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  • Author or Editor: Charles E. Rupprecht x
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Summary

Genetic recombination between field strains and vaccine strains of pseudorabies virus (prv) has been suggested as a scenario that might arise from use of deletion-mutant modified-live vaccine strains, particularly those strains attenuated by deletions within the thymidine kinase (tk -) gene locus. To address this hypothesis experimentally, it is necessary to screen large numbers of prv isolates for their tk genotype. Techniques to detect the native tk genotype are routinely used in molecular virology laboratories, but are time-consuming. We adapted the polymerase chain reaction to define the genotypic status of prv isolates with regard to the presence or absence of deletions in the tk gene locus. Used in tandem with the existing glycoprotein-specific elisa that discriminate between prv-vaccinated and field strain-infected swine populations, the described technique may help to clarify whether vaccine-derived recombinants are generated under natural conditions and after normal vaccine usage.

Free access
in American Journal of Veterinary Research

Summary

Efficacy of an sc-administered commercial inactivated vaccine for prevention of rabies was evaluated in domestic ferrets. Ferret immunity was challenged by the 1m inoculation of street rabies virus. All ferrets developed titers of rabies virus-neutralizing antibodies within 30 days of vaccination (geometric mean titer [GMT]=154, n=41) that were maintained for at least one year (GMT= 106, n=36), compared with no seroconversion in controls (GMT < 5, n=39). Following rabies virus challenge inoculation, 89% (32/36) of vaccinated ferrets survived vs < 6% (2/38) survival in control ferrets. These results demonstrate the protective efficacy of a commercial, inactivated rabies vaccine of at least one year's duration for domestic ferrets.

Free access
in Journal of the American Veterinary Medical Association

Summary

In 1995, 49 states, the District of Columbia, and Puerto Rico reported 7,877 cases of rabies in nonhuman animals and 4 cases in human beings to the Centers for Disease Control and Prevention. Nearly 92% (7,247 cases) were wild animals, whereas 8% (630 cases) were domestic species. The total number of reported cases decreased 4.2% from that of 1994 (8,230 cases). Most of the decline was the result of 17.1% fewer reported cases of rabies in raccoons in areas of the Northeast, where rabies is now enzootic rather than epizootic. Exceptions to this decline were detected in states where the virus has only recently entered raccoon populations or where ongoing epizootics persist. States experiencing increasing epizootic activity associated with this variant include Maine (3 cases in 1993 to 101 cases in 1995), North Carolina (9 cases in 1990 to 466 cases in 1995), Rhode Island (1 case in 1993 to 324 cases in 1995), and Vermont (45 cases in 1993 to 179 cases in 1995). The raccoon variant of the rabies virus is now present in Alabama, Pennsylvania, Vermont, West Virginia, and all Atlantic Seaboard states from Florida to Maine. In Ohio, this variant, last detected in 1992 as a single case, was again detected in 1996. Epizootics of rabies in foxes in west central Texas and in dogs and coyotes in southern Texas attributable to canine variants continue, with this state reporting 137 rabid foxes, 55 rabid dogs, and 80 of the 83 cases in coyotes during 1995. The number of rabid bats (787) increased by almost 25%, with cases reported by 47 of the 48 contiguous states. Nationally, reported cases of rabies in cattle (136) and cats (288) increased by 22.5 and 7.9%, respectively, whereas cases in dogs (146) decreased by 4.6%. Cats continued to be the domestic animal most frequently reported rabid. The cases of rabies reported in human beings were all caused by viral variants associated with bats. Eighteen states and Puerto Rico reported decreases in rabies in animals in 1995, compared with 28 states and the District of Columbia in 1994. Hawaii was the only state that did not report a case of rabies in 1995.

