Effects of virus setting

A total of 16 studies were included for review. Studies were of low methodological quality and there was high variability in study design, setting, context and outcome measures. Nine studies evaluated the effectiveness of hand hygiene interventions or practices in preventing laboratory-confirmed or possible influenza infection in the community setting; six studies showed a significant difference, three studies did not.

Seven studies assessed the effectiveness of hand hygiene practices in preventing laboratory-confirmed or possible influenza transmission in the community setting; two studies found a significant difference and five studies did not.

The effectiveness of hand hygiene against influenza virus infection and transmission in the community setting is difficult to determine based on the available evidence. In light of its proven effectiveness in other settings, there is no compelling evidence to stop using good hand hygiene practice to reduce the risk of influenza infection and transmission in the community setting.

Hand hygiene is a commonly recommended infection prevention and control measure to reduce the risk of influenza infection and transmission in health care and community settings. Hand hygiene practices have been found to be effective in reducing infection and transmission of healthcare-associated pathogens in the health care setting 3 ; in reducing non-pathogen-specific gastrointestinal and respiratory illnesses in the community setting 4 , 5 ; and for disinfection, removal of contaminants and reduction of the incidence of hospital-acquired infections in the health care setting 3.

Less frequently studied has been the degree of protection against influenza virus infection and transmission afforded by hand hygiene practices in the community setting. An initial scoping search of the literature identified two systematic reviews that came to different conclusions.

A review of randomized controlled trials found that hand hygiene as a co-intervention with facemask use in the community setting was efficacious against laboratory-confirmed influenza infection or influenza-like illness, but hand hygiene alone was not 6. Another review of intervention trials and observational studies found evidence of a reduction in influenza infection with hand hygiene interventions in schools, but no effect on secondary transmission of influenza in households in the community that had already experienced an index case 7.

A systematic review was undertaken to identify, review and synthesize the latest evidence on the effectiveness of hand hygiene as an intervention in preventing laboratory-confirmed or possible influenza infection and transmission in the community setting. The systematic review parameters, search strategy and analysis plan were established prior to the conduct of the review. Hand hygiene was defined as handwashing, hand antisepsis and actions taken to maintain healthy hands and fingernails 8.

The search strategy Appendix 1 was developed in collaboration with a research librarian. Searches were restricted to articles published in English or French.

They were conducted in a community setting, which is defined as a non-health care, open setting without confinement and without special care for the participants e. They were observational studies that assessed hand hygiene as an exposure of interest e.

They assessed a multicomponent intervention for which hand hygiene could not be reasonably expected to exert an independent influence. They were not clinical research studies e. Study selection was completed independently by two reviewers. Reference lists of included studies and relevant secondary research articles retrieved through the search were also searched to identify relevant publications.

One reviewer KM performed data extraction and quality appraisal and a second reviewer performed validation LZ. Data were extracted on study design, population, setting, hand hygiene intervention i.

Disagreements between the two reviewers were resolved by discussion and reaching a consensus. Narrative data synthesis and analysis were planned to summarize the direction, size and statistical significance of reported effect estimates for various study-defined outcomes and to explore overall patterns in the data extracted from included studies.

If possible, meta-analyses were planned to assess the association of hand hygiene with influenza outcomes by income level of country of study, study design, setting, intervention evaluated and outcome assessed. After database searching, handsearching and removal of duplicates, records remained. After screening, records were identified for full-text review.

When all inclusion and exclusion criteria were applied, 16 studies—seven RCTs and nine observational studies—were available for review. Figure 1 summarizes the study selection process. Observational studies assessed using the Effective Public Health Practice Project Quality Assessment Tool found seven of nine observational studies as weak in quality 18 — 24 and two as moderate in quality 25 , The reviewers made a post-hoc decision to not perform a meta-analysis as the limited number of included studies were not adequate for grouping by the study characteristics of interest.

Of the seven included RCTs, six assessed the provision of hand sanitizer or soap with instructions on their use 11 — 14 , 16 , One RCT delivered an internet-based intervention educating and promoting handwashing without provision of any hand sanitizer or soap to participants None of these RCTs reported the instructions or education given to participants on handwashing or hand antisepsis in sufficient detail to compare the appropriateness of these interventions to best practices.

Of the nine included observational studies, four collected self-reported handwashing frequency 21 , 24 — Of the remaining five studies, one study dichotomized observed handwashing behaviour as observed or not observed 18 and one as frequent or infrequent These studies did not specify or report the use of handwashing criteria in estimating handwashing frequency or counting handwashing events.

