Severe acute respiratory syndrome coronavirus on hospital surfaces

Identifying Potential Provider and Environmental Contamination on a Clinical Biocontainment Unit Using Aerosolized Pathogen Simulants

The Johns Hopkins Hospital created a biocontainment unit (BCU) to care for patients with highly infectious diseases while assuring healthcare worker safety. Research to date for BCU protocols and practices are based on case reports and lessons learned from patient care and exercises. This study seeks to be the first to explore the influences of healthcare worker movement and personal protective equipment (PPE) doffing on the transport of simulant pathogen particles in a BCU. A cough device released 1 μm fluorescent polystyrene beads (PSLs) in the patient room. PSL transport was then examined under 2 scenarios: (1) PSL release only, no healthcare workers; and (2) PSL release during 5-minute simulated activity by healthcare workers. Airborne PSL concentrations were quantified every second for 30 minutes per scenario by 7 optical particle sensors located throughout the BCU. PSLs were not detected in the donning room at any time nor in the doffing room during the first test scenario where no healthcare worker was present. The main difference detected between the tested scenarios was the presence of PSLs in the doffing room when healthcare workers were removing PPE, potentially due to re-aerosolization of PSLs off the exterior PPE surface or opening of the patient room door. Future work will further explore the potential for re-aerosolization of particles off of PPE during doffing. The present study provides the groundwork for a systematic method for evaluating the BCU and doffing procedures for their respective safety, and it also pilots a systematic method for evaluating potential pathogen exposure pathways for BCU healthcare workers.

Role of viral bioaerosols in nosocomial infections and measures for prevention and control

The presence of patients with diverse pathologies in hospitals results in an environment that can be rich in various microorganisms including respiratory and enteric viruses, leading to outbreaks in hospitals or spillover infections to the community. All hospital patients are at risk of nosocomial viral infections, but vulnerable groups such as older adults, children and immuno-compromised/-suppressed patients are at particular risk of severe outcomes including prolonged hospitalization or death. These pathogens could transmit through direct or indirect physical contact, droplets or aerosols, with increasing evidence suggesting the importance of aerosol transmission in nosocomial infections of respiratory and enteric viruses. Factors affecting the propensity to transmit and the severity of disease transmitted via the aerosol route include the biological characteristics affecting infectivity of the viruses and susceptibility of the host, the physical properties of aerosol particles, and the environmental stresses that alter these properties such as temperature and humidity. Non-specific systematic and individual-based interventions designed to mitigate the aerosol route are available although empirical evidence of their effectiveness in controlling transmission of respiratory and enteric viruses in healthcare settings are sparse. The relative importance of aerosol transmission in healthcare setting is still an on-going debate, with particular challenge being the recovery of infectious viral bioaerosols from real-life settings and the difficulty in delineating transmission events that may also be a result of other modes of transmission. For the prevention and control of nosocomial infections via the aerosol route, more research is needed on identifying settings, medical procedures or equipment that may be associated with an increased risk of aerosol transmission, including defining which procedures are aerosol-generating; and on the effectiveness of systematic interventions on aerosol transmission of respiratory and enteric viruses in healthcare settings.

Environmental Cleaning in Resource-Limited Settings

Purpose of review

Environmental surfaces in healthcare facilities, particularly in a patient room, are a critical pathway for healthcare-associated pathogen transmission. Despite well-established guides and recommendations regarding environmental surface cleaning and disinfection, there are several challenges in resource-limited settings. This viewpoint article will discuss the practice of environmental cleaning in resource-limited settings including challenges and relationship between environment and healthcare-associated infections in this setting and outlines pre-requisites to overcome these challenges.

Recent findings

Despite several barriers and challenges, environmental cleaning is a crucial component to help reduce transmission of healthcare-associated infections and multi-drug-resistant pathogens as well as emerging infectious disease-associated pathogens in resource-limited settings. However, there is a need to develop a multi-modal strategy together with a mechanism for monitor and feedback to improve the practices of environmental cleaning in resource-limited settings.

Summary

Additional researches on the barriers and implementation gaps and the role of collaborative network as well as how to apply technology would provide significant insights on the practices of environmental cleaning in resource-limited settings.

Isolation and identification of human coronavirus 229E from frequently touched environmental surfaces of a university classroom that is cleaned daily

Frequently touched surfaces of a university classroom that is cleaned daily contained viable human coronavirus 229E (CoV-229E). Tests of a CoV-229E laboratory strain under conditions that simulated the ambient light, temperature, and relative humidity conditions of the classroom revealed that some of the virus remained viable on various surfaces for 7 days, suggesting CoV-229E is relatively stable in the environment. Our findings reinforce the notion that contact transmission may be possible for this virus.

