Stochastic modeling of bovine tuberculosis dynamics in white-tailed deer.

Chronic wasting disease (CWD), a prion disease affecting North American cervids, has been discovered in at least 12 states and provinces throughout the continent. Since 2002, a number of states and provinces have initiated surveillance programs to detect CWD in native cervid populations. However, many questions remain about the appropriate methods, geographic scope, and number of samples required for an effective CWD surveillance program. We provide an improved statistical method to calculate the probability of detecting CWD in primary sample units (e.g., county or deer management unit) that also considers deer abundance and the nonrandom distribution of CWD and hunter harvests. We used this method to analyze data from a statewide CWD detection program conducted in Wisconsin during the autumns of 2002 and 2003 to determine the distribution of CWD in white-tailed deer (Odocoileus virginianus). Deer heads were collected at hunter registration stations, and brainstem (obex) and retropharyngeal lymph nodes were removed for disease testing. Our analysis includes samples from >35,000 deer collected outside the known affected area. The probability of detecting chronic wasting disease at a prevalence of 1% varied from 0.89 to > or =0.99 among the 56 primary sample units. Detection probabilities for 1% CWD prevalence were >0.9 in 55 primary sample units, and >0.99 in 10. Detection probabilities will be higher in areas where CWD prevalence exceeds 1%. CWD-positive deer were detected in eight primary sample units surrounding the known affected area during surveillance activities. Our approach provides a novel statistical technique to accommodate nonrandom sampling in wildlife disease surveillance programs.

Bovine tuberculosis (bTB) prevalence substantially increased over the past two decades with relatively high impact on large dairy herds, raising the concern of regulatory authorities and industry stakeholders, and threatening animal and public health. Lack of resources, together with the economic and social consequences of whole-herd stamping-out, makes depopulation an impractical disease control alternative in these herds. The increase in bTB prevalence was associated with demographic and management changes in the dairy industry in Uruguay, reducing the efficacy of the current control programme (i.e. status quo) based on intradermal serial testing with caudal fold- and comparative-cervical tuberculin test-and-slaughter of reactors (CFT-CCT). Here, we aimed to assess the epidemiological effectiveness of six alternative control scenarios based on test-and-slaughter of positive animals, using mathematical modelling to infer bTB-within-herd dynamics. We simulated six alternative control strategies consisting of testing adult cattle (>1year) in the herd every 3months using one test (in vivo or in vitro) or a combination in parallel of two tests (CFT, interferon-gamma release assay-IGRA- or enzyme-linked immunosorbent assay). Results showed no significant differences overall in the time needed to reach bTB eradication (median ranging between 61 and 82months) or official bovine tuberculosis-free status (two consecutive negative herd tests) between any of the alternative strategies and the status quo (median ranging between 50 and 59months). However, we demonstrate how alternative strategies can significantly reduce bTB prevalence when applied for restricted periods (6, 12 or 24months), and in the case of IGRAc (IGRA using peptide-cocktail antigens), without incurring on higher unnecessary slaughter of animals (false positives) than the status quo in the first 6months of the programme (p-value<.05). Enhanced understanding bTB-within-herd dynamics with the application of different control strategies help to identify optimal strategies to ultimately improve bTB control and bTB eradication from dairies in Uruguay and similar endemic settings.

