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Rabies in insectivorous bats of western Canada
Abstract and Figures
A total of 1,745, 362, and 536 bats collected in Alberta, British Columbia, and Saskatchewan, respectively, was tested for rabies virus between 1979 and 1983. Only one (0.1%) of 769 bats collected at random from buildings was infected with rabies virus in contrast to 95 (5%) of 1,874 symptomatic, rabies-suspect bats submitted for testing. The pattern of infection in the rabies-suspect bats was similar in Alberta and Saskatchewan, but differed in British Columbia. Rabies was diagnosed in four species of bats in each of Alberta and Saskatchewan, but in seven species in British Columbia. Annual prevalence in rabies-suspect bats was similar in colonial species within each province. Rabies was found rarely in suspect little brown bats (Myotis lucifugus) (less than 1%). In suspect big brown bats (Eptesicus fuscus), the prevalence was low in Saskatchewan (3%), moderate in Alberta (10%), and high in British Columbia (25%). Big brown bats accounted for over 55% of the rabid bats detected in each province. Annual prevalence reported in silver-haired bats (Lasionycteris noctivagans) and hoary bats (Lasiurus cinereus) was variable in all three provinces. Rabies is enzootic in northern insectivorous bats.
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... And while a recent report of Canada-wide rabies surveillance data, which includes some of the data in this study, found that big brown bats have the highest prevalence of rabies nationally (17.1%) (Segers et al. 2021), these estimates are unlikely to reflect actual rabies prevalence. This is due to both the mode of sampling (i.e., passive) and that infection with rabies makes bats much more likely to be encountered by people than other causes of death such as dehydration (Pybus 1986;Klug et al. 2011). Specifically, passive sampling is unable to properly assess rabies prevalence because rabid bats exhibit behaviors that will bring them into contact with humans (Pybus 1986;Klug et al. 2011). ...
... This is due to both the mode of sampling (i.e., passive) and that infection with rabies makes bats much more likely to be encountered by people than other causes of death such as dehydration (Pybus 1986;Klug et al. 2011). Specifically, passive sampling is unable to properly assess rabies prevalence because rabid bats exhibit behaviors that will bring them into contact with humans (Pybus 1986;Klug et al. 2011). For example, bats with furious rabies may be hyperactive and aggressive, while bats with paralytic rabies may be placid and appear friendly or tame, both making them more likely to be detected by people (Fenton et al. 2020). ...
Identifying causes of wildlife mortality can yield an understanding of the factors that impact wildlife health. This is particularly significant for species that are facing population declines because this information can inform conservation and management practices. We evaluated causes of mortality for bats in British Columbia, Canada, submitted to the provincial veterinary laboratory between 2015 and 2020, and assessed whether cause of death varied by species and (or) was associated with bat characteristics (e.g., sex and body condition). Of the 275 bats included in this study, the most frequent cause of death was cat depredation (24%), followed by blunt force trauma (23%). Bats that died by cat depredation tended to be in good body condition compared with those that died from other causes, and male bats were more likely to die from blunt force trauma compared with females. Emaciation was also an important cause of mortality (21%) and 8% of bats died due to rabies, with the greatest rabies prevalence in big brown bats (Eptesicus fuscus (Palisot de Beauvois, 1796)). Our results demonstrate the potential burden of cat depredation on healthy bats and highlight the need for strategies to decrease cat depredation to support healthy bat populations.
... Although mesocarnivores such as coyotes (Canis latrans), foxes (Urocyon cineroargenteus, Vulpes spp.), raccoons (Procyon lotor), and skunks (Mephitits mephitis, Spilogale putorius) constitute other RABV reservoirs in North America [1], none are currently known reservoirs in Washington State or bordering jurisdictions (British Columbia, Idaho, and Oregon) [4,13,17]. Trends in bat rabies surveillance in North America have been described previously [18][19][20][21][22][23][24], but the most recent description of bat rabies epidemiology in the Pacific Northwest dates back to 1985 [25,26]. ...
