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Helminth parasites of the fox (Vulpes vulpes) in New South Wales.

A total of 930 foxes (Vulpes vulpes) from New South Wales were examined for the presence of gastro-intestinal helminth parasites. The cestodes were represented by Taenia pisiformis with a prevalence of 15.7%, T. serialis (22.6%), T. taeniaeformis (0.1%), Spirometra erinacei (28.7%) and Dipylidium caninum (8.3%). No specimens of T. ovis, T. hydatigena or Echinococcus granulosus were encountered. Toxocara canis was the most prevalent nematode and occurred in 35.2% of foxes. Other nematodes encountered were Uncinaria stenocephala with a prevalence of 30.6%, Ancylostoma caninum (7.5%), Trichuris vulpis (2.7%) and Cyathospirura dasyuridis (0.3%). Oncicola sp was found in 1 fox. The prevalence of various parasites in foxes varied between different regions of New South Wales. All parasites, except S. erinacei and D. caninum were less prevalent in the western regions of the State. T. serialis and T. canis were more prevalent in male than female foxes. Of the parasites found T. serialis had the highest average burden per infected fox (17.9) and T. pisiformis had the lowest (2.8).

Animals↗

Prevalence of serum antibodies to canine adenovirus and canine herpesvirus in the European red fox (Vulpes vulpes) in Australia.

OBJECTIVES: To determine the seroprevalence and aspects of the epidemiology of canine adenovirus (CAdV) and canine herpesvirus (CaHV-1) in European red foxes (Vulpes vulpes) in Australia. DESIGN: Serum samples were collected opportunistically from foxes in 1991-1994 in Western Australia (WA) and South Australia (SA) and in 1980-1984 and 1990-1994 in New South Wales (NSW) and the Australian Capital Territory (ACT). The sera were examined for antibody to CAdV and CaHV-1 using ELISAs. Seroprevalence in the different regions was determined for both viruses and the CAdV data were analysed for interactions between decade of collection, age, season, region and gender using logistic regression. RESULTS: The overall prevalence of antibody to CAdV was 23.2% (308/1326) but was significantly higher in sera collected in the eastern states of Australia (47%: 233/498) than in WA (9%: 75/828). Overall, in NSW and the ACT, there was a significantly lower prevalence in juveniles than in adults and the prevalence in juveniles in the 1990s was significantly lower than in the 1980s. The prevalence was also significantly lower in the autumn than in the winter for juveniles but the reverse held for adults. The NSW and ACT data were subdivided into eastern (including the ACT) and western regions. This revealed a significantly higher prevalence in the winter than in the autumn for the west and the reverse in the east. In WA, the northern rangeland regions of WA had lower prevalence (1.9%) than the southern agriculture regions (10.7%). Seasonally, there was a peak prevalence in the spring dropping through the summer and autumn and rising again in the winter. This seasonal pattern was also found in the combined data for all sites in the 1990s. There was no gender difference in prevalence of CAdV either overall or in different regions. The overall prevalence of antibody to CaHV-1 was 2.2% (28/1300). The small number of positives allowed only limited statistical analysis that did not reveal any differences in decade of collection, age, season or region. CONCLUSIONS: CAdV infection is common in the Australian fox population whereas CaHV-1 infection is rare. For CAdV, the age and seasonal patterns of seroprevalence were generally consistent with the recruitment of young susceptible foxes into the population in the spring and the accumulation of infections with age. The differences in regional prevalences correlated with fox density. The low prevalence of antibody to CaHV-1 suggests that CaHV-1 may be a more suitable vector than CAdV for bait delivery of immunocontraceptive antigens to foxes in Australia.

Adenoviridae Infections↗

Fox predation as a cause of lamb mortality on hill farms.

Data collected between 1993 and 1996 from two Scottish hill farms were used to assess the potential importance of predation by foxes as a cause of lamb mortality. Farm 1 was in Midlothian and farm 2 in West Perthshire. Overall lamb mortality rates from birth onwards were 10.2 per cent for farm 1 and 9.3 per cent for farm 2. Sixteen lambs were identified as killed by foxes on the two farms during the four-year period. The minimum rates of fox predation were 0.6 per cent for farm 1 and 0.2 per cent for farm 2. All confirmed cases of fox predation were recorded during the period until the lambs were marked at about six weeks of age, and during this period another 53 lambs went missing from the two farms. Both groups of missing lambs were characterised by having significantly more siblings than the remaining lambs. A logistic regression model was able to classify the lambs killed by foxes and the missing lambs with 75 per cent accuracy on the basis of their birth rank alone. Of the total potential revenue from lamb production, the maximum losses due to confirmed fox predation in any one year were equivalent to 1.5 per cent on farm 1 and 0.6 per cent on farm 2.

