See other World News Articles
Title: Coronavirus could survive outside the body for 28 DAYS!
Source:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2863430/
URL Source: https://www.investmentwatchblog.com ... -outside-the-body-for-28-days/
Published: Jan 29, 2020
Author: Mike Rivero
Post Date: 2020-01-29 23:16:10 by Horse
Keywords: None
Views: 281
Comments: 12
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°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°C than at 4°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°C than at 20°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. Environmental surfaces have been recognized as likely contributors to the transmission of nosocomial viral infections (25). The question of whether hospital surfaces play a role in the spread of nosocomial viral infection took on particular urgency during the worldwide outbreak of severe acute respiratory syndrome (SARS). SARS was a novel coronavirus infection, and local and institutional outbreaks were driven in part by nosocomial spread; cases of SARS were documented in health care workers, patients, and visitors in health care facilities (20). During outbreaks in health care facilities, surface sampling for SARS coronavirus (SARS-CoV) revealed SARS-CoV nucleic acids on surfaces and inanimate objects (6, 10). This suggests that surfaces could be sources of virus transmission. Assessment of the risk posed by SARS-CoV on surfaces requires data on the survival of the virus on environmental surfaces and data on how this survival is affected by environmental variables, such as air temperature (AT) and relative humidity (RH). Because working with SARS-CoV requires specially trained personnel working under biosafety level 3 (BSL-3) laboratory containment conditions, there are significant challenges in studying this virus, and only limited data on its survival and response to environmental stressors are available. The use of surrogate coronaviruses has the potential to overcome these challenges and expand the available data on coronavirus survival on surfaces. In addition to SARS-CoV, there are two pathogenic human coronaviruses that are adapted to propagation and assay in cell culture, 229E and OC43, which could serve as surrogates for SARS-CoV in survival studies. However, previous studies suggested that the survival of 229E and OC43 on surfaces may be shorter than that of SARS-CoV (10, 35). To evaluate surrogates that might serve as more conservative models of SARS-CoV on surfaces, animal coronaviruses were chosen as surrogates for this study. Because SARS-CoV does not fall clearly into either of the two groups of mammalian coronaviruses, the following two potential surrogates representing the two groups were evaluated: transmissible gastroenteritis virus (TGEV), a diarrheal pathogen of swine and a member of coronavirus group 1, and mouse hepatitis virus (MHV), a respiratory and enteric pathogen of laboratory mice and a member of coronavirus group 2 (16). The advantages of using these two viruses as surrogates are the fact that they can be readily propagated and assayed in cell culture systems and the fact that there is no human infection risk. There has been some study of TGEV survival in aerosols (17), but the data on the environmental survival of this potential coronavirus surrogate for SARS-CoV are limited. The use of surrogates for studying the environmental survival of SARS-CoV can increase our understanding of the survival and persistence of this virus on environmental surfaces, the possible role of such surfaces in the transmission of SARS-CoV and other coronaviruses, and the risk posed by contaminated surfaces in outbreak settings. Therefore, this work was undertaken to determine the effect of AT and RH on the survival of the surrogate coronaviruses TGEV and MHV on hard nonporous surfaces. Go to: Survival experiments. SARS-CoV is excreted in body fluids, such as respiratory secretions and feces, that have high levels of protein and other biological organic matter. It is likely that virus deposited on health care surfaces is embedded in such proteinaceous, biological organic matter matrices. To simulate deposition and survival in such matrices, viral inocula were suspended in cell culture medium (which contained proteins, other organic biomolecules, physiological salts, and other constituents and resembled human secretions) and placed on test surfaces. The test surfaces were carriers that were 1-cm2 thin stainless steel coupons with a no. 4 polish. The carriers were prepared by washing them in 0.01% Tween 80, followed by one rinse with 70% ethanol, one rinse with distilled water, and autoclaving. For survival tests, 10 ¼l containing 104 to 105 MPN of test viruses was inoculated onto three replicate carriers per time point and placed in a controlled RH environment. Control carriers (time zero) were kept at each AT and RH until they were dry and were sampled immediately after drying. The exception was the carrier incubated at 40°C and 80% RH. Under these conditions, virus inactivation took place within a few hours. Consequently, the carriers were sampled beginning at 2 h after inoculation, when the virus inoculum was still wet. Sampling intervals were chosen after preliminary experiments to assess the maximum length of virus survival were performed. At 4°C and all RH values and at 20°C and 20% RH, carriers were sampled at 7-day intervals for up to 28 days. At 20°C and 50% RH or 80% RH, carriers were sampled at 24-h intervals