Soil samples were collected from around fresh and year-old bison carcasses and areas not associated with known carcasses in Wood Buffalo National Park during an active anthrax outbreak in the summer of 2001. Sample selection with a grid provided the most complete coverage of a site. Soil samples were screened for viable Bacillus anthracis spores via selective culture, phenotypic analysis, and PCR. Bacillus anthracis spores were isolated from 28.4% of the samples. The highest concentrations of B. anthracis spores were found directly adjacent to fresh carcasses and invariably corresponded to locations where the soil had been saturated with body fluids escaping the carcass through either natural body orifices or holes torn by scavengers. The majority of positive samples were found within 2 m of both year-old and fresh carcasses and probably originated from scavengers churning up and spreading the body fluid-saturated soil as they fed. Trails of lesser contamination radiating from the carcasses probably resulted from spore dissemination through adhesion to scavengers and through larger scavengers dragging away disarticulated limbs. Comparison of samples from minimally scavenged and fully necropsied carcass sites revealed no statistically significant difference in the level of B. anthracis spore contamination. Therefore, the immediate area around a suspected anthrax carcass should be considered substantially contaminated regardless of the condition of the carcass.

Anthrax outbreaks in northern Canada have implications for ongoing recovery efforts for the threatened wood bison and may pose a health risk to humans, other wildlife, and domestic livestock. RWED and WBNP maintain Anthrax Emergency Response Plans (AERPs) for their respective jurisdictions. An AERP is a pre-planned logistical framework for responding effectively and rapidly to an outbreak so as to minimize spread of the disease, reduce environmental load of spores available for future outbreaks, and minimize risk to public health. In this paper, we describe the main components of an AERP and outline areas for future research.

Aims: To investigate methods of improving anthrax spore detection with PLET.Methods and Results: Comparisons were made of PLET and blood-supplemented PLET to recover and distinguish spores of a variety of Bacillus species. Heat and ethanol purification of spores, and spore extraction from soil with water and high specific gravity sucrose plus non-ionic detergent, were also carried out.Conclusions: PLET was more selective and suitable than blood-supplemented PLET for detection of anthrax spores in the environmental specimens. However, PLET is not an optimal spore recovery medium. Purification of spores with ethanol was as effective as heat purification. High specific gravity sucrose plus detergent extraction solutions may be more sensitive than extraction with water.Significance and Impact of the Study: This study highlights shortcomings with the standard PLET isolation of anthrax spores and describes ways in which the procedure may be improved.

Aims: To determine the level of anthrax spore contamination in endemic regions of northern Canada between outbreaks. Methods and Results: Bacterial endospores were extracted from specimens via flotation and cultured on selective PLET medium. Of 588 environmental specimens collected, 11 (1.9%) contained viable anthrax spores. Conclusions: High environmental concentrations of anthrax spores in northern Canada appear limited to scavenger faeces and anthrax carcass sites. Burial and cremation appear equally effective at removing anthrax spores from the immediate environment, though cremation may be improved by re-burning cremation sites containing unburned animal hair. Significance and Impact of the Study: This study describes an effective anthrax spore detection system. It provides the first bacteriological evidence that mammalian scavengers can disseminate anthrax spores in northern Canada, and its results may be compared with future environmental studies of untreated anthrax carcass sites to help improve government response plans.

Between 1962 and 1971, six outbreaks of anthrax occurred in the bison herds of the Northwest Territories and northern Alberta.In response, the federal Health of Animals Branch dispatched staff veterinarians to oversee carcass disposal operations and later to take part in bison depopulation and vaccination programs.Recently, a collection of documents from that agency concerning the outbreaks was discovered in the federal archives.The collection includes field reports from the veterinarians that provide valuable, detailed, first-person accounts of the outbreaks and later programs, information which has generally been lacking in the published literature.The reports identify at least 1102 bison that died of anthrax during the six outbreaks, dozens more than reported previously.They also indicate that the disease spread into Wood Buffalo National Park in 1963, rather than in 1964, as reported previously.A minimum of 598 healthy bison were also killed in depopulation programs aimed at preventing the spread of anthrax into the Park, even though anthrax carcasses had already been discovered within the Park and the targeted regions would be repopulated within weeks.Coverage and revaccination rates were low throughout the vaccination program, and a further 828 bison died during the vaccine roundups.

