Sapro-Zoonotic Risks Posed by Wild Birds in Agricultural Landscapes

There are over 1400 catalogued human pathogens, with approximately 62% classified as zoonotic (Taylor et al., 2001). Most evidence of direct transmission of pathogens to humans involves domestic and companion animals, whereas the reservoir for most zoonoses is wildlife; yet there are relatively few well-documented cases for the direct involvement of transmission from wildlife to humans (Kruse et al., 2004). In part, this absence of evidence reflects the mobility of wildlife, the difficulty accessing relevant samples, and the smaller number of studies focused on characterizing wildlife pathogens relative to the human and veterinary literature (McDiarmid, 1969; Davis et al., 1971; Hubalek, 2004).

SCWDS Briefs: Volume 25, Number 4 (January 2010)

Table of Contents: White Nose Syndrome News CWD Found in Virginia Serosurveys of Feral Swine AI Serology in Wild Birds Chagas Disease Studies SCWDS Bont Tick Surveillance Brain Tumor in Deer Exotic Animal Imports and Public Health Loss of Two SCWDS Friends

METHODS OF CONTROLLING STARLINGS AND BLACKBIRDS

Most people have accepted the fact that all living things can be beneficial to mankind in some way or other. This is especially true of our wild birds, since they provide enjoyment and wholesome recreation for most of us, regardless of whether we live on farms or in the city. But despite the fact that wild birds are for the most part beneficial, at times individuals or populations of certain species can seriously affect man's interests. When such situations occur, some measures of relief are desirable and usually eagerly sought. This report is not intended to answer all the questions that may arise concerning problems with blackbirds and starlings; instead, it is merely a summary of measures used to protect agricultural crops from these birds.

SCWDS BRIEFS: Volume 21, Number 3 (October 2005)

H5N1 Influenza Virus in Wild Birds: A Fact Sheet Highly Pathogenic Avian Influenza Virus H5N1 and Wild Birds What are avian influenza viruses? What is a Highly Pathogenic Avian Influenza virus? What is “Bird Flu” and what is “HPAI H5N1”? What do we know about avian influenza viruses in wild birds? Do we have HPAI H5N1 in North America? Is there currently a public health risk associated with HPAI H5N1 in wild birds? Is there a domestic animal health risk associated with HPAI in wild birds? What is the possibility of HPAI H5N1 entering North America via migratory wild birds? What is the possibility of this virus being maintained in wild bird populations? Do we have surveillance for HPAI H5N1 in the United States? Additional information on HPAI can be found at these websites: The recognized geographic and species distribution of chronic wasting disease (CWD) has expanded since early September 2005 to include Hampshire County in the eastern panhandle of West Virginia National Fish and Wildlife Health Initiative Guiding Principles Eastern Equine Encephalitis (EEE) virus was isolated from seven white-tailed deer in southwestern Michigan during September 2005 During the past summer, more than 500 head of livestock in North Dakota and South Dakota were lost to one of the largest recorded anthrax outbreaks in U.S. history. Most of the losses were in cattle, but horses, bison, and farm-reared elk also were affected. Dr. John Fischer, Director of SCWDS, has received this year’s Special Recognition Award from the International Association of Fish and Wildlife Agencies (IAFWA). Dr. William Randolph Davidson is retiring in November 2005.

RELATED LAWS ON EXOTIC AND NATIVE WILD ANIMALS

This paper is submitted in an effort to acquaint the personnel of allied State agencies with related laws which control the public and private possession of live exotic and native wild animals. The need for this common knowledge of related laws by agencies with law enforcement responsibility is readily apparent when the annual number and related problems from imported or resident wild animals in California are examined. In addition to resident wild animal populations, millions of fish and thousands of mammals, birds, and reptiles enter California each year through the utilization of most methods of transportation. Most of these imported animals are exotic species from foreign lands which cannot be readily identified and pose various degrees of potential and actual threat to native wild life, agriculture, and public health if they are introduced into the wilds of this State. For the purpose of this report, a general picture of imported exotic animals is presented in an introduction, and specific animals with related laws are treated individu-ally under the headings of current laws and future regulations.

