Reproductive Capabilities of Female Nilgai (Boselaphus tragocamelus) in Southern Texas.

Free-ranging nilgai antelope (Boselaphus tragocamelus) are an understudied species, both on their native ranges of India, Pakistan, and Nepal and on their introduced ranges in southern Texas. Basic data related to population sizes, survival, reproduction, and recruitment are needed throughout their range to inform management and conservation decisions. We collected nilgai fetuses from 3 ranches in southern Texas, including East Foundation's El Sauz and Santa Rosa ranches, and the Norias Division of the King Ranch® from 2018-2021. We calculated the percentage of individuals that were pregnant in each of the sample years and overall. We determined monthly average, maximum, and minimum fetus length. Of 488 nilgai cows, we found 386 to be pregnant (79%) and 214 to be pregnant with twins (56%). We found nilgai cows as young as 1-year old to have fetuses and therefore to have reached sexual maturity. Sex ratios of fetuses during any sampling year did not differ. We found ample evidence supporting our hypothesis that nilgai are fecund on their introduced range of southern Texas. To prevent nilgai overpopulation and associated problems, harvest management strategies should be implemented, specifically on nilgai cows.

EFFECT OF PRESCRIBED FIRE ON THE VIABILITY OF BAYLISASCARIS PROCYONIS EGGS.

Baylisascaris procyonis is a zoonotic parasite that can cause serious health issues in their intermediate hosts. Eggs of the parasite are shed in the feces of raccoons (Procyon lotor), the definitive host, and can remain viable in the environment for years. Temperatures at 49 C are the LD50 for B. procyonis eggs. Our objective was to determine the effect of prescribed fire as a lethal control technique for B. procyonis eggs. Aliquots of 1,000 viable B. procyonis eggs were placed on the soil surface and at a depth of 2 cm within 10×10 m grass plots consisting of approximately 2,000 kg/ha and 4,000 kg/ha fuel loads. In addition, aliquots of 1,000 viable B. procyonis eggs were placed at 0, 0.7, 1.2, and 1.8 m from the fire's edge and within a 1 m2 circle of bare ground on the leading edge, center of circle, and trailing edge of the fire of similar plots. Prescribed fire killed B. procyonis eggs on the soil surface up to 0.7 m from the fire's edge at fuel loads of 4,000 kg/ha but was ineffective at depths of 2 cm. Fuel loads of 2,000 kg/ha killed only 50% of B. procyonis eggs on the soil surface at the fire's edge but was not effective killing eggs at greater distances or at soil depths. Prescribed fire can be used to reduce the quantity of B. procyonis eggs on the soil surface within an environment but will not be effective in eradicating the parasite eggs.

Gastrointestinal helminths in raccoons in Texas.

Raccoons (n=590) were collected from October 1999 to August 2003 from 35 counties across Texas, and gastrointestinal tracts were examined for helminth parasites. Prevalence was calculated and differences in mean abundance were examined among habitat ecoregions, age classes, and between sexes. Twenty different species of helminths (13 nematodes, two cestodes, two acanthocephalans, and three trematodes) were positively identified in the gastrointestinal tracts of 590 raccoons in Texas. Five of the 20 helminth species collected (Physaloptera rara, Placoconus lotoris, Molineus barbatus, Atriotaenia procyonis, and Macracanthorhynchus ingens) had a prevalence >20%. The total number of individuals of these five species (n=22,777) accounted for over 86% of the total number of individuals of all helminth species (n=26,426) collected. Subsequent analyses were based on these five helminths. Mean abundance differed among habitat ecoregions, age classes, and between sexes for all five parasites evaluated. This study is the most comprehensive statewide survey ever done of gastrointestinal helminths of raccoons across Texas. The five most prevalent helminths identified have all been reported in at least one previous survey, indicating that these parasites are not new to Texas and that raccoons are not naïve to the effects these parasites have on them. It may be helpful to wildlife rehabilitators, trappers, wildlife biologists, and other professionals to be aware of parasite abundance in raccoons from different areas of the state, as frequent human-raccoon interactions occur, and some of these parasites could be harmful to humans and domestic animals.

Feral swine contact with domestic swine: a serologic survey and assessment of potential for disease transmission.

