A Preliminary Note on Trichinosis Investigations in Alaska

Trichinosis in the arctic regions of the world has received considerable attention during recent years, particularly since the work of Roth (1948) in Greenland. In Connell's (1949) review of arctic trichinosis some Alaskan and Canadian records were included but, until now, little has been known of the status of the disease in Alaska. Information available at the present time indicates that the incidence of trichinosis is high in circumpolar carnivores and that marine mammals have a definite place in its epizootiology. Present knowledge cannot explain the survival of trichinosis in marine mammal populations, but it is evident that they may serve as important sources of human infection. Up to the present time the following mammals from Alaska have been found to be infected: From the arctic coast-polar bear, Thalarctas maritimus; arctic fox, Alapex lagapus irmuitus; red fox, Vulpes fulva alascemis; white whale, Delphinapterus leucas; Eskimo dog. From south of the Brooks Range--brown and grizzly bears, Ursus spp.; wolf, Canis lupus ssp.; wolverine. Gula l. luscus. At the time of writing, nearly ail species of land carnivores in Alaska have been examined as well as many other mammalian species less likely to be infected, including various rodents, shrews, and others.

METHODS OF CONTROLLING COYOTES, BOBCATS, AND FOXES

In reviewing methods of predator control, it would first seem appropriate to define what is meant "by "methods" and what is meant by "control." Taking the last term first, control, as applied to the predatory coyotes, bobcats, and foxes, may be defined as regulating the numbers of these animals to the point where the economic losses for which they are responsible will be reduced to a practicable minimum. In some situations, area control, i.e., limiting the numbers of the offending predator over wide areas, may be necessary for satisfactory reduction of economic losses; in other situations, spot control or localized reduction of numbers of a certain predator may be called for; in still other situations, elimination of an individual animal may be all the control that is needed. In no sense is control, as applied to coyotes, bobcats, and foxes, intended to mean extermi¬nation of a species. The term "methods" is interpreted as meaning the procedures employed against coyotes, bobcats, and foxes, and not the broader systems of predator control such as the paid hunter system, the extension system, or the much-discredited bounty system. For an excellent review of the systems of predator control, see Latham (l).

Notes on the Nunamiut Eskimo and Mammals of the Anaktuvuk Pass Region, Brooks Range, Alaska

Covers the physical attributes (physiography, climate and vegetation) of the Brooks Range, Alaska, as well as the Numamuit Eskimo people who lived there in the 1940s and before (including information about their livelihood, history, dwellings, clothing, food, transportation and hunting implements), and includes a list and description of the mammals that lived there (including shrews, grizzly bears, foxes, wolves, martens, ermines, weasels, minks, wolverines, otters, lynxes, hares, marmots, ground squirrels, red squirrels, lemmings, voles, beavers, porcupines, moose, caribou and sheep).

Landscape-Genetic Analysis of Population Structure in the Texas Gray Fox Oral Rabies Vaccination Zone

In west-central Texas, USA, abatement efforts for the gray fox (Urocyon cinereoargenteus) rabies epizootic illustrate the difficulties inherent in large-scale management of wildlife disease. The rabies epizootic has been managed through a cooperative oral rabies vaccination program (ORV) since 1996. Millions of edible baits containing a rabies vaccine have been distributed annually in a 16-km to 24-km zone around the perimeter of the epizootic, which encompasses a geographic area >4 x 105 km2. The ORV program successfully halted expansion of the epizootic into metropolitan areas but has not achieved the ultimate goal of eradication. Rabies activity in gray fox continues to occur periodically outside the ORV zone, preventing ORV zone contraction and dissipation of the epizootic. We employed a landscape-genetic approach to assess gray fox population structure and dispersal in the affected area, with the aim of assisting rabies management efforts. No unique genetic clusters or population boundaries were detected. Instead, foxes were weakly structured over the entire region in an isolation by distance pattern. Local subpopulations appeared to be genetically non-independent over distances >30 km, implying that long-distance movements or dispersal may have been common in the region. We concluded that gray foxes in west-central Texas have a high potential for long-distance rabies virus trafficking. Thus, a 16-km to 24-km ORV zone may be too narrow to contain the fox rabies epizootic. Continued expansion of the ORV zone, although costly, may be critical to the long-term goal of eliminating the Texas fox rabies virus variant from the United States.

