Leptospirosis

Question 1

What agent causes leptospirosis?

Answer 1

Bacterial spirochete

• Leptospirosis interogans
  
  • Autumnalis, Bratislava, Cannicola, Icteriohaemorrhagiae, Pomona
• Leptospirosis kirshneri
  
  • Grippotyphosa
• Specific serovars are host-adapted to certain reservoir species (all can affect humans)
• PATHOGENIC SEROVARS DO NOT REPLICATE OUTSIDE THE ANIMAL HOST

Question 2

How is leptospirosis maintained?

Answer 2

Animals

• Can persist in renal tubules without causing any disease
• Excreted in urine
• Evade immune responses

Question 3

Where (geographically) is leptospirosis more commonly seen?

Answer 3

Enzootic worldwide

• Warm and higher annual rainfall places (Hawaii, west coast, etc.)
• Early fall or summer

Question 4

What type of environment does leptospirosis thrive in?

Answer 4

• Alkaline soil
• Tropical and semitropical regions

Question 5

Who is the poster child for leptospirosis (most at risk)?

Answer 5

Adult (4-7 years) males

• Hounds, working and herding breeds (outdoor animals more exposed)

Question 6

How is leptospirosis transmitted?

Answer 6

• Eliminated by the urine > enter through abraded skin and intact mucous membranes
  
  • Excreted for years (even treated)
• Cats = subclinical

Question 7

What is the pathogenesis of leptospirosis in dogs?

Answer 7

• Renal tubular infection > acute interstitial nephritis and tubular dysfunction > acute kidney failure
• Mild hepatic necrosis and mild neutrophilic periportal hepatitis > acute liver failure

Question 8

What are the clinical signs in dogs with leptospirosis?

Answer 8

• Subclinical
• No associated between clinical signs and serovars
• Clinical signs in 7 days
  
  • Renal or hepatic failure (usually present with GI signs)*
    
    • PU/PD > oliguria/ anuria
    • Dehydration
    • V/D, inappetance, lethargy, or abdominal pain
    • Icteric
  • Acute febrile illness, pulmonary hemorrhage, uveitis, muscle pain, abortion in LA
• May develop chronic renal failure or chronic active hepatitis
• May clear infection in 2-3 weeks

Question 9

What lab changes can you see in a patient with leptospirosis?

Answer 9

• CBC
  
  • Acute: leukopenia
  • Subacute: leukocytosis
  • Thrombocytopenia
• Chemistry
  
  • Increased BUN and creatinine (renal failure) >80-90%
    
    • Cillindruria, pyuria, hematuria, isosthenuria, hyposthenuria
  • Increased ALT and ALP (ALP > ALT), increased bilirubin, increased GGT (liver disease)
• Diffuse interstitial patterns (interstitial lung disease)

Question 10

How do you diagnose a dog with suspected leptospirosis?

Answer 10

Clinical signs +

• Detection of antibodies
  
  • MAT > reacting dilution of serum with live leptospiral serovars and assessment of agglutination
    
    • Problem: exposure only and takes too long
    • Active infection:
      
      • MAT titer > 3200
      • 4-fold increase in titer over 2 weeks
      • Positive IgM ELISA
• Demonstration of organism
  
  • Microscopy (problem with intermittent shedding = false negatives)
  • Culture (before ABCs)
    
    • Tranpsort ASAP (special media)
    • Problem: growth is slow and overgrowth issues
• PCR (early infection
  
  • Problem: can be positive after recovery , disease or carrier
  • First 10 days blood, after 10 days urine (send both)
  • Detect nucleic acids

Question 11

How do you treat a dog positive for leptospirosis?

Answer 11

• Fluid therapy (preserve renal function and maintain hydration)
• Antibiotics
  
  • Doxycycline (GI side effects)
  • Ampicillin
  • First gen. cephalosporins + quinolones controversial
• CRTT or hemodialysis in anuric/ oliguric renal failure ($$$)
• Not much you can do to support hepatic disease
• Oxygen therapy/ mechanical ventilation for pulmonary hemorrhage

Question 12

What is the prognosis in a dog with leptospirosis?

Answer 12

Survival rates ~80% (conservatively + dialysis)

• Respiratory complications: mortality rate 36-50%
• Successful if BUN and creatinine WNL in 10-14 days
• Regeneration of damaged renal tissues continue over 4 weeks
• ALT and ALP decline faster than bilirubin
• Platelets improve within 1 week

Question 13

How can leptospirosis be prevented?

Answer 13

• WEAR GLOVES
• Vaccines
  
  • Reduce severity of disease
  • Not always necessary
    
    • High risk patients: 4-way lepto product at 12 weeks, 15 weeks, 6 months, 1 year (vaccinate more often)
  • Reactogenic vaccine

Question 14

Is leptospirosis zoonotic (dogs to humans)?

Answer 14

RARE IN HUMANS (get it form drinking dog urine)

• Infection through mucosal contact with water or soil contaminted with urine of infected animals
• Risk: veterinarians, farms, abattoir workers, recreational activities in water
• CAN CAUSE DEATH