Abstract
Summary
To elucidate the method of persistence of the rickettsialike agent of salmon poisoning disease of dogs, Neorickettsia helminthoeca, the authors failed to infect dogs in 2 tests by injection of eggs laid by flukes from infected dogs. In 5 tests by injection of dogs with fluke stages from dissected livers of Oregon snails, 3 resulted negatively, while in 2 others, the dogs developed characteristic severe infections, confirmed pathologically, after unusually prolonged incubation periods. Flukes and node tissues from antibiotic-treated, recovered dogs, and flukes from a refractory raccoon were shown to remain infectious. As little as 250 mg (one commercial capsule at one feeding) of aureomycin or terramycin were shown to save 15-pound beagles when given as late as the fourth day of fever compared to fatal infections in controls. In one titration experiment, node suspension was found to be infectious in a dilution of 10-6.7. Although the agent has been assigned to the Rickettsiaceae, it appears genetically distinct from Ehrlichia canis and Colesiota spp.
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