The Role of Wildlife in Human and Animal Disease

Strategies to assess and reduce risk associated with disease agents in wild animals must be based upon thorough knowledge of the epidemiology of the disease agent, specific local information, and other factors. Risk evaluation and management efforts will involve organizations with differing expertise and cooperation will be essential between wildlife management, public health, and domestic animal health agencies. Risk reduction strategies may be based upon manipulation of the disease agent, the host, the environment, and/or human activities. Management of human activity, particularly the promotion of biosecurity, may be the most efficient strategy because other measures are more difficult and expensive. The science of risk assessment and disease management in wildlife is growing and evolving as new situations arise and as new methods are developed to meet the needs of wildlife resource, animal agriculture and public health interest groups

Construction of Species-Specific PCR Primers for Detection of Coccidia Parasites in Captive-Reared Northern Bobwhites

Captive rearing and subsequent release of game birds, including northern bobwhites (Colinus virginianus), has become common in certain areas. In this practice, bobwhites are often raised in confinement to ‘flight ready’ and subsequently released for hunting. It is estimated that 30–40 million bobwhites are raised in captivity annually and some farms in the USA produce upwards of 1 million birds annually for this market. Raising game birds in these densities greatly facilitates the transmission of pathogenic organisms. Coccidiosis has been previously identified as an important disease in captive bobwhites and infection can lead to weight loss, diarrhea, poor feather growth, dehydration and, in severe cases, death. Eimeria lettyae, E. colini, and E. dispersa are the three described coccidia species from bobwhites. We investigated the prevalence and distribution of species of coccidia in captive bobwhite facilities throughout the United States. We collected litter or intestinal samples from 31captive bobwhite facilities originating from 13 states. Species-specific PCR primers were constructed against the internal transcribed spacer region 1 (ITS-1) of the ribosomal RNA gene of the various Eimeria spp. to aid in parasite detection and distinction. Primers were used to detect the specific Eimeria spp. in the collected samples. All 31 samples were positive for coccidia. Results of the primer survey disclosed E. lettyae, E. dispersa, and an unidentified Eimeria sp. in 20 (64.5%), 22 (72%), and 29 (93.5%) of the samples, respectively. Thirteen (41.9%) samples had 3 Eimeria spp. detected, 14 (45.2%) samples had 2 spp. detected, and 4 (12.9%) samples had 1 sp. detected. Flock age or geographical location was not associated with the presence of any particular Eimeria spp. To our knowledge, this is the first study of coccidia in captive bobwhites. Previous studies of Eimeria spp. in wild northern bobwhite are rare and disclosed variable prevalence rates ranging from 0 to 36%; no efforts were made to distinguish the coccidia species in these studies It would be helpful to use the species-specific primers constructed in this study to examine the prevalence and distribution of the Eimeria spp. in wild bobwhites from throughout their range to investigate the potential for captive-raised bobwhites to be a source of coccidiosis for wild bobwhites

Artificially decreased dissolved oxygen increases the persistence of Trichomonas gallinae in water

Water containing organic material has been shown to increase the persistence of the avian pathogenic protozoa, Trichomonas gallinae. We hypothesized that the decrease in dissolved oxygen due to microbes in the organic material could increase persistence of the microaerophilic trichomonads. Using simulated birdbaths, we determined 1) the levels of dissolved oxygen in distilled water with various amounts of organic material, 2) the concentration of the oxygen-scavenging enzyme Oxyrase®needed to achieve the dissolved oxygen levels obtained in organic material contaminated water, and finally, 3) the persistence of two T. gallinae isolates in Oxyrase®-supplemented water. An average of 9.6% dissolved oxygen was obtained with the addition of 15 g organic material to 500 ml of distilled water, whereas organic material-free water had 86.2% dissolved oxygen. The addition of 0.5% and 1.0% (vol/vol) Oxyrase® to organic material-free water yielded dissolved oxygen of 18.6% and 6.9%, respectively. Using 0.5% and 1.0% concentrations of Oxyrase®, we evaluated the persistence of two trichomonad isolates by inoculating ∼1 million trichomonads into 500 ml distilled water in triplicate. At various time-points, 0.5 ml aliquots of trichomonad-inoculated water were obtained and placed into Hollander Fluid media, incubated at 37 °C, and read by light microscopy every other day for 5 days. In our 1% Oxyrase® treatments, the longest recorded persistence of broad-winged hawk 1 increased from the previously reported 4hrs to 30hrs and Cooper\u27s hawk 4 from 16hrs to 30hrs. These results indicate that the mechanism for organic material-mediated trichomonad persistence is associated with decreased dissolved oxygen, further demonstrating the importance of keeping birdbaths free of organic debris to discourage trichomonad persistence