Baseline levels of organochlorine contaminants were established for Willow Ptarmigans (Lagopus lagopus) from two coastal areas in the western Canadian arctic. Egg, muscle and liver samples were tested for the presence of 21 organochlorines and 17 PCB congeners. All contaminants were below detection limits (< 0.1 ng/g for organochlorines and < 0.2 ng/g for PCB congeners) in the analysed eggs. Alpha-hexachlorocyclohexane, gamma-HCH and QCB were the only compounds detected in the muscle samples. In addition to these compounds, OCS, trans-Chlordane, trans-Nonachlor, p,p(1)-DDE, HC Epox and PCB #66/95 were detected in the liver samples. The level of contaminants detected in the ptarmigan studied was low. The implications of low-level contamination in ptarmigan and their sensitivity to contaminants is discussed in regard to their contribution to the arctic terrestrial food chain and their suitability as terrestrial ecosystem sentinel species in the Canadian Arctic.

During the first half of the century, the majority of anthrax outbreaks in Canada occurred in the southern portions of Ontario and Quebec and were often associated with pastures contaminated by effluent from textile industries dealing with imported animal materials. In 1952, introduction of Federal regulations requiring disinfection of these materials greatly reduced the incidence of anthrax in eastern Canada. Since 1962, domestic outbreaks of the disease have been reported almost exclusively in cattle in the western prairie provinces. Between 1962 & 1993, nine anthrax epizootics have been recorded in the bison herds of the Northwest Territories and northern Alberta resulting in the deaths of at least 1309 animals. During the northern epizootics there has been a strong sex bias in mortalities with the majority of carcasses being sexually mature bulls. The northern epizootics occur during drought conditions in the late summer, preceded by a wet spring, and end with the arrival of coolers weather. It has been hypothesized that stress factors associated with these meteorological conditions coupled with breeding stress during the late summer rut may predispose the bulls to infection. Alternatively, the meteorological conditions may work to concentrate anthrax spores in the environment into low lying wallows preferentially utilized by the bulls. Recent genetic analyses of Bacillus anthracis isolates from Canada and the United States have identified that, while closely related to isolates from domestic outbreaks, isolates from northern bison epizootics form their own distinct strain. This suggests that the establishment of anthrax in northern Canada was a singular event that occurred prior to the first recognized epizootic in 1962. A review of the agricultural history of northern Canada has identified several situations in the first half of the century which may have provided the opportunity for the transfer of anthrax from cattle to the indigenous bison.

Bacillus anthracis is the causative agent of anthrax, a serious and often fatal disease of wild and domestic animals. Central to the persistence of anthrax in an area is the ability of B. anthracis to form long-lasting, highly resistant spores. Understanding the ecology of anthrax spores is essential if one hopes to control epidemics. Studies on the ecology of anthrax have found a correlation between the disease and specific soil factors, such as alkaline pH, high moisture, and high organic content. Researchers initially suggested that these factors influenced vegetative anthrax bacilli. However, subsequent research has shown that vegetative cells of B. anthracis have very specific nutrient and physiological requirements and are unlikely to survive outside a host. Review of the properties of spores of B. anthracis and other Bacillus species suggests that the specific soil factors linked to epidemic areas reflect important environmental conditions that aid the anthrax spores in causing epidemics. Specifically, high levels of calcium in the soil may help to maintain spore vitality for prolonged periods, thereby increasing the chance of spores encountering and infecting a new host. Cycles of runoff and evaporation may collect spores dispersed from previous epidemics into storage areas, thereby concentrating them. Uptake of large doses of viable spores from storage areas by susceptible animals, via altered feeding or breeding behavior, may then allow the bacterium to establish infection and cause a new epidemic. Literature search for this review was done by scanning the Life Sciences Collection 1982-1994 using the keywords "anthrax" and "calcium and spore."

In July 1993 anthrax caused significant mortality in an isolated, free-ranging population of bison (Bos bison athabascae) west of Great Slave Lake in the Northwest Territories. There was no previous record of anthrax in this area. An emergency response was undertaken to reduce the scale of environmental contamination and dissemination of anthrax spores and hence to reduce the likelihood of future outbreaks. One-hundred-and-seventy-two bison, 3 moose (Alces alces), and 3 black bear (Ursus americanus) carcasses were found. Visual detection of carcasses was enhanced with the use of an airborne, remote infrared sensing camera mounted externally on a helicopter. Fifty-five percent of the carcasses were located in forested or shrub-covered sites where detection would not have been likely without the thermal imaging equipment. Carcasses were disposed of by incineration and the sites were decontaminated with formaldehyde. Application of formaldehyde to carcasses prevented scavenging. The outbreak occurred after a prolonged period of drying between April and mid-July 1993 which followed several successive years of flooding of bison habitat. The "spore concentration hypothesis" provides the most conservative explanation for the occurrence of anthrax under the observed conditions.