Objective—To evaluate epidemiologic features of
rabies virus variants in dogs and cats in the United
States during 1999 and assess the role of bat-associated
Sample Population—Rabies viruses from 78 dogs
and 230 cats.
Procedure—Brain specimens from rabid dogs and
cats were submitted for typing of rabies virus.
Historical information, including ownership and vaccination
status, was obtained for each animal.
Specimens were typed by use of indirect fluorescent
antibody assay or reverse transcriptase polymerase
chain reaction assay and nucleotide sequence analysis.
Results—Nearly all animals were infected with the
predicted terrestrial rabies virus variant associated
with the geographic location of the submission. A batassociated
variant of rabies virus was found in a single
cat from Maryland. More than half (53%) of submitted
animals were classified as owned animals, and
most had no known history of vaccination. One vaccination
failure was reported in a dog that did not
receive a booster dose of rabies vaccine after exposure
to a possibly rabid animal.
Conclusions and Clinical Relevance—Bat-associated
rabies virus variants were not a common cause of
rabies in dogs and cats during 1999. Vaccine failures
were uncommon during the study period. Because
most rabid dogs and cats were unvaccinated and
were owned animals rather than strays, educational
campaigns targeting owners may be useful. (J Am Vet
Med Assoc 2001;218:1939–1942)
OBJECTIVE To describe use of whole-genome sequencing (WGS) and evaluate the apparent sensitivity and specificity of antemortem tuberculosis tests during investigation of an unusual outbreak of Mycobacterium bovis infection in a Michigan dairy herd.
PROCEDURES All cattle in the index dairy herd were screened for bTB with the caudal fold test (CFT), and cattle ≥ 6 months old were also screened with a γ-interferon (γIFN) assay. The index herd was depopulated along with all barn cats and a dog that were fed unpasteurized milk from the herd. Select isolates from M bovis–infected animals from the index herd and other bTB-affected herds underwent WGS. Wildlife around all affected premises was examined for bTB.
RESULTS No evidence of bTB was found in any wildlife examined. Within the index herd, 53 of 451 (11.8%) cattle and 12 of 21 (57%) cats were confirmed to be infected with M bovis. Prevalence of M bovis–infected cattle was greatest among 4- to 7-month-old calves (16/49 [33%]) followed by adult cows (36/203 [18%]). The apparent sensitivity and specificity were 86.8% and 92.7% for the CFT and 80.4% and 96.5% for the γIFN assay when results for those tests were interpreted separately and 96.1% and 91.7% when results were interpreted in parallel. Results of WGS revealed that M bovis–infected barn cats and cattle from the index herd and 6 beef operations were infected with the same strain of M bovis. Of the 6 bTB-affected beef operations identified during the investigation, 3 were linked to the index herd only by WGS results; there was no record of movement of livestock or waste milk from the index herd to those operations.
CONCLUSIONS AND CLINICAL RELEVANCE Whole-genome sequencing enhanced the epidemiological investigation and should be used in all disease investigations. Performing the CFT and γIFN assay in parallel improved the antemortem ability to detect M bovis–infected animals. Contact with M bovis–infected cattle and contaminated milk were major risk factors for transmission of bTB within and between herds of this outbreak.