Ebola Virus Stability on Surfaces and in Fluids in Simulated Outbreak Environments

Emerging sexually transmitted viral infections: 1. Review of Ebola virus disease

This is the first in a series of articles reviewing four viral infections, Ebola virus, Zika virus, human T-cell lymphotropic virus, type 1 and hepatitis C virus, with an emphasis on recent advances in our understanding of their sexual transmission. With current day speed and ease of travel it is important for staff in sexual healthcare services to know and understand these infections when patients present to them and also to be able to advise those travelling to endemic regions. Following the recent resurgence in West Africa, this first article looks at Ebola virus disease (EVD). EVD has a high mortality rate and, of note, has been detected in the semen of those who have cleared the virus from their blood and have clinically recovered from the disease. As the result of emerging data, the WHO now recommends safe sex practices for all male survivors of EVD for 12 months after the onset of the disease or after having had two consecutive negative tests of semen specimens for the virus. This review provides an up-to-date summary of what is currently known about EVD and its implications for sexual health practice.

Censored Regression Modeling To Predict Virus Inactivation in Wastewaters

Among the many uncertainties presented by poorly studied pathogens is possible transmission via human fecal material or wastewaters. Such worries were a documented concern during the 2013 Ebola outbreak in West Africa. Using published experimental data on virus inactivation rates in wastewater and similar matrices, we extracted data to construct a model predicting the T90 (1 × log₁₀ inactivation measured in seconds) of a virus. Extracted data were as follows: RNA or DNA genome, enveloped or not, primary transmission pathway, temperature, pH, light levels, and matrix. From the primary details, we further determined matrix level of contamination, genus, and taxonomic family. Prior to model construction, three records were separated for verification. A censored normal regression model provided the best fit model, which predicted T90 from DNA or RNA structure, enveloped status, whether primary transmission pathway was fecal-oral, temperature, and whether contamination was low, medium, or high. Model residuals and predicted values were evaluated against observed values. Mean values of model predictions were compared to independent data and considering 95% confidence ranges (which could be quite large). A relatively simple model can predict virus inactivation rates from virus and matrix attributes, providing valuable input when formulating risk management strategies for little studied pathogens.

Disinfection of Ebola Virus in Sterilized Municipal Wastewater

Concerns have been raised regarding handling of Ebola virus contaminated wastewater, as well as the adequacy of proposed disinfection approaches. In the current study, we investigate the inactivation of Ebola virus in sterilized domestic wastewater utilizing sodium hypochlorite addition and pH adjustment. No viral inactivation was observed in the one-hour tests without sodium hypochlorite addition or pH adjustment. No virus was recovered after 20 seconds (i.e. 4.2 log10 unit inactivation to detection limit) following the addition of 5 and 10 mg L-1 sodium hypochlorite, which resulted in immediate free chlorine residuals of 0.52 and 1.11 mg L-1, respectively. The addition of 1 mg L-1 sodium hypochlorite resulted in an immediate free chlorine residual of 0.16 mg L-1, which inactivated 3.5 log10 units of Ebola virus in 20 seconds. Further inactivation was not evident due to the rapid consumption of the chlorine residual. Elevating the pH to 11.2 was found to significantly increase viral decay over ambient conditions. These results indicate the high susceptibility of the enveloped Ebola virus to disinfection in the presence of free chlorine in municipal wastewater; however, we caution that extension to more complex matrices (e.g. bodily fluids) will require additional verification.

