Natural and Experimental Persistence of Highly Pathogenic H5 Influenza Viruses in Slurry of Domestic Ducks, with or without Lime Treatment

Assessing infectivity of emerging enveloped viruses in wastewater and sewage sludge: Relevance and procedures

The emergence of SARS-CoV-2 has heightened the need to evaluate the detection of enveloped viruses in the environment, particularly in wastewater, within the context of wastewater-based epidemiology. The studies published over the past 80 years focused primarily on non-enveloped viruses due to their ability to survive longer in environmental matrices such as wastewater or sludge compared to enveloped viruses. However, different enveloped viruses survive in the environment for different lengths of time. Therefore, it is crucial to be prepared to assess the potential infectious risk that may arise from future emerging enveloped viruses. This will require appropriate tools, notably suitable viral concentration methods that do not compromise virus infectivity. This review has a dual purpose: first, to gather all the available literature on the survival of infectious enveloped viruses, specifically at different pH and temperature conditions, and in contact with detergents; second, to select suitable concentration methods for evaluating the infectivity of these viruses in wastewater and sludge. The methodology used in this data collection review followed the systematic approach outlined in the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines. Concentration methods cited in the data gathered are more tailored towards detecting the enveloped viruses' genome. There is a lack of suitable methods for detecting infectious enveloped viruses in wastewater and sludge. Ultrafiltration, ultracentrifugation, and polyethylene glycol precipitation methods, under specific/defined conditions, appear to be relevant approaches. Further studies are necessary to validate reliable concentration methods for detecting infectious enveloped viruses. The choice of culture system is also crucial for detection sensitivity. The data also show that the survival of infectious enveloped viruses, though lower than that of non-enveloped ones, may enable environmental transmission. Experimental data on a wide range of enveloped viruses is required due to the variability in virus persistence in the environment.

Avian Influenza outbreaks: Human infection risks for beach users - One health concern and environmental surveillance implications

Despite its popularity for water activities, such as swimming, surfing, fishing, and rafting, inland and coastal bathing areas occasionally experience outbreaks of highly pathogenic avian influenza virus (HPAI), including A(H5N1) clade 2.3.4.4b. Asymptomatic infections and symptomatic outbreaks often impact many aquatic birds, which increase chances of spill-over events to mammals and pose concerns for public health. This review examined the existing literature to assess avian influenza virus (AIV) transmission risks to beachgoers and the general population. A comprehensive understanding of factors governing such crossing of the AIV host range is currently lacking. There is limited knowledge on key factors affecting risk, such as species-specific interactions with host cells (including binding, entry, and replication via viral proteins hemagglutinin, neuraminidase, nucleoprotein, and polymerase basic protein 2), overcoming host restrictions, and innate immune response. AIV efficiently transmits between birds and to some extent between marine scavenger mammals in aquatic environments via consumption of infected birds. However, the current literature lacks evidence of zoonotic AIV transmission via contact with the aquatic environment or consumption of contaminated water. The zoonotic transmission risk of the circulating A(H5N1) clade 2.3.4.4b virus to the general population and beachgoers is currently low. Nevertheless, it is recommended to avoid direct contact with sick or dead birds and to refrain from bathing in locations where mass bird mortalities are reported. Increasing reports of AIVs spilling over to non-human mammals have raised valid concerns about possible virus mutations that lead to crossing the species barrier and subsequent risk of human infections and outbreaks.

Stability of the Virucidal Activity of Commercial Disinfectants against Avian Influenza Viruses under Different Environmental Conditions

Highly pathogenic avian influenza viruses (HPAIVs) have caused outbreaks in both domestic and wild birds during the winter seasons in several countries in the Northern Hemisphere, most likely because virus-infected wild ducks overwinter and serve as the primary source of infection for other birds in these countries. Several chemical disinfectants are available to deactivate these viruses outside a living organism. However, their virucidal activity is known to be compromised by various factors, including temperature and contamination with organic matter. Hence, the effectiveness of virucidal activity under winter field conditions is crucial for managing HPAIV outbreaks. To investigate the impact of the winter field conditions on the virucidal activity of disinfectants against AIVs, we assessed the stability of the virucidal activity of seven representative disinfectants that are commercially available for poultry farms in Japan against both LPAIVs and HPAIVs under cold and/or organic contamination conditions. Of the seven disinfectants examined, the ortho-dichlorobenzene/cresol-based disinfectant exhibited the most consistent virucidal activity under winter field conditions, regardless of the virus pathogenicity or subtype tested.