Role of fomites in SARS transmission during the largest hospital outbreak in Hong Kong

The epidemic of severe acute respiratory syndrome (SARS) had a significant effect on global society in the early 2000s and the potential of its resurgence exists. Studies on the modes of transmission of SARS are limited though a number of outbreak studies have revealed the possible airborne route. To develop more specific and effective control strategies, we conducted a detailed mechanism-based investigation that explored the role of fomite transmission in the well-known Ward 8A outbreak. We considered three hypothetical transmission routes, i.e., the long-range airborne, fomite and combined routes, in 1,744 scenarios with combinations of some important parameters. A multi-agent model was used to predict the infection risk distributions of the three hypothetical routes. Model selection was carried out for different scenarios to compare the distributions of infection risk with that of the reported attack rates and select the hypotheses with the best fitness. Our results reveal that under the assumed conditions, the SARS coronavirus was most possible to have spread via the combined long-range airborne and fomite routes, and that the fomite route played a non-negligible role in the transmission.

Patient safety: this is public health

Avoidable patient harm is a major public health concern, and may already have surpassed heart disease as the leading cause of death in the United States. While the public health community has contributed much to one aspect of patient harm prevention, infection control, the tools and techniques of public health have far more to offer to the emerging field of patient safety science. Patient safety practice has become increasingly professionalized in recent years, but specialist degree programs in the field remain scarce. Healthcare organizations should consider graduate training in public health as an avenue for investing in the professional development of patient safety practitioners, and schools and programs of public health should support further research and teaching to support patient safety improvement.

Infection Prevention and Control Guideline for Cystic Fibrosis: 2013 Update

The 2013 Infection Prevention and Control (IP&C) Guideline for Cystic Fibrosis (CF) was commissioned by the CF Foundation as an update of the 2003 Infection Control Guideline for CF. During the past decade, new knowledge and new challenges provided the following rationale to develop updated IP&C strategies for this unique population:

1.The need to integrate relevant recommendations from evidence-based guidelines published since 2003 into IP&C practices for CF. These included guidelines from the Centers for Disease Control and Prevention (CDC)/Healthcare Infection Control Practices Advisory Committee (HICPAC), the World Health Organization (WHO), and key professional societies, including the Infectious Diseases Society of America (IDSA) and the Society for Healthcare Epidemiology of America (SHEA). During the past decade, new evidence has led to a renewed emphasis on source containment of potential pathogens and the role played by the contaminated healthcare environment in the transmission of infectious agents. Furthermore, an increased understanding of the importance of the application of implementation science, monitoring adherence, and feedback principles has been shown to increase the effectiveness of IP&C guideline recommendations.

2.Experience with emerging pathogens in the non-CF population has expanded our understanding of droplet transmission of respiratory pathogens and can inform IP&C strategies for CF. These pathogens include severe acute respiratory syndrome coronavirus and the 2009 influenza A H1N1. Lessons learned about preventing transmission of methicillin-resistantStaphylococcus aureus(MRSA) and multidrug-resistant gram-negative pathogens in non-CF patient populations also can inform IP&C strategies for CF.

Transmission of SARS and MERS coronaviruses and influenza virus in healthcare settings: the possible role of dry surface contamination

Viruses with pandemic potential including H1N1, H5N1, and H5N7 influenza viruses, and severe acute respiratory syndrome (SARS)/Middle East respiratory syndrome (MERS) coronaviruses (CoV) have emerged in recent years. SARS-CoV, MERS-CoV, and influenza virus can survive on surfaces for extended periods, sometimes up to months. Factors influencing the survival of these viruses on surfaces include: strain variation, titre, surface type, suspending medium, mode of deposition, temperature and relative humidity, and the method used to determine the viability of the virus. Environmental sampling has identified contamination in field-settings with SARS-CoV and influenza virus, although the frequent use of molecular detection methods may not necessarily represent the presence of viable virus. The importance of indirect contact transmission (involving contamination of inanimate surfaces) is uncertain compared with other transmission routes, principally direct contact transmission (independent of surface contamination), droplet, and airborne routes. However, influenza virus and SARS-CoV may be shed into the environment and be transferred from environmental surfaces to hands of patients and healthcare providers. Emerging data suggest that MERS-CoV also shares these properties. Once contaminated from the environment, hands can then initiate self-inoculation of mucous membranes of the nose, eyes or mouth. Mathematical and animal models, and intervention studies suggest that contact transmission is the most important route in some scenarios. Infection prevention and control implications include the need for hand hygiene and personal protective equipment to minimize self-contamination and to protect against inoculation of mucosal surfaces and the respiratory tract, and enhanced surface cleaning and disinfection in healthcare settings.