Agriculture↗

Mortality due to fox predation in free-range poultry flocks in Britain.

Information derived from questionnaires sent to producers of free-range eggs, chickens, turkeys and geese was used to assess the extent of fox predation in terms of the density of the fox population and farm management factors. The mean reported bird mortality was less than 2 per cent for all the producers, but there were marked differences between them. Egg producers reported losing many more birds to foxes than other types of producer (up to 1000 birds in a laying cycle). On average, egg and goose producers lost the highest proportions of their total flocks (0.5 per cent). The extent of predation was not associated either with large-scale estimations of the density of the fox population or with variations in the farms' habitat. Chicken predation was not linked to differences in types of housing or fencing. However, there was a positive association between losses due to other causes and chicken predation. The results suggest that changes in farm management would be the most cost-effective means of reducing fox predation, rather than greater fox control.

Animals↗

Experimental La Crosse virus infection of red fox (Vulpes fulva), raccoon (Procyon lotor), opossum (Didelphis virginiana), and woodchuck (Marmota monax).

Susceptibility to infection, resulting viremia and antibody responses, and potential to provide infectious blood meals for Aedes triseriatus were determined and compared for the red fox (Vulpes fulva), raccoon (Procyon lotor), and opossum (Didelphis virginiana) exposed to La Crosse (LAC) virus transmitted by mosquitoes, Ae. triseriatus. Woodchucks (Marmota monax) were infected with LAC virus by needle and syringe. All 5 red foxes became viremic following the bite of a single LAC virus-infected female Ae. triseriatus. Maximum viremia titers were at or above the threshold of infection for Ae. triseriatus in 4 of 5 red foxes for 1-3 days. Biological transmission of LAC virus from infected red foxes to chipmunks (Tamias striatus) was accomplished by Ae. triseriatus. Neutralizing antibody titers in red foxes peaked between day 13 and 27 and were still detectable 3 months post-infection. Woodchucks appear to be efficient amplifiers of LAC virus. Three of 4 inoculated woodchucks became viremic. Maximum viremia titers were consistently above the experimentally determined threshold of infection for Ae. triseriatus. Raccoons and opossums were not as susceptible to LAC virus infection as were red foxes or woodchucks. Only 1 of 5 raccoons became viremic. The viremia titer was low and was detected on only 1 day. Four of 5 raccoons developed LAC virus-neutralizing antibody titers, however. None of the opossums became viremic and only 2 developed LAC virus-neutralizing antibody titers.

Aedes↗

Geographic information system-aided analysis of factors associated with the spatial distribution of Echinococcus multilocularis infections of foxes.

To investigate the influence of environmental factors on the spatial epidemiology of infections with Echinococcus multilocularis, foxes were sampled in a focal endemic region in the Northwest of Brandenburg, Germany, and examined for infection by the parasite. The locations where foxes were obtained were recorded in a geographic information system database. Positions of infected and uninfected foxes were analyzed on the background of geographic vector data of water, settlements, streets, forests, crop, and pasture. Fox positions were allocated to different land-use classes by use of a Landsat Thematic Mapper (TM) satellite image. Infected foxes were more frequently shot near water, in areas of high soil humidity, and on pastures, suggesting that dryness may limit the tenacity of E. multilocularis oncospheres. Thus open landscapes with humid soil seem to be favorable for the life cycle of the parasite. In contrast, infected foxes were significantly underrepresented in forest areas.

Animals↗

Leptospirosis in red foxes in Ontario.

The role of the red fox (Vulpes vulpes) in the epizootiology of leptospirosis in southwestern Ontario was investigated in 1973-1974. Leptospira interrogans serovar pomona (kennewicki by DNA analysis) was isolated from the kidneys of three of eight foxes tested. Severe hemorrhagic nephritis and interstitial nephritis were common to these foxes and to five others out of nine foxes examined. Autumnalis antibodies were detected at titers 10(-2) to 10(-5) in 12 of 100 fox sera. Pomona antibodies occurred in 6% of the sera, always accompanied by autumnalis antibodies, and at titers never exceeding the autumnalis titers. Cultural, serological, and pathological findings together indicated that the red fox could have been acting as an amplifier host, but not as a maintenance host, for pomona.

Animals↗

Diseases diagnosed in gray foxes (Urocyon cinereoargenteus) from the southeastern United States.