until virus was no longer detectable. At 40°C, carriers were sampled at 2-h intervals until virus was not detectable. Based on virus recovery experiments, 1.5% beef extract (pH 7.5) was used to elute viruses from carriers (data not shown). At desired time points, carriers were removed, placed in a 24-well plate, and covered with 1 ml beef extract. Viruses were eluted by agitation on a shaking platform (60 rpm) for 20 min at room temperature. Eluted samples were diluted in cell culture medium, and virus infectivity was assayed using the appropriate host cell line. Three replicate carriers were assayed per time point. The virus survival at each time point was expressed as log10(Nt/N0), where Nt is the virus concentration (in MPN/ml) at time t and N0 is the initial virus concentration (in MPN/ml) in the control sample at time zero. Statistical analysis. The statistical analysis was done using SAS (SAS Corp., Cary, NC) and GraphPad Prism 5 (GraphPad, San Diego, CA). The parameter log10(Nt/N0) versus time was used to perform a regression analysis for each virus and AT-RH condition. At the level of an individual measurement of log10 inactivation for each day, linear regression was conducted to determine the slope of the inactivation line. Slopes were also determined by linear regression using the mean log10 reduction value for each time point (3 replicates per point). Analysis of covariance (ANCOVA) was used to assess the effects of AT, RH, time, and virus type on viral inactivation at the level of each individual measurement. The ANCOVA model is Yijk = ¼0 + (¼1 + ±i + ²j + ³k)t + [ijk., where Yijk is log10 inactivation and the variables in the model are as follows: ±i is the virus (TGEV or MHV; i = 1 or 2), ²j is temperature (4°, 20°, and 40°C; j = 1, 2, or 3), ³k is RH (20%, 50%, and 80% RH; k = 1, 2, or 3), and t is the number of days exposed to each condition. ANCOVA was also used to determine if there was an interaction between AT and RH as a predictors of virus survival. This adds an interaction term, ´jk, to the model described above for effects on log10 inactivation. Using this term allowed evaluation of whether the coefficient days depends on the interaction between AT and RH, as well as each of the AT-RH conditions. Go to: RESULTS Inactivation of TGEV and MHV over time was measured for nine combinations of AT and RH. The survival of TGEV and MHV at 4°C and three RH levels is shown in Fig. Fig.1.1. At 4°C, infectious virus deposited on stainless steel surfaces at initial levels of 4 to 5 log10 MPN persisted for as long as 28 days, and the lowest level of inactivation over the 28-day experiment took place at 20% RH. There was a decrease in the observed log10 inactivation rate at 20% and 50% RH from day 21 to day 28. To better simulate the physical state in which viruses in patient secretions are deposited onto surfaces, viruses were not dispersed before inoculation. Therefore, possible clumping and aggregation effects may have resulted in variation in the physical state of the viral inocula on individual carriers, possibly contributing to the variations in the rates of reduction observed. With the exception of the 20% RH model, every linear regression model was statistically significant (P < 0.05) (the coefficient of the linear model was not equal to zero). The slopes of regression lines for TGEV and MHV inactivation at 4°C and each RH are shown in Table Table1.1. The levels of both viruses declined by <0.5 log10 over 28 days at 20% RH. Greater reduction took place at 50% RH, at which the levels of both viruses declined by ∼3.5 log10 after 21 days. At 80% RH, the TGEV level declined by 3.2 log10 over 28 days, and the MHV level declined by 2.5 log10. Poster Comment: Skip the science Mumbo Jumbo. Passenger planes returning from China need to be scrubbed down.
Post Comment Private Reply Ignore Thread
Top • Page Up • Full Thread • Page Down • Bottom/Latest
Begin Trace Mode for Comment # 1.
#1. To: Horse (#0)
Pretty much means that face masks will help very little, as any viruses that might be blocked by the facemask will remain on the face mask for a month. So if it's reused and handled and all that, then a contaminated mask will end up infecting it's owner.
#2. To: Pinguinite (#1)
Already has been published that you need goggles to protect your eyes. Chinese researchers found a ten year-old boy who had 5 relatives with the Wuhan virus. He was symptom free but had the virus and can carry it and infect others.
========= Already has been published that you need goggles to protect your eyes. you need goggles and then you need to know how to take them off and sterilize them and all that, too, so you don't spread the infection as for those face masks, I saw them being neatly padded and folded IN CHINA WITH BARE HANDS. Crazy. How do we know those people weren't contagious and passing it on through the NEW masks. Mike Adams says they are only meant to help keep the sick ones from spreading their germs through sneezing, coughing, etc., anyway.
These might help..
Top • Page Up • Full Thread • Page Down • Bottom/LatestCoronavirus could survive outside the body for 28 DAYS!
Replies to Comment # 1.
#3. To: Pinguinite, Horse (#1)
Pretty much means that face masks will help very little, as any viruses that might be blocked by the facemask will remain on the face mask for a month. So if it's reused and handled and all that, then a contaminated mask will end up infecting it's owner.
#12. To: Pinguinite (#1)
End Trace Mode for Comment # 1.