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Hierarchy of Susceptibility of Viruses to Environmental Surface Disinfectants: A Predictor of Activity Against New and Emerging Viral Pathogens


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Proper disinfection is crucial to interrupt the environmental spread of many viruses. In the case of new and emerging viruses still awaiting culture and full characterization, it is proposed that any official recommendations for disinfectant use be based on the well-established hierarchy of susceptibility to such chemicals as related to virus particle size and structure.
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Hierarchy of Susceptibility of Viruses to Environmental Surface
Disinfectants: A Predictor of Activity Against New and Emerging
Viral Pathogens
University of Ottawa, Centre for Research on Environmental Microbiology, Faculty of Medicine, 451 Smyth Rd, Ottawa,
ON, Canada K1H 8M5
Proper disinfection is crucial to interrupt the
environmental spread of many viruses. In the case
of new and emerging viruses still awaiting culture
and full characterization, it is proposed that any
official recommendations for disinfectant use be
based on the well-established hierarchy of
susceptibility to such chemicals as related to virus
particle size and structure.
Viruses represent nearly 15% of all infectious agents
catalogued as human pathogens (1). Viruses also
predominate in the list of nearly 40 human pathogens
discovered in the past 4 decades (2). Successful control of
many bacterial diseases, together with the discoveries of links
between viruses and chronic conditions, further enhance the
relative significance of viruses (3).
Although vaccination, insect vector control, screening
of blood and tissues, and barriers such as condoms can
effectively interrupt the spread of many viruses, others
require environmental control instead (4, 5); hand hygiene
and chemical disinfection of semicritical medical devices
and environmental surfaces constitute the backbone of such
control in healthcare settings. Hand hygiene and
disinfection of environmental surfaces are also crucial
where foods are handled.
In the United States, antiseptics are regulated by the U.S.
Food and Drug Administration (FDA), but that agency
currently has no system to review and register label claims of
such formulations against viruses (6). The FDA, which also
regulates chemi-sterilants and high-level disinfectants for use
on medical devices (7), requires data for efficacy against
viruses but simply refers to testing for virucidal activity as
specified by the U.S. Environmental Protection Agency
(EPA). The EPA deals mainly with environmental surface
disinfectants through specific rules on testing and approval of
label claims against human pathogens (see http://www. It also accepts the
use of surrogate organisms for claims of activity against
vegetative and spore-forming bacteria, mycobacteria, and
fungi (8). Apart from certain recently granted exceptions, this
does not apply to viruses, and testing is required against each
virus type to be listed on the product label. However, a
disinfectant can call itself a ‘virucide’ even with activity
against one or more enveloped, thus easier to kill, virus. This
is also in sharp contrast to regulations elsewhere. In Canada,
an environmental surface disinfectant can call itself a ‘general
virucide’ only upon demonstrated activity against the Sabin
vaccine strain of poliovirus type 1 (9), and in Europe, in
addition to the poliovirus, human adenovirus type 5 must be
used to make a similar claim (10). A general virucidal claim in
Australia requires testing against a poliovirus, an adenovirus,
and a herpesvirus; a parvovirus can be substituted for the
poliovirus (11). This paper highlights the implications of the
current EPA policy (http://www.
EPA+%2B+virus+surrogates&btnG) with particular
reference to new and emerging viral pathogens and proposes
an alternative.
The differences in the lipophilicity of enveloped
(hydrophobic) and nonenveloped (hydrophilic) viruses
were clearly delineated in the late 1950s (12, 13). Klein and
Deforest (14) subsequently showed that hydrophobic
viruses were considerably more susceptible to microbicidal
chemicals due to the presence of essential lipids in their
envelope. Among the hydrophilic ones, those with a
smaller particle diameter (25–35 nm) proved to be
comparatively less susceptible than those of a larger size
(40–75 nm). Those initial observations have been
repeatedly confirmed and extended over the years. The
Spaulding classification (15) is also frequently referred to
in this context; however, it relates exclusively to chemical
disinfectants to be used on medical and surgical devices,
which come under the purview of the FDA.
Table 1 is based on the hierarchy of susceptibility in
relation to the particle size of human pathogenic viruses when
tested under similar experimental conditions; other infectious
agents are included for contrast only. It should, however, be
noted here that nonenveloped viruses in general are often
considered more susceptible to chemical disinfectants than are
Received June 3, 2007. Accepted by AH July 11, 2007.
Corresponding author's e-mail:
mycobacteria (16). Although this may be true for the
larger-sized nonenveloped viruses, many types of
smaller-sized nonenveloped viruses show themselves to be
more difficult to inactivate than mycobacteria when tested
simultaneously (17). Prions are not included in the Table
because they are not only substantially different from viruses
in size and structure, but their communicability is also much
lower. Further, recent studies show them to be much less
resistant to chemicals than previously thought (18).
