Chapter 5 Threats
Ranaviruses are associated with diseases in wild and cultured fishes, amphibians, and reptiles (Robert et al. 2007; Gray et al. 2007) . They are reported to be most lethal to amphibian larvae with mortality rates as high as 90% or more (Harp and Petranka 2006; Gray et al. 2007) . In the United States, there is a high risk of exposure for wild populations to the ranavirus Frog Virus 3 (FV3). Host reservoirs for FV3 include exotic species such as African Clawed Frogs ( Xenopus laevis ), which are commonly raised in captivity for the pet trade and sold across the United States, where they are released into the wild (intentionally or accidentally) (Robert et al. 2007) . The Regina ranavirus is highly infectious and can be virulent to Caudata (urodela) amphibians such as the common Tiger Salamander, likely because they lack natural antimicrobial peptides associated with the more evolved immunosystems of other amphibian taxa (Froese et al. 2005; Sheafor et al. 2008) . Ranaviruses present at aquaculture facilities can be two to 10 times more lethal than wild strains and can pose a particular risk to frogs in the Ranidae family, thereby contributing to their population declines (Hickling 2011) . 5.13.2 Birds – Anticipated Impacts According to the NWHC, avian vacuolar myelinopathy (AVM) is a recently discovered neurological disease affecting waterbirds, primarily Bald Eagles and American Coots, in the southern United States. AVM has also been confirmed as the cause of death in Mallards, Buffleheads, Ring-necked Ducks, Canada Geese, Killdeer, and a Great Horned Owl. Birds affected with AVM lack muscle coordination and therefore have difficulty flying and swimming. The cause of the disease is unknown but has been linked through the food chain from plants to waterfowl to predators. A cyanobacterium is possibly the root cause. West Nile Virus (WNV) can infect a number of animals, including humans, horses, and birds. It was first documented in the United States in 1999 and has spread throughout North America. Birds do not normally show any symptoms of WNV infection but serve as natural reservoirs of the virus. However, some avian species, such as crows, appear to be susceptible to the virus. WNV was first documented in raptors in the summer of 2002. Since that time, this disease has been diagnosed in Bald Eagles in South Carolina as well as other states. There is some evidence that WNV has spread globally in part through transmission by migratory birds introducing the virus to other wildlife and humans (Rappole and Huba´lek 2003; Verhagen et al. 2014) . Avian influenza (bird flu) is a disease caused by any one of several influenza subtypes that can affect birds because they are a host reservoir (Alexander 2000; Kilpatrick et al. 2006; Olsen et al. 2006; Munster et al. 2007; Dugan et al. 2008; Verhagen et al. 2014) . Research has documented a high prevalence for infection in migratory ducks, geese, and swans (order Anseriformes) and in gulls, terns, and shorebirds (order Characdriiformes) (Webster et al. 1992; Alexander 2000; Olsen et al. 2006; Munster et al. 2007) . The prevalence for infection to occur during fall migration may occur because of the large number of birds that occur in concentrated areas and because there are a higher number of immunologically susceptible young of the year in the population (Webster et al. 1992; Hinshaw et al. 1985; Sharp et al. 1993; Munster et al. 2007) . Surveillance to detect the disease and monitoring infected
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2025 NC Wildlife Action Plan
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