Influenza A Viruses in Peridomestic Mammals

During recent years, serological evidence has shown that a number of peridomestic mammals (e.g., those commonly found in or around human structures) are naturally exposed to influenza A viruses (IAVs). In addition, experimental studies have demonstrated that many of these species can successfully replicate several different IAVs, including IAVs of high consequence to public or agricultural health. The replication of some IAVs within this group of mammals could have implications for biosecurity associated with poultry production and live bird markets in some regions of the world. Given this evidence, the need for further study and understanding of the role that peridomestic mammals may play in IAV dynamics is increasingly being recognized. This chapter will provide a general overview on IAV associations in peridomestic mammals, especially as they pertain to avian IAVs, and provide some general views and guidelines for sampling these species in various situations

Strength in numbers: Avian influenza A virus transmission to poultry from a flocking passerine

The effects of flock size of European starlings (Sturnus vulgaris) was experimentally manipulated to assess the potential of influenza A virus (IAV; H4N6) transmission from a flocking passerine to bobwhite quail (Colinus virginianus) through shared food and water resources to mimic starling intrusions into free-range and backyard poultry operations. Of the three starling flock sizes tested (n = 30, n = 20 and n = 10), all successfully transmitted the virus to all or most of the quail in each animal room (6/6, 6/6 and 5/6) by the end of the experimental period, as determined by seroconversion and/or viral RNAshedding. Although starlings have been shown to be inconsistent shedders of IAVs andwhen they do replicate and subsequently shed virus they typically do so at low to moderate levels, this study has provided evidence that relatively small flocks (i.e., 10 or possibly a smaller number) of this species can collectively transmit the virus to a highly susceptible gallinaceous bird species. Future work should assess if starlings can transmit IAVs to additional poultry species commonly found in backyard or free-range settings

Effects of freshwater crayfish on influenza A virus persistence in water

Several investigations have recently assessed the ability of some aquatic invertebrates to act as tools for avian influenza A virus (IAV) surveillance as well as their potential role(s) in IAV ecology. Because of this, as well as the high IAV seroprevalence rates noted in select mesocarnivores that commonly inhabit aquatic and semi-aquatic habitats, we evaluated the effects that freshwater crayfish have on IAV in water at three dose levels and monitored for the presence of IAV in crayfish tissues (gill and green gland) and haemolymph at multiple time points. At relatively high, medium 432 and low (approximately 10 , 10 and 10 EID50/ml, respectively) doses, mesocosms containing crayfish (Orconectes sp.) had less detectable IAV RNA present when final water samples were assayed (9 days post-contact [DPC]). In general, containers without crayfish present had nearly three-fold greater quantities of viral RNA at 9 DPC. A varying number of RNA positive samples were detected for the three crayfish sample types collected. Gill tissue produced the largest number of positive non-water samples (n = 26), with the highest quantities detected from crayfish sampled on 1 and 4 DPC (103.5 EID50 equivalent/ml). On a few occasions, gill (n = 8) and haemolymph samples (n = 1) produced higher quantities of viral RNA than their respective water samples or water samples collected 1–2 DPC earlier, but these differences were typically minor. Based upon water samples, statistical models indicated that the interaction of dose and crayfish exposure days explained most of the variation in these data. Future efforts should address if crayfish exposed to IAV-laden water have the capacity to successfully transmit IAVs to mammals and birds which frequently prey upon them

Inventory of wildlife use of mortality pits as feeding sites: implications of pathogen exposure

To better understand the use of mortality pits by wildlife and possible pathogen dissemination from the resulting wildlife contact in these areas, we used 8 camera traps on 4 mortality pits in Colorado from June to December 2014 to create a species inventory and establish use estimates for those species. We observed 43 species visiting (in or near) the mortality pits during 1,168 total camera trap days. Of these, 24 species directly interacted with the mortality pits or carcasses contained within them. The most common visitors to mortality pits were raccoons (Procyon lotor), coyotes (Canis latrans), domestic dogs (Canis lupus familiaris), mule deer (Odocoileus hemionus), bald eagles (Haliaeetus leucocephalus), blackbilled magpies (Pica hudsonia), corvid species (i.e., American crows [Corvus brachyrhynchos] or common ravens [Corvus corax]), great blue herons (Ardea herodias), house sparrows (Passer domesticus), and turkey vultures (Cathartes aura). Mammals were often solitary visitors to mortality pits, while birds often visited mortality pits in mixed flocks of 2 to 5 species, putting them at a higher risk of interspecific pathogen spread. Our findings indicate that many animals come into direct and indirect contact with interspecific and conspecific species at mortality pits