Two studies assessed self-reported quality of hand hygiene practice, that is, good or poor 20 , and optimal or suboptimal 23 , and of these, one defined optimal hand hygiene practice according to published best practices Another study collected self-reported information on adoption of various non-pharmaceutical interventions, including washing hands more often and hand sanitizer use Nine studies evaluated the effectiveness of hand hygiene interventions or practices in preventing laboratory-confirmed or possible influenza infection in the community setting, including two RCTs 13 , 15 , one cohort study 25 , three case-control studies 19 , 21 , 26 and three cross-sectional studies 18 , 20 , Study findings were mixed; six of nine studies found that some form of hand hygiene intervention or practice reduced laboratory-confirmed 21 , 26 or possible 15 , 18 , 20 , 23 influenza infection, while three studies found hand hygiene to be not statistically significantly associated with a decrease in influenza infection 13 , 19 , For the two RCTs, one found a significant association between handwashing and decreased risk of influenza-like illness 15 and the other found no effect on self-reported clinically diagnosed influenza for a workplace hand sanitizer intervention For the observational studies, which relied on self-reported 20 , 21 , 23 , 25 , 26 or observed 18 , 19 hand hygiene practice, most found statistically significantly lower likelihood of possible infection 18 , 20 , 21 , 23 , The limited number of heterogeneous studies did not allow for more granular qualitative analysis of findings.

The results are summarized in Table 1. Seven studies assessed the effectiveness of hand hygiene practices in preventing laboratory-confirmed or possible influenza transmission in the community setting, including five RCTs 11 , 12 , 14 , 16 , 17 , one cohort study 22 , and one case-control study A majority of these studies assessed influenza transmission in the community setting by estimating secondary attack rates SARs at the household level e.

Five of seven studies did not find a statistically significant association between hand hygiene intervention or practice and influenza transmission 11 , 12 , 14 , 16 , An RCT found a statistically significant difference in SARs for influenza-like illness across handwashing, handwashing and facemask, and control interventions 0.

A case-control study found that handwashing at least three times per day was statistically significantly associated with reduced likelihood of household transmission of pandemic influenza A H1N1 In four of five cluster RCTs conducted at the household level, hand hygiene intervention was implemented after the identification of the index case 11 , 12 , 16 , Two of these four studies assessed a subgroup of households where the intervention was implemented within a defined period after the onset of symptoms in the index case e.

Four of five cluster RCTs did not find statistically significant differences in SARs for laboratory-confirmed or possible influenza between hand hygiene and control groups 11 , 12 , 14 , 16 and one found mixed results depending on outcome The results are summarized in Table 2. The present systematic review identified 16 studies that assessed the impact of hand hygiene intervention or practice on influenza infection or transmission in the community setting.

Two-thirds of studies suggested hand hygiene practices may help prevent influenza infection. Most studies that looked at influenza transmission, however, had non-statistically significant results. Most studies had design elements associated with the potential for bias. The studies were too heterogeneous in design for meta-analysis. Our findings were similar to the two other systematic reviews conducted on this issue despite methodological differences in study selection.

Whereas we found both positive and negative studies, the Wong et al. Warren-Gash et al. After examination of the full texts, seventeen studies met the review's eligibility criteria. Great homogeneity was observed in the findings regarding the effect of temperature and humidity on the seasonal viability and transmissibility of COVID Cold and dry conditions were potentiating factors on the spread of the virus.

Environmental isolates of bacteria with antiviral ability have been found on several occasions. These microbes are able to produce metabolites, which adversely affect viral particles, or can use the viral capsid as a nutrient source Deng and Cliver a , b ; Ward The inactivation of viruses by bacterial cultures is temperature dependent.

The lower the temperature of the mixed waste, the longer the virus is able to persist. Moreover temperature could strongly influence microbial activity, and thus influence viral persistence Deng and Cliver Ward investigated the influence of mixed-liquor suspended solids MLSS of inactivated sludge on a poliovirus 1 survival.

The first experiment was conducted in order to determine the effect of MLSS on the recovery of poliovirus after a different period of time. The second experiment was designed to find out the role of different MLSS components in virus loss. Results of these studies indicate that MLSS contain a component s which can inactivate poliovirus 1. These components were pelleted during centrifugation, destroyed by autoclaving, and removed by filtration.

Consecutively, residual activity of an MLSS supernatant fraction was also studied to confirm the absence of antiviral activity in non-living heat-sensitive material in the MLSS.

Subsequent increasing activity of this supernatant, coupled with the previous results, strongly indicates the antiviral activity of some microbial species. Deng and Cliver demonstrated the antiviral effect of several bacterial cultures from swine manure slurry and mixed septic tank effluent. These cultures were identified as Micrococcus luteus , Staphylococcus epidermidis , Bacillus sp.

