Epizootic of Rabies in Alaska 1945-47 By RALPH B. WILLIAMS* Interior R ABIES, for many years in the Territory of Alaska, has occurred in both epizootic and enzootic form. No figuires are available as to the annual incidence of the disease among domestic animals and the wildlife in Alaska, but the following account will give some idea as to the nature of the problem. During 1945-47 the disease was found to be widely distributed over a major portion of Interior Alaska north of the Alaska Range, and from the Bering Sea and Arctic Ocean into adjacent Canada. This epizootic of 1945-47 was first reported in June, 1945, at Platinum, Goodnews Bay on the Bering Sea Coast. Red foxes exhibiting symptoms of "madness" were said to have attacked human beings, dogs, cats and even automobiles. During the following few months additional reports were received from various points along both Kuskowim and Yukon River Drainages. At this point it should be stated that reporting of rabies and other encephalitides of canines is exceedingly poor, therefore, it is not possible to give illustrations of the geographic distribution of the disease in the various species during the outbreak. Additional reports of rabies were received from time to time and it was possible to trace the spread up both the Yukon and Kuskokwim Rivers into the upper reaches of the Porcupine River, Black River, Salmon Fork area and Old Crow, after which no further report was received from this area. It is possible that we were concerned with a series of coincidental enzootics and that the disease discovered was not epizootic in nature. After the cessation of epizootics found in the Old Crow area, later reports indicated that the spread may have continued westward from the Yukon River Valley. The disease reached the Seward Peninsula and spread up the Arctic Coast to the Kobuk River during 1946-47, where it raised havoc among the sled dogs. Mr. F. Leigh Kerr, Senior X-Ray Technician, Alaska Territorial Department of Health, who traveled along the Arctic Coast reported that the dogs were so reduced in number as to cause an economic hardship among the Eskimos along the Kobuk River. In this section the sled teams are used rather extensively in freighting operations. Field Information. The reports from the field stated that foxes, dogs, wolves, and coyotes were susceptible to the disease. There did not appear to be any seasonal differences in its prevalence, but rather the morbidity rates depended on the concentrations of susceptible species. During the epizootic, dead foxes and those exhibiting symptoms of "madness" were found scattered over the localized tundra, and occasionally wolves and coyotes were found sick or dead. The outbreak, as with previous epitootics, followed a typical pattern in that usual source of infection to the * Director, Division of Public Health Laboratories, Alaska Territorial Department of Health, Juneau, I Alaska. - v [136]
Canadian Journal ot Comparative Medicine Rabies in Alaska Jneo 1949 [137r Vol. XIII, No. 6 l 1937 dogs was their being bitten by a "mad" fox which entered the villages and attacked them. Dogs bitten developed typical clinical symptoms, and if other dogs were attacked by such animals the infection was spread through the medium of the bite. Dogs tethered near to infected dogs did not develop symptoms as may be the case in some other diseases of northern dogs. Human beings exposed to infection were administered the human antirabies treatments. No deaths were reported from this cause among human beings. Great numbers of dogs were destroyed when they exhibited symptoms of encephalitides. George A. Williams, D.V.M., Assistant Alaska Territorial Veterinarian, found evidence that the disease was typical of clinical rabies in the dogs, but numerous animals suffering with other diseases were indiscriminately killed by their owners. Observations indicate that the affliction occurred in areas of Alaska when there were peak fox populations. Rabies in Foxes Experience in Alaska indicates that the members of the genera Vulpes and Alopex are the primary disseminators of the disease. They act as a reservoir of rabies infection and form the nucleus of many outbreaks. The disease as found among the foxes in Alaska presents nervous symptoms which are different from those encountered in the typical rabid dog. The furious form is milder in its manifestations and the foxes do not make the extensive journeys so characteristic of the rabid dog with this form of rabies. This may account to some degree for the rather
