Seroprevalence, isolation, first genetic characterization of Toxoplasma gondii, and possible congenital transmission in wild moose from Minnesota, USA.

Toxoplasma gondii infections are widespread in white-tailed deer (Odocoileus virginianus) but little is known of its prevalence in other cervids in the USA. Moose (Alces alces) is a popular large game animal, hunted for its meat and trophy antlers. Here, we report seroprevalence, isolation, and genetic characterization of T. gondii from moose from Minnesota. Antibodies against T. gondii were detected in 8 of 79 (10%) moose tested by the modified agglutination test (MAT 1:25 or higher). The myocardium of 68 moose was bioassayed individually in mice, irrespective of serological status. T. gondii was detected in three moose (2 adults, 1 3 weeks old). The parasite from 2 adults was further propagated in cell culture. PCR-RFLP genotyping of cell culture derived tachyzoites using 10 genetic markers, SAG1, SAG2 (5' and 3' SAG2, and alt.SAG2), SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico revealed two different ToxoDB PCR-RFLP genotypes (#5, designated TgMooseUS1, and #7, TgMooseUS2). The mice inoculated with myocardium of the juvenile moose developed antibodies against T. gondii, and DNA extracted from infected mouse brain was only partially characterized by PCR-RFLP genotyping, which suggests a potential new genotype. Result documented prevalence of T. gondii in moose, and its possible transplacental/transmammary transmission of T. gondii in moose.

Absence of SARS-CoV-2 in wildlife of northeastern Minnesota and Isle Royale National Park.

AIMS: We investigated the presence of SARS-CoV-2 in free-ranging wildlife populations in Northeastern Minnesota on the Grand Portage Indian Reservation and Isle Royale National Park. METHODS AND RESULTS: One hundred twenty nasal samples were collected from white-tailed deer, moose, grey wolves and black bears monitored for conservation efforts during 2022-2023. Samples were tested for viral RNA by RT-qPCR using the CDC N1/N2 primer set. Our data indicate that no wildlife samples were positive for SARS-CoV-2 RNA. CONCLUSIONS: Continued surveillance is therefore crucial to better understand the changing landscape of zoonotic SARS-CoV-2 in the Upper Midwest.

Spatial overlap of gray wolves and ungulate prey changes seasonally corresponding to prey migration.

BACKGROUND: Prey are more vulnerable during migration due to decreased familiarity with their surroundings and spatially concentrated movements. Predators may respond to increased prey vulnerability by shifting their ranges to match prey. Moose (Alces alces) and white-tailed deer (Odocoileus virginianus) are primary gray wolf (Canis lupus) prey and important subsistence species for Indigenous communities. We hypothesized wolves would increase use of ungulate migration corridors during migrations and predicted wolf distributions would overlap primary available prey. METHODS: We examined seasonal gray wolf, moose, and white-tailed deer movements on and near the Grand Portage Indian Reservation, Minnesota, USA. We analyzed GPS collar data during 2012-2021 using Brownian bridge movement models (BBMM) in Migration Mapper and mechanistic range shift analysis (MRSA) to estimate individual- and population-level occurrence distributions and determine the status and timing of range shifts. We estimated proportional overlap of wolf distributions with moose and deer distributions and tested for differences among seasons, prey populations, and wolf sex and pack affiliations. RESULTS: We identified a single migration corridor through which white-tailed deer synchronously departed in April and returned in October-November. Gray wolf distributions overlapped the deer migration corridor similarly year-round, but wolves altered within-range distributions seasonally corresponding to prey distributions. Seasonal wolf distributions had the greatest overlap with deer during fall migration (10 October-28 November) and greatest overlap with moose during summer (3 May-9 October). CONCLUSIONS: Gray wolves did not increase their use of the white-tailed deer migration corridor but altered distributions within their territories in response to seasonal prey distributions. Greater overlap of wolves and white-tailed deer in fall may be due to greater predation success facilitated by asynchronous deer migration movements. Greater summer overlap between wolves and moose may be linked to moose calf vulnerability, American beaver (Castor canadensis) co-occurrence, and reduced deer abundance associated with migration. Our results suggest increases in predation pressure on deer in fall and moose in summer, which can inform Indigenous conservation efforts. We observed seasonal plasticity of wolf distributions suggestive of prey switching; that wolves did not exhibit migratory coupling was likely due to spatial constraints resulting from territoriality.