Ebola Preparedness: Diagnosis Improvement Using Rapid Approaches for Proficiency Testing

The unprecedented 2015 Ebolavirus (EBOV) outbreak in West Africa was declared a public health emergency, making diagnosis and quality of testing a global issue. The accuracy of laboratory diagnostic capacity for EBOV was assessed in 2014 to 2016 using a proficiency testing (PT) strategy developed by the Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) in Biosecurity. Following a literature search, EBOV-specific gene targets were ranked according to the frequency of their use in published methods. The most commonly used gene regions (nucleoprotein [NP], glycoprotein [GP], and RNA-dependent RNA polymerase [L]) were selected for the design of in vitro RNA transcripts to be included in the simulated EBOV specimens used for EBOV detection with PCR-based assays. Specimens were tested for stability and found to be stable on long-term storage (1 year) at -80°C and on shorter-term storage in lyophilized form (1 week at ambient temperature and a subsequent week at -80°C). These specimens were used in three EBOV PTs offered from April 2014 to March 2016. In the first and third PTs, all laboratories (3/3 and 9/9, respectively) correctly identified specimens containing EBOV RNA transcripts, while in the second PT, all but one laboratory (5/6) correctly confirmed the presence of EBOV. The EBOV PT panel was useful for ensuring the competency of laboratories in detecting EBOV in the absence of readily available clinical samples. The simulated EBOV specimen was safe, stable, and reliable and can be used in lyophilized form for future EBOV PT programs, allowing simplicity of transport.

The Disinfection Characteristics of Ebola Virus Outbreak Variants

The recent Ebola virus outbreak in West Africa has forced experts to re-evaluate their understanding of how to best disinfect areas contaminated with infectious bodily fluids. Recent research has found that Ebola virus remains viable in blood for 7–10 days making appropriate disinfection crucial to infection control. We sought to determine if the three most important outbreak variants of Zaire ebolavirus (Mayinga, Kikwit and Makona) exhibit separate phenotypes when challenged with a range of sodium hypochlorite (NaOCl) concentrations or 70% ethanol (EtOH) at average West African temperature. The time dependent killing of Ebola virus was evaluated by measuring infectious virus and viral RNA (vRNA), to determine if RNA detection is a viable method for decontamination measurement in areas without high containment laboratory access. Makona was less susceptible to weaker concentrations of NaOCl (0.05 and 0.1%) than Mayinga and Kikwit. At the recommended concentration of NaOCl (≥0.5%) all of the variants were inert after 5 minutes of contact time. Similarly, all variants were inactivated by 70% EtOH after 2.5 minutes, only Makona was detected at 1 minute. In multiple instances, high amounts of vRNA was detected in the absence of infectious virus, suggesting that it does not serve as an accurate measure of remaining infectivity after cleansing.

Decontamination of a field laboratory dedicated to Ebola virus-infected patients

In 2015, the French Armed Forces deployed a biosafety level 3 (BSL3) field laboratory as a part of an Ebola treatment center in Guinea. When closing the center, laboratory decontamination operations were necessary. We present the decontamination protocols applied for the BSL3 field laboratory, making the entire module ready for a future use.

Survival and disinfection of an enveloped surrogate virus on Tyvek suits used for health care personal protective equipment

The survival and disinfection of bacteriophage Φ6, an enveloped surrogate virus, was evaluated on Tyvek suits used as health care personal protective equipment. After 6 hours there was 2-log₁₀ inactivation of virus on Tyvek suits at both 40% and 60% relative humidity. Both hypochlorite and quaternary ammonium produced a >3.21- and >4.33-log₁₀ reduction of the virus, respectively, after 1-minute contact time. Enveloped viruses can survive on Tyvek suits beyond the length of a single patient care encounter, but they can be inactivated by chemical disinfectants.

Ebola Virus Shedding and Transmission: Review of Current Evidence

BACKGROUND

The magnitude of the 2013-2016 Ebola virus disease outbreak in West Africa was unprecedented, with >28 500 reported cases and >11 000 deaths. Understanding the key elements of Ebola virus transmission is necessary to implement adequate infection prevention and control measures to protect healthcare workers and halt transmission in the community.

METHODS

We performed an extensive PubMed literature review encompassing the period from discovery of Ebola virus, in 1976, until 1 June 2016 to evaluate the evidence on modes of Ebola virus shedding and transmission.