Deer response to exclusion from stored cattle feed in Michigan, USA

Prevalence and risk factors of bovine tuberculosis in slaughtered cattle, Malawi

To the Editor: Intense wildlife management for hunting affects risks associated with zoonotic pathogens (1). White-tailed deer (Odocoileus virginianus) are increasingly managed by fencing, feeding, watering, and translocation to increase incomes from hunting in northern Mexico (2). These deer also play a major role in dissemination and reintroduction of pathogens and vectors from Mexico into the United States (3,4). White-tailed deer are suitable reservoir hosts for Mycobacterium bovis (1), and an M. bovis-positive white-tailed deer was recently found in Tamaulipas in northeastern Mexico (2). Brucellosis is widespread in many animal hosts in Latin America (5) and thus of interest in white-tailed deer. Another major zoonosis, sometimes linked to raw deer meat consumption, is hepatitis E, which is caused by genotypes of hepatitis E virus (HEV) (6). HEV is increasingly prevalent in red deer (Cervus elaphus) (7), but its prevalence in white-tailed deer is unknown. The objective of this study was to determine the prevalence of zoonotic pathogens in white-tailed deer in northern Mexico. This study was conducted under a scientific collecting permit issued by the Mexican Division of Animal and Wildlife Health and on 8 ranches in 3 states in northern Mexico (≈26–28°N, 99–100°W). Serum samples (n = 347) were collected during 2004–2009 in a cross-sectional survey for antibodies against HEV, Brucella spp., and mycobacteria. Deer were opportunistically sampled during live-capture operations as described by Cantu et al. (8). Bleeding was performed by using jugular venipuncture and vacuum tubes without anticoagulant. Samples were allowed to clot and centrifuged to collect serum that was stored at −20°C. Serum samples were tested for IgG against HEV by ELISA as described (7). Serum samples were also tested for antibodies against Brucella spp. by using a commercial ELISA (Ingezim Brucella Compac 2.0 Ingenasa, Madrid, Spain), according to the manufacturer’s instructions. Detection of antibodies cross-reacting with 2 widely used mycobacterial antigens, bovine purified protein derivative (PPD) and paratuberculosis protoplasmatic antigen 3 (PPA3), was conducted as described (9). The sensitivity and specificity of this assay have not been established for white-tailed deer, but it has been used in seroprevalence studies of wild boar and fallow deer (9,10). Insufficient volumes of serum samples prevented testing for antibodies against all pathogens (Table). Limited serum volume and lack of other (organ) samples also precluded additional analyses to verify presence of pathogens. Table Prevalence of serum antibodies against zoonotic pathogen antigens among white-tailed deer on 8 ranches, northern Mexico, 2004–2009* Prevalence was 62.7% (95% CI 54%–70%) for antibodies against HEV, 0.4% (95% CI 0%–2%) for antibodies against Brucella spp., 8.9% (95% CI 6%–13%) for antibodies against bovine PPD, and 2.6% (95% CI 1%–5%) for antibodies against PPA3 (Table). Antibody responses to bovine PPD were detected in deer from at 6 of 8 sampling sites; in deer from 3 of these sites, antibodies were also detected against PPA3 antigen. Seroprevalence against bovine PPD was higher than that against PPA3 (χ2 10.9, df 1, p<0.01). This cross-sectional survey of white-tailed deer in northern Mexico detected antibodies to several pathogens relevant to public and animal health. High prevalence of antibodies against HEV and frequent detection of antibodies against mycobacterial antigens are public health concerns. Prevalence of antibodies against HEV were 3× higher than that reported for red deer in Europe (7). This result suggests wide circulation of HEV in the study region and warrants further research, including detection and sequencing of virus RNA. Low Brucella spp. antibody prevalence confirms results of a study in this region (8). Antibody responses to bovine PPD were detected in serum samples from deer from most sampling sites, occasionally in the absence of antibodies against PPA3. These results, and a recent report of an M. bovis–positive white-tailed deer from this region (2), suggest that these deer may be contracting M. bovis in northern Mexico. If one considers that white-tailed deer are M. bovis reservoirs in other parts of North America and that risk factors such as supplemental feeding are present in northern Mexico, there is a high risk for pathogen transmission to animals and humans (1). White-tailed deer are probably exposed to several human pathogens that are relevant to human and animal health in northern Mexico. Although this cross-sectional survey provided only an indication of pathogen prevalence in the study populations, high antibody prevalence to HEV and mycobacterial antigens requires antigen-targeted surveillance. Risks associated with pathogen translocation by white-tailed deer are also relevant to neighboring states in Mexico and the United States.

Bovine tuberculosis at the human–livestock–wildlife interface and its control through one health approach in the Ethiopian Somali Pastoralists: A review

Sympatric populations of phylogenetically related species are often vulnerable to similar communicable diseases. Although some host populations may exhibit spatial structure, other hosts within the community may have unstructured populations. Thus, individuals from unstructured host populations may act as interspecific vectors among discrete subpopulations of sympatric alternate hosts. We used a cervid-bovine tuberculosis (Mycobacterium bovis) system to investigate the landscape-scale potential for bovine tuberculosis transmission within a nonmigratory white-tailed deer (Odocoileus virginianus) and elk (Cervus canadensis) community. Using landscape population genetics, we tested for genetic and spatial structure in white-tailed deer. We then compared these findings with the sympatric elk population that is structured and which has structure that correlates spatially and genetically to physiognomic landscape features. Despite genetic structure that indicates the white-tailed deer population forms three sympatric clusters, the absence of spatial structure suggested that intraspecific pathogen transmission is not likely to be limited by physiognomic landscape features. The potential for intraspecific transmission among subpopulations of elk is low due to spatial population structure. Given that white-tailed deer are abundant, widely distributed, and exhibit a distinct lack of spatial population structure, white-tailed deer likely pose a greater threat as bovine tuberculosis vectors among elk subpopulations than elk.