Aerosol transmission of infectious disease

OBJECTIVE

The concept of aerosol transmission is developed to resolve limitations in conventional definitions of airborne and droplet transmission.

METHODS

The method was literature review.

RESULTS

An infectious aerosol is a collection of pathogen-laden particles in air. Aerosol particles may deposit onto or be inhaled by a susceptible person. Aerosol transmission is biologically plausible when infectious aerosols are generated by or from an infectious person, the pathogen remains viable in the environment for some period of time, and the target tissues in which the pathogen initiates infection are accessible to the aerosol. Biological plausibility of aerosol transmission is evaluated for Severe Acute Respiratory Syndrome coronavirus and norovirus and discussed for Mycobacterium tuberculosis, influenza, and Ebola virus.

CONCLUSIONS

Aerosol transmission reflects a modern understanding of aerosol science and allows physically appropriate explanation and intervention selection for infectious diseases.

Probable transmission chains of Middle East respiratory syndrome coronavirus and the multiple generations of secondary infection in South Korea

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As of July 14, 2015, the South Korean outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) infection has involved 185 secondary infections belonging to three overlapping generations of cases who have contracted the virus almost exclusively in the healthcare environment.

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Fomite transmission may explain a significant proportion of the infections occurring in the absence of direct contact with infected cases.

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The analysis of publicly available data collected from multiple sources, including the media, is useful for describing the epidemic history of an infectious disease outbreak.

Background

In May 2015, South Korea reported its first case of Middle East respiratory syndrome coronavirus (MERS-CoV) infection in a 68-year-old man with a history of travel in the Middle East. In the presence of secondary infections, an understanding of the transmission dynamics of the virus is crucial. The aim of this study was to characterize the transmission chains of MERS-CoV infection in the current South Korean outbreak.

Methods

Individual-level data from multiple sources were collected and used for epidemiological analyses.

Results

As of July 14, 2015, 185 confirmed cases of MERS have been reported in the Korean outbreak. Three generations of secondary infection, with over half belonging to the second generation, could be delineated. Hospital infection was found to be the most important cause of virus transmission, affecting largely non-healthcare workers (154/184). Healthcare switching has probably accounted for the emergence of multiple generations of secondary infection. Fomite transmission may explain a significant proportion of the infections occurring in the absence of direct contact with infected cases.

Conclusions

Publicly available data from multiple sources, including the media, are useful to describe the epidemic history of an outbreak. The effective control of MERS-CoV hinges on the upholding of infection control standards and an understanding of health-seeking behaviours in the community.

Environmental sampling for respiratory pathogens in Jeddah airport during the 2013 Hajj season

BACKGROUND

Respiratory tract infections (RTIs) are common during the Hajj season and are caused by a variety of organisms, which can be transmitted via the air or contaminated surfaces. We conducted a study aimed at sampling the environment in the King Abdul Aziz International (KAAI) Airport, Pilgrims City, Jeddah, during Hajj season to detect respiratory pathogens.

METHODS

Active air sampling was conducted using air biosamplers, and swabs were used to sample frequently touched surfaces. A respiratory multiplex array was used to detect bacterial and viral respiratory pathogens.

RESULTS

Of the 58 environmental samples, 8 were positive for at least 1 pathogen. One air sample (1 of 18 samples, 5.5%) tested positive for influenza B virus. Of the 40 surface samples, 7 (17.5%) were positive for pathogens. These were human adenovirus (3 out of 7, 42.8%), human coronavirus OC43/HKU1 (3 out of 7, 42.8%), Haemophilus influenzae (1 out of 7, 14.2%), and Moraxella catarrhalis (1 out of 7, 14.2%). Chair handles were the most commonly contaminated surfaces. The handles of 1 chair were cocontaminated with coronavirus OC43/HKU1 and H influenzae.

CONCLUSION

Respiratory pathogens were detected in the air and on surfaces in the KAAI Airport in Pilgrims City. Larger-scale studies based on our study are warranted to determine the role of the environment in transmission of respiratory pathogens during mass gathering events (eg, Hajj) such that public health preventative measures might be better targeted.