SPECIES IN THE FECES: DNA METABARCODING TO DETECT POTENTIAL GASTROPOD HOSTS OF PARELAPHOSTRONGYLUS TENUIS Consumed By Moose (Alces Alces).

Our understanding of wildlife multihost pathogen transmission systems is often incomplete due to the difficulty of observing contact between hosts. Understanding these interactions can be critical for preventing disease-induced wildlife declines. The proliferation of high-throughput sequencing technologies provides new opportunities to better explore these cryptic interactions. Parelaphostrongylus tenuis, a multihost parasite, is a leading cause of death in some moose (Alces alces) populations threatened by local extinction in the midwestern and northeastern US and southeastern Canada. Moose contract P. tenuis by consuming infected gastropod intermediate hosts, but little is known about which gastropod species moose consume. To gain more insight, we used a genetic metabarcoding approach on 258 georeferenced and temporally stratified moose fecal samples collected May-October 2017-20 from a declining population in the north-central US. We detected moose consumption of three species of gastropods across five positive samples. Two of these (Punctum minutissimum and Helisoma sp.) have been minimally investigated for the ability to host P. tenuis, while one (Zonitoides arboreus) is a well-documented host. Moose consumption of gastropods documented herein occurred in June and September. Our findings prove that moose consume gastropod species known to become infected by P. tenuis and demonstrate that fecal metabarcoding can provide novel insight on interactions between hosts of a multispecies pathogen transmission system. After determining and improving test sensitivity, these methods may also be extended to document important interactions in other multihost disease systems.

Refining the moose serum progesterone threshold to diagnose pregnancy.

Pregnancy determination is necessary for sound wildlife management and understanding population dynamics. Pregnancy rates are sensitive to environmental and physiological factors and may indicate the overall trajectory of a population. Pregnancy can be assessed through direct methods (rectal palpation, sonography) or indicated using hormonal assays (serum progesterone or pregnancy-specific protein B, fecal progestogen metabolites). A commonly used threshold of 2 ng/ml of progesterone in serum has been used by moose biologists to indicate pregnancy but has not been rigorously investigated. To refine this threshold, we examined the relationship between progesterone concentrations in serum samples and pregnancy in 87 moose (Alces alces; 64 female, 23 male) captured from 2010 to 2020 in the Grand Portage Indian Reservation in northeastern Minnesota, USA. Pregnancy was confirmed via rectal palpation (n = 25), necropsy (n = 2), calf observation (n = 25) or characteristic pre-calving behavior (n = 6), with a total of 58 females determined pregnant and 6 not pregnant; 23 males were included to increase the non-pregnant sample size. Using receiver operating characteristic analysis, we identified an optimal threshold of 1.115 ng/ml with a specificity of 0.97 (95% confidence interval [CI] = 0.90-1.00) and a sensitivity of 0.98 (95% CI = 0.95-1.00). Progesterone concentrations were significantly higher in cases of pregnant versus non-pregnant cows, but we did not detect a difference between single and twin births. We applied our newly refined threshold to calculate annual pregnancy rates for all female moose (n = 133) captured in Grand Portage from 2010 to 2021. Mean pregnancy rate during this period was 91% and ranged annually from 69.2 to 100%. Developing a reliable method for determining pregnancy status via serum progesterone analyses will allow wildlife managers to assess pregnancy rates of moose without devoting substantial time and resources to palpation and calf monitoring.

Reconstructing landscapes of ungulate parturition and predation using vegetation phenology.