Canadian Journal of Raisi lsajune, 1949 [1381 Comparative Medicine Rabies in Alaska Vol X, No. slow extension of the disease in foxes from one area to another. The adult foxes usually establish localized territories in which they remain, and when affected they appear to maintain these claims even during the symptomatic stages. It is during these stages that the local foxes enter the villages and attack the dogs. The foxes are unafraid of man and have been known to attack automobiles and tractors in motion. Experience shows that affected foxes are seldom reported. The majority die without being found by man. It is, however, a common practice to salvage the skins of dead foxes found on the tundra. The process of skinning is a hazardous procedure if the foxes have died of rabies. The first cut is made around the gums, and the mouth is held open by the bare hands; the dissection is carried out by means of a small knife and traction with the fingers. The skin is pushed and pulled backward over the body and each limb and the tail is pulled free. It seems likely that this procedure when repeated as often as it must have been no doubt caused infections. The carcasses of these animals are disposed of on the open tundra with no attempt to destroy them or submit heads for laboratory examinations. There would, in most instances, have been no one available to diagnose rabies should a trapper have contracted the disease in this manner. We doubt that the two cases in the 1942-44 outbreak, which were diagnosed as rabies by physicians, would have been recognized as such by laymen. Nor is it likely that the Eskimos of Wainwright and Noorvik would have associated the final illness and death of natives with the healed wounds inflicted previously by wolves. Many of the foxes which do approach the villages, or attack human beings or. their dog teams, are killed and discarded without removal of the heads for laboratory examination. If it were possible to make an estimate it would be found that only a very small fraction of the cases that occur in the fox ever becomes a matter of record. It has been clearly, demonstrated, however, that where epizootics have been present for sometime they appear to reduce the fox population to an extremely low level. This was reported by Adolph Murie (1944) (1) that "in the spring of 1922 a trader told 0. J. Murie that foxes had been unusually abundant in the lower Kuskokwim country in 1907, and that they had died of a disease which was thought to be rabies, since several dogs bitten by the foxes had died." The control of fox rabies in Alaska presents a major problem because of the relationship of rabies in the dog and the possible involvement of men. No attempts to prevent the further progress of the disease in foxes or other wild animals have been made in Alaska. Control Measures Prior to 1945 efforts to control rabies were directed only against the dogs in a given village. The methods employed were merely to tiedown or restrain the activities of the dogs, and all animals demonstrating nervous symptoms were shot. The actual control measures were left strictly to the owners. Control measures in Alaska and the related North country can not be based on the theory that rabies is fundamentally a disease of dogs, as has been the case in England, where elimination of the scourge has been reported to be completed. The disease in Alaska is primarily one of the
Journal Comparative Medicine Ra~bies in Alaqka June, Vol. XIII, No.6 [13901 L'39" Table I Specimen Species* Origin Negri Remarks No. bodies 1 Red Fox Central, Alaska Atypical inclusions 2 Red Fox Circle Hot Springs, Alaska + Trapper bitten 3 Red Fox Fairbanks, Alaska 0 4 Red Fox Crooked Creek, Alaska + 5 Red Fox Alatna, Alaska + 6 Wolf Central, Alaska + 7 Dog Steven's Village, Alaska + 8 Dog Steven's Village, Alaska + 9 Dog Steven's Village, Alaska 0 Autolyzed 10 Dog Steven's Village, Alaska 0 Autolyzed 11 Red Fox Ruby, Alaska o Child bitten 12 Red Fox Beaver, Alaska + 13 Dog Nenana, Alaska + 14 Red Fox Tolovana, Alaska 0 15 Coyote Big Delta, Alaska o Autolyzed 16 Red Fox Old Crow, Y.T., Canada 0 Autolyzed *Heads only were examined. foxes and other wild animals with occasional cases appearing among the dogs in the various villages. The disease is controllable and even eradicable in the domestic animals, but the problem of control of rabies in wildlife has aspects vastly different. It seems necessary to reduce the numbers of highly susceptible wild species in an enzootic area, by year round trapping, hunting, controlled poisoning and other means. Cooperation between Federal and Territorial Agencies as well as the white and native population is an essential feature of the control of the disease in the Arctic and Subarctic. During the 1945-47 outbreak Doctor G. A. Williams introduced vaccination as an additional measure for control in the central area where the highest incidence was reported. A large number of valuable sled dogs were vaccinated and the villagers were instructed as to how to carry on the program. This was the only action taken to prevent the spread of the disease and the loss of economically important dogs. No action was taken to control or reduce the disease among the wildlife. Collection of Specimens The reports indicating the presence of rabies among the foxes and other canines coupled with the requests for human antirabies vaccines stimulated the author to request the U. S. Fish and Wildlife Service, Juneau, Alaska, to brief their Wildlife Agents on the collection of heads from suspicious animals for laboratory examination. All specimens studied in this report were collected by Ray Woolford, Wildlife Agent, U. S. Fish and Wildlife Service, Fairbanks, Alaska. Red Fox No. 1.-This animal was killed after it had attacked a sled dog on October 10, 1945 at Central, Alaska. The head was removed and forwarded to Juneau, Alaska, for laboratory examination. The dog attacked was shot on October 29, 1945, after he developed nervous symptoms