Diagnostic findings were reviewed on 157 sick or dead gray foxes (Urocyon cinereoargenteus) from the southeastern United States examined during the period 1972 through 1989. Most foxes (n = 118) originated from Georgia; fewer animals were from Florida, Kentucky, Maryland, Mississippi, North Carolina, South Carolina, Tennessee, Virginia and West Virginia. Etiologic diagnoses included canine distemper (n = 125), congenital absence of guard hairs (n = 7), traumatic injuries (n = 7), rabies (n = 3), suspected toxicoses (n = 3), verminous pneumonia due to Paragonimus kellicotti (n = 1), bacterial septicemia secondary to Dracunculus insignis (n = 1), and tick paralysis (n = 1). Concurrent toxoplasmosis or toxoplasmosis or cryptosporidiosis was noted in six and three foxes with canine distemper, respectively. Only lesion diagnoses were attainable for three foxes, and six cases were classified as undetermined. Canine distemper was diagnosed in 78% of the foxes, was geographically widespread, was detected in 16 of 18 yr, and exhibited a seasonal pattern of occurrence. These facts indicate that canine distemper is more significant as a mortality factor for gray foxes than all other infectious and noninfectious diseases combined.

Animal Diseases↗

Parasites of the arctic fox (Alopex lagopus) in Iceland.

Forty-four of 50 arctic foxes (Alopex lagopus) in Iceland harbored 15 species of intestinal parasites, including Protozoa: Eimeria sp. or Isospora sp. (in 4%); Trematoda: Cryptocotyle lingua (24%), Plagiorchis elegans (4%), Brachylaemus sp. (12%), Tristriata sp. (10%), and Spelotrema sp. (8%); Cestoda: Mesocestoides canislagopodis (72%), Schistocephalus solidus (2%), and Diphyllobothrium dendriticum (4%); Nematoda: Toxascaris leonina (50%), Toxocara canis (2%), Uncinaria stenocephala (4%), and eggs of the lung worm Capillaria aerophila (6%); and Acanthocephala: Polymorphus meyeri (8%) and Corynosoma hadweni (2%). Only four of the species previously had been recorded in Iceland. Eleven species are new records in Iceland and six appear to be new host records. Two additional nematodes, Stegophorus stercorarii and Syphacia sp., probably were ingested accidentally with the prey. Foxes from coastal habitats harbored 14 parasitic species while only five species were found in foxes from inland habitats. Arctic foxes from coastal habitats generally had higher helminth burdens and harbored more parasitic species per fox than foxes from inland habitats.

Acanthocephala↗

Evaluation of fox-chasing enclosures as sites of potential introduction and establishment of Echinococcus multilocularis.

Following detection of Echinococcus multilocularis in red foxes (Vulpes vulpes) illegally imported into South Carolina (USA) for release in fox-chasing enclosures, a survey for E. multilocularis was conducted in four enclosures in Georgia (USA) and six enclosures in South Carolina. Survey methods included examination of potential small mammal intermediate hosts (n = 390) for E. multilocularis larvae, examination of fox and coyote (Canis latrans) scats (n = 59) for taeniid eggs, and examination of one possible canine definitive hosts for adult E. multilocularis. All intermediate and definitive hosts examined were negative for E. multilocularis and taeniid eggs were not recovered from fox and coyote fecal samples. Thus, E. multilocularis may not yet be established in fox-chasing enclosures in Georgia and South Carolina. Despite the failure to demonstrate E. multilocularis in the fox-chasing enclosures surveyed, translocation of wild canids from known enzootic regions should be discouraged because E. multilocularis is known to be ecologically adaptable and because contact with potentially infected definitive hosts during translocation is a public health risk.

Animals↗

An indirect immunofluorescent test for detection of rabies virus antibodies in foxes.

The blood-containing fluids in the thoracic cavity or blood from the heart from 177 red foxes (Vulpes vulpes) in Slovenia were evaluated for rabies antibodies by rapid fluorescent focus inhibition test (RFFIT) and an adapted indirect immunofluorescent test (IIF) in 1994. We evaluated the usefulness of anti-dog fluorescein-isothiocyanate (FITC) conjugate instead of anti-fox FITC conjugate in detection of antibodies against rabies virus in fox sera. In the RFFIT test, 92 (52%) of the fox samples were positive and 70 (40%) samples were negative for rabies antibodies; 15 (8.5%) samples were not suitable for examination in this test. In the IIF test, 98 (55%) fox samples were positive and 79 (45%) sera were negative. The IIF test was suitable for the rapid detection of antibodies against rabies virus in foxes, as often required for vaccine efficacy trials.

Administration, Oral↗

Gray fox response to baits and attractants for oral rabies vaccination.