Survival of Respiratory Viruses on Fresh Produce

In addition to enteric viruses of fecal origin, emerging zoonotic viruses such as respiratory coronaviruses and influenza viruses may potentially be transmitted via contaminated foods. The goal of this study was to determine the recovery efficiencies and the survival of two respiratory viruses, namely, adenovirus 2 (Ad2) and coronavirus 229E (CoV229E), on fresh produce in comparison to the enteric poliovirus 1 (PV1). Adenovirus was recovered with efficiencies of 56.5, 31.8, and 34.8 % from lettuce, strawberries, and raspberries, respectively. Coronavirus was recovered from lettuce with an efficiency of 19.6 % yet could not be recovered from strawberries. Poliovirus was recovered with efficiencies of 76.7 % from lettuce, but only 0.06 % from strawberries. For comparison purposes, the survival of Ad2, CoV229E, and PV1 was determined for periods up to 10 days on produce. The enteric PV1 survived better than both respiratory viruses on lettuce and strawberries, with only ≤1.03 log10 reductions after 10 days of storage at 4 °C compared to CoV229E not being recovered after 4 days on lettuce and reductions of 1.97 log10 and 2.38 log10 of Ad2 on lettuce and strawberries, respectively, after 10 days. Nevertheless, these respiratory viruses were able to survive for at least several days on produce. There is therefore the potential for transfer to the hands and subsequently to the mucosa via rubbing the eyes or nose. In addition, some respiratory coronaviruses (e.g., severe acute respiratory syndrome coronavirus) and adenoviruses are also capable of replication in the gut and there is thus some potential for acquisition through the consumption of contaminated produce.

Human coronaviruses: insights into environmental resistance and its influence on the development of new antiseptic strategies

The Coronaviridae family, an enveloped RNA virus family, and, more particularly, human coronaviruses (HCoV), were historically known to be responsible for a large portion of common colds and other upper respiratory tract infections. HCoV are now known to be involved in more serious respiratory diseases, i.e. bronchitis, bronchiolitis or pneumonia, especially in young children and neonates, elderly people and immunosuppressed patients. They have also been involved in nosocomial viral infections. In 2002–2003, the outbreak of severe acute respiratory syndrome (SARS), due to a newly discovered coronavirus, the SARS-associated coronavirus (SARS-CoV); led to a new awareness of the medical importance of the Coronaviridae family. This pathogen, responsible for an emerging disease in humans, with high risk of fatal outcome; underline the pressing need for new approaches to the management of the infection, and primarily to its prevention. Another interesting feature of coronaviruses is their potential environmental resistance, despite the accepted fragility of enveloped viruses. Indeed, several studies have described the ability of HCoVs (i.e. HCoV 229E, HCoV OC43 (also known as betacoronavirus 1), NL63, HKU1 or SARS-CoV) to survive in different environmental conditions (e.g. temperature and humidity), on different supports found in hospital settings such as aluminum, sterile sponges or latex surgical gloves or in biological fluids. Finally, taking into account the persisting lack of specific antiviral treatments (there is, in fact, no specific treatment available to fight coronaviruses infections), the Coronaviridae specificities (i.e. pathogenicity, potential environmental resistance) make them a challenging model for the development of efficient means of prevention, as an adapted antisepsis-disinfection, to prevent the environmental spread of such infective agents. This review will summarize current knowledge on the capacity of human coronaviruses to survive in the environment and the efficacy of well-known antiseptic-disinfectants against them, with particular focus on the development of new methodologies to evaluate the activity of new antiseptic-disinfectants on viruses.

Comparison of surface sampling methods for virus recovery from fomites

The role of fomites in infectious disease transmission relative to other exposure routes is difficult to discern due, in part, to the lack of information on the level and distribution of virus contamination on surfaces. Comparisons of studies intending to fill this gap are difficult because multiple different sampling methods are employed and authors rarely report their method's lower limit of detection. In the present study, we compare a subset of sampling methods identified from a literature review to demonstrate that sampling method significantly influences study outcomes. We then compare a subset of methods identified from the review to determine the most efficient methods for recovering virus from surfaces in a laboratory trial using MS2 bacteriophage as a model virus. Recoveries of infective MS2 and MS2 RNA are determined using both a plaque assay and quantitative reverse transcription-PCR, respectively. We conclude that the method that most effectively recovers virus from nonporous fomites uses polyester-tipped swabs prewetted in either one-quarter-strength Ringer's solution or saline solution. This method recovers a median fraction for infective MS2 of 0.40 and for MS2 RNA of 0.07. Use of the proposed method for virus recovery in future fomite sampling studies would provide opportunities to compare findings across multiple studies.