Estimation of alkali dosage and contact time for treating human excreta containing viruses as an emergency response: a systematic review

Water, sanitation, and hygiene provisions are essential during emergencies to prevent infectious disease outbreaks caused by improper human excreta management in settlements for people affected by natural disasters and conflicts. Human excreta disinfection is required when long-term containment in latrines is not feasible on-site. Alkali additives, including lime, are effective disinfectants for wastewater and faecal sludge containing large amounts of solid and dissolved organic matter. The aim of this study was to determine the minimum dose and contact time of alkali additives for treating virus-containing human excreta in emergency situations. We used literature data collected by searching Google Scholar and Web of Science. The date of the last search for each study was 31th May 2023. Only peer-reviewed articles that included disinfection practices in combination with quantitative data for the physicochemical data of a matrix and viral decay were selected for data extraction. Two reviewers independently collected data from each study. We extracted datasets from 14 studies that reported quantitative information about their disinfection tests, including viral decay over time, matrix types, and physicochemical properties. Three machine learning algorithms were applied to the collected dataset to determine the time required to achieve specified levels of virus inactivation under different environmental conditions. The best model was used to estimate the contact time to achieve a 3-log10 inactivation of RNA virus in wastewater and faeces. The most important variables for predicting the contact time were pH, temperature, and virus type. The estimated contact time for 3 log inactivation of RNA virus was <2 h at pH 12, which was achieved by adding 1.8 and 3.1% slaked lime to wastewater and faeces, respectively. The contact time decreased exponentially with the pH of the sludge and wastewater. In contrast, the pH of the sludge and wastewater increased linearly with the slaked lime dosage. Lime treatment is a promising measure where long-term containment in latrine is not feasible in densely populated areas, as 1 day is sufficient to inactivate viruses. The relationship we have identified between required contact time and lime dosage is useful for practitioners in determining appropriate treatment conditions of human waste.

Treatment with Toll-like Receptor (TLR) Ligands 3 and 21 Prevents Fecal Contact Transmission of Low Pathogenic H9N2 Avian Influenza Virus (AIV) in Chickens

Transmission of H9N2 avian influenza virus (AIV) can occur in poultry by direct or indirect contact with infected individuals, aerosols, large droplets and fomites. The current study investigated the potential of H9N2 AIV transmission in chickens via a fecal route. Transmission was monitored by exposing naïve chickens to fecal material from H9N2 AIV-infected chickens (model A) and experimentally spiked feces (model B). The control chickens received H9N2 AIV. Results revealed that H9N2 AIV could persist in feces for up to 60-84 h post-exposure (PE). The H9N2 AIV titers in feces were higher at a basic to neutral pH. A higher virus shedding was observed in the exposed chickens of model B compared to model A. We further addressed the efficacy of Toll-like receptor (TLR) ligands to limit transmission in the fecal model. Administration of CpG ODN 2007 or poly(I:C) alone or in combination led to an overall decrease in the virus shedding, with enhanced expression of type I and II interferons (IFNs) and interferon-stimulating genes (ISGs) in different segments of the small intestine. Overall, the study highlighted that the H9N2 AIV can survive in feces and transmit to healthy naïve chickens. Moreover, TLR ligands could be applied to transmission studies to enhance antiviral immunity and reduce H9N2 AIV shedding.

Simultaneous Detection of SARS-CoV-2 and Influenza Virus in Wastewater of Two Cities in Southeastern Germany, January to May 2022

Dependent on the excretion pattern, wastewater monitoring of viruses can be a valuable approach to characterizing their circulation in the human population. Using polyethylene glycol precipitation and reverse transcription-quantitative PCR, the occurrence of RNA of SARS-CoV-2 and influenza viruses A/B in the raw wastewater of two treatment plants in Germany between January and May 2022 was investigated. Due to the relatively high incidence in both exposal areas (plant 1 and plant 2), SARS-CoV-2-specific RNA was determined in all 273 composite samples analyzed (concentration of E gene: 1.3 × 10⁴ to 3.2 × 10⁶ gc/L). Despite a nation-wide low number of confirmed infections, influenza virus A was demonstrated in 5.2% (concentration: 9.8 × 10² to 8.4 × 10⁴ gc/L; plant 1) and in 41.6% (3.6 × 10³ to 3.0 × 10⁵ gc/L; plant 2) of samples. Influenza virus B was detected in 36.0% (7.2 × 10² to 8.5 × 10⁶ gc/L; plant 1) and 57.7% (9.6 × 10³ to 2.1 × 10⁷ gc/L; plant 2) of wastewater samples. The results of the study demonstrate the frequent detection of two primary respiratory viruses in wastewater and offer the possibility to track the epidemiology of influenza by wastewater-based monitoring.