Free access
in Journal of the American Veterinary Medical Association

Summary

In 1994, 48 states, the District of Columbia, and Puerto Rico reported 8,224 cases of rabies in nonhuman animals and 6 cases in human beings to the Centers for Disease Control and Prevention. Nearly 93% (7,632 cases) were wild animals, whereas 7% (592 cases) were domestic species. The total number of reported cases decreased 13.4% from that of 1993 (9,498 cases), with most of the decline resulting from 19.2% fewer cases of rabies in raccoons. Two previously described epizootics of rabies involving the raccoon variant of the rabies virus have converged in North Carolina, and the resulting region is now continuous from Alabama and Florida in the South to Maine in the North. Epizootics of rabies in foxes in west central Texas and in dogs and coyotes in southern Texas continue to expand, with this state reporting 144 rabid foxes, 53 rabid dogs, and 77 of the 85 cases in coyotes during 1994. Maine and New Hampshire reported cases of rabies in foxes (6 and 9, respectively) for the first time in 10 years. Nationally, reported cases of rabies in dogs (153) increased by 17.7%, whereas cases in cattle (111) and cats (267) decreased by 14.6 and 8.3%, respectively. Cats continued to be the domestic animal most frequently reported rabid. Twenty-eight states and the District of Columbia reported decreases in rabies in animals in 1994, compared with 22 states, the District of Columbia, and Puerto Rico in 1993. Hawaii and Nebraska were the only states that did not report cases of rabies in 1994.

Free access
in Journal of the American Veterinary Medical Association

Summary

In 1993, 49 states, the District of Columbia, and Puerto Rico reported 9,495 cases of rabies in nonhuman animals and 3 cases in human beings to the Centers for Disease Control and Prevention. Greater than 93% (8,889 cases) were wild animals, whereas 6.4% (606 cases) were domestic species. The total number of reported cases increased 9.9% over that of 1992 (8,645 cases), with most of the increase resulting from continued spread of rabies in raccoons (37.1% increase in reported cases over 1992). The 2 epizootics of rabies in raccoons (Northeastern/mid-Atlantic and Southeastern regions) approach convergence in North Carolina (106 cases of rabies in 1993, compared with 49 in 1992). Maine, Rhode Island, and Vetmont remained the only New England states without reported cases associated with the raccoon variant of the rabies virus. New York reported 2,747 cases of rabies, the largest number of cases ever reported during a single year by any state. Increases in reported cases of rabies in Texas and 8 other geographically dispersed states were attributed mainly to larger numbers of reported cases of rabies in bats. Texas reported 71 of the 74 cases in coyotes during 1993 (70 of 75 cases in 1992). Nationally, reported cases of rabies in dogs (130) and cattle (130) each decreased by 29% in 1993, whereas cats (291 cases in 1993, compared with 290 in 1992) continued to be the domestic animal most frequently reported rabid. Twenty-two states and Puerto Rico reported decreases in rabies in animals in 1993, compared with 20 states, the District of Columbia, and Puerto Rico in 1992. Hawaii was the only state that did not report a case of rabies in 1993.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To assess the epidemiology of rabies in rodents and lagomorphs and provide information that will enable public health officials to make recommendations regarding postexposure prophylaxis for humans after contact with these animals.

Design—Cross-sectional epidemiological analysis.

Sample—Rodents and lagomorphs submitted to state laboratories for rabies diagnosis from 1995 through 2010.

Procedures—Positive samples were identified by use of direct fluorescent antibody testing, typed by sequencing of viral genes, and quantified via titration in mice or cell culture.

Results—737 rabid rodents and lagomorphs were reported from 1995 through 2010, which represented a 62.3% increase, compared with the number of rabid rodents and lagomorphs reported from 1979 through 1994. The most commonly reported rodents or lagomorphs were groundhogs (Marmota monax). All animals submitted to the CDC for additional viral characterization were positive for the raccoon rabies virus variant. Infectious virus or viral RNA was detected in salivary glands or oral cavity tissues in 11 of 13 rabid rodents.

Conclusions and Clinical Relevance—The increase in reported rabid rodents, compared with results of previous studies, appeared to be associated with spillover infections from the raccoon rabies epizootic during the first half of the study period. Analysis supported the assumption that rabies remained rare in rodents and lagomorphs. However, transmission of rabies virus via exposure to a rabid rodent or lagomorph may be possible. Given the rarity of rabies in these species, diagnostic testing and consideration of postexposure prophylaxis for humans with potential exposures should be considered on a case-by-case basis.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate knowledge, attitudes, and practices of deer owners following identification of a cluster of captive deer with rabies as an aid for the development of rabies prevention educational materials.

Design—Cross-sectional study.

Population—Captive-deer owners who were members of the Pennsylvania Deer Farmers Association.

Procedures—Information was obtained via a mailed, self-administered questionnaire.