Inactivation of surrogate coronaviruses on hard surfaces by health care germicides

Background

In the 2003 severe acute respiratory syndrome outbreak, finding viral nucleic acids on hospital surfaces suggested surfaces could play a role in spread in health care environments. Surface disinfection may interrupt transmission, but few data exist on the effectiveness of health care germicides against coronaviruses on surfaces.

Methods

The efficacy of health care germicides against 2 surrogate coronaviruses, mouse hepatitis virus (MHV) and transmissible gastroenteritis virus (TGEV), was tested using the quantitative carrier method on stainless steel surfaces. Germicides were o-phenylphenol/p-tertiary amylphenol) (a phenolic), 70% ethanol, 1:100 sodium hypochlorite, ortho-phthalaldehyde (OPA), instant hand sanitizer (62% ethanol), and hand sanitizing spray (71% ethanol).

Results

After 1-minute contact time, for TGEV, there was a log₁₀ reduction factor of 3.2 for 70% ethanol, 2.0 for phenolic, 2.3 for OPA, 0.35 for 1:100 hypochlorite, 4.0 for 62% ethanol, and 3.5 for 71% ethanol. For MHV, log₁₀ reduction factors were 3.9 for 70% ethanol, 1.3 for phenolic, 1.7 for OPA, 0.62 for 1:100 hypochlorite, 2.7 for 62% ethanol, and 2.0 for 71% ethanol.

Conclusion

Only ethanol reduced infectivity of the 2 coronaviruses by >3-log₁₀ after 1 minute. Germicides must be chosen carefully to ensure they are effective against viruses such as severe acute respiratory syndrome coronavirus.

Maintenance of influenza virus infectivity on the surfaces of personal protective equipment and clothing used in healthcare settings

OBJECTIVES

The maintenance of infectivity of influenza viruses on the surfaces of personal protective equipment and clothing is an important factor in terms of controlling viral cross-infection in the environment and preventing contact infection. The aim of this study was to determine if laboratory-grown influenza A (H1N1) virus maintained infectivity on the surfaces of personal protective equipment and clothing used in healthcare settings.

METHODS

Influenza A virus (0.5 mL) was deposited on the surface of a rubber glove, an N95 particulate respirator, a surgical mask made of non-woven fabric, a gown made of Dupont Tyvek, a coated wooden desk, and stainless steel. Each sample was left for 1, 8, and 24 h, and hemagglutination (HA) and 50% tissue culture infective dose (TCID(50))/mL were measured.

RESULTS

The HA titer of this influenza A virus did not decrease in any of the materials tested even after 24 h. The infectivity of influenza A virus measured by TCID(50) was maintained for 8 h on the surface of all materials, with the exception of the rubber glove for which virus infectivity was maintained for 24 h.

CONCLUSIONS

Our results indicate that the replacement/renewal of personal protective equipment and clothing by healthcare professionals in cases of exposure to secretions and droplets containing viruses spread by patients is an appropriate procedure to prevent cross-infection.

Maintenance of influenza virus infectivity on the surfaces of personal protective equipment and clothing used in healthcare settings

Objectives

The maintenance of infectivity of influenza viruses on the surfaces of personal protective equipment and clothing is an important factor in terms of controlling viral cross-infection in the environment and preventing contact infection. The aim of this study was to determine if laboratory-grown influenza A (H1N1) virus maintained infectivity on the surfaces of personal protective equipment and clothing used in healthcare settings.

Methods

Influenza A virus (0.5 mL) was deposited on the surface of a rubber glove, an N95 particulate respirator, a surgical mask made of non-woven fabric, a gown made of Dupont Tyvek, a coated wooden desk, and stainless steel. Each sample was left for 1, 8, and 24 h, and hemagglutination (HA) and 50% tissue culture infective dose (TCID₅₀)/mL were measured.

Results

The HA titer of this influenza A virus did not decrease in any of the materials tested even after 24 h. The infectivity of influenza A virus measured by TCID₅₀ was maintained for 8 h on the surface of all materials, with the exception of the rubber glove for which virus infectivity was maintained for 24 h.

Conclusions

Our results indicate that the replacement/renewal of personal protective equipment and clothing by healthcare professionals in cases of exposure to secretions and droplets containing viruses spread by patients is an appropriate procedure to prevent cross-infection.