Feral swine (Sus scrofa) are present in 38 of the 50 United States, and their populations continue to expand. Domestic swine are widely regarded as vulnerable to diseases harbored by feral swine. Our objectives were to determine antibody prevalence for selected pathogens in Texas feral swine populations and identify contact events between feral and domestic swine. Overall prevalence of antibodies against brucellosis and pseudorabies virus was 11% and 30%, respectively. Antibodies to porcine reproductive and respiratory disease virus were detected in 3% of feral swine from southern Texas. All samples tested negative for antibodies to classical swine fever virus. To determine the frequency of contact events between feral swine and domestic swine in neighboring facilities, we analyzed movement data from 37 adult feral swine that were trapped < or =10 km from domestic swine facilities and equipped with geographic positioning system collars. Seven of the 37 feral swine had contact (relocated within 100 m) with domestic swine. We found that contact between feral swine and domestic swine occurred predominantly at night. Additionally, we analyzed 60 consecutive days of experimental track plots around pens that contained domestic swine and empty control pens, and found greater visitation by feral swine to the domestic swine pens. Our data demonstrate that feral swine have direct contact with domestic swine, which presents opportunity for disease transmission.

Prevalence of infectious agents in free-ranging white-tailed deer in northeastern Mexico.

The objectives of this study were to determine the prevalence of antibodies against brucellosis, leptospirosis, infectious bovine rhinotracheitis virus, and bovine viral diarrhea virus (BVDV) in white-tailed deer (Odocoileus virginianus) in northeastern Mexico. Deer (n=521) were captured from helicopter using a netgun on 15 ranches covering 62,114 ha in the states of Coahuila, Nuevo Leon, and Tamaulipas during spring 2004. The prevalence of antibodies against Leptospira, infectious bovine rhinotracheitis, BVDV, and brucellosis were 5.6, 41.1, 63.5, and 0%, respectively, indicating that white-tailed deer and cattle may share disease agents when cohabiting in northeastern Mexico.

Immunologic and molecular identification of Babesia bovis and Babesia bigemina in free-ranging white-tailed deer in northern Mexico.

The suitability of white-tailed deer (Odocoileus virginianus) as hosts for the cattle ticks Rhipicephalus (Boophilus) microplus and Rhipicephalus (Boophilus) annulatus, has been well documented. These ticks have a wide host range, and both transmit Babesia bovis and Babesia bigemina, the agents responsible for bovine babesiosis. Although this disease and its vectors have been eradicated from the United States and some states in northern Mexico, it still is a problem in other Mexican states. It is not known if wild cervids like white-tailed deer can act as reservoirs for bovine babesiosis. The purpose of this study was to determine if B. bovis and B. bigemina or antibodies against them occur in white-tailed deer in the states of Nuevo Leon and Tamaulipas, Mexico. Twenty blood samples from white-tailed deer from two ranches were collected and tested with a nested polymerase chain reaction (nested PCR) and indirect immunofluorescence antibody test (IFAT) for B. bovis and B. bigemina. Eleven samples were positive for B. bigemina and four for B. bovis by nested PCR; amplicon sequences were identical to those reported in GenBank for B. bovis (Rap 1) and B. bigemina. Results of the IFA test showed the presence of specific antibodies in serum samples. This is the first report of the presence of B. bovis and B. bigemina in white-tailed deer using these techniques and underscores the importance of cervids as possible reservoirs for bovine babesiosis.

Use of Remote Cameras to Monitor the Potential Prevalence of Sarcoptic Mange in Southern Texas, USA.

Sarcoptic mange, caused by the mite Sarcoptes scabiei , is a common, highly contagious skin disease that has been reported from more than 100 species of mammals, including humans. Our objectives were to 1) determine the prevalence of sarcoptic mange within mammals from southern Texas, and 2) determine the efficacy of using remote cameras to estimate mange prevalence. We collected remote camera photographs from a 64-km2 area and blood and skin scrapings from 166 mammals representing 12 species in southern Texas, US during 2012-13. Only 16% of the 344,395 photograph series were of animals with an appearance consistent with sarcoptic mange and only individuals of four species: 16/25 feral hogs ( Sus scrofa ), 13/28 white-tailed deer ( Odocoileus virginianus ), 18/25 coyotes ( Canis latrans ), and 1/5 nilgai ( Boselaphus tragocamelus ) displayed alopecia, seborrhea, and crusted lesions that were consistent with mange. However, only feral hogs, coyotes, and white-tailed deer had mites present within skin scrapings. Two photographs of each collected mammal that displayed characteristics consistent with mange (n=83 animals; 166 photographs) were reviewed in a blind trial by a veterinarian experienced with cases of mange. The veterinarian correctly identified 18 and 97 animals from photographs as positive and negative for mange, respectively, with 19, 9, and 23 animals from photographs being false positive, false negative, and inconclusive, respectively. Moderate to severe cases of mange were readily identifiable via photographs; however, mild cases and summer coats often were misdiagnosed, making the technique of debatable use.