Low viral doses are sufficient to infect cottontail rabbits with avian influenza A virus

Influenza A viruses (IAVs) have been reported in wild lagomorphs in environments where they share resources with waterfowl. Recent studies have conclusively shown that a North American lagomorph, cottontail rabbits (Sylvilagus sp.), become infected following exposure to IAVs and can shed significant quantities of virus. However, the minimum infectious dose and the efficiency of various routes of infection have not been evaluated. Thirty-six cottontail rabbits were used in a dose response study assessing both the oral and nasal routes of infection. The nasal route of infection proved to be the most efficient, as all cottontail rabbits shed viral RNA following inoculation with doses as low as 102 EID50. The oral route of infection was less efficient, but still produced infection rates of ≥ 50% at relatively low doses (i.e., 103 and 104 EID50). These results suggest that cottontail rabbits are highly susceptible to IAVs at low exposure doses that have been routinely observed in environments contaminated by waterfowl. Furthermore, this study supports earlier observations that cottontail rabbits may pose a biosecurity risk to poultry operations, as a virus-contaminated water source or contaminated environment, even at low viral titers, could be sufficient to initiate viral replication in cottontail rabbits

Effects of Deepwater Horizon oil on feather structure and thermoregulation in gulls: Does rehabilitation work?

Impacts of large-scale oil spills on avian species are far-reaching.While media attention often focuses on lethal impacts, sub-lethal effects and the impacts of rehabilitation receive less attention. The objective of our study was to characterize effects of moderate external oiling and subsequent rehabilitation on feather structure and thermoregulation in gulls. We captured 30 wild ring-billed gulls (Larus delawarensis) and randomly assigned each individual to an experimental group: 1) controls, 2) rehabilitated birds (externally oiled, rehabilitated by washing), or 3) oiled birds (externally oiled, not rehabilitated). We externally oiled birds with weathered MC252 Deepwater Horizon oil (water for controls) and collected feathers and thermography imagery (FLIR) approximately weekly for four weeks to investigate feather structure (quantified using a barbule clumping index) and thermoregulatory ability (characterized by internal body temperature and external surface temperature). Post-oiling feather clumping was significantly higher in oiled and rehabilitated birds compared to controls, but steadily declined over time in both groups. However, feather microstructure in rehabilitated birds was indistinguishable from controls within three weeks of washing whereas the feathers of oiled birds were still significantly clumped a month post oiling. Internal body temperatures didn\u27t differ in any of the groups, suggesting birds maintain thermoregulatory homeostasis in spite of moderate external oiling. External temperatures for rehabilitated birds didn\u27t differ from controls within a week of rehabilitation. Overall, rehabilitation procedures were effective and washed birds were in better condition compared to non-rehabilitated, oiled birds. This study provides evidence that the benefits of rehabilitation for moderately oiled birds likely outweigh the costs with regard to feather structure and thermoregulation.While feather preening and time were insufficient to reestablish baseline fine scale feather structure in moderately oiled birds, the significant clumping reduction over time may indicate that rehabilitation of lightly oiled birds may not be necessary and deserves further study

Shedding Light on Avian Influenza H4N6 Infection in Mallards: Modes of Transmission and Implications for Surveillance

Background: Wild mallards (Anas platyrhychos) are considered one of the primary reservoir species for avian influenza viruses (AIV). Because AIV circulating in wild birds pose an indirect threat to agriculture and human health, understanding the ecology of AIV and developing risk assessments and surveillance systems for prevention of disease is critical. Methodology/Principal Findings: In this study, mallards were experimentally infected with an H4N6 subtype of AIV by oral inoculation or contact with an H4N6 contaminated water source. Cloacal swabs, oropharyngeal swabs, fecal samples, and water samples were collected daily and tested by real-time RT-PCR (RRT-PCR) for estimation of viral shedding. Fecal samples had significantly higher virus concentrations than oropharyngeal or cloacal swabs and 6 month old ducks shed significantly more viral RNA than 3 month old ducks regardless of sample type. Use of a water source contaminated by AIV infected mallards, was sufficient to transmit virus to naïve mallards, which shed AIV at higher or similar levels as orally-inoculated ducks. Conclusions: Bodies of water could serve as a transmission pathway for AIV in waterfowl. For AIV surveillance purposes, water samples and fecal samples appear to be excellent alternatives or additions to cloacal and oropharyngeal swabbing. Furthermore, duck age (even within hatch-year birds) may be important when interpreting viral shedding results from experimental infections or surveillance. Differential shedding among hatch-year mallards could affect prevalence estimates, modeling of AIV spread, and subsequent risk assessments