Free-ranging, Northern Bobwhite Submissions to the Southeastern Cooperative Wildlife Disease Study (1982-2015)

There are concerns regarding population declines of northern bobwhite (Colinus virginianus) over the past 4 decades (Palmer et al. 2011). Infectious and noninfectious diseases are among the limiting factors that potentially influence bobwhite demographics (Applegate 2014). The last update of diseases of bobwhite was presented at the Second National Quail Symposium in 1982 (Davidson et al. 1982). Since that report, scientists at the Southeastern Cooperative Wildlife Disease Study (SCWDS) have examined 133 wild bobwhites from 13 states. The SCWDS is a cooperative between states and the University of Georgia and obtains cases from the cooperating states. In this update, we focus on the diagnostic testing results from wild birds and exclude other cases that were examined during this period. We searched the SCWDS database for all bobwhite cases 1985–2016 and examined the individual case reports for 133 wild bobwhite quail. During this period, the majority of cases originated from Florida, Georgia, and Kansas, where research was being conducted on bobwhite populations. A diagnosis could not be clearly identified in all cases and some otherwise healthy bobwhites were submitted for screening; therefore, we have narrowed the focus of this report to a subset of 78 bobwhites. Wild bobwhites that were submitted by SCWDS state cooperators had an approximately even distribution between male and female birds (26 F: 19 M; 2 unknown sex). Adults (20 F, 10 M) predominated over juvenile birds (6 F, 7 M, 2 unknown sex). Trauma (physical injury) was the diagnosis in 17 female and 38 male bobwhites submitted during this period. Three each of male and female birds were considered to have no health problems. Some of the most frequent findings in diagnosed bobwhites were possible Physaloptera sp. infection (n = 9, 17.0%), avian pox (n = 7, 14.9%), intoxication (lead and carbamate; n = 5, 10.6%), corneal opacity (n = 4, 8.5%), Sarcocystis sp. infection (n = 3, 6.4%), and fungal pneumonia (n = 2, 4.25%). Some parasitic infections (e.g., coccidiosis) were thought to be associated with mortality based on necropsy and laboratory findings while a number of the parasites were determined to be incidental findings (e.g., Sarcocystis and Physaloptera) based on necropsy and laboratory findings. Corneal opacity was found in 4 birds, but the cause was not determined. The most striking findings were that trauma (e.g., physical injury) or avian pox were among the most common causes of mortality in free-ranging quail. Iatrogenic (researcher) causes of mortality (n = 5, 10.6%) associated with complications from radiotransmitters and small mammal trapping also occurred. This latter urges careful consideration among bobwhite researchers. The cause of population declines in bobwhites are likely multifactorial. We hope that morbidity and mortality investigations can provide some insight into potential limiting factors for bobwhites and assist wildlife managers with population management decisions

Tetratrichomonas and Trichomonas spp.-Associated Disease in Free-Ranging Common Eiders (Somateria mollissima) from Wellfleet Bay, MA and Description of ITS1 Region Genotypes

During an outbreak of Wellfleet Bay virus (WFBV) in common eiders (Somateria mollissima) from the Cape Cod region of Massachusetts, several birds were diagnosed with trichomonosis consisting of multiple trichomonad species. Six birds were examined, with trichomonads found in ceca in four birds and associated typhlitis in three of these four birds. PCR and DNA sequencing utilizing trichomonad-specific primers targeting the ITS1 region of the ribosomal DNA (rDNA) revealed the presence of Tetratrichomonas gallinarum in the gastrointestinal tracts of five birds and Trichomonas spp. in the livers of two birds, one of which had a dual Te. gallinarum-Trichomonas gallinae infection. Sequence analysis revealed no variation between Te. gallinarum sequences whereas the ITS1 sequences obtained from the other Trichomonas spp. demonstrated the presence of multiple genotypes. One sequence had 100% identity to a Trichomonas sp. previously isolated from a Cooper\u27s hawk (Accipiter cooperii) and the other sequence was 100% identical to a previously described Tr. gallinae isolate obtained from a Pacific Coast band-tailed pigeon (Patagioenas fasciata monilis). These findings suggest Te. gallinarum and other Trichomonas spp. possibly contributed to morbidity and mortality in this species. Furthermore, to the authors\u27 knowledge, this is the first report of trichomonad-associated disease in a free-ranging sea duck