[140] Canadian Journal of Rabies in Alaska Je, 1949 Comparative Medicine Vbeol. iniij No. 6 and, to quote the owner, he was "definitely off the beam." Instructions to hold the dog until death and request for its head were ignored. The owner was said to have buried the carcass. Fox, Dog, Wolf and Coyote Heads No.'s 2 to 16.-These heads were collected over a period of time and held at sub-zero temperatures until delivery to the Division of Public Health Laboratories on February 27, 1946. Wolf No. 6 was shot December 23, 1945 at Central, Alaska, but the exact dates of the other individual collections were not known. Neither were the circumstances surrounding their collection known, other than that the animals exhibited nervous symptoms. The shipment contained 8 foxes, 5 dogs, 1 wolf and 1 coyote. Table I gives the points of collection of these specimens. Fox No. 2 bit a trapper at Circle Hot Springs and Fox No. 11 bit a child at Ruby, Alaska. Both were taken to Fairbanks, Alaska where human antirabies treatments were administered. Specimens No. 7 to 10 were a portion of some 24 dogs which died from illness suggestive of clinical rabies in Steven's Village. Some 50 dogs had died or were destroyed by June 20, 1946 at this village. Microscopic Examinations Numerous smears and impression preparations of Ammon's horn of the hippocampus, cerebral and cerebellar cortex were made from the brain tissue of each specimen received. These were stained by Seller's (1927) (2) method. The stained impressions of the brain tissue of Fox No. 1, contained inclusion bodies, but autolysis made it impossible to distinguish their true character with any certainty. It was possible, however, to demonstrate inclusions with characteristics indistinguishable from Negri bodies in foxes No. 2, 4, 5, and 12; dogs 7, 8, and 13 and wolf No. 6. No inclusions were found in the remaining specimens, some of which were received in various stages of decomposition. Table II Inoculum-Brain tissue mouse (Red Fox 1).03 cc x 1-10 Lockes solution. Experimental Route of No. No. Days Animal Inoculation Died _ Negri bodies 1st Symptoms Death Mice Intracerebral 8 8 8-10 10-12 + Animal Inoculations Portions of the brain tissues obtained were suspended in neutral glycerine. They were forwarded to the late Doctor R. G. Green, at the University of Minnesota, for inoculaton into mice. The glycerolated specimens were ground up on arrival and diluted 1-10 in Locke's solution. The tissues from Fox No. 1, were badly autolyzed, and well overgrown with bacteria of a resistant type. The virus did not produce Negri bodies readily. The organisms present when inoculated into mice were pathogenic and produced an infection which hid any symptoms of rabies. It was necessary to get rid of the contamination before the injection of additional mice. The virus on purification, however, killed mice regularly in ten to twelve days with the production of Negri bodies. Table II shows
Canadian Journal of Rabi Alak June, 1949 Comparative Medicine es i aska Vol. XIII,N..6 [N'1J [1A41 the results of the inoculation of purified mouse brain tissue. Table III shows the results of the inoculations of mice with brain tissue from the specimens which had not undergone marked changes resulting from delays in transit. The mice showed tremors, paralysis, convulsions and complete prostration which terminated in death. The mortality rates can be found in Table IV. The average time of death was between 12 and 16 days, except for the virus from Dog No. 13 and Fox No. 14 with which there were prolonged periods, averaging from 19.8 to 16.8 days with only seven of the eight mice inoculated dying by the 24th day. No mice were held more than 24 days after inoculations. Table Ill Inoculum-brain tissue diluted 1-10.03 cc Lockes solution Route-Intracerebral. March 6, 1946 Source of virus-specimen No. 2 4 5 6 7 8 11 12 13 14 3-16... 3-17... 1 1 3-18.2 3-19...1 2 1 1 2 1 1 3-20.o5 2 1 2 1 4 2 3-21...1 1 1 1 1 4 4 2 1 3-22...3 4 3-23...3 2 1 1 3-24.1 1 1 3-25... 3 3-26... 3-27... 2 3-28... 1 Total Dead... 8 8 8 8 8 8 8 8 7 7 Negri Bodies... + + + + + + + + + + Chart showing dates and number of mice dead. Discussion The evidence presented established the fact that rabies is wide spread over interior Alaska and reached epizootic proportions during 1945-47, after which time it subsided as appears to be characteristic of the disease among wild animals. It is shown that the causative virus is well established in wildlife population and rabies in the fox presents a major problem in control. This evidence is supported by the recent studies of P. J. G. Plummer (3,4) in the Canadian Northwest Territories. His studies showed the presence of rabies has been established at Baker Lake, Aklavik, Frobisher Bay and Cambridge Bay, areas representative of Eastern, Central and Western parts of the Northwest Territories. The fox and wolf was found to be affected and, as in Alaska, the incidence among the wild species is unknown. The wild animals, in Alaska, especially the fox, constitutes a reservoir of infection for dogs and other species, including man. The studies thus far made indicate that the investigations should be continued to determine the incidence of rabies and to differentiate it from the other encephalitides of canines which have been collectively known under the term "Northern Dog Disease."