FINDINGS

Ebola virus has been isolated by cell culture from blood, saliva, urine, aqueous humor, semen, and breast milk from infected or convalescent patients. Ebola virus RNA has been noted in the following body fluids days or months after onset of illness: saliva (22 days), conjunctiva/tears (28 days), stool (29 days), vaginal fluid (33 days), sweat (44 days), urine (64 days), amniotic fluid (38 days), aqueous humor (101 days), cerebrospinal fluid (9 months), breast milk (16 months [preliminary data]), and semen (18 months). Nevertheless, the only documented cases of secondary transmission from recovered patients have been through sexual transmission. We did not find strong evidence supporting respiratory or fomite-associated transmission.

Ebola Virus Persistence in Semen Ex Vivo

On March 20, 2015, a case of Ebola virus disease was identified in Liberia that most likely was transmitted through sexual contact. We assessed the efficiency of detecting Ebola virus in semen samples by molecular diagnostics and the stability of Ebola virus in ex vivo semen under simulated tropical conditions.

Ebola Virus RNA Stability in Human Blood and Urine in West Africa's Environmental Conditions

We evaluated RNA stability of Ebola virus in EDTA blood and urine samples collected from infected patients and stored in West Africa's environmental conditions. In blood, RNA was stable for at least 18 days when initial cycle threshold values were <30, but in urine, RNA degradation occurred more quickly.

Ebola virus and arthropods: a literature review and entomological consideration on the vector role

Ebola virus is a pathogen responsible for a severe disease that affects humans and several animal species. To date, the natural reservoir of this virus is not known with certainty, although it is believed that fruit bats (Chiroptera: Pteropodidae) play an important role in maintaining the virus in nature. Although information on viral transmission from animals to humans is not clear, the role of arthropods has come under suspicion. In this article, we review the potential role of arthropods in spreading Ebola virus, acting as mechanical or biological vectors.

Comparison of the Aerosol Stability of 2 Strains of Zaire ebolavirus From the 1976 and 2013 Outbreaks

The largest outbreak of Ebola virus disease began in Guéckédou, Guinea, West Africa, in December 2013 and rapidly spread to major population centers in 3 West African countries. Early reports in some scientific and public media speculated that the virus had evolved to more effectively transmit between humans. One route of transmission postulated was aerosol transmission, although there was little epidemiological evidence to support this claim. This study investigates the viability of 2 Zaire ebolavirus strains within aerosols at 22°C and 80% relative humidity over time. The results presented here indicate that there is no difference in virus stability between the 2 strains and that viable virus can be recovered from an aerosol 180 minutes after it is generated.

Effectiveness of Four Disinfectants against Ebola Virus on Different Materials

The West Africa Ebola virus (EBOV) outbreak has highlighted the need for effective disinfectants capable of reducing viral load in a range of sample types, equipment and settings. Although chlorine-based products are widely used, they can also be damaging to equipment or apparatus that needs continuous use such as aircraft use for transportation of infected people. Two aircraft cleaning solutions were assessed alongside two common laboratory disinfectants in a contact kill assay with EBOV on two aircraft relevant materials representative of a porous and non-porous surface. A decimal log reduction of viral titre of 4 is required for a disinfectant to be deemed effective and two of the disinfectants fulfilled this criteria under the conditions tested. One product, Ardrox 6092, was found to perform similarly to sodium hypochlorite, but as it does not have the corrosive properties of sodium hypochlorite, it could be an alternative disinfectant solution to be used for decontamination of EBOV on sensitive apparatus.

Bloodborne Viral Pathogen Contamination in the Era of Laboratory Automation

BACKGROUND

The CDC states that laboratory testing for persons under investigation for Ebola virus disease can be safely performed using automated laboratory instruments by adhering to bloodborne pathogen practices. We therefore sought to investigate the levels of viral contamination of a total laboratory automation (TLA) system to guide risk mitigation strategies for handling infectious agents.

METHODS

Environmental swabs followed by PCR for hepatitis B (HBV) and hepatitis C (HCV) viruses were taken from a chemistry TLA system during routine clinical use and after running a small number of high-titer HCV samples. Control experiments were performed to ensure the recovery of DNA and RNA viruses by swabs from a representative nonporous surface.