Rabies is a widespread zoonosis that recently reached epidemic proportions in gray foxes (Urocyon cinereoargenteus) in central Texas. The objectives of this study were to determine bait and attractant preferences among captive gray foxes, to determine the behavioral responses of gray foxes to selected bait-attractant combinations, and to evaluate baits as a delivery mechanism of oral rabies vaccines. Trials were conducted to determine bait preferences of captive gray foxes to selected baits and attractants. Tested baits consisted of a polymer-bound cube made of either dog food meal or fish meal, a polymer-bound cylinder made of dog food meal, and a wax-lard cake that was enhanced with marshmallow or chicken flavoring. Attractants were additives to baits that exuded sweet, sulfurous, fruity, fatty, cheesy, honey, and fishy odors and flavors. Captive gray foxes (n = 31) exhibited a preference for marshmallow wax cakes and polymer dog food baits with a lard interior and granulated sugar exterior. However, gray foxes exhibited chewing behaviors consistent with ingesting an oral vaccine only with the wax cake baits.

Administration, Oral↗

Elimination of rabies from red foxes in eastern Ontario.

The province of Ontario (Canada) reported more laboratory confirmed rabid animals than any other state or province in Canada or the USA from 1958-91, with the exception of 1960-62. More than 95% of those cases occurred in the southern 10% of Ontario (approximately 100,000 km2), the region with the highest human population density and greatest agricultural activity. Rabies posed an expensive threat to human health and significant costs to the agricultural economy. The rabies variant originated in arctic foxes: the main vector in southern Ontario was the red fox (Vulpes vulpes), with lesser involvement of the striped skunk (Mephitis mephitis). The Ontario Ministry of Natural Resources began a 5 yr experiment in 1989 to eliminate terrestrial rabies from a approximately 30,000 km2 study area in the eastern end of southern Ontario. Baits containing oral rabies vaccine were dropped annually in the study area at a density of 20 baits/km2 from 1989-95. That continued 2 yr beyond the original 5 yr plan. The experiment was successful in eliminating the arctic fox variant of rabies from the whole area. In the 1980's, an average of 235 rabid foxes per year were reported in the study area. None have been reported since 1993. Cases of fox rabies in other species also disappeared. In 1995, the last bovine and companion animal cases were reported and in 1996 the last rabid skunk occurred. Only bat variants of rabies were present until 1999, when the raccoon variant entered from New York (USA). The success of this experiment led to an expansion of the program to all of southern Ontario in 1994. Persistence of terrestrial rabies, and ease of elimination, appeared to vary geographically, and probably over time. Ecological factors which enhance or reduce the long term survival of rabies in wild foxes are poorly understood.

Administration, Oral↗

Optimising spring oral vaccination campaigns of foxes against rabies.

To optimise spring vaccination campaigns the following set of data has been analysed; (i) population dynamics of the red fox, (ii) onset and progress of the reproductive season, and (iii) maternal immunity and the immune response of fox cubs to oral vaccination. The field data originated from foxes caught in Bavaria, Germany. The results of our analysis clearly demonstrate that certain periods during spring are less suitable for bait distribution. If the objective of a vaccination campaign is to reach only the adult foxes, it is suggested to conduct the campaign during the first half of March. If also young foxes are to be vaccinated, baits should not be distributed before the end of May in previously baited areas, because a large segment of the young fox population can not be vaccinated effectively before this date as a result of maternally transferred immunity. In areas vaccinated for the first time, baits can be distributed earlier, since 5 weeks old cubs are already immunocompetent.

Administration, Oral↗

Development of a recombinant vaccinia-rabies vaccine for oral vaccination of foxes against rabies.

To improve both safety and stability of the vaccines used in the field to vaccinate foxes against rabies by the oral route, a recombinant vaccinia virus, expressing the immunizing G protein of rabies virus (VVTGg RAB-26D3 187 X P strain) has been developed. The c-DNA corresponding to the glycoprotein of the ERA strain of rabies virus has been inserted into the thymidine kinase (TK) gene of the vaccinia virus (Copenhagen strain). The efficacy of this recombinant strain was tested by the oral route, primarily in foxes. The duration of immunity conferred by the VVTGg RAB, a minimum of 12 months in cubs and 18 months in adult animals, corresponds to the length of protection required for fox vaccination in the field. VVTGg RAB innocuity was tested in foxes and in domestic animals as well as in numerous wild animal species that could compete with the red fox in consuming vaccine baits in Europe. During a minimum of 28 days post vaccination, neither clinical signs nor lesions were observed in any of the vaccinated animals. Moreover no transmission of immunizing amounts of the recombinant occurred in the red fox or the other species tested. To study the stability of the vaccine strain, baits containing the vaccine were placed in the field. Despite considerable variations of environmental temperatures, the VVTGg RAB titre remained stable after one month in the field. Since all the baits are taken within one month, it can be assumed that most of the animals taking the baits are effectively vaccinated.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

Reference data on the anatomy and serum biochemistry of the silver fox.