Assessing Potential Environmental Contamination by Baylisascaris procyonis Eggs from Infected Raccoons in Southern Texas.

Baylisascaris procyonis is a large ascarid of raccoons (Procyon lotor) and is a zoonotic threat. We documented the potential rate a raccoon population can contaminate their environment with B. procyonis eggs. We estimated the population size of raccoons using a 9 × 7 trapping grid of Havahart traps, identified locations of raccoon scats through systematic searches, and enumerated the distance B. procyonis eggs passively travel from site of origin upon scat decay. During an 8-week capture period, the raccoon population was estimated to be 19.6 ± 1.3 raccoons within the 63-ha study area (1 raccoon/3.2 ha). There were 781 defecation sites, of which 744 (95.3%) were isolated sites and 37 (4.7%) were latrine sites. Fifty-three (6.8%) defecation sites occurred in areas associated with human structures (commensal zone). Of the noncommensal sites, 9 (1.2%) and 719 (98.8%) sites were identified as latrine sites and isolated scats, respectively. More latrine sites were located within the commensal zone (p < 0.0001, [Formula: see text]) than proportionately available space. Twenty-five raccoon scats containing B. procyonis eggs were allowed to decay on level bare soil by way of simulated rain events, 13 were allowed to desiccate naturally in the environment, and 12 were allowed to desiccate and, subsequently, experience a simulated 1 cm rain event; eggs were found 49 ± 6, 28 ± 8, and 68 ± 8 cm from the initial scat location, respectively. We calculated that a single B. procyonis-infected raccoon could contaminate 0.03 ± 0.01 ha/year with B. procyonis eggs. Our findings indicate that B. procyonis represents a substantial risk to humans in areas where infected raccoons and humans co-occur.

Neospora caninum in Axis Deer ( Axis axis ) and Fallow Deer ( Dama dama ) in Northern Mexico.

Serum samples from 18 axis deer ( Axis axis ) and 19 fallow deer ( Dama dama ) were analyzed with an enzyme-linked immunosorbent assay for Neospora caninum antibodies. Two axis (11%) and two fallow deer (11%) were positive for N. caninum antibodies.

Environmental Temperatures in Southern Texas, USA: Implications for Survival of Baylisascaris procyonis Eggs.

Baylisascaris procyonis is an intestinal nematode of raccoons ( Procyon lotor ). Within intermediate hosts, larvae can cause visceral, ocular, and neural migrans. Humans, especially children, have become infected after ingestion of larvated eggs at raccoon latrines. Eggs of B. procyonis have a thermal death point of 62 C. During 2012, we assessed the likelihood of thermal lethality on B. procyonis eggs in southern Texas. We recorded temperature every 30 min with data loggers placed on the ground in full sun and in the shade, buried 5 cm underground and the ground surface exposed to full sun or in shade, in attics with and without exhaust fans, in woodpiles, in sheds, in tree crevices, and in cars parked in the sun. Such locations represented common raccoon latrine sites or locations where B. procyonis eggs could be found. In addition, data loggers placed about 135 cm above the ground in full sun and in shade were used as controls to acquire ambient temperature. The hottest month was August (maximum 44 C), with 15 d that exceeded 38 C. However, only the car reached the lethal temperature limit, and only for 1 h. Southern Texas has one of the warmest climates in the contiguous US; however, it is unlikely that the southern Texas climate is hot enough to kill B. procyonis eggs.

Permeability and Viability of Baylisascaris procyonis Eggs in Southern Texas Soils.

Baylisascaris procyonis is a nematode whose definitive host is the raccoon ( Procyon lotor ). Adult parasites are not particularly pathogenic to raccoons; however, larvae in intermediate hosts can cause visceral, ocular, and neural larva migrans. Humans serve as dead-end hosts, and pathological responses are similar to those found in infected intermediate hosts. Infected raccoons expose intermediate hosts through their feces, which can contain millions of B. procyonis eggs. Our objective was to determine how the quantity and viability of B. procyonis eggs in soil changed over time within different soil texture, moisture, and sun exposure. To examine egg survival and movement through soil we placed 100 B. procyonis eggs on 100 squares in 48 boxes representing a full factorial treatment of soil texture, moisture, and sun level. We monitored egg percolation and survival for 2 yr, removing (at 0, 1, 3, 6, 12, 18, and 24 mo) 5 squares from each box and counting the number of viable eggs at each depth in the soil column. Dry soils were mainly impermeable; even after 2 yr, >60% of B. procyonis eggs remained on the surface of all soil textures. Wet soils were more permeable than dry soils, but even in wet sandy soils where the greatest egg movement occurred, it required 1 yr before 60% of eggs transitioned from the soil surface to the next soil depth. For all soil textures, moistures, sun exposures, and depths, >92% of B. procyonis eggs remained viable after 2 yr in the southern Texas environment. Therefore, high exposure risk exists for potential hosts because B. procyonis eggs remain viable on or near the soil surface for at least 2 yr.