Observations on Some Natural-Focal Zoonoses in Alaska

In Alaska, as in arctic and subarctic Eurasia, important natural-focal zoonoses are rabies, brucellosis, tularemia, trichinosis, alveolar hydatid disease, cystic hydatid disease, and diphyllobothriasis. Most frequently affected are aboriginal peoples in villages within biocenoses that include the natural parasite-host assemblages. Pathogens are transmitted to man from wild animals and from dogs, which are important as synanthropic hosts. The prevalence and rate of transmission of certain pathogens in natural foci are related to the numerical density of small mammals, especially rodents, which may themselves be involved as hosts, and on which the numbers of their predators ultimately depend, such as is evident in the natural cycles of Echinococcus multilocularis and of rabies virus. Some pathogens in northern regions exhibit biological Characteristics that separate them from morphologically indistinguishable strains at lower latitudes (e.g., Trichinella spiralis and E. granulosus). Host-parasite relationships may also differ, as in the Arctic where rabies virus is maintained in populations of foxes, without significant involvement of mammals of other groups. Faunal interchanges during and after the Pleistocene period have influenced the distribution of parasite-host assemblages in Alaska.

Epizootiologic Survey of Mycobacterium Bovis in Wildlife and Farm Environments in Northern Michigan

Bovine tuberculosis (bovine TB), caused by Mycobacterium bovis, has reemerged in northern Michigan, USA, with detections in white-tailed deer (Odocoileus virginianus) in 1994 and in cattle in 1998. Since then, significant efforts have been directed toward reducing deer densities in the area in the hopes of reducing the bovine TB prevalence rate in deer and eliminating spillover of the disease into cattle. Despite the success of the efforts to reduce deer densities, additional cattle herds have become infected. Other mammals can be infected with M. bovis, and some carnivores and omnivores had been found to be infected with the disease in northern Michigan, USA. We conducted a multiyear surveillance effort to detect bovine TB in wild species of mammals in the Michigan, USA, outbreak area. From 2002 to 2004, tissue samples from 1,031 individual animals of 32 species were collected, processed, and cultured for M. bovis. Only 10 (1.0%) were culture-positive for M. bovis (five raccoons [Procyon lotor], four opossums [Didelphis virginiana], and one grey fox [Urocyon cinereoargenteus]). We also found two raccoons and four opossums to be positive for Mycobacterium avium. We collected 503 environmental samples from cattle farms recently identified as bovine TB positive; none yielded positive M. bovis culture results. Finally, we used infrared cameras to document wildlife use of four barns in the area. Many avian and mammalian species of wildlife were observed, with raccoons being the most commonly observed species. This surveillance study identified no new wildlife species that should be considered significant reservoirs of bovine TB in the outbreak area in northern Michigan, USA. However, the relatively high, apparent bovine TB prevalence rates in some carnivorous and omnivorous species, their relatively long life spans, and their frequent use of barns, suggests that removal of raccoons, opossums, foxes, and coyotes (Canis latrans) should be considered when a newly infected farm is depopulated of cattle.