Viruses and Environmental Control
As stated earlier, many viruses have been discovered since
1968 (2, 19) and others have re-emerged (20), together
causing substantial numbers of human cases and
fatalities (21). Table 2 gives examples of the nonenveloped
viruses among those. Several of the listed viruses have the
potential to remain viable on nonporous surfaces and thus
their spread via such vehicles is potentially interruptible with
proper disinfection of the environment. Rotaviruses are a
suitable example, as they can survive well on environmental
surfaces (22), and their spread in experimental (23) as well as
field (24) settings can be prevented through the use of
chemical disinfection.
The discovery of a new pathogen elicits an immediate
demand for guidance on the selection and use of disinfectants
for its environmental control. In the United States, the primary
source for any such guidance is the Centers for Disease
Control and Prevention (CDC), which normally bases its
recommendations on EPA-registered label claims (25). This
may not readily apply to a newly discovered virus, particularly
a nonenveloped virus in which a greater degree of confidence
is essential for its environmental control.
The following additional factors may hinder the ready
availability of the information needed to base such
recommendations: (1) The agent may be refractory to growth
in lab animals and cell cultures, thus limiting experimentation
with it; human noroviruses illustrate this point well. (2)Even
if a newly discovered virus is cultivable in the laboratory, its
classification at biosafety level 3 or 4 would severely restrict
the number of laboratories that could handle it and thus
Table 1. Hierarchy of susceptibility of human pathogens to chemical disinfectants
Level of
susceptibility Microbial class Virus family Examples of human pathogenic viruses
Lowest Bacterial spores
Small nonenveloped viruses (25–35 nm) Astroviridae
B19, bocavirus
Entero, hepatitis A, rhino
¯Large nonenveloped viruses (40–70 nm) Adenoviridae
Fungal conidia
Vegetative bacteria, yeast
Highest Enveloped viruses Arenaviridae Lymphocytic choriomeningitis
Bornaviridae Borna
Bunyaviridae Hanta, Rift Valley Fever
Coronaviridae SARS
Filoviridae Marburg, Ebola
Flaviviridae Yellow fever, hepatitis C
Hepadnaviridae Hepatitis B
Herpesviridae Cytomegalo, varicella
Orthomyxoviridae Influenza
Paramyxoviridae Mumps, measles
Poxviridae Smallpox, vaccinia
Rhabdoviridae Rabies
Retroviridae Human immunodeficiency
Togaviridae Rubella
impede the development of information on its susceptibility to
chemicals potentially applicable for its environmental control.
(3) Recently enhanced restrictions on the transportation of
infectious agents in general would also limit the availability of
the virus to researchers otherwise capable of testing
environmental surface disinfectants against it. (4) Lack of
vaccination and therapy against the virus may put staff at
testing labs at undue risk of laboratory-associated infections,
as shown by the severe acute respiratory syndrome (SARS)
incident in Singapore (26).
An Alternative Approach
An alternative approach in dealing with newly discovered
nonenveloped viruses is to apply the hierarchy of disinfectant
susceptibility as it relates to their size and structure (Table 1).
One plausible scenario is that a newly discovered virus is
assigned a tentative grouping based on either direct electron
microscopy only or by molecular and immunological means
with or without culture in the laboratory. Even this
preliminary information has a reasonable predictive value
based on the already available data on the relationship
between virus particle size and structure and susceptibility to
environmental surface disinfectants.
It is recommended that the data to be submitted for
consideration by the EPA be based on an approved carrier test
using at least one large-sized nonenveloped virus and one
small-sized nonenveloped virus. The actual choice of the
viruses may be determined depending on the predominant
clinical picture of the new or emerging virus under
consideration and the testing initiated with the following
criteria and conditions in mind: (1) The virus in question must
first be identified as to its tentative grouping, and the CDC
must make a formal announcement to that effect.
(2) Manufacturers of environmental surface disinfectants
must submit data to the EPA supporting claims of activity of
the proposed product against a virus expected to be equally or
less susceptible than the newly discovered virus. (3) Claims of
hierarchy-based virucidal activity must be limited only to
those products already classified as broad-spectrum and
hospital-grade disinfectants. (4) Claims for anticipated
activity against the target virus will not be allowed on product
label or in mass media, but may possibly be allowed on
company Web sites and tech bulletins. (5) Such a claim based
on the hierarchy of susceptibility to disinfectants will be
allowed only until actual information on the agent’s
susceptibility to environmental surface disinfectants becomes
available from actual testing which has been accepted by the
EPA. (6) Limited disinfectants and sanitizers, as defined by
the EPA, will be excluded from consideration in this context.
Since the work of Klein and Deforest (14) and
Spaulding (15), we know of many more human pathogenic
viruses and also better understand their susceptibility to a wider
variety of chemical disinfectants using more sophisticated test
methods (27). This information, while confirming the original
tenets, should allow for greater confidence in the scheme
proposed here. It should also be noted that the Spaulding
scheme was developed for the decontamination of medical
devices and is limited in its relevance to the chemical
disinfection of environmental surfaces.
