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Browsing by Author "Davis, April, author"

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    Pathogenesis and immunity of rabies virus infection in bats
    (Colorado State University. Libraries, 2007) Davis, April, author; Bowen, R. A., advisor; Blair, Carol D., advisor
    Rabies is one of the oldest known viral diseases and, with a >99% fatality rate, it is also one of the most deadly. Although a major public health concern, human deaths due to rabies in the developed world are rare. Worldwide, statistics are very different as rabies kills in excess of 50,000 humans per year, most often the result of canine rabies variants. During the 1950's, canine rabies cases began decreasing in the United States as a result of vaccination efforts, followed by a decrease in human rabies cases. Rabies in insectivorous bats was first reported in the US in the 1950's and has now been reported in most North American bat species. Over the last 20 years, 92% of the human rabies cases have been the result of a bat variant. This purpose of this work was to expand our knowledge of rabies variants associated with silver hair bats, Mexican free-tailed bats, and big brown bats. The goal of the first study was to characterize disease progression between two closely related big brown bat rabies variants. The data from this experiment indicated that changes in the rabies virus genome may have profound effects on infectivity and virulence. The second study was designed to determine if rabies virus could be transmitted to bats through the aerosol route. Outbred mice and two species of bats were exposed to three variants of rabies virus by aerosol exposure. Although all bats survived the aerosol exposure, 44% of the mice died of rabies. Following exposure, anti-rabies virus neutralizing antibodies were demonstrated in all bats. Following an intramuscular inoculation of rabies virus six months after the aerosol exposure, the number of seropositive bats that developed rabies was equal to the control bats. The third study examined the dynamics of rabies virus infection in bats from colonies in Texas and Colorado. The ability of healthy wild bats incubating rabies to transmit rabies virus was also examined. Rabies virus antigen was found in 50% of the salivary glands from rabid bats yet infectious rabies virus was isolated from less than 35% of rabid bats. Evaluation of of bats from both the field and in captive colonies demonstrated that approximately 0.5-2% of clinically healthy bats were in the incubation phase of rabies virus infection.