RESULTS

Of 79 baseline swabs for nucleic acids performed on the TLA system, 10 were positive for HBV and 8 for HCV. Viral nucleic acid was consistently detected from swabs taken from the distal inside surface of the decapper discharge chute, with areas adjacent to the decapper instrument and the centrifuge rotor also positive for HBV or HCV nucleic acid. Contamination was occasionally detected on exposed surfaces in areas without protective barriers between samples and personnel. After running known HCV-positive samples, at least one additional site of contamination was detected on an exposed area of the line.

CONCLUSIONS

A low level of viral contamination of automated clinical laboratory equipment occurs in clinical use. Given the risks associated with highly infectious agents, there is a need for risk-mitigation procedures when handling all samples.

Broad and Temperature Independent Replication Potential of Filoviruses on Cells Derived From Old and New World Bat Species

Filoviruses are strongly associated with several species of bats as their natural reservoirs. In this study, we determined the replication potential of all filovirus species: Marburg marburgvirus, Taï Forest ebolavirus, Reston ebolavirus, Sudan ebolavirus, Zaire ebolavirus, and Bundibugyo ebolavirus. Filovirus replication was supported by all cell lines derived from 6 Old and New World bat species: the hammer-headed fruit bat, Buettikofer's epauletted fruit bat, the Egyptian fruit bat, the Jamaican fruit bat, the Mexican free-tailed bat and the big brown bat. In addition, we showed that Marburg virus Angola and Ebola virus Makona-WPGC07 efficiently replicated at 37°C, 37°-41°C, or 41°C, contrary to the hypothesis that temporal elevation in temperature due to flight affects filovirus replication in bats.

Ebola Virus Stability Under Hospital and Environmental Conditions

The West African outbreak of Ebola virus (EBOV) is largely contained, but sporadic new cases continue to emerge. To assess the potential contribution of fomites to human infections with EBOV, we tested EBOV stability in human blood spotted onto Sierra Leonean banknotes and in syringe needles under hospital and environmental conditions. Under some of these conditions, EBOV remained infectious for >30 days, indicating that EBOV-contaminated items may pose a serious risk to humans.

Differences in the Comparative Stability of Ebola Virus Makona-C05 and Yambuku-Mayinga in Blood

In support of the response to the 2013–2016 Ebola virus disease (EVD) outbreak in Western Africa, we investigated the persistence of Ebola virus/H.sapiens-tc/GIN/2014/Makona-C05 (EBOV/Mak-C05) on non-porous surfaces that are representative of hospitals, airplanes, and personal protective equipment. We performed persistence studies in three clinically-relevant human fluid matrices (blood, simulated vomit, and feces), and at environments representative of in-flight airline passenger cabins, environmentally-controlled hospital rooms, and open-air Ebola treatment centers in Western Africa. We also compared the surface stability of EBOV/Mak-C05 to that of the prototype Ebola virus/H.sapiens-tc/COD/1976/Yambuku-Mayinga (EBOV/Yam-May), in a subset of these conditions. We show that on inert, non-porous surfaces, EBOV decay rates are matrix- and environment-dependent. Among the clinically-relevant matrices tested, EBOV persisted longest in dried human blood, had limited viability in dried simulated vomit, and did not persist in feces. EBOV/Mak-C05 and EBOV/Yam-May decay rates in dried matrices were not significantly different. However, during the drying process in human blood, EBOV/Yam-May showed significantly greater loss in viability than EBOV/Mak-C05 under environmental conditions relevant to the outbreak region, and to a lesser extent in conditions relevant to an environmentally-controlled hospital room. This factor may contribute to increased communicability of EBOV/Mak-C05 when surfaces contaminated with dried human blood are the vector and may partially explain the magnitude of the most recent outbreak, compared to prior outbreaks. These EBOV persistence data will improve public health efforts by informing risk assessments, structure remediation decisions, and response procedures for future EVD outbreaks.

Systematic review of the literature on viral persistence and sexual transmission from recovered Ebola survivors: evidence and recommendations

OBJECTIVE

The main aim of this article is to present a comprehensive, systematic review on evidence of sexual transmission from Ebola survivors and persistence of Ebola virus in body fluids of relevance to sexual transmission, and additionally to review condom effectiveness against sexual transmission of Ebola.