New human pathogenic viruses continue to come to
light (28) and it is quite likely that such discoveries will
continue well into the future, while those already known may
also emerge or re-emerge as a result of ongoing societal
changes (2). In view of this, and in the United States in
particular, the existing regulations with regard to awarding
label claims for virucidal activity need urgent review. This
issue is especially pertinent when it comes to new and
emerging viral pathogens of humans. The proposed system,
based on the already well-recognized hierarchy of disinfectant
susceptibility, is not only scientifically valid, but it will not
require a major overhaul of the existing regulations.
The concept of using indicator strains for classes of
microbial pathogens has been in place for some time now.
More recently, the EPA has begun to allow surrogate viruses to
be used to substantiate virucidal activity for
Table 2. Examples of nonenveloped viruses discovered as new and/or emerging since 1968
Year of
Virus family (approximate
particle size in nm) Associated disease(s)
Enterovirus 70 1968 Picornaviridae (30) Acute hemorrhagic conjunctivitis; rare cases of paralysis
Coxsackievirus A24 (variant) 1970 Picornaviridae (30) Acute hemorrhagic conjunctivitis
Enterovirus 71 1969 Picornaviridae (30) Aseptic meningitis; hand-foot-mouth disease
Norovirus (Norwalk agent) 1972 Caliciviridae (30) Acute gastroenteritis
Rotavirus 1973 Reoviridae (70) Acute gastroenteritis
Parvovirus Bl9 1975 Parvoviridae (25) Aplastic anemia
Hepatitis E 1988 Unclassified (30) Hepatitis
Anellovirus 1997 Circoviridae (17) Hepatitis
Bocavirus 2005 Parvoviridae (25) Respiratory infections
difficult-to-culture human pathogenic viruses such as
hepatitis B ( and
hepatitis C viruses (
files/hepcbvdvpcol.pdf), and norovirus (
oppad001/pdf_files/initial_virucidal_test.pdf). Further, the
concept of allowing the use of data based on testing with
surrogate viruses has been accepted by the EPA for new and
emerging enveloped viruses. As a general rule, nonenveloped
viruses are more stable outside hosts and have a greater
potential to spread by environmental means (29, 30).
Therefore, in the interest of human health and proper infection
control, the public and professionals alike have an immediate
need for recommendations to counter new and emerging viral
pathogens based on the best available science. It is
scientifically justifiable to substantiate those public health
recommendations and determine product efficacy based on
prior testing of environmental surface disinfectants with
appropriately related surrogate viruses using valid test
methods. Such an arrangement would add value to, and place
greater confidence in, any guidance issued by agencies such
as the CDC and EPA.
Comments on the manuscript were sought and received
from the Innovation and Reform Group (IRG) representing
The Clorox Co. (Pleasanton, CA), The Procter & Gamble
Co. (Cincinnati, OH), and Reckitt Benckiser, Inc.
(Montvale, NJ). The interaction with IRG was coordinated
by Pat Quinn of the Accord Group (Washington, DC). IRG
also financed travel for a meeting with the Antimicrobials
Division of the EPA.
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... The causative pathogen, foot-and-mouth disease virus (FMDV), is a small, nonenveloped, single-stranded RNA virus of the family Picornaviridae, genus Aphthovirus [3]. Generally, non-enveloped viruses are more stable outside their hosts and have a higher possibility of spreading via environmental agents [4,5]. Therefore, environmental control using the proper chemical disinfectants is important for the prevention and control of infectious diseases, along with vaccination, surveillance, and quarantine [6]. ...
... The U.S. Environmental Protection Agency (EPA) allows surrogate viruses to be used for substantiating virucidal activity not only for difficult-to-culture pathogenic viruses but also for new and emerging viruses [4]. The approach is based on the scientific rationale that if disinfectants inactivate more challenging surrogates than specific target organisms, then they should be expected to inactivate the target organism [42]. ...
... With this approach, EPA ranks viral pathogens with respect to their tolerance or resistance to chemical disinfectants and divides the viruses into three subgroups based on size. Most susceptible to most resistant tiers of viruses are: enveloped, large (50-100 nm) non-enveloped, and small (<50 nm) enveloped viruses [4,43]. Incidentally, many studies identified that non-enveloped viruses are more resistant to inactivation than enveloped viruses, though they can vary depending on the virus type and disinfectant formulation [9,44]. ...