Enhanced vegetation index (EVI) data can be used to identify and define the space in which ungulates practice parturition and encounter predation. This study explores the use of EVI data to identify landscapes linked to ungulate parturition and predation events across space, time, and environmental conditions. As a case study, we used the moose population (Alces alces) of northern Minnesota in the USA. Using remotely sensed EVI data rasters and global positioning system collar data, we quantified how vegetation phenology and moose movement shaped the births and predation of 52 moose calves from 2013 to 2020 on or adjacent to the Grand Portage Indian Reservation. The known sources of predation were American black bears (Ursus americanus, n = 22) and gray wolves (Canis lupus, n = 28). Satellite-derived data summarizing seasonal landscape features at the local level revealed that landscape heterogeneity use by moose can help to quantitatively identify landscapes of parturition and predation in space and time across large areas. Vegetation phenology proved to be differentiable between adult moose ranges, sites of cow parturition, and sites of calf predation. Landscape characteristics of each moose group were consistent and tractable based on environment, suggesting that sites of parturition and predation of moose are predictable in space and time. It is possible that moose selected specific landscapes for parturition despite risk of increased predation of their calves, which could be an example of an "ecological trap." This analytical framework can be employed to identify areas for future ungulate research on the impacts of landscape on parturition and predation dynamics.

Statistical population reconstruction of moose (Alces alces) in northeastern Minnesota using integrated population models.

Given recent and abrupt declines in the abundance of moose (Alces alces) throughout parts of Minnesota and elsewhere in North America, accurately estimating statewide population trends and demographic parameters is a high priority for their continued management and conservation. Statistical population reconstruction using integrated population models provides a flexible framework for combining information from multiple studies to produce robust estimates of population abundance, recruitment, and survival. We used this framework to combine aerial survey data and survival data from telemetry studies to recreate trends and demographics of moose in northeastern Minnesota, USA, from 2005 to 2020. Statistical population reconstruction confirmed the sharp decline in abundance from an estimated 7,841 (90% CI = 6,702-8,933) in 2009 to 3,386 (90% CI = 2,681-4,243) animals in 2013, but also indicated that abundance has remained relatively stable since then, except for a slight decline to 3,163 (90% CI = 2,403-3,718) in 2020. Subsequent stochastic projection of the population from 2021 to 2030 suggests that this modest decline will continue for the next 10 years. Both annual adult survival and per-capita recruitment (number of calves that survived to 1 year per adult female alive during the previous year) decreased substantially in years 2005 and 2019, from 0.902 (SE = 0.043) to 0.689 (SE = 0.061) and from 0.386 (SE = 0.030) to 0.303 (SE = 0.051), respectively. Sensitivity analysis revealed that moose abundance was more sensitive to fluctuations in adult survival than recruitment; thus, we conclude that the steep decline in 2013 was driven primarily by decreasing adult survival. Our analysis demonstrates the potential utility of using statistical population reconstruction to monitor moose population trends and to identify population declines more quickly. Future studies should focus on providing better estimates of per-capita recruitment, using pregnancy rates and calf survival, which can then be incorporated into reconstruction models to help improve estimates of population change through time.

NEONATE HEALTH AND CALF MORTALITY IN A DECLINING POPULATION OF NORTH AMERICAN MOOSE (ALCES ALCES AMERICANUS).

Moose (Alces alces americanus) populations in many areas along the southern extent of the North American moose range, including Minnesota, have experienced decline. Ascertaining neonate health and cause-specific mortality is critical where calf survival is low and understanding underlying causes of population dynamics is important. To investigate moose neonate health and causes of mortality, we studied 43 calves shortly after parturition during 2013-15 and 2018. The observed natural calf mortality rate was 84% by the following January of each calving season. Most natural calf mortalities were caused by black bear (Ursus americanus) or wolf (Canis lupus) predation or associated injuries (71%) but also included stillbirth (16%), orphaning (7%), generalized bacterial infection (3%), and hunter harvest (3%). Neonate health was evaluated in 27 calves by hematology, serum biochemistry profile, and maternally derived immunoglobulin. General health parameters were mostly within an expected range for normal health and adequate maternal immunoglobulin transfer. Importantly, these data contribute to a growing body of literature on moose neonate health and is the first report, to our knowledge, of maternally derived immunity in moose neonates.

Spatial compartmentalization: A nonlethal predator mechanism to reduce parasite transmission between prey species.