Effect of short-term coyote removal on populations of coyote helminths.

Coyote (Canis latrans) removal programs often are initiated despite the potential population regulatory mechanism of parasitism with increased coyote density. We investigated the effect of intensive, short-term coyote removal on population levels of helminths in juvenile and adult coyotes from western Texas. Coyotes were killed by aerial gunning every 3 mo for 2 yr on two 5,000 ha areas, which reduced the overall coyote density of these areas by about 50%. Two other 5,000 ha areas were used as comparison sites where a limited number of coyotes were killed each season. Densities on comparison sites remained stable throughout the study at a mean +/- 1 SE of 0.14 +/- 0.01 coyotes/km2. Twelve helminth species consisting of seven nematodes (Ancylostoma caninum, Physaloptera rara, Toxascaris leonina, Dirofilaria immitis, Spirocerca lupi, Oslerus osleri, and Capillaria aerophila), three cestodes (Taenia pisiformis, Taenia multiceps, and Mesocestoides sp.), one acanthocephalan (Oncicola canis), and one trematode (Alaria marcianae) were found in 252 coyotes. Of these, A. caninum, P. rara, T. multiceps, T. pisiformis, T. leonina, and S. lupi were common species. Rank-transformed values for the mean abundances of A. caninum and T. multiceps and A. caninum, T. multiceps, and S. lupi were reduced in juvenile and adult coyotes, respectively, from the removal sites compared to respective helminth abundances in similar age class coyotes from comparison sites. Because A. caninum has been suggested as a population regulator of coyotes, a coyote removal program that results in a reduced density of coyotes and at the same time causes a reduced abundance of A. caninum, may in fact negate the regulatory effect that A. caninum has on coyote populations.

Acute effects of aflatoxin on northern bobwhites (Colinus virginianus).

Aflatoxin is a widely occurring and harmful mycotoxin produced by strains of Aspergillus spp. growing on vegetable matter. We investigated the concentration of aflatoxin needed to impair normal physiologic responses and induce acute morbidity and mortality in Northern Bobwhites (Colinus virginianus). Ten wild-caught adult bobwhites (five males and five females) from southern Texas were randomly assigned to each treatment group (0, 100, 500, 1,000, and 2,000 parts per billion (ppb) aflatoxin; n=50). We orally administered 100 µL of aflatoxin, derived from Aspergillus flavus, once per week for 4 wk and monitored bird mass, daily feed consumption, liver histology, and blood chemistries. An in vitro white blood cell proliferation test was conducted using spleen tissue to determine the effect of aflatoxin on the immune system. There was no mortality in the control groups, whereas mortalities occurred in all treatment groups except in the 100 ppb aflatoxin treatment. Immunosuppression, reduction in gamma-globulin, glucose, and gamma-glutamyltransferase blood levels, and abnormal liver histology were observed in aflatoxin-exposed quail. Blood chemistry indicated cellular damage to the liver and kidneys. We concluded that short-term, acute doses of aflatoxin as low as 100 ppb can be detrimental to the health of Northern Bobwhites.

Frequency of deposition and location of Baylisascaris procyonis eggs in raccoon feces.

Baylisascaris procyonis is a large ascarid nematode found in the small intestine of raccoons (Procyon lotor). Infection with larvae of B. procyonis can produce visceral, ocular, and neural larval migrans in humans. Infected raccoons can shed millions of eggs a day in their feces. However, it is unknown whether eggs are consistently shed or whether eggs occur at irregular intervals by the population of female nematodes within a host. We trapped, infected, and collected daily fecal samples from 11 raccoons maintained in captivity. Eggs from B. procyonis were obtained from anterior, central, and posterior sections of raccoon feces, isolated by flotation, and quantified under 100× magnification. Naturally infected raccoons were collected and used as a comparison with the experimentally infected group. All raccoons in the experimental group (n=11) became infected with B. procyonis after consuming one infected mouse. Additionally, differential egg deposition rates were observed among individual raccoons from the experimental and naturally infected groups. Mean number of eggs per gram of feces (means±SE) was 16,563±4,321, which was less than previously reported for the species. However, no differences (F(2,30)=0.84, P=0.45) were noted in mean number of eggs per gram of feces among fecal sections. Wildlife biologists, veterinarians, health officials, and researchers of B. procyonis should collect daily fecal samples for a minimum of 3 days before identifying a raccoon as negative for B. procyonis infection. However, it does not matter where within the fecal matter the sample is obtained.