Spatial and Temporal Spread of Bovine Tuberculosis in Wild White-Tailed Deer in Michigan

In 1975, a wild white-tailed deer infected with bovine tuberculosis was shot in the northeastern Lower Peninsula, Michigan. The shooting of a second infected deer in the same area in 1994 triggered ongoing disease surveillance in the region. By 2002, bovine tuberculosis had been confirmed in 12 Michigan counties: from 449 deer; two elk; 41 non-cervid wildlife; one captive cervid facility and 28 cattle herds. We analyzed geographic spread of disease since the surveillance began and investigated factors influencing the prevalence of disease within the infected area. These analyses reveal that 78 percent of tuberculous deer came from within a 1560 km2 'core' area, within which the prevalence of apparent disease averaged 2.5 percent. Prevalence declined dramatically outside of the core and was an order of magnitude lower 30 km from its boundary. This prevalence gradient was highly significant (P<0.0001) and did not alter over the 6 year surveillance period (P= 0.98). Within the core, deer density and supplemental feeding by hunters were positively and independently correlated with tuberculosis prevalence in deer. Together, these two factors explained 55 percent of the variation in prevalence. We conclude that bovine tuberculosis was already well established in the deer population in 1994, that the infected area has not expanded significantly since that time, and that deer over-abundance and food supplementation have both contributed to ongoing transmission of disease. Managers are currently enforcing prohibitions on deer feeding in the core and are working to lower deer numbers there through increased hunting pressure.

Wild Boar and Red Deer Display High Prevalences of Tuberculosis-Like Lesions in Spain

We describe the distribution of tuberculosis-like lesions (TBL) in wild boar (Sus scrofa) and red deer (Cervus elaphus) in Spain. Animals with TBL were confirmed in 84.21% of mixed populations (n = 57) of red deer and wild boar and in 75% of populations of wild boar alone (n = 8) in central and southern Spain (core area). The prevalence of TBL declined towards the periphery of this region. In the core area, the prevalence ranged up to 100% in local populations of wild boar (mean estate prevalence 42.51%) and up to 50% in red deer (mean estate prevalence 13.70%). We carried out exploratory statistical analyses to describe the epidemiology of TBL in both species throughout the core area. Prevalence of TBL increased with age in both species. Wild boar and red deer mean TBL prevalence at the estate level were positively associated, and lesion scores were consistently higher in wild boars than in red deer. The wild boar prevalence of TBL in wild boar did not differ between populations that were or were not cohabiting with red deer. Amongst the wild boars with TBL, 61.19% presented generalized lesions, and the proportion of generalized cases was similar between sex and age classes. In red deer, 57.14% of TBL-positive individuals presented generalized lesions, and the percentage of generalized cases increased with age class, but did not differ between the sexes. These results highlight the potential importance of wild boar and red deer in the maintenance of tuberculosis in south central Spain.

Risk Factors Associated With the Prevalence of Tuberculosis-Like Lesions in Fenced Wild Boar and Red Deer in South Central Spain

In recent decades the management of large game mammals has become increasingly intensive in south central Spain (SCS), resulting in complex epidemiological scenarios for disease maintenance, and has probably impeded schemes to eradicate tuberculosis (TB) in domestic livestock. We conducted an analysis of risk factors which investigated associations between the pattern of tuberculosis-like lesions (TBL) in wild boar (Sus scrofa) and red deer (Cervus elaphus) across 19 hunting estates from SCS and an extensive set of variables related to game management, land use and habitat structure. The aggregation of wild boar at artificial watering sites was significantly associated with an increasing risk of detecting TBL in both species, which probably relates to enhanced opportunities for transmission. Aggregation of wild boar at feeding sites was also associated with increased risks of TBL in red deer. Hardwood Quercus spp. forest availability was marginally associated with an increased risk of TB in both species, whereas scrubland cover was associated with a reduced individual risk of TBL in the wild boar. It is concluded that management practices that encourage the aggregation of hosts, and some characteristics of Mediterranean habitats could increase the frequency and probability of both direct and indirect transmission of TB. These findings are of concern for both veterinary and public health authorities, and reveal tuberculosis itself as a potential limiting factor for the development and sustainability of such intensive game management systems in Spanish Mediterranean habitats.