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In South Korea, testing disinfectants against foot-and-mouth disease virus (FMDV) that are contagious in livestock or that require special attention with respect to public hygiene can be manipulated only in high-level containment laboratories, which are not easily available. This causes difficulties in the approval procedure for disinfectants, such as a prolonged testing period. Additionally, the required biosafety level (BSL) in the case of FMDV has hindered its extensive studies. However, this drawback can be circumvented by using a surrogate virus to improve the performance of the efficacy testing procedure for disinfectants. Therefore, we studied bacteriophage MS2 (MS2) and bovine enterovirus type 1 (ECBO) with respect to disinfectant susceptibility for selecting a surrogate for FMDV according to the Animal and Plant Quarantine Agency (APQA) guidelines for efficacy testing of veterinary disinfectants. Effective concentrations of the active substances in disinfectants (potassium peroxymonosulfate, sodium dichloroisocyanurate, malic acid, citric acid, glutaraldehyde, and benzalkonium chloride) against FMDV, MS2, and ECBO were compared and, efficacies of eight APQA-listed commercial disinfectants used against FMDV were examined. The infectivity of FMDV and ECBO were confirmed by examination of cytopathic effects, and MS2 by plaque assay. The results reveal that the disinfectants are effective against MS2 and ECBO at higher concentrations than in FMDV, confirming their applicability as potential surrogates for FMDV in efficacy testing of veterinary disinfectants.
... Similar to autoclaving and other sterilization procedures, HHP technology is measured with the inactivation of spore-carrying biological indicators (BIs) consistent with international standards [21]. Indicators are populated with a non-harmful colony of Geobacillus stearothermophilus (1 × 10 6 and 2.2 × 10 6 organisms) which can be disinfected alongside room surfaces giving a visible confirmation of sporicidal efficacy and providing confidence in the inactivation of lesser-resistant pathogens as well [22,23]. ...
... Biological indicators introduced into the room to monitor the HHP fogging cycle repeatedly resulted in successful inactivation demonstrating sporicidal efficacy of the disinfection treatment and indicating efficacy against less hardy pathogens [16,22,23]. The HHP system has been effective against C. difficile spores in a three-part soil load [14,15], which, in combination with the sporicidal efficacy seen in this study, suggests that it may likewise be used for combatting the fastidious and pathogenic C. difficile in a healthcare environment. ...
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Background Environmental contamination contributes to hospital associated infections, particularly those caused by multi-drug resistant organisms (MDRO). This study investigated bioburden presence on surfaces in a critical care center’s patient rooms following typical environmental services (EVS) practices and following intervention with hybrid hydrogen peroxide™ (HHP™) fogging. Methods Upon patient discharge, following standard cleaning or cleaning with ultraviolet (UV) light use, patient rooms were sampled by swabbing for adenosine triphosphate (ATP) and aerobic colony counts (ACC) from five preset locations. Rooms were then fogged via HHP technology using chemical indicators and Geobacillus stearothermophilus biological indicators for sporicidal validation monitoring. Following fogging, rooms were sampled again, and results were compared. Results A 98% reduction in ACC was observed after fogging as compared to post EVS practices both with and without UV light use. No statistical difference was seen when comparing cleaning to cleaning with UV light use. Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa were identified following EVS practices and not detected following HHP fogging. ATP samples were reduced 88% by fogging application. Chemical and biological indicators confirmed correct application of HHP fogging, as seen through its achievement of a 6-log reduction of bacterial spores. Conclusion HHP fogging is a thorough and efficacious technology which, when applied to critical care patient rooms, significantly reduces bioburden on surfaces, indicating potential benefits for implementation as part of infection prevention measures.
... The EPA, therefore, enacted a policy in 2016 enabling efficacy claims against emerging viruses to be made without having provided registration data specifically for those viruses. In its Guidance to Registrants 16 , the EPA has made note of the hierarchy of pathogen susceptibility to microbicides [17][18][19][20][21] in recognizing that efficacy against one enveloped virus implies efficacy against other enveloped viruses. The EPA policy provides a "process that can be used to identify effective disinfectant products for use against emerging viral pathogens and to permit registrants to make limited claims of their product's efficacy against such pathogens. ...
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The World Health Organization’s R&D Blueprint list of priority diseases for 2022 includes Lassa fever, signifying the need for research and development in emergency contexts. This disease is caused by the arenavirus Lassa virus (LASV). Being an enveloped virus, LASV should be susceptible to a variety of microbicidal actives, although empirical data to support this expectation are needed. We evaluated the virucidal efficacy of sodium hypochlorite, ethanol, a formulated dual quaternary ammonium compound, an accelerated hydrogen peroxide formulation, and a p-chloro-m-xylenol formulation, per ASTM E1052-20, against LASV engineered to express green fluorescent protein (GFP). A 10-μL volume of virus in tripartite soil (bovine serum albumin, tryptone, and mucin) was combined with 50 μL of disinfectant in suspension for 0.5, 1, 5, or 10 min at 20–25 °C. Neutralized test mixtures were quantified by GFP expression to determine log10 reduction. Remaining material was passaged on Vero cells to confirm absence of residual infectious virus. Input virus titers of 6.6–8.0 log10 per assay were completely inactivated by each disinfectant within 1–5 min contact time. The rapid and substantial inactivation of LASV suggests the utility of these microbicides for mitigating spread of infectious virus during Lassa fever outbreaks.