A]Canadian Journal of Raisi lsajune, 1949 I[142] 'JComparative c^mp^tjueior Medicine Rabies - in AlaskaVo.IN. Vol. XlIi. No. 6 Authentic records are not kept in the vast unsettled Arctic and Subarctic, therefore, epidemiological studies present impossible tasks in the gathering of evidence of past and present epizootics and human infections Ḋue to the existing transportation facilities in the Arctic and Subarctic, prior to this outbreak we have experienced considerable difficulties in obtaining suitable specimens for laboratory examination. Dogs and other species which succumb to the disease are not buried or destroyed. The burning of carcasses presents a problem because of the Table IV AVERAGE MORTALrIY PERIOD IN MICE SOURCE OF VMUS AND PLACE OF ORIGIN FOX FOX FOX WOLF DOG Circle Hot Springs Crooked Creek Alatna Central Steven's Village No. Days No. Days No. Days No. Days No. Days 8 15.8 8 15.1 8 12.6 8 15.7 8 14.8 DOG FOX FOX DOG FOX Steven's Village Ruby Beaver Nenana Tolovana No. Days No. Days No. Days No. Days No. Days 8 14.2 8 13.5 8 13.7 7 19.8 7 16.8 1 I~~~~~~~~~~~~~~~~~~~~~~~~ lack of fire wood through many parts of the Arctic and due to the permafrost over much of Interior Alaska, burial is out of the question. What effect variations in sub-zero temperatures under Arctic conditions may have on the virus in animal tissues is not known, but desiccation occurs to some degree in the tissues. Experimentation to show if there is any loss of infectivity under such conditions may be an important consideration in the application of control measures. Studies should include cross immunity tests with the rabies virus isolated in the Arctic, the street virus strains of the United States and the Pasteur fixed rabies virus, to determine immunological relationships. The case reports from Arctic and Subarctic Alaska indicate that the rates among human beings appear to be very low. The heavier and more protective nature of the wool and fur clothing worn in these latitudes, along with the lack of adequate medical facilities in many sections and the frequency or infrequency with which salivary glands are invaded by rabies virus in Arctic and Subarctic animals, infected in nature, may account to some degree for the low rates. The ability of the rabies virus isolated to invade the salivary glands of susceptible species was not demonstrated by laboratory methods in this outbreak. Summary 1. The problem of rabies in Alaska has been presented, showing that during the 1945-47 epizootic it was possible to demonstrate the disease in 7 foxes, 3 dogs and 1 wolf by clinical and laboratory examination. 2. Evidence presented indicates that foxes may be the reservoir of infection in Alaska.
Jun., 1949 ri3i Canadian Journal of Rabies in Alaska Vol. XIII, No.6 13 Comparative Medicine 6 '' 3. The disease seems well established in wild life, and control measures may have to be directed against foxes and other species during outbreaks. Acknowledgements Thanks are due Miss Helen E. Walsh, Alaska Territorial Department of Health and Dr. R. G. Green, University of Minnesota for technical assistance in this study, to Mr. Jack O'Connor and Mr. Ray Woolford, U. S. Fish and Wildlife Service in the collection of specimens and to Dr. George A. Williams, Assistant Alaska Territorial Veterinarian for reports as to the clinical nature of the disease. References 1. MURIE, ADOLPH, 1944. The Wolves of Mi. McKinley U.S. Nat. Park Fauna Ser., 5: 211. 2. SELLERS, T. F. 1947. A New Method of Staining Negri Bodies of Rabies Am. J. Pub. Health, 17: 1080-1081. 3. PLUMMER, P. J. G. 1947. Preliminary Note on Arctic Dog Disease and Its Relationship to Rabies. Can. J. Comp. Medicine 11: 154-160. 4. PLUMMER, P. J. G. 1947. Further Note on Arctic Dog Disease and Its Relationship to Rabies Can. J. Comp. Medicine 16: 330-334. Tuberculin Testing in Restricted Areas TO: District Veterinarians and all Full-Time, Part-Time and Accredited Veterinarians. Ottawa, May 7th, 194,9 O N AND after May 9th, 1949, all herd tests of cattle within restricted areas must be conducted under the restricted area plan by either full or part-time. Divisional veterinarians. Accordingly, no charge may be made for testing cattle under the restricted area or accredited herd plan. Cattle intended for export, proceeding from herds, the health status of which meets the requirements of United States Bureau of Animal Industry, order 379, of April 5th, 1949, effective May 9th, 1949, may be tuberculin tested by accredited veterinarians for export purposes. Before signing or endorsing export health charts, Divisional veterinarians must take particular care to ascertain that the health status of the herd from which the cattle to be exported originate, is in accordance with the requirements of United States Bureau of Animal Industry, order 379, of April 5th, 1949. -T. Childs, Veterinary Director General.