DESIGN

We performed a systematic review of viral persistence in body fluids of relevance to sexual transmission of Ebola survivors and evidence of sexual transmission of Ebola, and carried out a targeted review of condom effectiveness.

RESULTS

We identified nine published original articles presenting results on persistence of Ebola virus in relevant body fluids, or reporting suspect sexual transmission from Ebola survivors. We also included unpublished reports from the current 2014/2015 Ebola epidemic in West Africa. We found no articles reporting on condom effectiveness, but have included a targeted review on general condom efficacy and effectiveness.

CONCLUSIONS

We conclude that the risk of sexual transmission from people who have recovered from Ebola cannot be ruled out. We found the longest duration of persistent Ebola RNA in a relevant body fluid from a survivor, to be reported from a man in Sierra Leone who had reverse transcriptase PCR (RT-PCR) positive semen 284 days after symptom onset. In line with current WHO recommendations. We recommend that men are offered the possibility to test their semen regularly for presence of Ebola RNA from 3 months post-symptom onset. Safe sex practices including sexual abstinence, or else condom use, are recommended by WHO until semen has tested negative twice, or in absence of testing for at least 6 months post-symptom onset. Based on evidence reviewed, we conclude that male and female latex condoms offer some protection against EBOV compared to no condom use. Survivors should be offered access to care and prevention, in order to provide them with possibilities to mitigate any risks that may occur, and efforts should be linked to destigmatising activities.

Assessment of Environmental Contamination and Environmental Decontamination Practices within an Ebola Holding Unit, Freetown, Sierra Leone

Evidence to inform decontamination practices at Ebola holding units (EHUs) and treatment centres is lacking. We conducted an audit of decontamination procedures inside Connaught Hospital EHU in Freetown, Sierra Leone, by assessing environmental swab specimens for evidence of contamination with Ebola virus by RT-PCR. Swabs were collected following discharge of Ebola Virus Disease (EVD) patients before and after routine decontamination. Prior to decontamination, Ebola virus RNA was detected within a limited area at all bedside sites tested, but not at any sites distant to the bedside. Following decontamination, few areas contained detectable Ebola virus RNA. In areas beneath the bed there was evidence of transfer of Ebola virus material during cleaning. Retraining of cleaning staff reduced evidence of environmental contamination after decontamination. Current decontamination procedures appear to be effective in eradicating persistence of viral RNA. This study supports the use of viral swabs to assess Ebola viral contamination within the clinical setting. We recommend that regular refresher training of cleaning staff and audit of environmental contamination become standard practice at all Ebola care facilities during EVD outbreaks.

Persistence of Ebola Virus in Sterilized Wastewater

In the wake of the ongoing 2014/2015 Ebola virus outbreak, significant questions regarding the appropriate handling of Ebola virus-contaminated liquid waste remain, including the persistence of Ebola virus in wastewater. To address these uncertainties, we evaluated the persistence of Ebola virus spiked in sterilized domestic sewage. The viral titer decreased approximately 99% within the first test day from an initial viral titer of 106 TCID50 mL-1; however, it could not be determined if this initial rapid decrease was due to aggregation or inactivation of the viral particles. The subsequent viral titer decrease was less rapid, and infectious Ebola virus particles persisted for all 8 days of the test. The inactivation constant (k) was determined to be -1.08 (2.1 days for a 90% viral titer decrease). Due to experimental conditions, we believe these results to be an upper bound for Ebola virus persistence in wastewater. Wastewater composition is inherently heterogeneous; subsequently, we caution that interpretation of these results should be made within a holistic assessment, including the effects of wastewater composition, dilution, and potential exposure routes within wastewater infrastructure. While it remains unknown if Ebola virus may be transmitted via wastewater, these data demonstrate a potential exposure route to infectious Ebola virus via wastewater and emphasize the value of a precautionary approach to wastewater handling in an epidemic response.