... It has been shown that SARS-CoV-2, under environmental conditions, remains viable in aerosols up to 3 h and on plastic and stainless steel up to 3 days, meaning that effective surface sanitizers can prevent indirect contact transmission (van Doremalen et al., 2020). Enveloped viruses, such as Coronaviruses, are more susceptible to disinfectants due to the presence of essential lipids in their envelope (Sattar et al., 2007), thus underlining the importance of such products in preventing direct contact transmission. The use of chemical disinfectants represents a widely accepted practice to prevent and control infections and to protect healthcare workers, patients, and people at a high risk of severe illness. ...
In this study we evaluated the antiviral activity of the Silver Barrier® disinfectant against SARSCoV-2. Silver Barrier® showed time- and concentration-dependent antiviral activity against SARSCoV-2. After 5 min contact time, Silver Barrier® at 0.002% showed a strong inhibitory effect (p<0.001), with a 2-fold reduction of viral genome copy numbers, and a robust suppression (94%) of SARS-CoV-2 infectivity. Considering the effects obtained in solution and within a very short time, Silver Barrier® stands as an excellent new candidate for the disinfection of work environments, especially at the healthcare level, where there are people at high risk of serious illnesses.
... This is because they are applied at much higher concentrations and allowed longer contact time. Perfume often make up part of their component (Evans et al., 2002;Sattar, 2007). However, humans are encouraged to continually make use of sanitizers to guarantee good hygienic practices Gains and challenges met so far ...
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Nearly all nations in the globe have been impacted by COVID-19, otherwise known as coronavirus infection brought on by new SARS-Cov-2, which has been dubbed a global pandemic. Contact with sick people and handling contaminated surfaces are the main ways that coronavirus is disseminated. However, as of July 2020, it had impacted more than 33 million people worldwide. Aside from the use of personal protective equipment (PPE), alcohol-based sanitizers, and personal cleanliness, the use of disinfectants to successfully decrease or stop the spread is of paramount importance. Since surfaces and people are recognized to be the sources of COVID -19 transmissionsglobally, disinfecting these areas is a good way to stop the disease from spreading. Many ideas and models have been developed to manage the novel virus, but these models are always being updated to reflect how well the virus has adapted to various domains and sections of the global community. With little to no scientific support, theories have been spread about the unique virus's ability to survive. The use of disinfectants of various kinds is one general control technique being implemented globally to combat the new Covid-19. The likelihood of infection increases the longer a person who is not infected is in close contact with an infected person. As of now, coughing or sneezing by an infected person continues to be the predominant method of transmission.It looks like a decent idea to use a disinfectant to render droplets on surfaces inactive in order to stop the spread of COVID-19. Chemistry, concentration, contact time, and coverage are particularly significant factors when thinking about disinfection. The disinfectants play a crucial role in stopping the spread of COVID-19 in the environment and ensuring everyone's safety. The global economy has experienced significant economic decline as a result of this epidemic. It is advised to properly dispose of COVID-19 management supplies in order to prevent the spread of other instances or another type of health problem
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Unlabelled: The awareness of the health implication of Covid-19 pandemic marked an increase consumption of various dietary and herbal supplements (DHS) for the deterrence and/or prophylaxis against the novel emerging and infectious disease. However, there is little indication of the usefulness or otherwise of their use in alleviating symptoms of COVID-19. Objectives: To investigate the pattern and determinants of DHS use among the Nigerian population for the prevention and treatment of COVID-19. Design: Cross-sectional questionnaire survey. Setting: Older adolescents and adults residing in Nigeria. Participants: Participants (n = 645) residing in the Nigeria were recruited from different geo-political zones and various ethnic groups. Primary and secondary outcomes: Prevalence and determinants for the use of different DHS for the prevention and treatment of COVID-19 in Nigeria, and sources of information for DHS use. Results: Most participants (425, 65.9%) believed that dietary supplements are necessary during infectious disease outbreak, but a fewer proportion believed that supplements can be used in conjunction with other drugs to treat Covid-19. Vitamin C was the most known (70.0%) and Vitamin A. The least known (0.3%) dietary supplement Approximately half (50.2%) of the study subjects, more than a third (37.8%) and less than a quarter (22.7%) were aware that Folic acid, vitamin D and vitamin E are DS. Herbal dietary supplements mentioned as known by the study participants included Garlic (46.5%), Ginger (44.7%), Tumeric (36.3%), Moringa (40.0%) and Ginseng (26.3%). Citrus fruit as a DS was recognized by fewer (6.5%) study participants and only 1.6% referred to herbal tea as DHS. In all, 571 (88.5%) of the study participants took DHS during the Covid-19 pandemic with males 1.5 times more likely to take DHS than females (χ2 = 3.09, P-value = 0.08, OR = 1.54, 95% CI = 0.95, 2.47) during the pandemic. Participants reported lesser consumption of Selenium (27, 4.2%), Iron (20,3.1%), Zinc (61, 9.5%) and calcium (101, 15.7%) to prevent/treat Covid-19. Majority (271, 42.0%) of the study participants mentioned "health worker" as source of information on DHS while 13% mentioned "Social media". The sociodemographic determinants of DHS practices used to prevent/treat COVID-19 during the pandemic included older age group of 61-70 years, widows, secondary level of education and not employed. Conclusions: The findings showed widespread use of DHS for the prevention and treatment of COVID-19. The use of DHS in this study was mainly guided by health workers with a marginal role of social media and Mass media. These findings call for a more robust consolidative tactic towards DHS to ensure its proper and safe use.
