The distribution of West Nile virus (WNV) is dependent on the occurrence of both susceptible avian reservoir hosts and competent mosquito vectors. Both factors can be influenced by geographic variables such as land use/landcover, elevation, human population density, physiographic region, and temperature. The current study uses geographic information systems (GIS) and logistic regression analyses to model the distribution of WNV in the state of Georgia based on a wild bird indicator system, and to identify human and environmental predictor variables that are important in the determination of WNV distribution. A database for Georgia was constructed that included (1) location points of all the avian samples tested for WNV, (2) local land use classifications, including temperature, physiographic divisions, land use/landcover, and elevation, (3) human demographic data from the U.S. Census, and (4) statistics summarizing land cover, elevation, and climate within a 1-km-radius landscape around each sample point. Logistic regression analysis was carried out using the serostatus of avian collection sites as the dependent variable. Temperature, housing density, urban/suburban land use, and mountain physiographic region were important variables in predicting the distribution of WNV in the state of Georgia. While weak, the positive correlation between WNV-antibody positive sites and the urban/suburban environment was consistent throughout the study period. The risks associated with WNV endemicity appear to be increased in urban/ suburban areas and decreased in the mountainous region of the state. This information may be used in addressing regional public health needs and mosquito control programs.

Urbanization is a widespread phenomenon that is likely to influence the prevalence and impact of wildlife pathogens, with implications for wildlife management and public health policies toward zoonotic pathogens. In this study, wild songbird populations were sampled at 14 sites along an urban rural gradient in the greater metropolitan Atlanta (Georgia, USA) area and tested for antibodies to West Nile virus (WNV). The level of urbanization among sites was quantitatively assessed using a principal component analysis of key land use characteristics. In total, 499 individual birds were tested during the spring and summer over three years (2004-2006). Antibody prevalence of WNV increased from rural to urban sites, and this trend was stronger among adult birds relative to juveniles. Furthermore, antibody prevalence among Northern Cardinals (Cardinalis cardinalis) was significantly higher than in other songbird species along the urban gradient. Findings reported here indicate that ecological factors associated with urbanization can influence infection patterns of this vector-borne viral disease, with likely mechanisms including changes in host species diversity and the tolerance or recovery of infected animals.

Prior to the emergence of the A/goose/Guangdong/1/1996 (Gs/GD) H5N1 influenza A virus, the long‐held and well‐supported paradigm was that highly pathogenic avian influenza (HPAI) outbreaks were restricted to poultry, the result of cross‐species transmission of precursor viruses from wild aquatic birds that subsequently gained pathogenicity in domestic birds. Therefore, management agencies typically adopted a prevention, control, and eradication strategy that included strict biosecurity for domestic bird production, isolation of infected and exposed flocks, and prompt depopulation. In most cases, this strategy has proved sufficient for eradicating HPAI. Since 2002, this paradigm has been challenged with many detections of viral descendants of the Gs/GD lineage among wild birds, most of which have been associated with sporadic mortality events. Since the emergence and evolution of the genetically distinct clade 2.3.4.4 Gs/GD lineage HPAI viruses in approximately 2010, there have been further increases in the occurrence of HPAI in wild birds and geographic spread through migratory bird movement. A prominent example is the introduction of clade 2.3.4.4 Gs/GD HPAI viruses from East Asia to North America via migratory birds in autumn 2014 that ultimately led to the largest outbreak of HPAI in the history of the United States. Given the apparent maintenance of Gs/GD lineage HPAI viruses in a global avian reservoir; bidirectional virus exchange between wild and domestic birds facilitating the continued adaptation of Gs/GD HPAI viruses in wild bird hosts; the current frequency of HPAI outbreaks in wild birds globally, and particularly in Eurasia where Gs/GD HPAI viruses may now be enzootic; and ongoing dispersal of AI viruses from East Asia to North America via migratory birds, HPAI now represents an emerging disease threat to North American wildlife. This recent paradigm shift implies that management of HPAI in domestic birds alone may no longer be sufficient to eradicate HPAI viruses from a given country or region. Rather, agencies managing wild birds and their habitats may consider the development or adoption of mitigation strategies to minimize introductions to poultry, to reduce negative impacts on wild bird populations, and to diminish adverse effects to stakeholders using wildlife resources. The main objective of this review is, therefore, to provide information that will assist wildlife managers in developing mitigation strategies or approaches for dealing with outbreaks of Gs/GD HPAI in wild birds in the form of preparedness, surveillance, research, communications, and targeted management actions. Resultant outbreak response plans and actions may represent meaningful steps of wildlife managers toward the use of collaborative and multi‐jurisdictional One Health approaches when it comes to the detection, investigation, and mitigation of emerging viruses at the human‐domestic animal‐wildlife interface.

Wild caught rock pigeons (Columba livia) with antibodies to West Nile virus were monitored for 15 months to determine antibody persistence and compare results of three serologic techniques. Antibodies persisted for the entire study as detected by epitope-blocking enzyme-linked immunosorbent assay and plaque reduction neutralization test. Maternal antibodies in squabs derived from seropositive birds persisted for an average of 27 days.West Nile virus (WNV) (Flaviviridae family, Flavivirus genus) is maintained in a bird-mosquito transmission cycle, and wild bird surveillance has proven effective in tracking the spread of this virus in North America. Since extensive avian mortality has been associated with WNV infection in North America, much of this surveillance has concentrated on deadbird testing (16). As demonstrated with other arboviruses, such as St. Louis encephalitis virus (SLEV), eastern equine encephalitis virus, and western equine encephalitis virus, serologic testing of birds represents another tool for further investigating WNV epidemiology (7,8,14).The duration of the antibody response, test performance, and persistence of maternal antibodies can complicate interpretation of serologic results. Information on the persistence of antibodies to WNV in avian species is currently limited. Experimentally, persistence of neutralizing antibodies to the North American strain of WNV in rock pigeons (Columba livia) was demonstrated over a 9-week period postinoculation and in chickens over a 28-day period postinoculation (9, 11). Pigeons inoculated with an African strain of WNV maintained antibodies for 16 months (12). Recaptured naturally infected wild birds in South Africa with initial WNV antibody titers of Ͼ40 lost demonstrable antibody by hemagglutination inhibition (HAI) in as few as 3 weeks (13).The objectives of this study were the following: (i) to determine the long-term persistence of antibodies to WNV in naturally infected rock pigeons, (ii) to compare the long-term utility of commonly used WNV serologic techniques (plaque reduction neutralization test [PRNT], HAI, and epitope-blocking enzyme-linked immunosorbent assay [ELISA]), and (iii) to determine the persistence of maternal antibodies to WNV in squabs derived from these naturally infected birds.Thirty rock pigeons, 20 seropositive for WNV and 10 negative controls, were captured in April 2003 in Atlanta, Georgia. All birds were banded and housed in a mosquito-free facility for 60 weeks. Venipuncture was performed on each bird upon entry and at 3-week intervals by wing vein. Serum samples were stored at Ϫ70°C.Using WNV (Georgia isolate DES-107-01) and SLEV (strain TBH-28), PRNTs were performed following standard protocols (1, 10). Titers were expressed as the reciprocal of serum dilutions reducing the number of plaques Ͼ90% (PRNT 90 ). Samples with PRNT 90 titers to WNV which were fourfold greater than titers to SLEV were considered seropositive for WNV. HAI assays were performed at the Florida Department of Health using a published protocol (5). Th...