associated with conditions of crowding and poor hygiene. Using data from the 2006 E coli O157:H7 outbreak in 2006 in the United States associated with contaminated spinach, Seto et al developed a model that showed that secondary person-to-person transmission was similar to that in previous E coli outbreaks (≈12%). The model suggests that even a modestly effective hygiene promotion strategy to interrupt secondary transmission (prevention of only 2%-3% of secondary illnesses) could result in a reduction of ≈5% to 11% of symptomatic cases.27Seto EYW, Soller JA, Colford JM. Strategies to reduce person-to-person transmission during widespread Escherichia coli O157:H7 outbreak (Available at: www.cdc.gov/eid). Emerg Infect Dis 2007;13:861.Google Scholar Respiratory tract infections are largely caused by viruses. In the United States, viruses account for up to 69% of respiratory infections.28Monto A.S. Sullivan K.M. Acute respiratory illness in the community: frequency of illness and the agents involved.Epidemiol Infect. 1993; 110: 145-160Crossref PubMed Google Scholar The common cold is reported to be the most frequent, acute infectious illness to humans.29Dingle J.H. Badger G.F. Jordan Jr., W.S. Illness in the home: a study of 25,000 illnesses in a group of Cleveland families. The Press of Western Reserve University, Cleveland1964Google Scholar Data from the United States suggest that the mean number of respiratory illnesses experienced per year in adults is approximately 1.5 to 3.0, and, in children under 5 years of age, it is approximately 3.5 to 5.5.28Monto A.S. Sullivan K.M. Acute respiratory illness in the community: frequency of illness and the agents involved.Epidemiol Infect. 1993; 110: 145-160Crossref PubMed Google Scholar Approximately 80% of upper RT infections are caused by rhinoviruses. Other species causing acute rhinitis are coronaviruses, parainfleunza viruses (PIV), respiratory syncytial viruses (RSV), and adenoviruses.30Van Cauwenberge P.B. van Kempen M.J. Bachert C. The common cold at the turn of the millennium.Am J Rhinol. 2000; 14: 339-343Crossref PubMed Google Scholar Although colds are generally mild and self-limiting, they represent a significant economic burden because of loss in productivity and medical costs. Furthermore, secondary infections produce complications, such as otitis media, sinusitis, or lower respiratory infections including pneumonia, with its risk of mortality, particularly in elderly adults. Several studies have demonstrated that colds are also a trigger for asthma.31Gem J.E. Busse W.W. The effects of rhinovirus infections on allergic airway responses.Am J Respir Crit Care. 1995; 152: S40-S45Crossref PubMed Google Scholar RSV is the major cause of viral RT infection in young children worldwide. Child day care attendance in North America caries with it a very high risk of RSV infection within the first 2 years of lif