Background:
Rabies is a zoonotic viral disease that can affect all mammals. In the United States, the majority of human rabies cases are caused by bats, which are the only known reservoirs for rabies virus (RABV) in Washington State. We sought to characterize bat RABV epidemiology in Washington among bats submitted by the public for RABV testing.
Methods:
We examined temporal and spatial trends in RABV positivity (% positive) for taxonomically identified bats submitted to diagnostic laboratories during 2006-2017. For a subset of Myotis species, we evaluated sensitivity and predictive value positive (PPV) of morphological identification keys, using mitochondrial markers (cytochrome b) as a reference. For bats tested during 2000-2016, we analyzed RABV positivity by circumstances of encounters with humans, cats, and dogs.
Results:
During 2006-2017, RABV positivity for all bat species was 6.0% (176/2,928). Among species with ≥100 submissions, RABV positivity was 2.0%-11.7% and highest among big brown bats (Eptesicus fuscus). An increasing trend in annual positivity was significant only for big brown bats (P = 0.02), and was circumstantially linked to a geographic cluster. Sensitivity and PPV of morphological identification keys was high for M. evotis but varied for M. lucifugus, M. californicus, M. yumanensis, and M. septentrionalis. A positive RABV result was significantly associated with nonsynanthropic species, abnormal behavior, abnormal hiding, injury, biting, found in a body of water, found alive, found outdoors, and caught by a dog.
Conclusion:
Monitoring passive RABV surveillance trends enables public health authorities to perform more accurate risk assessments. Differences in temporal and spatial trends in RABV positivity by bat species indicate the importance of collecting taxonomic data, although morphological identification can be unreliable for certain Myotis species. Current public health practices for RABV exposures should be maintained as RABV infection in bats can never be excluded without diagnostic testing.
... Totalt 1882 flaggermus ble testet hvorav ingen testet positivt (Whitby et al. 1996). Andre studier fra USA og Spania har vist at prevalensen av viruspositive flaggermus kan ligge fra 0,1 % til 3 % (Trimarchi et al. 1977, Pybus 1986, Steece et al. 1989, Serra-Cobo et al. 2002, men at prevalensen av antistoffer i perioder hos enkelte kolonier kan vaere mye høyere (figur 4). Det har også vaert spekulert i om kliniske utbrudd kan ses i sammenheng med ulike stressfaktorer (Rønsholdt et al. 1998). ...
... For example, among bats of several species tested in Alberta, more than 84% were young animals born that year (Dorward et al., 1977). Only occasionally, E. fuscus bats were found rabid in winter (Pybus, 1986). ...
Among mammals, bats are second only to rodents in their number of species. The order is subdivided into two suborders: flying foxes (Megachiroptera) that inhabit the Old World tropics and the smaller-bodied bats (Microchiroptera) that are distributed globally, except in Antarctica. Rabies is described in representatives of both suborders on all continents. Given the issue of size alone, one can expect a greater absolute number of rabid bats to account for disease prevalence as well as a greater density of the species occupying any given space, compared with larger-bodied carnivores. Considering the variety of divergent lyssaviruses, the order Chiroptera is proposed as being primarily affected during adaptation of plant and arthropod rhabdoviruses to mammalian hosts. Presumably, adaptation occurred somewhere in the Old World, perhaps in Africa or Eurasia, where most divergent non-RABV lyssaviruses are found. The ecologic advantages offered by flight enhance the potential for invasion of new areas and rapid dispersal of viruses by bats, much more readily than by terrestrial mammals. Two human cases of Australian bat lyssavirus infection are described to date and are discussed in this chapter.
... El primer caso de rabia en murciélagos no hematófagos fue reportado en Estados Unidos en 1953 en un niño atacado por un murciélago insectívoro 21,22 . En este país, 30 de las 39 especies presentes de murciélagos, están infectadas con el virus rábico y 21 de los 36 casos humanos registrados, entre 1981 y octubre de 1997, fueron debidos a variantes virales circulantes en murciélagos no hematófagos 21,23 . La prevalencia de anticuerpos contra el virus de la rabia en murciélagos oscila entre el 10,3% en Perú, hasta el 32 %, en México. ...