Epidemiology of the lymphatic-dwelling filarioid nematode Rumenfilaria andersoni in free-ranging moose (Alces alces) and other cervids of North America

Background: Moose (Alces alces) are a culturally and economically valued species in Minnesota, where the northeast population has decreased by 60 % since 2006. The cause of the decline is currently unclear; however, parasites, predation, and climate change have all been implicated. Nematode parasites are important pathogens in North American moose, potentially causing severe disease and mortality. Recent spread of Rumenfilaria andersoni, a filarioid nematode of moose, has been documented in Finnish cervids; however, little is known about the epidemiology of this parasite in North America. Methods: To investigate the prevalence and distribution of R. andersoni, 584 blood samples were collected from live-captured and dead animals and screened microscopically for the presence of microfilariae using a modified Knott's test. Microfilariae were identified based on morphological characteristics. A subset of Knott's-positive animals was subjected to polymerase chain reaction (PCR) with filarioid-specific primers targeting the first internal transcribed spacer region (ITS-1) of the rRNA gene cluster. Results: Rumenfilaria microfilariae were present in 20.5 % of Minnesota moose (n = 352), with slight fluctuations observed over four years. Minnesota white-tailed deer (Odocoileus virginianus) (n = 2) and moose (n = 44) from Alaska, Montana, Washington, Maine, and New Hampshire also harbored R. andersoni, suggesting this parasite occurs widely throughout North American moose herds, and white-tailed deer can serve as a patent host. Sequence analysis of cervid blood (moose, n = 15; white-tailed deer, n = 1) confirmed the identity of R. andersoni and revealed the existence of two distinct clades. Genetic comparisons of R. andersoni isolates from North America and semi-domesticated Finnish reindeer found the two groups to be closely related, supporting previous hypotheses that R. andersoni was recently introduced into Finland by the importation of deer from the United States. Conclusions: To the best of our knowledge these observations represent the first report of R. andersoni within the contiguous United States and reveal this nematode as a common parasite of North American moose and white-tailed deer. Although the implications of R. andersoni infection on moose health is unclear, increased awareness of this parasite will help prevent unintentional introduction of R. andersoni into naive populations via the translocation of wild and captive cervids.Peer reviewe

Emergence of the arterial worm Elaeophora schneideri in moose (Alces alces) and tabanid fly vectors in northeastern Minnesota, USA

Background Moose (Alces alces) are a culturally and economically valued species in Minnesota. However, the moose population has experienced a sudden, marked decline in their range, including extirpation in the northwest and a 66% decline in the last decade in the northeast portions of the state. Although the exact cause of this decline is unclear, parasitic metastrongylid and filarioid nematode infections are known causes of morbidity and mortality in moose across North America. Methods To determine if these parasitic nematodes could be contributing to the Minnesota moose population decline, we molecularly examined banked tissues obtained from moose that died of known and unknown causes for the presence of nematode DNA. Extracted brain DNA of 34 individual moose was amplified utilizing primers targeting the 18S rRNA gene and internal transcribed spacer regions of nematodes. Results DNA sequencing revealed that PCR products obtained from 15 (44.1%) of the moose were 99% identical to Parelaphostrongylus tenuis, a metastrongylid known to cause neurological disease and death. Additionally, brain tissue from 20 (58.8%) individuals yielded sequences that most closely aligned with Elaeophora schneideri, a parasite associated with neurological impairment but previously unreported in Minnesota. Setaria yehi, a common filarioid parasite of deer, was also detected in the brain tissue of 5 (14.7%) moose. Molecular screening of 618 captured tabanid flies from four trapping sites revealed E. schneideri was present (6%) in the Minnesota environment and transmission could occur locally. Prevalence rates among the flies ranged between 0–100% per trapping site, with Chrysops spp. and Hybomitra spp. implicated as the vectors. Conclusions Ultimately, these data confirm that P. tenuis is widespread in the Minnesota moose population and raises the question of the significance of E. schneideri as a contributing factor to morbidity and mortality in moose

Frequent Cross-Species Transmission of Parvoviruses among Diverse Carnivore Hosts

Although parvoviruses are commonly described in domestic carnivores, little is known about their biodiversity in nondomestic species. A phylogenetic analysis of VP2 gene sequences from puma, coyote, gray wolf, bobcat, raccoon, and striped skunk revealed two major groups related to either feline panleukopenia virus (“FPV-like”) or canine parvovirus (“CPV-like”). Crossspecies transmission was commonplace, with multiple introductions into each host species but, with the exception of raccoons, relatively little evidence for onward transmission in nondomestic species