Effects of air temperature and relative humidity on coronavirus survival on surfaces

Assessment of the risks posed by severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) on surfaces requires data on survival of this virus on environmental surfaces and on how survival is affected by environmental variables, such as air temperature (AT) and relative humidity (RH). The use of surrogate viruses has the potential to overcome the challenges of working with SARS-CoV and to increase the available data on coronavirus survival on surfaces. Two potential surrogates were evaluated in this study; transmissible gastroenteritis virus (TGEV) and mouse hepatitis virus (MHV) were used to determine effects of AT and RH on the survival of coronaviruses on stainless steel. At 4 degrees C, infectious virus persisted for as long as 28 days, and the lowest level of inactivation occurred at 20% RH. Inactivation was more rapid at 20 degrees C than at 4 degrees C at all humidity levels; the viruses persisted for 5 to 28 days, and the slowest inactivation occurred at low RH. Both viruses were inactivated more rapidly at 40 degrees C than at 20 degrees C. The relationship between inactivation and RH was not monotonic, and there was greater survival or a greater protective effect at low RH (20%) and high RH (80%) than at moderate RH (50%). There was also evidence of an interaction between AT and RH. The results show that when high numbers of viruses are deposited, TGEV and MHV may survive for days on surfaces at ATs and RHs typical of indoor environments. TGEV and MHV could serve as conservative surrogates for modeling exposure, the risk of transmission, and control measures for pathogenic enveloped viruses, such as SARS-CoV and influenza virus, on health care surfaces.

Methods for the recovery of a model virus from healthcare personal protective equipment

Aims:  To develop methods for recovering a model virus (bacteriophage MS2) from healthcare personal protective equipment (PPE).

Methods and Results:  Nine eluents were evaluated for recovery of infectious MS2 from PPE: 1·5% beef extract (BE) pH 7·5 with and without 0·1% Tween 80, 1·5% BE pH 9·0 with and without 0·1% Tween 80, 3% BE pH 7·5 with and without 0·1% Tween 80, 3% BE pH 9·0 with and without 0·1% Tween 80 and PBS with 0·1% Tween 80. Methods were applied to experimentally contaminated PPE. Elution followed by two‐step enrichment assay could recover virus inputs as low as 1·5 log₁₀, and could recover >90% of inoculated virus from used items of experimentally contaminated PPE worn by human volunteers.

Conclusions:  BE was effective for recovering infectious viruses from a range of PPE materials.

Significance and Impact of the Study:  PPE plays a crucial role in interrupting transmission of infectious agents from patients to healthcare workers (HCWs). The fate of micro‐organisms when PPE is removed and disposed of has important consequences for infection control. Methods described here can be used to conduct rigorous studies of viral survival and transfer on PPE for risk assessments in infection control and HCW protection.

Exploration of the effectiveness of social distancing on respiratory pathogen transmission implicates environmental contributions

Background. In both military and civilian settings, transmission of respiratory pathogens may be due to person-to-person and environmental contributions. This possibility was explored in a military training setting, where rates of febrile respiratory illness (FRI) often reach epidemic levels.

Methods. Population size and FRI rates were monitored over 10 months in the units of 50–90 individuals. Some units were open to the influx of potentially infectious convalescents (hereafter referred to as “open units,” and some were closed to such an influx (hereafter referred to as “closed units”). Virologic testing and polymerase chain reaction analysis were used to detect adenovirus on surface structures.

Results. The odds ratio (OR) associated with FRI in closed units, compared with open units, was 1.13 (95% confidence interval [CI], 0.99–1.28). The OR in units with a population greater than the median size, compared with units with a population lower than the median size was 1.38 (95% CI, 1.23–1.55). Between 5% and 9% of surface samples obtained from selected units harbored viable adenovirus.

Conclusions. FRI rates were not reduced in units that were closed to potentially contagious individuals. These findings imply that the primary source of the pathogen is likely environmental rather than human, and they underscore what is known about other virus types. Diligence in identifying the relative roles of different transmission routes is suggested for civilian settings similar to those described in the current study.