Clinically healthy silver foxes obtained from a closed colony were investigated for the purpose of establishing base-line data for this species. The anthropometry (body weight; body length; length and width of the head; width, depth, and circumference of the chest; length of the tail), anatomical measurements (weight; longitudinal and transverse length; thickness of the main organs) and serum biochemical assays (AST, ALT, ALP, LDH, CK, lipase, GGT, T-Cho, beta-Lipo, TG, Phos-Lip, Tp, T-Bil, UA, BUN, Crea, Glu, Ca, IP, Mg, Fe, Na, K, Cl, LDH and CK isoenzymes) were carried out. The data were presented as mean values with standard deviations, and compared with those of the dog. The coefficient of variation (CV) for each of the anthropometric parameters was low, except for that of female body weight for which the CV was 17%. The body size of the male was larger than the female, and the weights of the main organs, corresponding to body size, were greater than the female. The results were equivalent to those for a Beagle dog aged between 3 and 5 months. Significant differences between the sexes were detected in the following parameters: concentrations of BUN, beta-Lipo and T-Bil (p less than 0.01); concentration of Mg and Glu (p less than 0.05); activity of LDH and lipase (p less than 0.05). The biochemical data ware uniform with some exceptions. These were AST (142 IU/l) and ALP (122 IU/l) in a 5-year-old male fox, Glu (over 200 mg/dl) in four 2-year-old female foxes, CK (629 IU/l) in a 2-year-old female fox, and finally CK (366 IU/l) and lipase (428 IU/l) in an 8-year-old female fox, all of which were elevated. These data were similar to the reference values for the dog previously reported. The reference values presented in this report for the silver fox will be valuable as a guide for clinical diagnosis and research.

Age Factors↗

[Pathogenesis of experimental rabies infection in foxes and cats infected with viruses isolated from hamsters (Cricetus cricetus)].

All the infected foxes (9) contracted the disease and died from rabies the 20th-21st day from infection with the virus isolated from hamster. Out of the total number of 9 cats experimentally infected by intramuscular infection, seven showed symptoms of clinical disease on the 18th-34th day from infection. The infected dogs, wolves and rabbits did not show clinical disease. In the post mortem examination of eight foxes the rabies virus or rabies antigen was detected in all parts of the CNS and in n. ischiadicus. Of the extraneural organs, the virus was present, in all animals, in the pharyngeal salivary glands, and in one fox also in the tongue. The bioassay on the eye was positive in all cases. The rabies antigen was detected in 4 foxes in the thigh muscle, in liver and spleen, and in all 8 foxes in lungs and cornea, in 5 cases in kidney, and in 3 cases in heart and tongue. Seven cats were examined post mortem by the inoculation test on mice and the PMIF-staining test; it was found that the rabies virus, or rabies antigen, was distributed in the same manner as in foxes.

Animals↗

Effects of handling and physical restraint on rectal temperature, cortisol, glucose and leucocyte counts in the silver fox (Vulpes vulpes).

The present paper describes the effects of handling and one hour of physical restraint on rectal temperature (Trec), plasma cortisol, plasma glucose and leucocyte counts in six 8-months old silver fox vixens (Vulpes vulpes). Mean Trec in silver foxes 5 min after capture was 40.1 degrees C and increased during restraint, showing a maximum of 40.8 degrees C at 30 min thereafter. Supplementary, deep body temperature (Tb) was recorded with surgically implanted biotelemetry devices in 6 adult silver fox vixens kept isolated from environmental disturbances in a barn. Mean Tb in these foxes ranged between 38.0-38.4 degrees C, showing a diurnal variation and being at the lowest between 0700-1600 hour. When a person approached a fox and was present for 5 min, Tb increased rapidly. The results indicated that a stress-induced hyperthermia (SIH) was evoked rapidly within the first registration at 5 min after capture, and that this response continued during one hour of physical restraint. Plasma glucose and plasma cortisol levels increased during one hour of physical restraint, whereas numbers of lymphocytes, total white blood cell counts, and total granulocytes decreased. Furthermore, previously reported base levels of plasma cortisol and plasma glucose were exceeded. The results indicate that the hypothalamic-pituitary-adrenal (HPA) axis and the sympathoadrenal medullary (SAM) system were activated within 5 min of handling and restraint. Furthermore, hyperthermia is a promising indicator of acute stress in silver foxes.

Animals↗