Rabies Prevalence in Migratory Tree-Bats in Alberta and the Influence of Roosting Ecology and Sampling Method on Reported Prevalence of Rabies in Bats

Abstract

ABSTRACT:The migratory tree-roosting hoary bat (Lasiurus cinereus) and silver-haired bat (Lasionycteris noctivagans) are among the bat species with the highest reported prevalence of rabies in North America. However, bats submitted for rabies testing typically have been those that have come in contact with humans or pets. Given the roosting ecology of L. cinereus and L. noctivagans, contact with healthy individuals of these species is expected to be rare, with a bias in contact and submission of infected individuals and thus an overestimation of rabies prevalence. We tested 121 L. cinereus and 96 L. noctivagans specimens, collected during mortality surveys at wind energy facilities in Southern Alberta, Canada in 2007 and 2008, for rabies. None of the L. cinereus (0%) and one L. noctivagans (1%) tested positive for rabies. Prevalence of rabies was significantly lower than previously reported estimates, passive and active, for L. cinereus and L. noctivagans. In a review of the literature including multiple bat species, we found a significant difference in estimates of rabies prevalence based on passive versus active surveillance testing. Furthermore, roosting ecology influenced estimates of rabies prevalence, with significantly higher prevalence among passive surveillance submissions of nonsynanthropic species compared to synanthropic species, a trend not evident in active surveillance reports. We conclude that rabies prevalence in randomly collected L. cinereus and L. noctivagans is low and comparable to active surveillance estimates from other species (#1%), and that roosting ecology influences estimates of rabies prevalence among bats submitted to public health laboratories in North America.

Evolutionary History and Phylogeography of Rabies Viruses Associated with Outbreaks in Trinidad

“…This surveillance program mainly targets apparently healthy bats from known roosts primarily in the south of the country and is typically guided by public reporting of bat biting cases, so there is some surveillance bias. Nonetheless, this rabies positive rate is comparable to rates of 1% or less reported in natural bat populations elsewhere [47] but is lower than rates of up to 3.3% (n = 12,227) estimated for Trinidad on the basis of histopathological analysis for the presence of Negri bodies in brain tissues during the 1930's [41], [48]. The passive surveillance system in the United States receives more than 20,000 bats (found sick or inside human dwellings) annually for rabies testing, of which close to 6% are confirmed rabid [49].…”

Dreaming the Bat Out of the Shadow

“…Like other mammals, they are susceptible to rabies. However, less than one percent of bats has rabies (Klug et al, 2011). Nevertheless, there are few other animals that carry such a strong association with rabies.…”

“…The rest feed on insects, fruits, small mammals, or fish. Scientific studies have shown that one percent of wild bats are rabid, and in the past fifty years, less than forty humans have contracted rabies from a bat (Klug, Turnelle, Ellison, Baerwald, & Barclay, 2011). Yet the general public holds onto the image of the bat as a vampiric disease carrier that is to be feared.…”

Rabies Surveillance Among Bats in Tennessee, Usa, 1996–2010

“…Bat species was a key predictor of rabid bats and the highest proportion was observed among lasiurine bats. These results likely reflect differences in bat roosting ecology (Klug et al 2011). Bats that come into contact with the public may be more likely to be sick and behaving unnaturally, particularly among inconspicuous species.…”

“…Surveillance of bat rabies across the US has demonstrated consistent seasonal patterns (Constantine 1967;Brass 1994) as well as regional and species level variation in the proportion of rabid bats among submissions (Mondul et al 2003;Patyk et al 2012). Some peridomestic bat species are submitted annually in high numbers for passive surveillance yet have low proportions of rabid specimens (e.g., little brown bats, Myotis lucifugus and big brown bats, Eptesicus fuscus), whereas forest-dwelling bats are submitted in much lower numbers but have markedly higher proportions of rabid specimens (e.g., hoary bats, Lasiurus cinereus and silver-haired bats) (Klug et al 2011). Furthermore, the species composition of bat submissions varies by state and region (Childs et al 1994;Pape et al 1999;Parker et al 1999;Mayes et al 2013) and may reflect the natural geographic range and abundance of certain bat species across the US, although the criteria for submission of bats for laboratory diagnosis varies among states and could influence apparent geographic trends (Patyk et al 2012).…”