Validation of a screening method for the detection of colistin-resistant \u3ci\u3eE. coli\u3c/i\u3e containing mcr-1 in feral swine feces

A method was developed and validated for the detection of colistin-resistant Escherichia coli containing mcr-1 in the feces of feral swine. Following optimization of an enrichment method using EC broth supplemented with colistin (1 μg/mL) and vancomycin (8 μg/mL), aliquots derived from 100 feral swine fecal samples were spiked with of one of five different mcr-1 positive E. coli strains (between 100 and 104 CFU/g), for a total of 1110 samples tested. Enrichments were then screened using a simple boil-prep and a previously developed real-time PCR assay for mcr-1 detection. The sensitivity of the method was determined in swine feces, with mcr-1 E. coli inocula of 0.1–9.99 CFU/g (n=340), 10–49.99 CFU/g (n=170), 50–99 CFU/g (n=255), 100–149 CFU/g (n=60), and 200–2200 CFU/g (n=175), which were detected with 32%, 72%, 88%, 95%, and 98% accuracy, respectively. Uninoculated controls (n = 100) were negative for mcr-1 following enrichment

Influenza A virus surveillance, infection and antibody persistence in snow geese (Anser caerulescens)

Some snow geese (Anser caerulescens) migrate between Eurasia and North America and exhibit high seroprevalence for influenza A viruses (IAVs). Hence, these birds might be expected to play a role in intercontinental dispersal of IAVs. Our objective in this manuscript was to characterize basic incidence and infection characteristics for snow geese to assess whether these birds are likely to significantly contribute to circulation of IAVs. Thus, we 1) estimated snow goose infection prevalence by summarizing \u3e 5,000 snow goose surveillance records, 2) experimentally infected snow geese with a low pathogenic IAV (H4N6) to assess susceptibility and infection dynamics and 3) characterized long-term antibody kinetics. Infection prevalence based on surveillance data for snow geese was 7.88%, higher than the infection rates found in other common North American goose species. In the experimental infection study, only 4 of 7 snow geese shed viral RNA. Shedding in infected birds peaked at moderate levels (mean peak 102.62 EID50 equivalents/mL) and was exclusively associated with the oral cavity. Serological testing across a year post-exposure showed all inoculated birds seroconverted regardless of detectable shedding. Antibody levels peaked at 10 days post-exposure and then waned to undetectable levels by 6 months. In sum, while broad-scale surveillance results showed comparatively high infection prevalence, the experimental infection study showed only moderate susceptibility and shedding. Consequently, additional work is needed to assess whether snow geese might exhibit higher levels of susceptibility and shedding rates when exposed to other IAV strains

DNA Persistence in Predator Saliva from Multiple Species and Methods for Optimal Recovery from Depredated Carcasses

Molecular forensics is an important component of wildlife research and management. Using DNA from noninvasive samples collected at predation sites, we can identify predator species and obtain individual genotypes, improving our understanding of predator–prey dynamics and impacts of predators on livestock and endangered species. To improve sample collection strategies, we tested two sample collection methods and estimated degradation rates of predator DNA on the carcasses of multiple prey species. We fed carcasses of calves (Bos taurus) and lambs (Ovis aires) to three captive predator species: wolves (Canis lupus), coyotes (C. latrans), and mountain lions (Puma concolor). We swabbed the carcass in the field, as well as removed a piece of hide from the carcasses and then swabbed it in the laboratory. We swabbed all tissue samples through time and attempted to identify the predator involved in the depredation using salivary DNA. We found the most successful approach for yielding viable salivary DNA was removing hide from the prey and swabbing it in the laboratory. As expected, genotyping error increased through time and our ability to obtain complete genotypes decreased over time, the latter falling below 50% after 24 h. We provide guidelines for sampling salivary DNA from tissues of depredated carcasses for maximum probability of detection