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Coronavirus disease 2019 (COVID-19) is primarily a respiratory illness, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The pandemic outbreak of SARS-CoV-2 across the world has been responsible for high morbidity and mortality, which emphasizes the role of the environment on virus persistence and propagation to the human population. Since environmental factors may play important roles in viral outbreaks, and the severity of the resulting diseases, it is essential to take into account the role of the environment in the COVID-19 pandemic. The SARS-CoV-2 may survive outside the human body from a few hours to a few days, depending upon environmental conditions, probably due to the relatively fragile envelope of the virus. The shedding and persistence of SARS-CoV-2 in the environment on animate and inanimate objects contributes to the risk of indirect transmission of the virus to healthy individuals, emphasizing the importance of various disinfectants in reducing the viral load on environmental surface and subsequently control of SARS-CoV-2 in the human population.
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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for the ongoing pandemic of Coronavirus Disease 2019 (COVID-19). Other members of the enveloped RNA virus family Coronaviridae have been responsible for a variety of human diseases and economically important animal diseases. Disinfection of air, environmental surfaces, and solutions is part of infection prevention and control (IPAC) for such viruses and their associated diseases. This article reviews the literature on physical inactivation (disinfection) approaches for SARS-CoV-2 and other coronaviruses. Data for thermal (heat) inactivation, gamma irradiation, and ultraviolet light in the C range (UVC) irradiation have been reviewed. As expected, the susceptibilities of different members of the Coronaviridae to these physical inactivation approaches are similar. This implies that knowledge gained for SARS-CoV-2 should be applicable also to its emerging mutational variants and to other future emerging coronaviruses. The information is applicable to a variety of disinfection applications, including IPAC, inactivation of live virus for vaccine or laboratory analytical use, and waste stream disinfection.
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Viruses exhibit a marked variation in their susceptibilities to chemical and physical inactivation. Identifying a trend within these variations, if possible, could be valuable in the establishment of an effective and efficient infection control or risk mitigation strategy. It has been observed that non-enveloped viruses are generally less susceptible than enveloped viruses and that smaller sized viruses seem less susceptible than larger viruses. A theory of a “hierarchy” of pathogen susceptibility has been proposed and widely referenced. This concept provides a useful general guide for predicting the susceptibility of a newly emerged pathogen. It also serves as a theoretical basis for implementing a limited scale viral inactivation study that is to be extrapolated onto many other viruses. The hierarchy concept should be interpreted with caution since the actual viral inactivation efficacy may, in some cases, be different from the general prediction. The actual efficacy is dependent on the type of chemistry and application conditions. The order of susceptibility is not always fixed; and viruses within the same family or even the same genus may exhibit drastic differences. This chapter reviews viral inactivation data for several commonly used chemistries against non-enveloped viruses, highlighting the cases wherein the order of susceptibility varied or even flipped. Possible underlying mechanisms are also discussed.
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Chemical disinfection is widely practiced as a means of controlling and preventing the spread of infectious diseases. Although disinfection of bacteria has been widely studied, much less attention has been paid to the virucidal potential of commonly used disinfectants in spite of the low infective dose of many human pathogenic viruses. This review considers what is known about the disinfection of viruses and the virucidal properties of different classes of disinfectant chemicals. It focuses on virus disinfection from a practical viewpoint and also critically evaluates the testing techniques currently used for examining the efficacy of disinfectant products.
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A model was developed to examine the effects of disinfectants on the transmission of infectious rotavirus from a dried surface to humans. The initial experiments were designed to find a method of preserving rotavirus infectivity during drying. Culture-adapted human rotavirus (CJN strain) was dried at room temperature in different organic suspensions, including fecal matter, several laboratory media, and nonfat dry milk (NDM). Recoveries of infectious virus were then compared. Fecal matter provided little protection in this study relative to distilled water, but the other suspensions were quite protective, especially NDM, which consistently allowed recoveries of greater than 50%. When 10(3) focus-forming units of unpassaged CJN virus were dried in NDM and administered to subjects who licked the dried material, 100% (8 of 8) became infected. The effect of Lysol brand disinfectant spray (LDS) was next examined. Although NDM provided some protection against inactivation by LDS, spraying under conditions recommended by the manufacturer consistently caused the CJN virus titer to decrease greater than 5 log10. Consumption of CJN virus (10(3) focus-forming units) sprayed with LDS caused no infection in 14 subjects, whereas 13 of 14 subjects who consumed the unsprayed virus became infected (P less than 0.00001). The methods developed in this study could be used to test the effects of other disinfectants on the spread of infectious rotavirus from inanimate surfaces to humans.