Introduction: Rabies is fatal zoonoses caused by an RNA virus of the gender Lyssavirus, it is transmitted to humans through the saliva of infected animal bite, contamination of an open wound, scratch, abrasion or laceration of a mucous membrane or infected nervous tissue. It has been found further transmission to humans by inhalation of rabies virus present in aerosol suspended in the air of caves where bats live in large numbers, as well as in laboratory accidents and by transplanting organs infected with the virus. This penetrates from the injury to the nerve endings and by retrograde axonal transport enters to the Central Nervous System whose commitment explains the clinical manifestations in its encephalitic and paralytic forms, the latter of which is characterized by loss of force initiated in the bitten limb and spread to the other limns as a flaccid paralysis, resembling a Guillain Barré syndrome (GBS). Objective: To present a case of a patient female, resident from a urban area of Barrancabermeja, died of rabies, whose clinic picture was diagnosed as a GBS and necropsy revealed a rabies encephalitis. Results: Adult female with clinical features of flaccid quadriparesis, dysphagia, and dyspnea, diagnosed as GBS and hospitalized in the intensive care unit of a health institution level III of the city of Bucaramanga, who died 23 days after starting his neurological symptoms. By questioning her family it was established a bat bite 2 months before and autopsy determined rabies encephalitis. Discussion: This report seeks to draw attention on a new episode of human rabies transmitted by bats in an urban area of the department of Santander, Colombia to carry out preventive activities to prevent the occurrence of new cases and alert medical personnel to act diligently and early to any possible rabies accident, and that improper handling of these can contribute to a new case of fatal disease. Also, given the frequency of cases of GBS in our hospitals to bear in mind in its differential diagnosis, the rabies in its paralytic form and insist on a history of being bitten by bats or other animals thus have been months or even years before. Salud UIS 2010; 42: 139-151.
... Between 2001 and 2009, the proportion of rabid bats was highest in the fall (15.6%). The apparent seasonality of bat rabies during the study interval is consistent with other reports (Constantine 1967; Pybus 1986; Burnett 1989; Mondul al. 2003; Blanton et al. 2007; Balsamo et al. 2009). Such studies demonstrate an overall increasing trend in the proportion of rabid bats from the lowest values in winter months to a peak in the late summer or fall. ...
Rabies remains an important public health concern in the United States, with most human cases associated with bat rabies virus variants. Cases of rabies virus (RV) infection in bats are widely distributed across the continental United States and elsewhere in the Americas. In this retrospective study, data on bats submitted to state laboratories for RV diagnosis between 2001 and 2009 were analyzed to investigate epidemiological trends in the United States. Season, region, and roosting habits were the primary risk factors of interest. During the study interval, more than 205,439 bats were submitted for RV diagnosis, and 6.7% of these bats were rabid. Increased odds of a submitted bat being rabid were associated with species that exhibit inconspicuous roosting habits, bats originating in the Southwest, and bats submitted for diagnosis during the fall. Periodic analysis of zoonotic disease surveillance is recommended to detect changes in trends regarding geographic distribution, seasonal fluctuations, and host associations; this is particularly necessary, as existing trends may be influenced by climate change or other emerging factors.