Assessment of the Antiviral Properties of Zeolites Containing Metal Ions

The antiviral properties of zeolite (sodium aluminosilicate) powders amended with metal ions were assessed using human coronavirus 229E, feline infectious peritonitis virus (FIPV), and feline calicivirus F-9. Zeolites containing silver and silver/copper caused significant reductions of coronavirus 229E after 1 h in suspension. The silver/copper combination yielded a >5.13-log₁₀ reduction within 24 h. It was also the most effective (>3.18-log₁₀) against FIPV after 4 h. Other formulations were ineffective against FIPV. On plastic coupons with incorporated silver/copper-zeolites, >1.7-log₁₀ and >3.8-log₁₀ reductions were achieved for coronavirus 229E and feline calicivirus within 24 h, respectively. Silver/copper zeolite reduced titers of all viruses tested, suggesting that it may be effective against related pathogens of interest [i.e., SARS coronavirus, other coronaviruses, human norovirus (calicivirus)]. Of note, it was effective against both enveloped and nonenveloped viruses. Metal-zeolites could therefore possibly be used in applications to reduce virus contamination of fomites and thus the spread of viral diseases.

Certainties and uncertainties facing emerging respiratory infectious diseases: lessons from SARS

Every emerging infectious disease is a challenge to the whole of mankind. There are uncertainties regarding whether there will be a pandemic, if it will be caused by the highly pathogenic H5N1 influenza virus, when or where it will occur, how imminent or how severe it will be. No one can accurately predict if and when a given virus will become a pandemic virus. Pandemic prevention strategies must be based on preparing for the unexpected and being capable of reacting accordingly. There is growing evidence that infection control measures were helpful in containment of severe acute respiratory syndrome (SARS) as well as avian influenza. Compliance of standard infection control measures, intensive promotion of hand and respiratory hygiene, vigilance and triage of patients with febrile illness, and specific infection control measures are key components to contain a highly contagious disease in hospital and to protect healthcare workers, patients and visitors. The importance of standard precautions for any patient and cleaning and disinfection for the healthcare environment cannot be overemphasized. SARS illustrated dramatically the potential of air travel and globalization for the dissemination of an emerging infectious disease. To prevent the potential serious consequences of pandemic influenza, timely implementation of pharmaceutical and non-pharmaceutical interventions locally within the outbreak area is the key to minimizing global spread. Herein, we relate our perspective on useful lessons derived from a review of the SARS epidemic that may be useful to physicians, especially when looking ahead to the next epidemic.

How often do you wash your hands? A review of studies of hand-washing practices in the community during and after the SARS outbreak in 2003

We reviewed evidence of hand-washing compliance in community settings during the 2003 SARS outbreak. Literature was searched through PubMed, Cochrane Library, Wan Fang database and Google. English and Chinese papers were reviewed. Studies containing data on hand-washing, self-reported or directly observed, in community settings were selected. Case-control studies and studies in healthcare settings were excluded. Fourteen studies were reviewed. Self-reported hand-washing compliance increased in the first phase of the SARS outbreak and maintained a high level 22 months after the outbreak. The decline of hand-washing in Hong Kong after SARS was relatively slow. A significant gender difference in hand-washing compliance (female > male) was found in eight studies. The importance of family support and 'significant female others' in hand hygiene promotion are noted. The impact of education is uncertain. Perceived susceptibility to and severity of SARS, and perceived efficacy of hand-washing in preventing SARS, also predicted self-reported hand-washing compliance.

Inactivation of viruses on surfaces by ultraviolet germicidal irradiation

In many outbreaks caused by viruses, the transmission of the agents can occur through contaminated environmental surfaces. Because of the increasing incidence of viral infections, there is a need to evaluate novel engineering control methods for inactivation of viruses on surfaces. Ultraviolet germicidal irradiation (UVGI) is considered a promising method to inactivate viruses. This study evaluated UVGI effectiveness for viruses on the surface of gelatin-based medium in a UV exposure chamber. The effects of UV dose, viral nucleic acid type (single-stranded RNA, ssRNA; single-stranded DNA, ssDNA; double-stranded RNA, dsRNA; and double-stranded DNA, dsDNA), and relative humidity on the virus survival fraction were investigated. For 90% viral reduction, the UV dose was 1.32 to 3.20 mJ/cm2 for ssRNA, 2.50 to to 4.47 mJ/cm2 for ssDNA, 3.80 to 5.36 mJ/cm2 for dsRNA, and 7.70 to 8.13 mJ/cm2 for dsDNA. For all four tested viruses, the UV dose for 99% viral reduction was 2 times higher than those for 90% viral reduction. Viruses on a surface with single-stranded nucleic acid (ssRNA and ssDNA) were more susceptible to UV inactivation than viruses with double-stranded nucleic acid (dsRNA and dsDNA). For the same viral reduction, the UV dose at 85% relative humidity (RH) was higher than that at 55% RH. In summary, results showed that UVGI was an effective method for inactivation of viruses on surfaces.