Efficacy of Liming Forest Soil in the Context of African Swine Fever Virus

Since September 2020, Germany has experienced the first ever outbreak of African swine fever (ASF). The first known cases occurred exclusively in wild boar in forest areas in Brandenburg and Saxony; in July 2021, infected domestic pigs were also confirmed for the first time. As wild boar are considered the main reservoir for the virus in the European region, an effective interruption of this infection chain is essential. In particular, the removal and safe disposal of infected carcasses and the direct disinfection of contaminated, unpaved ground are priorities in this regard. For the disinfection, highly potent as well as environmentally compatible disinfectants must be used, which are neither influenced in their effectiveness by the soil condition nor by increased organic contamination. Thus, in this study, slaked lime, milk of lime and quicklime (1% to 10% solutions) were selected for efficacy testing against the test virus recommended by the German Veterinary Society (DVG), Modified Vaccinia Ankara virus (MVAV), and ASF virus (ASFV) in conjunction with six different forest soils from Saxony in two different soil layers (top soil and mineral soil) each. In summary, 10% of any tested lime type is able to inactivate both MVAV and ASFV under conditions of high organic load and independent of the water content of the soil. At least a 4 log reduction of the virus titer in all tested forest soil types and layers and by all applied lime types was observed. In conclusion, the high efficacy and suitability of all tested lime products against both viruses and in the presence of high organic load in forest soil can be confirmed and will help to control ASF spread.

Avian Influenza in Wild Birds and Poultry: Dissemination Pathways, Monitoring Methods, and Virus Ecology

Avian influenza is one of the largest known threats to domestic poultry. Influenza outbreaks on poultry farms typically lead to the complete slaughter of the entire domestic bird population, causing severe economic losses worldwide. Moreover, there are highly pathogenic avian influenza (HPAI) strains that are able to infect the swine or human population in addition to their primary avian host and, as such, have the potential of being a global zoonotic and pandemic threat. Migratory birds, especially waterfowl, are a natural reservoir of the avian influenza virus; they carry and exchange different virus strains along their migration routes, leading to antigenic drift and antigenic shift, which results in the emergence of novel HPAI viruses. This requires monitoring over time and in different locations to allow for the upkeep of relevant knowledge on avian influenza virus evolution and the prevention of novel epizootic and epidemic outbreaks. In this review, we assess the role of migratory birds in the spread and introduction of influenza strains on a global level, based on recent data. Our analysis sheds light on the details of viral dissemination linked to avian migration, the viral exchange between migratory waterfowl and domestic poultry, virus ecology in general, and viral evolution as a process tightly linked to bird migration. We also provide insight into methods used to detect and quantify avian influenza in the wild. This review may be beneficial for the influenza research community and may pave the way to novel strategies of avian influenza and HPAI zoonosis outbreak monitoring and prevention.

Serological Evidence of Backyard Pig Exposure to Highly Pathogenic Avian Influenza H5N8 Virus during 2016-2017 Epizootic in France

In autumn/winter 2016-2017, HPAI-H5N8 viruses belonging to the A/goose/Guandong/1/1996 (Gs/Gd) lineage, clade 2.3.4.4b, were responsible for outbreaks in domestic poultry in Europe, and veterinarians were requested to reinforce surveillance of pigs bred in HPAI-H5Nx confirmed mixed herds. In this context, ten pig herds were visited in southwestern France from December 2016 to May 2017 and serological analyses for influenza A virus (IAV) infections were carried out by ELISA and hemagglutination inhibition assays. In one herd, one backyard pig was shown to have produced antibodies directed against a virus bearing a H5 from clade 2.3.4.4b, suggesting it would have been infected naturally after close contact with HPAI-H5N8 contaminated domestic ducks. Whereas pigs and other mammals, including humans, may have limited sensitivity to HPAI-H5 clade 2.3.4.4b, this information recalls the importance of implementing appropriate biosecurity measures in pig and poultry farms to avoid IAV interspecies transmission, a prerequisite for co-infections and subsequent emergence of new viral genotypes whose impact on both animal and human health cannot be predicted.