The Antimicrobials Division has set ambitious goals to continue to protect public health and the environment, while improving service to registrants and other stakeholders. The Agency will expand its post-registration efficacy testing of tuberculocides and other hospital disinfectants with the opening of its new testing laboratory in Ft. George G. Meade, MD. This activity is crucial to ensuring that public health pesticides remain effective after they are on the market. Outreach and cooperative interagency activities are also expanding, especially in preventing food borne infections and preventing hospital-acquired infections. These illnesses each cost the United States billions of dollars annually in direct and indirect medical costs. The EPA is participating in several interagency food safety activities, and is increasing its contacts with industry and consumer associations, as well as with FDA and USDA. To enhance its role in preventing hospital-acquired infections, EPA is also working closely with health and user groups, state and local organizations, and OSHA and FDA. There are numerous variables and issues which effect the registration of antimicrobial products, and the EPA must constantly balance them in accordance with its primary mission of protecting human health and the environment. This article has provided a broad summary of some of the regulatory and scientific requirements, challenges and highlights of registering disinfectants, sanitizers and sterilants with the EPA. However, because the antimicrobials market is a fast moving and highly competitive arena with new technologies and issues constantly developing, new policies and procedures are often on the horizon. Therefore, for more information, individuals should refer to the referenced material for complete and current information on policy, procedures and requirements.
Aim: To provide a practical action plan for effective infection control of norovirus outbreak in acute paediatric wards.Methods: We report the infection control measures that were implemented to terminate and to prevent nosocomial spread of norovirus gastroenteritis in an open-designed paediatric ward.Results: Nine children, one visitor, and one medical student were affected in a norovirus gastroenteritis outbreak in an acute paediatric ward. Vomiting was the main presenting symptom. The outbreak was rapidly terminated three days after implementation of stringent infection control measures and there was no second wave of attack. These measures included strict contact precautions, prompt isolation and cohorting of symptomatic patients, vigorous environmental cleansing with concentrated disinfectant (hypochlorite solution 1000 ppm), meticulous handling of waste products, and efficient contact tracing of exposed patients, family members, and medical students.Conclusion: Prompt implementation of stringent infection control measures and contact tracing can rapidly terminate the norovirus outbreak and prevent a second wave of infection. Children with unexplained vomiting and those with contact history of gastroenteritis should be properly triaged, isolated, and investigated for possible infective causes, including norovirus-induced gastroenteritis.
Outbreaks of viral diarrhoea are common in hospitals, particularly in the geriatric and children's wards. Person-to-person spread is the most frequent mode of transmission of infection. Establishment of alerting mechanisms, liaison with laboratories with electron microscopy facilities for making the diagnosis, isolation of patients, use of appropriate disinfectants and maintaining good lines of communication are all important for successful control of these outbreaks.
There is mounting concern regarding the efficacy of many germicides on the market because officially recognized germicidal tests for various classes of microorganisms vary widely and often lack reproducibility and proper quantitation. We report here a carrier method for simultaneously and quantitatively assessing the efficacy of liquid chemical germicides against a mixture of microorganisms of varying degrees of resistance. In the test, each small glass cup (10 mm wide x 14 mm long) was contaminated with 10 microliters of a standardized mixture of Staphylococcus aureus, Mycobacterium bovis bacille Calmette-Guérin, Trichophyton mentagrophytes spores, Sabin poliovirus type 1, and Bacillus stearothermophilus spores in 5% fetal bovine serum. The inoculum was dried for 60 minutes under ambient conditions and covered with 60 microliters of the disinfectant under test or a balanced salt solution control for the desired contact time. The carrier was then placed in 2940 microliters of an eluent and the eluates assayed separately for the five microorganisms. Tap water was used to dilute the test product as needed. Of the 11 products tested, 2% alkaline glutaraldehyde, 0.6% sodium hypochlorite (about 5000 ppm free chlorine), and a 0.4% quarternary ammonium compound containing 23% hydrochloric acid were effective against all five challenge organisms. A hard-surface spray containing 0.1% o-phenylphenol with 79% ethanol was effective against all but bacterial spores; 70% (volume/volume) ethanol alone and povidone-iodine (1% available iodine) were effective against S. aureus, the mycobacterium, and the fungus; a 3% solution of peroxygen compounds was effective only against S. aureus and the poliovirus; 1.5% chlorhexidine gluconate, 0.06% quaternary ammonia compound, and 0.03% o-phenylphenol + 0.03% p-tertiary amylphenol could inactivate nothing but S. aureus; and 3% hydrogen peroxide was ineffective in all tests. This method shows promise for use with various classes of microorganisms, individually or as mixtures. Its application should enable the classification of germicides according to spectrum of activity.
