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Differing pathogenicity of two strains of the same leptospirosis
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Nephrology Differing Pathogenicity of Two Strains of the Same Leptospirosis Background Leptospirosis is a re-emerging disease of dogs that can be transmitted to humans. Substantial increase in the diagnosis of leptospirosis in dogs in the United States and Canada has occurred in the last 20 years. In the United States, Leptospira interrogans serovars canicola and icterohaemorrhagiae were the most common causes of leptospirosis in dogs. Bacterins against serovars canicola and icterohaemorrhagiae markedly reduced the incidence of disease. However, more recent causes of leptospirosis in dogs have been L kirschneri serovar grippotyphosa, L interrogans serovar bratislava, and L interrogans serovar pomona. Bacterins of serovars canicola and icterohaemorrhagiae are not protective against the newer causes of leptospirosis in dogs. Objectives To develop a method for inducing acute leptospirosis in dogs. Procedure Thirty-one, 9-week-old female beagles were randomly assigned to 2 inoculation groups or a control group. Puppies were inoculated on 3 successive days by conjunctival instillation of L kirschneri serovar grippotyphosa strain 82 (12 dogs)
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or strain RM 52 (14 dogs). Five control dogs were similarly inoculated with sterile media. Clinical signs, clinicopathologic variables, anti-leptospiral antibody titers, and evidence of leptospires in tissues and body fluids were evaluated. Dogs were euthanized and necropsied on days 7, 14, 22, or 28 after inoculation or as required because of severe illness. Results Clinical signs in infected dogs included conjunctivitis, lethargy, diarrhea, dehydration, vomiting, and icterus. Laboratory findings in infected dogs included azotemia, hyperphosphatemia, increased anion gap, hyperbilirubinemia, and an increase in serum alkaline phosphatase activity. Leptospires were cultured from the kidneys (11 of 12 dogs), urine (6 of 9 dogs), aqueous humor (9 of 12 dogs), blood (in each of 12 dogs), and liver (in each of 12 dogs) of dogs inoculated with strain 82. Only 3 of 14 dogs became infected after inoculation with strain RM 52. Histopathologic lesions in infected dogs included interstitial nephritis, renal tubular degeneration and necrosis, pulmonary hemorrhage, and hepatic edema and perivasculitis. Author Conclusion Conjunctival exposure to L. kirschneri serovar grippotyphosa strain 82 in unvaccinated puppies consistently results in acute leptospirosis. Inoculation with strain 52 was less pathogenic (3 of 14 inoculated puppies became infected). This method of infection by serovar grippotyphosa can be used to study the pathogenesis and prevention of leptospirosis in dogs. Inclusions Seven figures, 3 tables, 29 references. Editor Annotation During the last 10 years, there has been an increase in the number of dogs with leptospirosis from which clinicians have isolated or detected serologic evidence to support the involvement of L. kirschneri serovar grippotyphosa, L. interrogans serovar bratslava, and L. interrogans serovar pomona. The purpose of this study was to inoculate dogs with L. kirschneri serovar grippotyphosa into controlled conditions and document clinical signs, change in results of hemograms and serum biochemical analyses, and gross and histologic lesions. A
serologic titer of greater than 1:50 was not detected in any dogs inoculated with either strain. Clinicians should be aware of mode(s) of transmission of leptospirosis, and the acute clinical signs and laboratory data, even without significant titers. (MM) Greenlee, JJ, Bolin CA, Alt DP, et al. Clinical and pathologic comparison of acute leptospirosis in dogs caused by two strains of Leptospira kirschneri serovar grippotyphosa. Am J Vet Res 2004;65:1100-1107.
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Nephrology Differing Pathogenicity of Two Strains of the Same Leptospirosis Background Leptospirosis is a re-emerging disease of dogs that can be transmitted to humans. Substantial increase in the diagnosis of leptospirosis in dogs in the United States and Canada has occurred in the last 20 years. In the United States, Leptospira interrogans serovars canicola and icterohaemorrhagiae were the most common causes of leptospirosis in dogs. Bacterins against serovars canicola and icterohaemorrhagiae markedly reduced the incidence of disease. However, more recent causes of leptospirosis in dogs have been L kirschneri serovar grippotyphosa, L interrogans serovar bratislava, and L interrogans serovar pomona. Bacterins of serovars canicola and icterohaemorrhagiae are not protective against the newer causes of leptospirosis in dogs. Objectives To develop a method for inducing acute leptospirosis in dogs. Procedure Thirty-one, 9-week-old female beagles were randomly assigned to 2 inoculation groups or a control group. Puppies were inoculated on 3 successive days by conjunctival instillation of L kirschneri serovar grippotyphosa strain 82 (12 dogs)
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or strain RM 52 (14 dogs). Five control dogs were similarly inoculated with sterile media. Clinical signs, clinicopathologic variables, anti-leptospiral antibody titers, and evidence of leptospires in tissues and body fluids were evaluated. Dogs were euthanized and necropsied on days 7, 14, 22, or 28 after inoculation or as required because of severe illness. Results Clinical signs in infected dogs included conjunctivitis, lethargy, diarrhea, dehydration, vomiting, and icterus. Laboratory findings in infected dogs included azotemia, hyperphosphatemia, increased anion gap, hyperbilirubinemia, and an increase in serum alkaline phosphatase activity. Leptospires were cultured from the kidneys (11 of 12 dogs), urine (6 of 9 dogs), aqueous humor (9 of 12 dogs), blood (in each of 12 dogs), and liver (in each of 12 dogs) of dogs inoculated with strain 82. Only 3 of 14 dogs became infected after inoculation with strain RM 52. Histopathologic lesions in infected dogs included interstitial nephritis, renal tubular degeneration and necrosis, pulmonary hemorrhage, and hepatic edema and perivasculitis. Author Conclusion Conjunctival exposure to L. kirschneri serovar grippotyphosa strain 82 in unvaccinated puppies consistently results in acute leptospirosis. Inoculation with strain 52 was less pathogenic (3 of 14 inoculated puppies became infected). This method of infection by serovar grippotyphosa can be used to study the pathogenesis and prevention of leptospirosis in dogs. Inclusions Seven figures, 3 tables, 29 references. Editor Annotation During the last 10 years, there has been an increase in the number of dogs with leptospirosis from which clinicians have isolated or detected serologic evidence to support the involvement of L. kirschneri serovar grippotyphosa, L. interrogans serovar bratslava, and L. interrogans serovar pomona. The purpose of this study was to inoculate dogs with L. kirschneri serovar grippotyphosa into controlled conditions and document clinical signs, change in results of hemograms and serum biochemical analyses, and gross and histologic lesions. A
serologic titer of greater than 1:50 was not detected in any dogs inoculated with either strain. Clinicians should be aware of mode(s) of transmission of leptospirosis, and the acute clinical signs and laboratory data, even without significant titers. (MM) Greenlee, JJ, Bolin CA, Alt DP, et al. Clinical and pathologic comparison of acute leptospirosis in dogs caused by two strains of Leptospira kirschneri serovar grippotyphosa. Am J Vet Res 2004;65:1100-1107.