Abiotic Factors Affecting the Persistence of Avian Influenza Virus in Surface Waters of Waterfowl Habitats

Abstract

dAvian influenza (AI) virus can remain infectious in water for months, and virus-contaminated surface water is considered to be a source of infection within wild waterfowl populations. Previous work has characterized the effects of pH, salinity, and temperature on viral persistence in water, but most of that work was done with modified distilled water. The objective of this study was to identify the abiotic factors that influence the duration of AI virus persistence in natural surface water. Surface water samples were collected from 38 waterfowl habitats distributed across the United States. Samples were submitted to the U.S. Geological Survey National Water Quality Laboratory for chemical analysis and the University of Georgia for viral reduction time analysis. Samples were filtered with 0.22-m filters, and the durations of persistence of three wild-bird-derived influenza A viruses within each water sample at 10, 17, and 28°C were determined. The effects of the surface water physicochemical factors on the duration of AI viral persistence in laboratory experiments were evaluated by multivariable linear regression with robust standard errors. The duration of AI virus persistence was determined to be longest in filtered surface water with a low temperature (<17°C), a neutral-to-basic pH (7.0 to 8.5), low salinity (<0.5 ppt), and a low ammonia concentration (<0.5 mg/liter). Our results also highlighted potential strain-related variation in the stability of AI virus in surface water. These results bring us closer to being able to predict the duration of AI virus persistence in surface water of waterfowl habitats. Wild birds are considered to be the primordial reservoir for influenza A virus, with species within the orders Anseriformes and Charadriiformes having the largest and most diverse genetic pool of viruses (1, 2). Within these wild bird hosts, replication of avian influenza (AI) virus occurs primarily in the epithelial cells of the intestinal tract, and large amounts of virus are shed in feces (3, 4). The virus contaminates the surrounding aquatic environment, where it remains infectious, facilitating indirect transmission between birds (5-8). Environmental persistence of AI virus has been determined to be important for the epidemiology of the virus within wild bird populations and within aquatic habitats, and surface water is considered to be the major site of environmental contamination (9-12).The persistence of AI virus in water has been confirmed through environmental surveillance and laboratory-based investigations (6, 13-16). The temperature, pH, and salinity of the water have been identified as important determinants of the duration of persistence (8,(15)(16)(17)(18)(19). Using modified distilled water as a laboratory model, Brown et al. (16) determined that AI viruses are most stable in water with a neutral-to-basic pH (7.4 to 8.2), low salinity (Ͻ20 ppt), and a low temperature (Ͻ17°C). These general trends are supported by further laboratory investigations using natural surface water samples (8,15,1...

Occurrence of microbial indicators, pathogenic bacteria and viruses in tropical surface waters subject to contrasting land use

“…Studies have shown that a high persistence of influenza A viruses in environmental waters which can remain infectious over a long period, depending on the strain types and environmental factors (e.g. salinity, temperature, pH) (Dublineau et al, 2011;Keeler et al 2013Keeler et al , 2014Stallknecht et al, 1990;Webster et al, 1992). In this study, a high detection rate of influenza A virus was found (64.5%), which is higher than those previously reported in France (44.4%) (Deboosere et al, 2011) and Netherlands (40%) (Heijnen and Medema, 2011).…”

Viruses Associated With Foodborne Infections

“…The virus is present in the faeces of wild waterfowl, water contaminated by their faeces, domestic poultry secretions (respiratory and faeces) and aerosolised respiratory secretions from infected animals. The virion is usually very labile (Markey et al, 2013b) but it has been shown that avian influenza virus is infectious for months in low temperature water and for over a week in water at 22°C (Hinshaw et al, 1979;Markwell and Shortridge, 1982) with increased survival when water has neutral to basic pH (7.0-8.5) and low ammonia concentrations (Keeler et al, 2014). It is also stable in frozen lakes (Shoham et al, 2012), allowing maintenance in the environment and infection of waterfowl from year to year.…”

Highly pathogenic avian influenza A subtype H5N8

“…For H5N1 and H7N2 for example, it has been reported that these viruses retained their infectivity for a few days in faeces or manure kept at ambient temperature (Lu et al, 2003;Songserm et al, 2005).Tenacity, i.e. In general, avian influenza viruses are more stable with decreasing temperatures and in fresh to brackish salinities (Brown et al, 2007;Keeler et al, 2014). aerosol, water, faeces, carcass/meat) and environmental conditions (temperature, salinity, pH, protein content, among many others) (EFSA, 2008).…”