Monitoring of Transmission of Tuberculosis between Wild Boars and Cattle: Genotypical Analysis of Strains by Molecular Epidemiology Techniques

An epidemiological survey for the monitoring of bovine tuberculosis transmission was carried out in western Liguria, a region in northern Italy. Fifteen Mycobacterium bovis strains were isolated from 63 wild boar samples (62 from mandibular lymph nodes and 1 from a liver specimen). Sixteen mediastinal lymph nodes of 16 head of cattle were collected, and 15 Mycobacterium bovis strains were subsequently cultured. All M. bovisstrains isolated from cattle and wild boars were genotyped by spoligotyping and by restriction fragment length polymorphism (RFLP) analysis with the IS6110 and IS1081 probes. All M. bovis strains showed the typical spoligotype characterized by the absence of the 39 to 43 spacers in comparison with the number in M. tuberculosis. A total of nine different clusters were identified by spoligotyping. The largest cluster included 9 strains isolated from wild boars and 11 strains isolated from cattle, thus confirming the possibility of transmission between the two animal species. Fingerprinting by RFLP analysis with the IS6110 probe showed an identical single-band pattern for 29 of 30 strains analyzed, and only 1 strain presented a five-band pattern. The use of IS1081 as a second probe was useful for differentiation of M. bovis from M. bovis BCG but not for differentiation among M. bovis strains, which presented the same undifferentiated genomic profile. In relation to the epidemiological investigation, we hypothesized that the feeding in pastures contaminated by cattle discharges could represent the most probable route of transmission of M. bovis between the two animal species. In conclusion, our results confirmed the higher discriminatory power of spoligotyping in relation to that of RFLP analysis for the differentiation of M. bovis genomic profiles. Our data showed the presence of a common M. bovis genotype in both cattle and wild boars, confirming the possible interspecies transmission of M. bovis.

Book Review of Birds of the Great Plains by Bob Jennings, Ted T. Cable, and Roger Burrows

Though intended as a field guide to the birds of the Great Plains, this book seems to serve best as a general introduction to Great Plains birds and will mostly benefit those casually interested in birds. The definition of Great Plains the book uses is rather broad, and some species are included that, in my opinion, aren't really birds of the Great Plains. For example, several warblers are included as breeding species although they nest within the book's definition of the region only in the conifer or mixed forest of north-central to northwestern Minnesota, which isn't really a part of the Great Plains proper.

Dogs Gone Wild: Feral Dog Damage in the United States

Feral dogs have been documented in all 50 states and estimates of damage in the U.S. from these animals amount to >$620 million annually. In Texas alone, it is estimated that over $5 million in damage to livestock annually can be attributed to feral dogs. We reviewed national statistics on feral dog damage reported to USDA, APHIS, Wildlife Services for a 10-year period from 1997 through 2006. Damage by feral dogs crossed multiple resource categories (e.g., agriculture, natural resources); some examples of damage include killing and affecting the behavior and habitat use of native wildlife; killing and maiming livestock; and their role as disease vectors to wildlife, domestic animals, and humans. We review the role of dog damage in the U.S., synthesize the amount of damage between resource categories (agriculture, human health and safety, disease, and natural resources), and report trends in dog damage during the 10-year period. Results showed an increase in dog damage across all resource categories indicating the importance of management.

Comparison of Endocrine Response to Stress Between Captive-Raised and Wild-Caught Bighorn Sheep

Stress hormones in Rocky Mountain bighorn sheep (Ovis canadensis canadensis), produced in response to environmental changes, road development, or high population density, may impact their immune systems to a threshold level that predisposes them to periodic, large-scale mortality. We compared the stress response to a novel environmental situation and repeated handling between bighorn sheep born and raised in captivity (CR) and bighorn sheep born in the wild (WC) and brought into captivity. We measured plasma epinephrine, norepinephrine, cortisol, and fecal glucocorticoid metabolites (FGM). Three weeks after each group’s arrival we used a one-time drop-net event to elicit an acute stress response, and we collected blood samples from each sheep over 35 minutes, as well as one fecal sample. We collected blood and fecal samples from both groups on 7 other occasions over the subsequent 6 months. We also collected fecal samples from the pen at approximately 24-hour intervals for 3 days following every handling event to monitor the stress response to handling. We found that CR sheep had a stronger autonomic nervous system response than WC sheep, as measured by epinephrine and norepinephrine levels, but we found a very similar hypothalamic–pituitary–adrenal axis (HPA) response, measured by cortisol levels, to the acute stress event of a drop-net restraint. We also found that once the WC sheep had acclimated, as indicated by the return to the initial baseline FGM levels within 12 weeks, the CR and WC groups’ HPA responses to sampling events were not significantly different from one another. Fecal samples can provide a noninvasive mechanism for managers to monitor baseline FGM for a given herd. Using long-term monitoring of FGM rather than values from a single point in time may allow managers to correlate these levels to outside influences on the herd and better understand the impacts of management changes, population density, or increased human developments on the health of the sheep population.