Among zoonotic diseases recognized in bats, rabies is one of the best studied, due in part due to its long history of investigation, and because of the significance of rabies for public health. Defined as an acute progressive encephalitis, rabies is caused by a diversity of viruses included in the genus Lyssavirus. Bats are the principal reservoirs for the majority of these pathogens. In the New World, bats maintain circulation of numerous phylogenetic lineages of only one species, Rabies virus. In contrast, Old World bats harbor circulation of several other lyssaviruses. Surveillance records and applied research demonstrate that bats develop rabies and succumb to the disease as do other mammalian hosts. However, circulation patterns of lyssaviruses in bat populations are different from those observed in carnivore populations: bats appear less susceptible, rarely demonstrate "furious" rabies, and do not always excrete virions in saliva. In addition, older historical surveys and a few unsubstantiated experimental studies had suggested the possibility of a "carrier" state in rabies-infected bats, but such speculation requires further corroboration. Vampire bat rabies causes substantial agricultural, economical, and public health concerns in Latin America, where these bats are present from Mexico to Argentina (and parts of the Caribbean). After elimination of dog-mediated rabies in the US and Canada, bats (nonhematophagous) are the major sources of human rabies. Many of the human cases are referred to as "cryptic", likely because people do not frequently pay the necessary attention to small superficial wounds inflicted by bat teeth. Only limited information on human rabies of bat origin is available in the Old World. One characteristic of bat lyssaviruses is their prominent genetic and antigenic diversity. Conventional rabies biologics may not elicit reliable cross-protection against such viruses. The development of new biologics, coupled with educational campaigns for the general public and health professionals alike, and novel management of the disease in bat populations, may help to alleviate emerging issues associated with bat rabies.
Descreve-se a epidemiologia da raiva animal na região de Araçatuba, noroeste do estado de São Paulo, durante o período de 1993 a 2007, com base nos resultados dos diagnósticos realizados em laboratórios da região, utilizando as técnicas de imunofluorescência direta e inoculação intracerebral em camundongos. De 10.579 amostras analisadas, 4,9% foram positivas (518/10.579). Os casos em cães corresponderam a 67% (346/518) do total e ocorreram entre 1993 a 1997. Dentre as demais amostras positivas, 16% do total (84/518) foi detectado em bovinos e 9,7% (50/518) em morcegos. Dos 42 municípios da região, 23 (55%) apresentaram pelo menos um caso positivo da doença, sendo que 13 deles registraram casos em morcegos. Foram identificados três ciclos distintos da raiva na região Noroeste do Estado de São Paulo, o ciclo urbano caracterizado predominantemente pela raiva canina (1993 a 1997) e os ciclos aéreo e rural, a partir de 1998 com predominância de casos em quirópteros nas áreas urbanas e em herbívoros.
Genetic variability within and among 10 geographically distinct populations of Greenfinches (Carduelis chloris) was assayed by directly sequencing a 637 BP part of the mtDNA control region from 194 individuals. Thirteen variable positions defined 18 haplotypes with a maximum sequence divergence of 0.8% Haplotype (h = 0.28-0.77) and nucleotide (pi = 0.058-0.17%) diversities within populations were low, and decreased with increasing latitude (h:r(s) = -0.81; pi: r(s) = -0.89). The distribution of pairwise nucleotide differences fit better with expectations of a ''sudden expansion'' than of an ''equilibrium'' model, and the estimates of long term effective population sizes were considerably lower than current census estimates, especially in northern European samples. Selection is an unlikely cause of observed patterns because the distribution of variability conformed to expectations of neutral infinite alleles model and haplotype diversity across populations was positively correlated with heterozygosity !HE) in nuclear genes (I; = 0.74, P < 0.05). Hence, a recent bottleneck, followed by serial bottlenecking during the process of post-Pleistocene recolonization of northern Europe, together with recent population expansion provide a plausible explanation for the low genetic diversity in the north. Genetic distances among populations showed a clear pattern of isolation-by-distance, and 14% of the haplotypic variation was among populations, the rest being distributed among individuals within populations. In accordance with allozyme and morphological data, a hierarchical analysis of nucleotide diversity recognized southern European populations as distinct from northern European ones. However, the magnitude of divergence in mtDNA, allozymes and morphology were highly dissimilar (morphology > mtDNA > allozymes).