Rabies in Experimentally Infected Bears, Ursus spp., with Epizootiologic Notes

Ten black bears, Ursus americanus Pallas, and three brown bears, U. arctos Linnaeus, were inoculated with rabies virus from naturally infected foxes in Alaska. The bears were more resistant than canine species, requiring at least 1,000 MLD50 of virus for infection. Low titres or negative results were obtained in salivary glands titrated in mice. Clinical course of the disease, post mortem findings, and microscopic lesions are described. Microscopic lesions were more· severe in brown bears, in which the inflammatory response was distinguished by the presence of numerous eosinophils in the perivascular infiltrate and among cells diffusely infiltrating the parenchyma. In both species, inclusion bodies were found only in the Purkinje cells of the cerebellum. Rabies is discounted as a factor in unprovoked attacks by bears on man at high latitudes. The epizootiology of rabies in a region where bears are numerous is discussed, with the conclusion that rabid foxes usually do not excrete sufficient quantities of virus in the saliva to infect bears. German title: Tollwut bei experimentell infizierten Bären, Ursus spp., mit epizootiologischen Anmerkungen German abtract: Zehn Schwarzbären, Ursus americanus Pallas, und drei Braunbären, U. arctos Linnaeus, wurden mit einem von Füchsen in Alaska isolierten Feldstamm des Tollwutvirus infiziert. Die Untersuchungsergebnisse lassen erkennen, daß Bären eine größere Resistenz gegenüber Tollwutinfektion aufweisen als hundeartige Karnivoren, und zwar konnten sie nicht mit weniger als 1000 MLD50 des Tollwutvirus infiziert werden. Das Virus war selten nachweisbar in den Speicheldrüsen der tollwuterkrankten Bären. Klinik und Pathologie der Tollwut bei Bären wurden kurz beschrieben. Die im Gehirn vorkommenden entzündlichen Veränderungen waren bei Braunbären besonders schwer und unterschieden sich durch die Häufigkeit der eosinophilen Leukozyten in den perivasculären und Gewebs-Infiltraten. Bei beiden Arten wurden Einschlußkörperchen nur in den Purkinje-Zellen beobachtet. Die Epizootiologie der Tollwut auf der Alaska-Halbinsel, wo Bären häufig vorkommen, wurde besprochen. Die Ergebnisse deuten an, daß Füchse wenig Virus mit dem Speichel ausscheiden, und selten soviel, daß es für die Infektion von Bären ausreicht. French title: La rage expérimentale chez les ours, Ursus spp., avec observations épizootiologiques French abstract: Dix ours noirs, Ursus americanus Pallas, et trois ours bruns, U. arctos Linnaeus, ont été inoculés avec de virus rabique provenant des renards infectés naturellement dans l'Alaska. Les ours Ont été plus résistants au virus que des espèces canines, et pour produire l'infection chez les ours, au moins 1000 MLD50 ont été requis. La titration des glandes salivaires chez des souris a données des titres peu éléves ou des résultats négatifs. La course clinique de la maladie, les observations des autopsies, et les lésions microscopiques sont decrites. Les lésions microscopiques les plus sévères ont été observées chez les ours bruns, dans lesquels la réponse inflammatoire a été distinguée par la présence de nombreux éosinophiles dans l'infiltration périvasculaire et parmi les cellules infiltrées diffusément dans Ie parenchyme. Chez les deux espèces des ours, des corps d'inclusion ont été trouvés seulement dans les cellules de Purkinje du cervelet. On a discuté l'épizootiologie de la rage dans une région où des ours sont nombreux, avec la conclusion qu'il y a dans la salive des renards rabiques une quantité de virus insuffisante pour infecter les ours. é ó í á ú Spanish title: Rabia en osos, Ursus spp., infectados experimentalmente, con anotaciones epizootológicas Spanish abstract: Diez osos negros, Ursus americanus Pallas, y tres osos pardos, U. arctos Linea, se infectaron con una estirpe campal de virus rábico aislada de zorros en Alasca. Los resultados de la experiencia permiten reconocer que los osos presentan una resistencia mayor frente a la infección rábica que los carnívoros cánidos, pues no se pudieron infectar con menos de 1.000 DML50 de virus rábico. El virus era muy raras veces identificable en las glándulas salivales de los osos enfermos de rabia. Se describen sucintamente la clínica y patología de la rabia en los osos. Las modificaciones inflamatorias en el cerebro eran muy graves en el oso pardo y se distinguían por la frecuencia de los leucocitos eosinófilos en los infiltrados perivasculares e hísticos. En ambas especies solo se hallaron corpúsculos de inclusión en las células de Purkinje. Se discute la epizootología de la rabia en la península de Alasca, donde es frecuente Ia presencia de osos. Los resultados señalan que los zorros eliminan poco virus con la saliva y casi nunca en cantidad tal que fuese suficiente para infectar los osos.

Dynamics of the Arctic Fox Population on St. Lawrence Island, Bering Sea

English abstract: We hypothesized that the arctic fox, Alopex lagopus (Linnaeus), population on St. Lawrence Island was cyclic and that its fluctuations in size. structure, and productivity were correlated with the relative size of the population of northern voles, Microtus oeconomus Pallas, the primary prey. Based on a nine-year study, we determined that the variations in size of the fox and vole populations were similar, but they both were of low amplitude and not closely correlated. The high pregnancy rate (mean, 86%/yr) and numbers of young conceived (mean, 11.5/pregnancy) did not vary significantly among years, probably because of the consistently abundant and diverse food supply available to the foxes. The age composition of the trappers' catch of foxes each winter also was comparatively stable, but it was closely correlated with the size of the vole population in the previous summer. The survival of the young foxes during the summer probably was dependent on the availability of the voles, The composition of the catch also appeared to be influenced by immigration of faxes from the adjacent continents via the pack ice. French abstract: Nous avons émis I'hypothèse que la population du renard arctique, Alopex lagopus (Linnaeus), sur I'île Saint Lawrence était cyclique el que les fluctuations concernant sa tailIe, sa structure et sa productivité étaient corrélées à la taille relative de la population du campagnol nordique. Microtus oeconomus Pallas, sa principale proie. En nous appuyant sur une étude menée sur neuf ans, nous avons déterminé que les variations dans la taille des populations du renard et du campagnol étaient semblables. mais que toutes deux avaient une faible amplitude et n'étaient pas corrélées de façon étroite. Le taux de grossesse élevé (moyenne 86 p. cent/an) et Ie nombre dc petits conçus (moyenne 11,5/grossesse) ne variaient pas de façon significative au cours des ans, probablement à cause de I'abondance et de la variété de sources de nourriture pour les renards. La composition d'âge des prises des trappeurs était également stable d'un hiver à I'autre, mais elle était corrélée de façon étroite avec la taille de la population dc campagnols au cours de I'été précédent. La survie des renardeaux au cours de I'été dépendait probablement de la disponibilité des campagnols. La composition des prises semblait aussi être influencée par I'immigration des renards venant des terres continentales adjacentes par la voie de la banquise.