Experimental Bolbophorus damnificus (Digenea: Bolbophoridae) Infections in Piscivorous Birds

In order to determine potential definitive hosts of the digenetic trematode, Bolbophorus damnificus, two American White Pelicans (Pelecanus erythrorhynchos), two Double-crested Cormorants (Phalacrocorax auritus), two Great Blue Herons (Ardea herodias), and two Great Egrets (Ardea alba) were captured, treated with praziquantel, and fed channel catfish (Ictalurus punctatus) infected with B. damnificus metacercariae. Patent infections of B. damnificus, which developed in both American White Pelicans at 3 days post-infection, were confirmed by the presence of trematode ova in the feces. Mature B. damnificus trematodes were recovered from the intestines of both pelicans at 21 days post-infection, further confirming the establishment of infection. No evidence of B. damnificus infections was observed in the other bird species studied. This study provides further evidence that Double-crested Cormorants, Great Blue Herons, and Great Egrets do not serve as definitive hosts for B. damnificus.

An Investigation of Wild Bee Diversity and Abundance in Plots Managed by The Nature Conservancy in South-Central Nebraska and of Beneficial Arthropods Associated with Native Nebraska Flora

Insect pollination is an essential ecosystem service, and bees are the principal pollinators of wild and cultivated plants. Habitat management and enhancement are a proven way to encourage wild bee populations, providing them with food and nesting resources. I examined bee diversity and abundance in plots managed by The Nature Conservancy near Wood River, NE. The plots were seeded with 2 seed mixes at 2 seeding rates: high diversity mix at the recommended rate, high diversity mix double the recommended rate, Natural Resources Conservation Service (NRCS) conservation planting (CP) 25 mix at one-half the recommended rate, and NRCS CP25 mix at the recommended rate. I measured wild bee abundance and diversity, and established a database of wild bees associated with the plots. I also compared genus richness and abundance among the plots using and aerial net and blue vane traps to collect bees. Significant differences were not observed in genus richness and diversity among the plots; however, plot size and the ability of blue vane traps to draw bees from a long distance may have influenced my results. In 2008, 15 genera and 95 individual bees were collected using an aerial net and in 2009, 32 genera and 6,103 individual bees were collected using blue vane traps. I also studied the beneficial insects associated with native Nebraska flora. Seventeen species of native, perennial flora were established in 3 separate plots located in eastern Nebraska. I transplanted four plants of each species in randomized 0.61 m x 0.61 m squares of a 3.05 m x 9.14 m plot. Arthropods were sampled using a modified leaf blower/vacuum. Insects and other arthropods were identified to family and organized into groups of predators, parasites, pollinators, herbivores, and miscellaneous. Associations between plant species and families of beneficial arthropods (predators, parasites, and pollinators) were made. Pycnanthemum flexuosum Walter attracted significantly more beneficial arthropod families than 7 other species of plants tested. Dalea purpurea Vent and Liatris punctata Hook also attracted significantly fewer beneficial arthropod families than 4 other species of plants tested. In total, 31 predator, 11 parasitic, 4 pollinator, 31 herbivore, and 10 miscellaneous families of arthropods were recorded.

A Fixed Netting System as a Means of Excluding Birds From a Domestic Waste Landfill

Many bird species are attracted to landfills which take domestic or putrescible waste. These sites provide a reliable, rich source of food which can attract large concentrations of birds. The birds may cause conflicts with human interest with respect to noise, birds carrying litter off site, possible transmission of pathogens in bird droppings and the potential for birdstrikes. In the UK there is an 8 mile safeguarding radius around an airfield, within which any planning applications must pass scrutiny from regulatory bodies to show they will not attract birds into the area and increase the birdstrike risk. Peckfield Landfill site near Leeds, West Yorkshire was chosen for a trial of a netting system designed to exclude birds from domestic waste landfills. The site was assessed for bird numbers before the trial, during the netting trial and after the net had been removed. A ScanCord net was installed for 6 weeks, during which time all household waste was tipped inside the net. Gull numbers decreased on the site from a mean of 1074 per hourly count to 29 per hourly count after two days. The gull numbers increased again after the net had been removed. Bird concentrations in the surroundings were also monitored to assess the effect of the net. Bird numbers in the immediate vicinity of the landfill site were higher than those further away. When the net was installed, the bird concentrations adjacent to the landfill site decreased. Corvids were not affected by the net as they fed on covered waste which was available outside the net throughout the trial. This shows that bird problems on a landfill site are complex, requiring a comprehensive policy of bird control. A supporting bird scaring system and clear operating policy for sites near to airports would be required.