A comparison of poliovirus 1 inactivation in raw mixed waste, autoclaved mixed waste, and bacterium-free filtrate of raw mixed waste demonstrated that virus inactivation is related, at least in part, to microbial activity in similar environmental conditions. Inhibition of poliovirus 1 inactivation by protease inhibitors suggested that antiviral activity of mixed waste was partially due to proteolytic enzymes produced by bacteria in wastes.

Bacteria may also produce substances that inactivate viruses by processes other than enzymatic ones, e. Pseudomonas aeruginosa can produce substances with molecular weights below Da which appear to inactivate viral particles. Substances with such low molecular weights cannot act enzymatically and they are referred to as virolytic substances Cliver and Hermann ; Deng and Cliver Deng and Cliver a studied the role of the microbial activity of animal wastes in inactivation of HAV.

Ten out of 31 bacterial isolates were able to efficiently inactivate HAV. The inactivation capacity of four of the nine culture filtrates was significantly reduced by incubation with selected protease inhibitors before the virus was added.

These inhibitors did not affect the activities of the other five culture filtrates. From a public health point of view, biofilms have been already regarded as a common cause of bacterial infections. It has also been hypothesised that produced exopolymeric substances EPS may protect biofilms from viruses, especially phage penetration Sutherland et al. Recent studies have revealed that, even in the absence of specific enzymatic reactions, viral particles are able to penetrate inside the EPS structure of mucoid biofilms.

Moreover during biofilms erosion or sloughing, protected immobilised viral particles may be released in the environment, and then contact their target host commencing the viral infectious cycle Briandet et al. Viral attachment rates to biofilms vary greatly and may depend on many factors such as the biofilm or viral characteristics size, shape, isoelectric point , and concentration of viral particles Helmi et al.

Helmi et al. Infectious viral particles were detected in the drinking water biofilm for up to 6 days after inoculation, whilst the viral genome was still detectable at day After the contact time of 1 h, concentrations of 0.

These results can be explained by the fact that MS2 is more negatively charged than other tested viruses. Due to this fact, differences or similarities between apparent attachments can be explained by variation between efficiencies of viral recovery.

Results published by Quignon et al. This hypothesis is supported by the study of Storey and Ashbolt Phages MS2 and B were recovered from biofilm in the presence of the average concentration of 0. In comparison, Duran et al. Storey and Ashbolt b compared the inactivation of two phages B and MS2 within biofilms. Results indicated that the subpopulation of approximately 0. The level of viral protection may depend on parameters such as the composition, thickness, or structure of biofilms. Various studies have suggested that biofilms may trap and accumulate virus-sized particles and produce a potential reservoir of human or bacterial pathogens.

In natural environments, biofilms are mixed microbial cultures normally consisting of predominantly prokaryotes with some eukaryotes Sutherland et al. Although virus attachments to biofilms have been observed experimentally and contamination of natural biofilms with pathogenic viruses can be very low, biofilms should be considered as a protective reservoir for pathogenic viruses, and could be responsible for numerous persistent viral infections Lacroix-Gueu et al.

Due to the importance in preventing the spread of viruses in healthcare settings and food establishments, the effect of chemical disinfectants on contaminated surfaces has been extensively studied.

Some studies demonstrated that suspension tests performed with the same disinfectants showed different virus inactivation rates, thus failing to provide a reliable indication of the extent of virus disinfection on surfaces. The activity of disinfectants is strongly related to RH and temperature Casella and Schmidt-Lorenz ; Theilen et al. Viruses without envelope are more resistant to desiccation. Biocides that have activity against both enveloped and non-enveloped viruses include chlorine- and iodine-releasing agents, peracids and ozone.

Their effectiveness depends on the nature of the virus, the surface carrier, the presence of interfering substances such as organic soil or hard water salts, and contact time. However, some cleaning products or disinfectants are ineffective against viruses, and can result in viral spread or cross-contamination of surfaces Boone and Gerba Chemical disinfection on food contact surfaces and rising food items with sanitizers is generally relied on prevention and control food-borne outbreaks.

Numerous authors have reported on the efficacy of disinfectants for the inactivation of cultivable viruses using standard suspension tests, but data for gastroenteritis viruses and HAV are lacking Seymour and Appleton This is partially due to the lack of methods for propagation of these viruses in vitro Gulati et al.

Sufficient detection of infectious viral particles in the environment is affected by several obstacles such as: virus size, the large variability amongst and within viral genera, the low concentration, the presence of substances which can interfere with analysis procedures, the limits of detection of proposed techniques, and absence of reliable controls. Therefore, appropriate sampling and sensitive detection methods are necessary to help better understanding of viral transmission routes.