Chronic wasting disease (CWD) is a fatal prion disease that affects the cervid species, including white-tailed deer (WTD) (Odocoileus virginianus) and mule deer (MD) (Odocoileus hemionus). Interspecies transmission of CWD is highly variable and dependent upon multiple factors. CWD of MD is transmissible to sheep after intracranial inoculation, with clinical signs and incubation periods similar to scrapie. This study used sheep and transgenic mice to investigate the susceptibility of sheep to the CWD agent from WTD (WTD sheep CWD) when intracranially inoculated and to characterize the agent in subsequent passages. Fifteen Suffolk sheep with PRNP genotypes VRQ/ARQ, ARQ/ARQ, or ARQ/ARR were inoculated intracranially with the CWD agent from WTD. Western blots and enzyme immunoassays (EIA) were performed on brain and lymphoid tissues to analyze misfolded prion protein (PrPSc) accumulation. PrPSc was detected in 2 of 15 sheep (both ARQ/ARQ sheep) in the brainstem at the level of the obex, with a mean incubation period (MIP) of 39 months. In affected sheep, the distribution of PrPSc was limited to the central nervous system (CNS). Brain material from one positive sheep (ARQ/ARQ) was used to inoculate mice expressing the cervid (Tg12) and ovine (Tg338) prion protein gene. Passage of the WTD sheep CWD agent into cervidized mice resulted in an attack rate of 83% for PrPSc detection, with a mean incubation period of 377 days for all mice, while passage into ovinized mice resulted in no clinical signs or demonstration of PrPSc. These results were compared to those of passage of MD CWD agent from sheep (MD sheep CWD) into cervidized and ovinized mice. There was an 86% attack rate in cervidized mice with a mean incubation period of 646 days for all mice and an attack rate of 100% in ovinized mice with a mean incubation period of 282 days. This data suggests that WTD CWD is unlikely to present a major risk to sheep but could be transmissible back to the cervid population. However, MD sheep CWD could present a risk to both the cervid and sheep populations.

Bovine tuberculosis (TB) has been discovered in unprecedented levels in Michigan's white-tailed deer (Odocoileus virginianus) herd. Human practices have facilitated the spread of bovine TB in white-tailed deer, and public cooperation is necessary to reduce the spread of the disease. Social data can determine public support for eradication strategies, as well as identify targets and messages for ongoing communication efforts. We conducted a survey of 5 bovine TB-issue stakeholder groups to assess and compare attitudes toward bovine TB-related topics and support for eradication and eradication policies. We also identified knowledge levels and interest in future bovine TB issue communications and preferences for communication sources. Results indicated that stakeholders supported the bovine TB eradication goal, but were less supportive of specific eradication policies. Stakeholders held different beliefs about threats posed by bovine TB, and about the means through which the disease is transmitted; ...

A retrospective study was conducted to test the hypothesis that supplemental feeding of white-tailed deer (Odocoileus virginianus) from 1995 to 1997 was associated with the prevalence of bovine tuberculosis (TB) in free-ranging deer in northeastern Michigan. Bovine TB prevalence data were obtained from an ongoing surveillance program, while data relating to supplemental feeding and other risk factors were collected via in-person interviews. A multivariable Poisson regression modeling approach was used to test the stated hypothesis while controlling for other risk factors. Of the 389 potential participants, 59% agreed to participate in the study. Results showed that supplemental feeding of deer was associated with bovine TB in white-tailed deer. Specific risk factors associated with increasing risk for bovine TB were locating feed sites in areas with high levels of hardwood forests (O.R. = 1.8, 95% C.I. = 1.3-2.4), other large-scale feeding sites in the area (O.R. = 1.1, 95% C.I. = 1.0-1.2), the number of deer fed per year (O.R. = 3.9, 95% C.I. = 1.4-11.4), the numbers of feed sites spreading grain (O.R. = 14.7, 95% C.I. = 2.2-98.9), the quantity of grains provided at the site (O.R. = 1.4, 95% C.I. = 1.1-1.7), and the quantity of fruits and vegetables provided (O.R. = 1.4, 95% C.I. = 1.2-1.7). Conversely, factors associated with decreasing risk of bovine TB were locating feed sites in areas with high levels of hardwood forests (O.R. = 0.1, 95% C.I. = 0.02-0.4), locating feed sites in forests (O.R. = 0.05, 95% C.I. = 0.01-0.4), and the level of sites providing grain (O.R. = 0.1, 95% C.I. = 0.01-0.3). The results of this study suggest that banning the practice of supplemental feeding is a valid policy for control of bovine tuberculosis in free-ranging white-tailed deer.

