Leptospirosis

1. Leptospirosis Clinical Medicine 3 Neal Villanueva, DVM

2. Definition • Gram negative spirochete (helical) • 200 serovars • Most common serovars affecting dogs • L. canicola- Dog is the reservoir host • L. icterohemorrhagiae • L. grippotyphosa • L. pomona • L. bratislava • Rare in cats

4. Pathophysiology • Penetrate skin or mucous membranes and enters the bloodstream (4-7 days) • Spreads systemically (2-4 days) • Transitory fever, leukocytosis and anemia. • Capillary and endothelial cell damage  petechial hemorrhages • Liver- • hepatic necrosis • Kidney- • damages renal tubules and replicates in the tubular epithelial cells • Death • Secondary to renal failure • Acute septicemia and/or DIC

6. Transmission • Direct • Host to host • Contact with infective urine • Postabortion discharge • Sexual contact • Indirect • Exposure to infective urine to a contaminated environment where the organism can survive. • Vegetation • Soil • Food, water • bedding

8. Environmental factors • Warm and moist environment • Wet season/high rainfall areas of temperate regions • Low-lying areas (marsh, muddy, irrigated) • Tropical and subtropical • T°- 7-10°C (44.6-50°F) to 34-36°C (93-96°F) • Water • ↑ survival in stagnant water • Slightly alkaline pH • Can survive 180 days in wet soil, longer in standing water.

10. Signalment • Species • Dogs • Cats- rare • Age • Young dogs without passive maternal antibodies • Severe disease • Old dogs with adequate antibody titer levels seldom exhibit clinical disease unless exposed to a serovar not in the vaccine • No cross immunity between serovars

11. Clinical Signs • History • Peracute to subacute disease • Fever • Sore muscles, stiffness • Weakness • Anorexia • Depression • Vomiting • Dehydration • Diarrhea +/- blood • Death

12. Chronic • Sub-clinical illness • Fever of unknown origin • PU/PD • Chronic renal failure

13. Physical Exam- peracute to acute • Tachypnea • Rapid, irregular pulse • Poor capillary perfusion • Hematemesis • Hematochezia • Melena • Epistaxis • Injected mucous membranes • Petechial/ecchymotic hemorrhages • Reluctance to move, hyperesthesia and stiff gait • Hematuria • Conjuctivitis,rhiniteis

14. Diagnosis • Suggestive history • Exposure to stagnant water, host animals and wooded areas • Lack of prior vaccination • Fever and renal and/or hepatic involvement are suggestive. • Increased risk factors • Middle-aged dogs • Large breed, mixed breed, hound dogs • Dogs living in urban areas • Terriers, toy breeds

15. Laboratory findings • CBC • Leukopenia during leptospiremia  leukocytosis +/- left shift. • Thrombocytopemia • Normocytic normochromic anemia • Serum chemistry • Azotemia, hyperphosphatemia, hypercalcemia • Hyponatremia, hypochloremia, hypokalemia if vomiting • Hyperkalemia w/ oliguria or anuria • +/- elevated hepatic values (AALT, AST, ALKPhos, Tbil)

16. Specific Tests • Microscopic Agglutination Test (MAT) • 4 fold increase in titers over a 2-4 week period • Or a single test result of 1:800 + is diagnostic • Unable to differentiate b/t infection and vaccination • Polymerase Chain Reaction test (PCR) • Positive before seroconversion  earlier diagnosis • 100% sensitivity, 83% specificity • Sensitivity may result in false positives

17. Treatment • Supportive care and fluid therapy • Elimination of leptospiremia • Ampicillin • Amoxicillin • Penicillin • Elimination of carrier state • Doxcycline • Tetracycline • azithromycin

18. Prevention • Vaccination • L. canicola • L. icterohaemorrhagiae • L. pomona • L. gryppotyphosa • Only lasts 6-8 months, recommend booster q6m. • No cross protection from other serovars

20. Zoonotic potential • Recreational water sources, floods • Occupational • Keep lepto suspect animals separate • Handle urine/urine contaminated items with latex gloves • Facemasks and goggles when hosing contaminated areas

21. Questions?