It is obvious that physical properties of the surface could further reduce recovery of viral particles form surfaces. Viruses can be trapped within the matrix, especially if the surface is porous Scherer et al. Therefore, sampling and detection methods must be sensitive enough to detect low levels of viral particles. Cell culture methods are sensitive and can determine infectivity of isolated viral particles, but these methods are time consuming.

Moreover, there is a problem of interference amongst viruses, which are able to grow on the same cell line e. HAV or reovirus. Even if this cytopathic effect is evident, the identification of isolated agents requires additional techniques for confirmation of virus strain or type.

Finally, cultivation methods cannot be used for non-cell culture viruses e. For enumeration of infectious viruses it is necessary to use cell culture in a quantitative format, e. The number of infectious viruses remaining in the sample is compared with the number which was introduced, and a statistical procedure can be performed to calculate any degree of decline.

Molecular methods are an alternative which can be used for virus detection. They can be used for all types of viruses, require a short time for execution, can determine different agents in the same sample, and allow identification of non-cultivable virus.

Nevertheless, analyses may be hindered by inhibitory substances present in the environment, so there is a risk of occurrence of false negative results. Due to this fact it is necessary to implement internal amplification controls. Moreover viruses detected by these techniques are not necessary infectious.

Molecular methods can reveal nucleic acid originating from partially denatured viral particles. Thus, viral capsid is still capable of protecting nucleic acid, but the viral particle is not infectious. Therefore, the combination of molecular techniques and cell culture methods should be used for the detection of viruses Cliver ; Cook In conclusion, there is strong evidence to suggest that transmission of viruses via contaminated surfaces is a significant factor contributing to the spread of disease.

Virological monitoring of surfaces can be very useful in risk analysis to identify ways of viruses spreading, to monitor environmental pollution, and thus assess the risk of infection. Moreover detection of viral contamination of the environment allows molecular epidemiologic and phylogenetic data for virus surveillance and circulation. This study was supported by Grants No.

National Center for Biotechnology Information , U. Food Environ Virol. Published online Feb 4. Vasickova , 1 I. Pavlik , 1 M. Verani , 2 and A. Carducci 2. Zeno, Pisa, Italy Find articles by M. Zeno, Pisa, Italy Find articles by A. Author information Article notes Copyright and License information Disclaimer. Zeno, Pisa, Italy. Corresponding author. Received Nov 24; Accepted Jan This article is made available via the PMC Open Access Subset for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source.

Keywords: Pathogenic viruses, Environmental factors, Surveillance, Biofilms. Viruses Spread Via Contaminated Fomites Nearly one thousand different types of viruses are known to infect humans, whilst the most common viral illnesses are produced by enteric and respiratory viruses Barker et al. Viral Gastroenteritis and Hepatitis Viruses that infect a host organism via the gastrointestinal tract are excreted in faeces and may be also present in vomit Seymour and Appleton There are two types of viruses infecting gastrointestinal tract: Capable of primarily multiplying in the intestine.

Respiratory Infections Respiratory viral infections are a major health burden Winther et al. Factors Affecting Virus Survival on Surfaces The potential of viral spreading via contaminated surfaces depends particularly on the ability of the viruses to maintain infectivity whilst they are in the environment Boone and Gerba Open in a separate window.

Virus Characterisation and Classification The most important aspects affecting virus survival are biological factors like the presence of the envelope and virus type. Relative Humidity Effect of relative humidity RH varies within virus type.

Temperature However the degree of virus survival on surfaces is affected by temperature, it depends also on the virus type and RH.

Sunlight and UV Ultraviolet radiation is the crucial virucidal agent, which primary targets viral nucleic acid but also modifies capsid proteins. Type of Surface Several studies have compared the survival of different types of viruses on porous and non-porous surfaces. Adsorption State and Organic Matter The extent and state of virus adsorption on surfaces has an important influence on virus survival. Interaction of Pathogenic Viruses with Other Microorganisms During their Presence on Surfaces Data about the influence of other microorganisms on virus survival are contradictory.

Negative Influence of Other Microorganisms on Virus Survival One proposed mechanism of viral loss in the environment is inactivation by the direct or indirect action of microorganisms. Viruses Within Biofilms From a public health point of view, biofilms have been already regarded as a common cause of bacterial infections.

Specific Antiviral Chemicals Due to the importance in preventing the spread of viruses in healthcare settings and food establishments, the effect of chemical disinfectants on contaminated surfaces has been extensively studied. Viruses are made by hackers to make money and stuff. Its illegal. The effects that the quokkapox virus has on the host is weakening the immune system.

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