This study was conducted to determine the impact of predation on productivity of whitetailed deer (Odocoileus virginianus) in South Texas by removing predators from one area and comparing the results to a control area. A total of 188 coyotes (Canis latrans) and 120 bobcats (Lynx rufus) were removed during predator removal efforts on the approximately 5,400-acre (2,186-ha) experimental area from 1 February to 30 June 1971 and 1972. Aerial counts in 1971, a severe drought year, revealed a fawn:doe ratio of 0.47 in the experimental predator removal area compared to 0.12 in the control area. In 1972 more favorable climatic conditions led to higher deer productivity in both areas, but the relative difference between the two areas was maintained. The experimental area had a fawn:doe ratio of 0.82 compared to 0.32 on the control area. Counts from roads indicated a decline in fawn:doe ratio with increasing distance from the experimental area. These data indicate that deer populations in this locality could be increased with a very intensive predator control program. To justify such a predator control program on the basis of present information, however, a more intensive hunter harvest would probably be required to hold the deer herd below the density level where starvation, diseases, or other factors begin to take their toll. J. WILDL. MANAGE. 38(4):854-859 Regardless of underlying circumstances, certain canid predators have at times developed a specialization for preying on ungulates to the point of drastically curtailing the population (Errington 1946). Selecting against the young of these conspicuous, relatively slow-breeding forms would be potentially very destructive (Allee et al. 1949:374). That predators can specialize by preying on the young of an ungulate species has been suggested by studies involving the coyote and antelope (Antilocapra americana) in Texas (Jones 1949) and Arizona (Arrington and Edwards 1951), the lynx (Lynx canadensis) and caribou (Rangifer tarandus) in Newfoundland (Bergerud 1971), the black-backed jackal (Canis mesomelas) and blesbok (Damaliscus dorcas phillipsi) in South Africa (du Plessis 1972), and the coyote and whitetailed deer in South Texas (White 1966:83, Knowlton 1968). Recent studies with ear-marked (Knowlto 1964) and radio-tagged (Cook et al. 1971) white-tailed deer fawns on the Welder Wildlife Refuge in South Texas have suggested that coyote predation was responsible for substantial juvenile mortality, and that this was likely the major factor stabilizing the dense and generally healthy deer herd on the refuge. Speculation has arisen concerning the fate of white-tailed deer fawns in other portions of South Texas. On th Ki g Ranch in Kleberg County the deer population is maintained at around 3-6 deer per 100 acres (40.5 ha) (Kiel, unpublished data). On other areas of the Rio Grande Pla n of South Texas an average of 3.5-5.5 deer per 100 acres exists (Harwell and Kierce 1972), whereas on the Welder Refuge pproximately 15-18 deer per 100 acres are fo nd (Cook et al. 1971). The deer population in much of the Central Mineral Region of Texas also approximates 18 per 100 acres (Teer et al. 1965). Teer et al. (1965) found average embryo counts for adult white-tailed deer to range from 0.96 to 1.29, whereas yearlings averaged 0.75. Average embryo counts of adult 1 Research supported by the Caesar Kleberg Research Program in Wildlife Ecology through the Texas Agricultural Experiment Station. 854 J. Wildl. Manage. 38 (4):1974 This content downloaded from 157.55.39.163 on Sun, 20 Nov 2016 04:24:27 UTC All use subject to http://about.jstor.org/terms PREDATOR REMOVAL AND DEER o Beasom 855 deer in South Texas have been found to range between 1.24 and 1.81 per doe (Barron and Harwell 1973). Illige (1951) found an average production of 1.28 embryos per doe (adults and yearlings) in a county adjoining the present study area. Postpartum fawn:doe (including adults and yearlings) ratios in Kleberg County, South Texas, however, are rarely greater than 0.3 (Kiel, unpublished data). Evidence suggests that the relatively low whitetail net productivity is a result of high fetal or early postnatal mortality. This study originated as part of a more intensive study on Rio Grande wild turkeys (Meleagris gallopavo intermedia). It was designed to investigate the effects of predator removal on net productivity of both the turkey and white-tailed deer. Gratitude is extended to W. H. Kiel, Jr., biologist, King Ranch, Inc. who provided advice and assistance throughout the study. The enthusiastic field support of D. A. Stiles, J. C. Hutchinson, W. A. Sandifer, H. H. Haucke, R. G. Sims, R. L. Mitchell, and F. S. Guthery during certain phases of the project is gratefully appreciated. E. D. Ables offered many helpful suggestions on the preparation of the manuscript.