Baylisascaris procyonis in raccoons in Texas and its relationship to habitat characteristics.

Raccoons (n=590) were collected from October 1999 to August 2003 from 35 counties across Texas, USA, and gastrointestinal tracts were examined for Baylisascaris procyonis. We documented B. procyonis in central and eastern Texas. Baylisascaris procyonis occurred in 5.4% raccoons in Texas with an overall mean abundance and mean intensity of 0.4+/-0.1 and 7.4+/-2.3, respectively. Prevalence was higher in central Texas ecoregions and on clayey soil texture than other regions or soil textures of Texas. Mean parasite abundance was highest in the Postoak Savanna ecoregion located in central Texas. Our findings expanded the range of B. procyonis in Texas and confirmed that areas of Texas with clayey soil texture are more vulnerable to B. procyonis transmission. This study gives a better understanding of where B. procyonis may occur in Texas and which environmental characteristics are better suited for B. procyonis occurrence and transmission, especially in areas where likelihood of frequent human contact with raccoons and their feces increases.

Polymorphic microsatellite markers for the striped skunk, Mephitis mephitis, and other mephitids.

We report 10 polymorphic microsatellite loci primers developed for striped skunks (Mephitis mephitis), a widespread mesocarnivore in North America. Numbers of alleles in these loci ranged from seven to 14 and the observed heterozygosity ranged from 0.76 to 1.0. These primers will be useful for studying population dynamics of skunks where rabies is endemic and will be useful to estimate genetic relatedness among females sharing winter dens. Most of these primers amplify across species within the Mephitidae.

Epizootiology of Babesia bovis and Babesia bigemina in free-ranging white-tailed deer in northeastern Mexico.

Species of Rhipicephalus (Boophilus) ticks are the vectors of babesiosis (cattle fever tick), which are distributed worldwide. White-tailed deer (Odocoileus virginianus) are important secondary hosts for the cattle fever ticks, Rhipicephalus (B.) annulatus and Rhipicephalus (B.) microplus. White-tailed deer are capable of sustaining Boophilus spp. tick populations in the presence or absence of cattle. The objectives of this study were to determine the frequency of Babesia bovis and Babesia bigemina and the prevalence of antibodies to them and identify possible risk factors for bovine babesiosis in white-tailed deer in 3 northeastern states of México. Whole blood and serum samples (n = 457) were collected from white-tailed deer in the states of Coahuila, Nuevo Leon, and Tamaulipas during the spring of 2004. Samples were tested for B. bovis and B. bigemina by nested polymerase chain reaction (n-PCR) (the primers for B. bovis identified the gene Rap-1 and B. bigemina were specific primers) and by an indirect immunofluorescence antibody test (IFAT). A questionnaire was given to each ranch to obtain information about management practices. Logistic regression methods were used to test the association between management factors and the dependent variable of positive n-PCR or IFAT. Nineteen (4.2%) samples were positive to B. bigemina and 6 (1.7%) were positive to B. bovis by n-PCR. Serological testing showed 59.9% (n = 274) of deer sampled were positive to B. bovis and 5.4% (n = 25) were positive to B. bigemina antibodies. The logistic model varied with different dependent variables. With positive n-PCR and B. bigemina as the dependent variable, 3 factors were associated: habitat (presence of brush and exotic grasses; odds ratio (OR), 3.3; 95% confidence interval (CI), 1.3-8.5), grazing system (continuous grazing OR 4.0; CI, 1.3-12.2), and tick treatment frequency (3-4 mo; OR 7.0, CI 1.4-34.3; 5-6 mo; OR, 11.0; CI, 1.9-62.7; > 6 mo; OR, 4.6; CI, 0.9-23.3). These findings suggest that white-tailed deer may act as a reservoir for the 2 bovine Babesia spp. and that white-tailed deer may be important in the epidemiology of babesiosis. However, evidence is not available to support whether white-tailed deer are, or are not, likely to be a host that could complete the transmission cycle of Babesia spp. These results suggest that additional research is needed to demonstrate the importance of white-tailed deer as a Babesia spp. infection source for ticks.