Effectiveness of handwashing in preventing SARS: a review

This review examines the literature, including literature in Chinese, on the effectiveness of handwashing as an intervention against severe acute respiratory syndrome (SARS) transmission. Nine of 10 epidemiological studies reviewed showed that handwashing was protective against SARS when comparing infected cases and non‐infected controls in univariate analysis, but only in three studies was this result statistically significant in multivariate analysis. There is reason to believe that this is because most of the studies were too small. The evidence for the effectiveness of handwashing as a measure against SARS transmission in health care and community settings is suggestive, but not conclusive.

Laboratory Containment of SARS Virus

Following the severe acute respiratory syndrome (SARS) outbreak in 2003, a large number of clinical and environmental samples containing/potentially containing SARS coronavirus (SARS-CoV) as well as SARS-CoV stocks were retained in clinical and research laboratories. The importance of laboratory biosafety was demonstrated by the occurrence of laboratory incidents in Singapore, Taiwan and Beijing. It is imperative that safe practice and techniques, safety equipment and appropriate facility design should be in place to reduce or eliminate exposure of laboratory workers, other persons and the outside environment to SARS-CoV containing materials. Discussion on laboratory containment of SARS-CoV was initiated in Hong Kong in August 2003. It was agreed that an inventory of all specimens with the potential presence of SARS-CoV collected for any diagnostic or research purposes from November 2002 to July 2003 should be established in each laboratory. They should be stored in a secure place at the appropriate biosafety level with access control. Un-needed samples collected during the period should be destroyed. These laboratories should be audited to ensure inventories are updated. The audit should include safety and security measures to detect irregularities. Any laboratory accidents involving materials suspected of containing SARS-CoV should be reported to the authorities and all personnel exposed closely followed medically. A contingency plan should be in place in the laboratory and a drill conducted regularly to test its efficacy. By January 2004, all clinical laboratories performing SARS-CoV testing in Hong Kong set up inventories to document location and types of SARS-CoV containing materials retained in their laboratory. Audits of these laboratories in 2004 showed that laboratory safety and containment requirements as recommended were generally met. Key words: Contingency plan, Laboratory safety, Virus inventory, Virus survival

Viral load distribution in SARS outbreak

Airborne transmission may have resulted in an outbreak of SARS in Hong Kong.

An unprecedented community outbreak of severe acute respiratory syndrome (SARS) occurred in the Amoy Gardens, a high-rise residential complex in Hong Kong. Droplet, air, contaminated fomites, and rodent pests have been proposed to be mechanisms for transmitting SARS in a short period. We studied nasopharyngeal viral load of SARS patients on admission and their geographic distribution. Higher nasopharyngeal viral load was found in patients living in adjacent units of the same block inhabited by the index patient, while a lower but detectable nasopharyngeal viral load was found in patients living further away from the index patient. This pattern of nasopharyngeal viral load suggested that airborne transmission played an important part in this outbreak in Hong Kong. Contaminated fomites and rodent pests may have also played a role.

Survival of severe acute respiratory syndrome coronavirus

Background. The primary modes of transmission of severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) appear to be direct mucus membrane contact with infectious droplets and through exposure to formites. Knowledge of the survival characteristics of the virus is essential for formulating appropriate infection-control measures.

Methods. Survival of SARS-CoV strain GVU6109 was studied in stool and respiratory specimens. Survival of the virus on different environmental surfaces, including a laboratory request form, an impervious disposable gown, and a cotton nondisposable gown, was investigated. The virucidal effects of sodium hypochlorite, house detergent, and a peroxygen compound (Virkon S; Antec International) on the virus were also studied.

Results. SARS-CoV GVU6109 can survive for 4 days in diarrheal stool samples with an alkaline pH, and it can remain infectious in respiratory specimens for >7 days at room temperature. Even at a relatively high concentration (10⁴ tissue culture infective doses/mL), the virus could not be recovered after drying of a paper request form, and its infectivity was shown to last longer on the disposable gown than on the cotton gown. All disinfectants tested were shown to be able to reduce the virus load by >3 log within 5 min.

Conclusions. Fecal and respiratory samples can remain infectious for a long period of time at room temperature. The risk of infection via contact with droplet-contaminated paper is small. Absorbent material, such as cotton, is preferred to nonabsorptive material for personal protective clothing for routine patient care where risk of large spillage is unlikely. The virus is easily inactivated by commonly used disinfectants.