Thesis (Ph. D.)--Oklahoma State University, 1971. Includes bibliographical references (leaves 128-134). Photocopy of typescript. Ann Arbor:
Seven colonies of Eptesicus fuscus , the big brown bat, and five colonies of Myotis lucifugus , the little brown bat, in New York State were sampled for rabies virus and virus-neutralizing antibody. Eight of 278 E. fuscus were found to have virus, while 18 of 187 had antibody titers of ≥1:8. One of 333 M. lucifugus yielded virus, while three of 127 had antibody. These data demonstrate the presence of rabies virus as well as immunity to rabies in some insectivorous bats of New York State. Evaluation of these findings in relation to the epizootiology of the disease in bats requires further investigation.
Ninety-eight wolves and 75 coyotes from the forested regions of Alberta were examined for helminths. Fourteen species (2 trematodes, 8 cestodes, and 4 nematodes) were recovered from wolves, with a mean of 2.6 and a maximum of 6 species per wolf; 18 species (3 trematodes, 8 cestodes, and 7 nematodes) were recovered from coyotes, with a mean of 2.0 and a maximum of 6 species per coyote. Helminths common in wolves were Taenia hydatigena (79% of the wolves infected), Echinococcus granulosus (72%), Taenia krabbei (52%), Toxascaris leonina (14%), and Taenia pisiformis (13%), Toxascaris leonina (52%), Alaria americana (33%), Taenia pisiformis (31%), Uncinaria stenocephala (16%), and Filaroides osleri (15%) were common in coyotes. Metorchis conjunctus, Taenia omissa, and T. taeniaeformis appear to be new records for wolves and M. conjunctus, Taenia twitchelli, Diphyllobothrium sp., and Capillaria aerophila appear to be new for coyotes.High indexes of similarity (and comparable indexes of diversity) suggest that t...
The infection rate among eight species of bats submitted for rabies diagnosis in Alberta during 1979-82 was 4.6%. Prevalence of rabies was greatest (24%) for hoary bats Lasiurus cinereus, while the big brown bat Eptesicus fuscus was the species in which rabies was most commonly diagnosed, and the species submitted most frequently for rabies diagnosis was the little brown bat Myotis lucifugus. The rabies infection rate among male hoary bats was significantly greater than in either sex of all other submitted species. The frequency of rabies diagnosis in hoary bats submitted during 1979-82 was also significantly higher than in those submitted between 1971 and 1978. There has been a significant decrease in the rabies prevalence or infection rate of little brown bats since 1971-78.
Thesis (Ph. D.)--University of Minnesota. Bibliography: leaves 111-119.
Chiropteran rabies in Florida is analyzed for the 20-year period 1954 to 1973. The examination of 6,447 bats between 1954 and 1961 yielded 55 (0.85%) positive animals. From 1962 to 1973 however, 2,293 bats examined yielded 236 (10.3%) positive. The yellow bat, Lasiurus intermedius floridanus, accounted for 183 (63.1%) of all cases of chiropteran rabies. Sporadic cases occurred throughout the state with more being reported from the central portion of the state. Cases have been reported every month of the year, peaking in July and August. There were no significant differences in the distribution of rabies in colonial or noncolonial bats by sex or age. There were also no significant differences in the number of reported human and dog contacts made by rabid and non-rabid bats. Clinically ill bats found negative for rabies had a significantly higher contact rate with cats than did rabid bats.
Six hundred and twenty-eight insectivorous bats originating from seven provinces were submitted to this Institute for rabies diagnosis between August 1, 1963 and December 31, 1967. Brain tissue was examined by the fluorescent antibody technique and the mouse infectivity test was carried out with brain, salivary gland, interscapular adipose tissue and kidney samples. Rabies virus was detected in 44 bats, 29 of which were from Ontario, 12 from British Columbia and three from Manitoba. Most of the positive cases were diagnosed in summer months. Seven species were represented among the specimens found to be rabid; there were 32 big brown bats, three hoary bats, three silver-haired bats, two little brown bats, one eastern pipistrelle, one Keen myotis and one red bat. Another bat which was not identified also proved to be infected with rabies.