Studies on the Pathogenesis of Rabies in Insectivorous Bats

Sulkin, S. Edward; Allen, R; Sims, Ruth; Krutzsch, Philip H.; Kim, Chan-Soo

doi:10.1084/jem.112.4.595

Cited by 38 publications

(19 citation statements)

References 15 publications

(26 reference statements)

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“…Hibernation submodel (September 22-April 5; 197 d). During hibernation, disease progression is likely suspended because of cold temperatures and metabolic effects associated with torpor (34,35). Infectious bats die quickly from the disease (Table 1), and more than likely do not make it into hibernation.…”

Section: Methodsmentioning

confidence: 99%

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Host and viral ecology determine bat rabies seasonality and maintenance

George

Webb

Farnsworth

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

175

186

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Rabies is an acute viral infection that is typically fatal. Most rabies modeling has focused on disease dynamics and control within terrestrial mammals (e.g., raccoons and foxes). As such, rabies in bats has been largely neglected until recently. Because bats have been implicated as natural reservoirs for several emerging zoonotic viruses, including SARS-like corona viruses, henipaviruses, and lyssaviruses, understanding how pathogens are maintained within a population becomes vital. Unfortunately, little is known about maintenance mechanisms for any pathogen in bat populations. We present a mathematical model parameterized with unique data from an extensive study of rabies in a Colorado population of big brown bats (Eptesicus fuscus) to elucidate general maintenance mechanisms. We propose that life history patterns of many species of temperate-zone bats, coupled with sufficiently long incubation periods, allows for rabies virus maintenance. Seasonal variability in bat mortality rates, specifically low mortality during hibernation, allows long-term bat population viability. Within viable bat populations, sufficiently long incubation periods allow enough infected individuals to enter hibernation and survive until the following year, and hence avoid an epizootic fadeout of rabies virus. We hypothesize that the slowing effects of hibernation on metabolic and viral activity maintains infected individuals and their pathogens until susceptibles from the annual birth pulse become infected and continue the cycle. This research provides a context to explore similar host ecology and viral dynamics that may explain seasonal patterns and maintenance of other bat-borne diseases. chiroptera | pathogen persistence | torpor M any aspects of wildlife biology are strongly seasonal, including population dynamics of wildlife diseases (1, 2). Although mechanisms of seasonal variation of human pathogens have been well explored (3), the mechanisms for seasonality of wildlife diseases are not as well understood. Rabies virus dynamics in temperate zone bat populations exhibit a strong seasonal pattern in the number of rabies cases (Fig. 1), unlike mammalian carnivores (4). Previous analyses of bat rabies virus (BRV) using passive surveillance samples have demonstrated a higher prevalence in the spring, but especially during autumn, throughout the United States (5). However, no definitive mechanism for the seasonal pattern of rabies in bats has been described. In addition, how rabies virus is maintained within bat populations remains unclear. Here, we explore factors that drive pathogen maintenance and simultaneously explain the unique seasonal patterns of rabies in bats.Each year, rabies virus infection causes in excess of 55,000 human deaths globally, mostly from dog bites in developing countries (6). Successful vaccination programs of domesticated animals have virtually eliminated dog rabies in North America over the past 50 y, and more recent vaccination strategies for wildlife populations have controlled rabies virus in other carniv...

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Section: Methodsmentioning

confidence: 99%

“…During torpor, the metabolic rate also reduces to low levels correlating to ambient temperatures (32,33). Experimental research (34,35) suggests that cooler temperatures slow viral development rates in bats. Thus, facultative heterothermy causes seasonal variation in rabies incubation periods across the different seasons.…”

mentioning

confidence: 99%

Host and viral ecology determine bat rabies seasonality and maintenance

George

Webb

Farnsworth

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

175

186

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“…As the global climate warms, it is possible that more diseases enzootic in bat populations of the tropics and subtropics will move northward into the USA, with potential consequences for bat populations and human health. Disease transmission cycles are governed in part by the proportion of time each year that animals are active and interacting with each other (Dobson & Hudson 1995), and there is evidence that torpor suspends the progression of viral diseases in bats (though this notion has received perplexingly little recent attention; La Motte 1958, Sadler & Enright 1959, Sulkin et al 1960. Thus, climate warming has the potential not only to move diseases into the USA and increase the length of time during the year when bats are in active contact with each other, but also to decrease any dampening effect torpor might have on disease expression and transmission.…”

Section: Effects Of Anthropogenic Change On Disease Dynamicsmentioning

confidence: 99%

Broadening the focus of bat conservation and research in the USA for the 21st century

Weller¹,

Cryan²,

O’Shea³

2009

Endang. Species. Res.

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Appropriately, bat conservation in the USA during the 20th century focused on species that tend to aggregate in large numbers and locations (e.g. maternity roosts, hibernacula) where populations are most vulnerable. Extensive research into habitat needs (primarily for roosting) of reproductive females during the previous 2 decades has produced a wealth of information useful for developing conservation strategies for this group in their summer roost areas. However, the ecological needs of males, non-reproductive females, and juveniles have received far less attention, as have the ecological needs of all bats outside the pup-rearing season. Hence, it is unlikely that a single paradigm could comprehensively address conservation needs of all demographic groups within a species because they may have different seasonal distributions, reproductive strategies, and thermoregulatory needs. Herein, we recommend research into a wider spectrum of demographic groups and seasons to form a more holistic vision of the conservation needs of bats. We urge greater attention to understanding thermo-energetic and reproductive underpinnings of observed patterns of seasonal distribution and habitat selection by bats in the USA. Such understanding is instrumental for development of scientifically sound conservation strategies to confront emerging threats to conservation of bats in the 21st century: climate change, disease, habitat degradation, and environmental contaminants. We discuss interconnections among these emerging threats and the fundamental need to incorporate understanding of thermo-energetic strategies of bats in development of conservation strategies or legislation to mitigate potential impacts on bat populations of the USA.

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“…Virus titers in the few animals which developed evidence of infection while in simulated hibernation were 10-1 or less, while titers in the various tissues of animals kept in the warm room ranged from 1 log unit to as high as 10-46.5 The higher virus titers observed in the tissues of the little brown bats reflect the increased susceptibility of this animal compared with the Mexican free-tailed bat. 28 Because of the evidence that rabies virus strains isolated from bats differed in certain ways from canine street virus it was felt that studies on the pathogenesis of rabies using a bat rabies virus would better reflect what occurs in nature.2938 Table 3 …”

Section: Resultsmentioning

confidence: 99%