The health-care facility environment is rarely implicated in disease transmission, except among patients who are immunocompromised. Nonetheless, inadvertent exposures to environmental pathogens (e.g., Aspergillus spp. and Legionella spp.) or airborne pathogens (e.g., Mycobacterium tuberculosis and varicella-zoster virus) can result in adverse patient outcomes and cause illness among health-care workers. Environmental infection-control strategies and engineering controls can effectively prevent these infections. The incidence of health-care--associated infections and pseudo-outbreaks can be minimized by 1) appropriate use of cleaners and disinfectants; 2) appropriate maintenance of medical equipment (e.g., automated endoscope reprocessors or hydrotherapy equipment); 3) adherence to water-quality standards for hemodialysis, and to ventilation standards for specialized care environments (e.g., airborne infection isolation rooms, protective environments, or operating rooms); and 4) prompt management of water intrusion into the facility. Routine environmental sampling is not usually advised, except for water quality determinations in hemodialysis settings and other situations where sampling is directed by epidemiologic principles, and results can be applied directly to infection-control decisions. This report reviews previous guidelines and strategies for preventing environment-associated infections in health-care facilities and offers recommendations. These include 1) evidence-based recommendations supported by studies; 2) requirements of federal agencies (e.g., Food and Drug Administration, U.S. Environmental Protection Agency, U.S. Department of Labor, Occupational Safety and Health Administration, and U.S. Department of Justice); 3) guidelines and standards from building and equipment professional organizations (e.g., American Institute of Architects, Association for the Advancement of Medical Instrumentation, and American Society of Heating, Refrigeration, and Air-Conditioning Engineers); 4) recommendations derived from scientific theory or rationale; and 5) experienced opinions based upon infection-control and engineering practices. The report also suggests a series of performance measurements as a means to evaluate infection-control efforts.
Suspension tests for virucidal activity of chemical germicides are easier to perform, but they normally do not present the test product with a strong enough challenge. In contrast, carrier tests, where the test virus is dried on an animate or inanimate surface, offer the test formulation a higher level of challenge because it first has to penetrate successfully the inoculum to gain access to and inactivate the target organism on the carrier. Since pathogens in nature are normally found adsorbed to surfaces and/or embedded in organic or cellular debris, the results of carrier tests are more relevant to predicting the activity of chemical germicides under field situations. The method described below uses discs (1 cm in diameter) of brushed stainless steel discs as carriers. Ten micro l of the test virus in a soil load is placed on each disc and the inoculum dried under ambient conditions. The dried inoculum is then exposed to 50 micro l of the test formulation or a control solution for a defined contact time at the specified temperature. EBSS (0.95 ml) is added to each carrier holder to dilute/neutralize the germicide, the inoculum eluted and the eluates titrated in cell cultures to determine the degree of loss in virus viability. At least five test and three control carriers are used in each test. Controls are also included to test for toxicity of the test formulation to the host cells and any interference sub-cytotoxic levels of the formulation may have on the ability of the virus to infect the cells. The method has been used with several types of human and animal pathogenic viruses to test the activity of all major classes of chemical germicides against them.
The preparation of a cholesterol adsorption column and its application to the study of virus-lipid interactions are described. A number of viruses were found to adsorb strongly to the cholesterol, whereas the accompanying protein impurities passed through the column without adsorption. Of the viruses tested, namely, influenza, Newcastle disease, vaccinia, coliphages, and poliovirus, only poliovirus failed to adsorb.The saturation of cholesterol columns with influenza virus was found to have the kinetics characteristic of chromatographic and ion exchange adsorption columns. The adsorption was independent of ionic environment and temperature.The presence of active virus on the cholesterol was demonstrated by (a) recovery of hemagglutinin after ether-water partitioning, (b) infectivity determinations, or (c) antigenicity measurements.Suspensions of cholesterol-adsorbed influenza virus produced higher antibody titers in chicks than equal amounts of aqueous virus. This was ascribed to the adjuvant effect of cholesterol.Virus adsorbed to cholesterol particles was capable of combining with specific antibodies.
EXCERPT Along with proper hand hygiene, disinfection of contaminated surfaces and medical instruments has been a key method of preventing patient‐to‐environment‐to‐patient transmission of infectious agents via the hands of healthcare workers.1‐3 However, there is growing concern regarding the increase in antibiotic‐resistant pathogens for which environmental and device contamination may play a role in disease transmission, such as methicillin‐resistant Staphylococcus aureus (MRSA), vancomycin‐resistant Enterococcus (VRE), Clostridium difficile, and multidrugresistant aerobic gram‐negative bacilli (eg, Pseudomonas aeruginosa and Acinetobacter).1 Proper use of disinfectants plays an important role in reducing person‐to‐person transmission of these pathogens.