Results—The questionnaire response rate was 59% (249/425). One hundred three of 206 (50%) respondents had incomplete knowledge of rabies virus vectors, transmission, severity, and prevention measures. Birds or snakes were incorrectly identified as rabies vectors by 96 of 213 (45%) respondents, and most (≥ 94%) respondents identified rabies virus reservoirs as vectors. Ninety of 231 (39%) respondents identified death as an outcome of rabies, and 184 of 235 (78%) respondents would seek emergency treatment if they suspected exposure. Only 62 of 235 (26%) respondents would wash a wound immediately. The majority of respondents (173/239 [72%]) did not know the clinical signs of rabies in deer. Nine respondents indicated that they vaccinated their deer against rabies, and the majority of respondents (158/214 [74%]) would be willing to vaccinate.

Conclusions and Clinical Relevance—Findings suggested that deer owners in Pennsylvania have a basic knowledge of rabies; however, knowledge, attitudes, and practices regarding prevention of rabies transmission could be improved considerably. Rabies educational materials for deer owners should focus on postexposure procedures, disease severity, recognition of rabies in deer, and changes in management practices such as vaccination to prevent rabies.

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in Journal of the American Veterinary Medical Association

Objective

To document the number of human contacts with bait containing liquid vaccinia-rabies glycoprotein (V-RG) vaccine, to evaluate factors that might affect human contact with bait-vaccine units, and to summarize adverse reactions in people after contact with vaccine.

Design

Retrospective 4-year survey of directors of 6 oral rabies vaccination programs.

Sample Population

Human residents in areas of vaccination programs.

Procedure

Data were collected from report forms and telephone conversations with directors of oral rabies vaccination programs in Florida, Massachusetts, New Jersey, Texas, and New York. Data collected included information regarding human contact with bait and vaccine, sex and age of person involved in contact, human population density, bait density, type of labeling used on bait, and other factors.

Results

Human contact with bait was more likely in areas where bait had white labels (vs lettering in black ink) and in areas with high human population densities. Directors of all programs reported that human contact with bait-vaccine units was minimal. Adverse reactions in exposed people were not reported. On the basis of these findings, concerns about V-RG vaccine posing a substantial public health risk remain unfounded.

Clinical Implications

Directors of oral rabies vaccination programs should systematically collect information about exposures and potential factors affecting exposure of people to bait-vaccine units. People with substantial exposure to V-RG vaccine should be evaluated for immune status and any resulting symptoms should be documented and monitored. (J Am Vet Med Assoc 1998;213:1413-1417)

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

Objective

To determine susceptibility, incubation and morbidity periods, clinical signs, serologic response, and excretion of virus in domestic ferrets inoculated with rabies virus.

Animals

55 domestic ferrets.

Procedure

5 groups of 10 ferrets were inoculated with rabies virus, IM, at doses of 105.5 to 101.5 median mouse intracerebral lethal dose. Ferrets were observed and behavior was recorded. Rectal temperature, body weight, and samples from the oral cavity and samples of saliva and blood were obtained. Virus isolation was attempted, using intracranial mouse inoculation and cell culture. Virus neutralizing antibodies were determined by rapid fluorescent focus inhibition test. Ferrets were euthanatized immediately if clinical signs were severe. Rabies was confirmed by direct immunofluorescent antibody test.

Results

Mean incubation period was 33 days (range, 16 to 96 days). Clinical signs included ascending paralysis, ataxia, cachexia, bladder atony, fever, hyperactivity, tremors, and paresthesia. Mean morbidity period was 4 to 5 days (range, 2 to 10 days). Virus antigen was detected in brain tissue from all clinically rabid ferrets. Ferrets given the highest viral dose were euthanatized and had VNA; ferrets receiving the next dilution also were euthanatized, but only 4 had seroconverted. Of 17 ferrets that survived, 5 seroconverted. Survivors remained clinically normal except for 1 that recovered with severe paralytic sequelae. Rabies virus was isolated from the salivary gland of 1 ferret that was euthanatized.

Conclusions and Clinical Relevance

Rabies should be considered as a differential diagnosis in any ferret that has acute onset of paralysis or behavioral changes and a condition that rapidly deteriorates despite intense medical intervention. (Am J Vet Res 1997;58:1327–1331)

Free access
in American Journal of Veterinary Research