Predators can modulate disease transmission within prey populations by influencing prey demography and behavior. Predator-prey dynamics can involve multiple species in heterogeneous landscapes; however, studies of predation on disease transmission rarely consider the role of landscapes or the transmission among diverse prey species (i.e., spillover). We used high-resolution habitat and movement data to model spillover risk of the brainworm parasite (Parelaphostrongylus tenuis) between two prey species [white-tailed deer (Odocoileus virginianus) and moose (Alces alces)], accounting for predator [gray wolf (Canis lupus)] presence and landscape configuration. Results revealed that spring migratory movements of cervid hosts increased parasite spillover risk from deer to moose, an effect tempered by changes in elevation, land cover, and wolf presence. Wolves induced host-species segregation, a nonlethal mechanism that modulated disease emergence by reducing spatiotemporal overlap between infected and susceptible prey, showing that wildlife disease dynamics may change with landscape disturbance and the loss of large carnivores.

Influence of bactibilia after preoperative biliary stenting on postoperative infectious complications.

The aim of this study was to correlate the bactibilia found after preoperative biliary stenting with that of the bacteriology of postoperative infectious complications in patients with obstructive jaundice. One hundred thirty-eight patients (83% malignant and 17% benign etiologies) with obstructive jaundice had both their bile and all postoperative infectious complications cultured. Eighty-six (62%) had preoperative biliary stents (stent group) and 52 (38%) did not (no-stent group). There were no differences for age, sex, incidence of malignancy, type of operation, estimated blood loss, transfusion requirements, hospital length of stay, morbidity, or mortality rates between the two groups. Of 31 infectious complications, 23 were in the stent group and eight were in the no-stent group (P > 0.05), but only 13 (42%) infectious complications had bacteria that were also cultured from the bile. Only wound infection (P = 0.03) and bacteremia (P = 0.04) were more likely to occur in stented patients. Taken together, these data show that preoperative biliary stenting increases the incidence of bactibilia, bacteremia, and wound infection rates but does not increase morbidity, mortality, or hospital length of stay. Jaundiced patients can undergo preoperative biliary stenting while maintaining an acceptable postoperative morbidity rate.

Pancreatic duct strictures are a common cause of recurrent pancreatitis after successful management of pancreatic necrosis.

BACKGROUND: Successful surgical management of pancreatic necrosis can result in structural changes that cause recurrent pancreatitis. The purpose of this study is to review our clinical experience managing recurrent pancreatitis in patients after successful pancreatic debridement. METHODS: We retrospectively reviewed 98 patients with pancreatic necrosis treated by debridement who made a complete recovery at our institution over an 8-year period (January 1995 to January 2003). RESULTS: Fourteen patients (14%) developed recurrent pancreatitis 5 to 39 months (median, 15 months) after recovery. Five patients (36%) had pancreatic pseudocysts and 9 (64%) had radiologic evidence of obstructive pancreatitis. All patients had either a high-grade pancreatic duct stricture (N=7) or complete duct cutoff (N=7), localized to the pancreatic neck (N=10) or proximal pancreatic body (N=4) identified by either endoscopic retrograde cholangiopancreatography or magnetic resonance cholangiopancreatography. Two patients failed endoscopic stent therapy. All patients required re-operative treatment: 6 distal pancreatectomy, 6 pancreatico-jejunostomy Roux-en-Y, and 2 cystojejunostomy Roux-en-Y with no recurrence of pancreatitis after a median follow-up of 22 months. CONCLUSIONS: Recurrent pancreatitis occurs in 14% of patients after successful pancreatic debridement. Pancreatic duct obstruction in the neck or proximal body is the primary etiologic factor. Re-operation directed at alleviating this ductal obstruction by resection or drainage is effective.

Efficacy of venous reconstruction in patients with adenocarcinoma of the pancreatic head.

Pancreaticoduodenectomy is often avoided in patients with portal or superior mesenteric venous involvement due to the perception that venous resection is complex, morbid, and carries a poor long-term survival. Our recent experience using state-of-the-art imaging and strict resection criteria show that venous reconstruction increases operative time, transfusion requirements, intensive care unit stay, and total hospital length of stay, but has no significant impact on operative morbidity rates, mortality rates, or the incidence of positive histologic margins. Kalpan-Meier life table analysis shows similar survival curves when compared to a contemporary cohort of patients who do not undergo venous reconstruction.