Experimental persistent infection with bovine viral diarrhea virus in white-tailed deer

Cache Valley virus (CVV) is a mosquito-borne bunyavirus (family Bunyaviridae, genus Orthobunyavirus) that is enzootic throughout much of North and Central America. White-tailed deer (Odocoileus virginianus) have been incriminated as important reservoir and amplification hosts. CVV has been found in a diverse array of mosquito species, but the principal vectors are unknown. A 16-year study was undertaken to identify the primary mosquito vectors in Connecticut, quantify seasonal prevalence rates of infection, and define the spatial geographic distribution of CVV in the state as a function of land use and white-tailed deer populations, which have increased substantially over this period. CVV was isolated from 16 mosquito species in seven genera, almost all of which were multivoltine and mammalophilic. Anopheles (An.) punctipennis was incriminated as the most consistent and likely vector in this region on the basis of yearly isolation frequencies and the spatial geographic distribution of infected mosquitoes. Other species exhibiting frequent temporal and moderate spatial geographic patterns of virus isolation within the state included Ochlerotatus (Oc.) trivittatus, Oc. canadensis, Aedes (Ae.) vexans, and Ae. cinereus. New isolation records for CVV were established for An. walkeri, Culiseta melanura, and Oc. cantator. Other species from which CVV was isolated included An. quadrimaculatus, Coquillettidia perturbans, Culex salinarius, Oc. japonicus, Oc. sollicitans, Oc. taeniorhynchus, Oc. triseriatus, and Psorophora ferox. Mosquitoes infected with CVV were equally distributed throughout urban, suburban, and rural locales, and infection rates were not directly associated with the localized abundance of white-tailed deer, possibly due to their saturation throughout the region. Virus activity in mosquitoes was episodic with no consistent pattern from year-to-year, and fluctuations in yearly seasonal infection rates did not appear to be directly impacted by overall mosquito abundance. Virus infection in mosquitoes occurred late in the season that mostly extended from mid-August through September, when adult mosquito populations were visibly declining and were comparatively low. Findings argue for a limited role for vertical transmission for the perpetuation of CVV as occurs with other related bunyaviruses.

Biological hurdles to the control of TB in cattle: A test of two hypotheses concerning wildlife to explain the failure of control

Artificial Water Ponds (AWP) are widely employed for preserving and managing white-tailed deer (Odocoileus virginianus) in arid, and tropical regions of Mexico. However, there is a significant knowledge gap concerning the impact of these AWP on white-tailed deer activity. To determine the effect of AWP on the ecological aspects of white-tailed deer, we assessed the visitation rates and activity patterns of this species in AWP and compared them with areas devoid of water such as Dirt Roads (DR) using camera traps during the dry season within the seasonal wetland region of Nicte Ha, situated in western Campeche, Mexico. The research was conducted in a highly seasonal tropical wetland area at the Nicte-Ha UMA in southwestern Campeche, México. We established set camera trap stations during the dry season of 2019, 2020, and 2021 in seven AWP and 12 DR that operated for at least 80 days and compared the white-tailed deer visitation rate (measured as the Relative Abundance Index, RAI) and activity patterns among both treatments and across the three studied years. We collected a total of 3,640 independent records of white-tailed deer (2,584 in AWP and 1,056 in DR) for three years, with a combined effort of 3,978 camera days (1,306 camera days in AWP and 2,672 in DR). Our analysis revealed that the Relative Abundance Index (RAI) was consistently higher in the AWP than the DR across the three study years. However, we examined RAI variations over the three years and observed differences in the AWP, while the DR exhibited a relatively stable pattern. In the case of the activity patterns, we observed that white-tailed deer were primarily diurnal, with a significant overlap in activity between the two treatment areas. Nonetheless, within the AWP, the species exhibited continuous daytime activity, whereas, in the PR, distinct activity peaks occurred during sunrise and sunset. The results show that the presence of AWP in Nicte Ha has important effects on the presence of white-tailed deer during the dry season since we observed that there is a higher RAI in the sites where there is AWP compared to the PR sites. In the case of activity patterns, the AWP sites maintain constant activity throughout the day compared to DR, where activity peaks associated with sunrise and sunset occur. Our results show the importance that this type of structure has for the management of the species during the dry season of the year in Nicte Ha and the potential benefits of these structures in tropical seasonal areas, especially under a scenario in which drought during the dry season may be more severe in the near future due to the global change.