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Description:
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The raccoon , Procyon lotor , is considered a major wildlife reservoir of rabies in the southeastern United States and is currently spreading its distribution as a vector of rabies . A survey was conducted in Mobile and Baldwin counties to evaluate the nature and frequency of rabies virus neutralizing antibodies in the local raccoon population . Cerebrospinal fluid and blood samples were collected while animals were sedated , and upon release individuals were ear tagged and vaccinated with a 1 ml
intramuscular injection of Imrab® rabies vaccine . All brain samples were negative (0 /18 ) for the presence of rabies virus . All cerebrospinal fluid (0 /145 ) and prevaccination serum samples (0 /153 ) were negative for rabies virus neutralizing antibodies (VNA ) . The absence of rabies is most likely attributed to the virus not being detected during this investigation . Of the twelve raccoons with post -vaccination blood samples , five were seronegative with titers < 1 :5 , and seven were seropositive ranging from 1 :9 - 1 :60 . No raccoons mounted an anamnestic response before day 5 , thus it is assumed that all raccoons had not previously been exposed to rabies . Immunity or resistance may have played a role in the raccoons within the study area .
Additionally , an epidemic model was designed to examine the spatial spread of raccoon rabies , and emphasized the importance of understanding the transmission and spread of the disease in a natural environment . The individual -based geographic model divided the study area into a rectangular grid with each cell representing an average home range of 1 km with a potential density of 20 animals /km^ . Raccoons were allowed to randomly move to neighboring cells from high to low densities . The model consisted of a series of linked subroutines describing not only the local population movement patterns , but also population demographics (reproduction and mortality ) and exposure to rabies . When rabies was present in the population , the model monitored disease transmission and rabies pathogenesis in each individual . Probabilities of contact , exposure , and immunity determined the outcome of a rabies exposure . Additional surveillance data is needed to assess and refine epidemic models for wildlife diseases . |