Studies on the Helminth Fauna of Alaska. XXVII. The Occurrence of Larvae of Trichinella spiralis in Alaskan Mammals

Publisher Website
Google Scholar
Abstract
Muscle tissue samples from 2433 Alaskan mammals, representing 42 spp., were processed by the artificial digestion method to determine the presence of larvae of T. spiralis. Larvae were found in 23 spp., and in 285 individual animals. Numbers of host-species examined and the percentages of infection found are as follows: 20 Ursus arctos, 50%; 23 Ursus americanus, 21.7%; Thalarctos maritimus 52.9%; 225 dogs, 45.3%; 8 Canis latrans 12.5%; 154 Canis lupus 33.1%; 76 Vulpes vulpes alascensis, 40.8% (first report of trichinosis in the red fox in arctic America); 222 Alopex lagopus 7.2%; 51 Mustela erminea arctica 35.3%; 2 Mustela rixosa eskimo 50%; 38 Gulo gulo 50%; 17 Felis lynx canadensis 23.5%; 53 Lepus americanus dalli 3.8%; 129 Citellus undulatus 0.8%; 94 Tamiasciurus hudsonicus 4.3%; 118 Lemmus sibiricus trimucronatus 0.8%; 49 Clethrionomys rutilus dawsoni 4%; 57 Microtus miurus muriei 1.8%; 113 Ondatra zibethica 0.9%; 29 Castor canadensis 3.4%; 49 Delphinapterus leucas 2%; 310 seals of genus Phoca, 0.6%; 126 Erignathus barbatus 0.8%. Those examined and found negative were: 18 shrews of genus Sorex; 18 Martes americana actuosa; 43 Mustela vison; 7 Lutra canadensis; 20 Enhydra lutris; 13 Ochotona collaris; 9 Marmota m. caligata; 1 Glaucomyssabrinus; 7 Dicrostonyx torquatus rubricatus; 10 Microtus pennsylvanicus, 234 Microtus oeconomus; 3 Erethizon dorsatum myops; 15 whales of family Balaenidae; 51 Odobenus rosmarus divergens; 4 Eumetopias jubata; 101 Callorhinus ursinus cyanocephalus (C. M. Herman s data). In addition to the above, 18 ungulates examined were negative; of 261 Rattus norvegicus, 10.7% per positive; 102 birds representing 17 spp. were examined, and of these one Pomarine jaeger was found to harbor larvae, but this is regarded as erroneous until confirmed experimentally. Five outbreaks of trichinosis in man in Alaska are cited. Intradermal tests were made in the following localities: 232 on St. Lawrence Island, 9% positive; 71 in Wainwright, 28% positive; 17 in Anaktuvuk Pass, 5.8% positive. Data concerned with tests performed on man in Canada are cited. It is suggested that the occurrence of T. spiralis in man, in domesticated animals, and man''s commensals, is independent of the natural cycle in wild mammals. It is believed that man in Alaska usually becomes infected through failure to cook properly the flesh of wild mammals used as food. Much comparative data on occurrence of T. spiralis in wild mammals in Eurasia is presented. Modes of possible transmission of the parasite are discussed. Small mammals may become infected through eating carrion. It is thought that in Alaska carnivores most frequently become infected with T. spiralis through eating carcasses of other carnivores. Further study is planned.
Keywords