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SAM Module C infectious diseases > Leptospirosis > Flashcards

Leptospirosis Flashcards

1
Q

What is the importance of Leptospirosis?

A

Common in dogs
Rare in cats
Both can be carriers and shed in urine
In humans - flu like symptoms, nothing, mild, or Weil’s disease

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2
Q

What is leptospirosis?

A

Gram -ve spriochete
250 serovars
Each serovar adapted to a different host

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3
Q

How is it transmitted?

A

On fomites/ soil/ water or through bite

placental/ venereal

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4
Q

How do reservoir hosts act?

A

Low levels of clinical disease

Shed disease from the renal tubules for a long time

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5
Q

What are the risk factors for leptospirosis?

A 
3m after high rainfall
Exposure to wildlife and their u+
Living close to outdoor water sources
Outdoor hunting (cats)
Presence of infected resevoir hosts
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6
Q

Outline the use of vaccines

A

Needs a higher dose of antigen to prevent renal carrier state and prevent u+ shedding compared to preventing clincal disease
L2 - icerohaemorrhagiae and canicola - only 34% of main infections
L4 - covers against 84%
3 weeks until the onset of immunity
Lasts 12 months
First vax 6-9 weeks
2nd 10-13
Annual re-vax, ideally a few months before the peak season

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7
Q

Outline the pathophysiology of infection

A

Penetrates intact mucosae/ abraided skin
haematogenous spread
Exact mechanism causing tissue damage is unknown
Immunotoxic mechanism
7d incubation
Initial immune evasion until adaptive immune response occurs
Possible persistence in immune priviledged sites - e.g. eye and renal tubule

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8
Q

What are the main organ manifestations

A

99.7% renal
36% hepatic with hyperbilirubinaemia
70% pulmonary
18% haemorrhagic (DIC)

Approx 44% one organ system, with a quarter each having 2 or 3 systems affected

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9
Q

What are the indications to prompt a search for lepto?

A

AKI
isothenuria with glucosuria without hyperglycaemia
Acute hepatopathy +/- jaundice
Acute resp distress +/- haemoptysis of unclear aetiology with focal or generalised reticulonodular interstitial pattern +/- patchy alveolar conditions

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10
Q

What slightly less common findings should prompt you to consider lepto?

A 
Acute h+ d+
Pyrexia
Uveitis/ retinal bleeding
Myocardial damage
Repro complications
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11
Q

What may you find on haematology?

A

Mild to severe thrombocytopaenia
Mild to severe anaemia
Neutrophilia

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12
Q

What may you find on biochem?

A 
Azotaemia
Raised liver enzymes, esp ALP (tbili > 10 is -ve prognositic indicator)
High or low K+/ Phos
Low Na, Low Cl
High CK
High troponin
High cPLi

(leptospires inhibit Na-K ATPase in the renal tubule

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13
Q

What may you find on urine analysis?

A

Blood, glucose, protein, haem, pyruria, bilirubinuria
isosthenuria
granular casts

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14
Q

What may you find on coags?

A

15% high PT and aPPT
75% high fibrinogen

100% C-reactive protein
75% haptoglobin

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15
Q

What may you see on U/S?

A 
Organomegaly (liver/spleen/kidney)
Ascites
Pancreatitis
Thickened stomach/ intestines
Lymphadenomegaly
Kidneys - increased echogenicity of the meduallry band, mild pyelectasia, peri-renal fluid accumulation
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16
Q

What is LPHS?

A

Lung Pulmonary Haemorrhagic

Bilateral, non lobar
Initially caudodorsal lung fields
Interstitial nodular to diffuse alveolar pattern
Rarely mild pleural effusion

Rads may underestimate changes - CT may be better

17
Q

What are the main options for dx?

A 
Culture
MAT
dark microscopy
PCR
ELISA
18
Q

Outline the use of culture

A

V slow
Only available test for serovars
Insensitive
Not widely available

19
Q

Outline the use of dark microscopy

A

On u+ samples
Poor sens and spec
Need fresh u+ sample
False +ves poss

20
Q

What are the 2 besst tests?

A

PCR and MAT

21
Q

Outline MAT

A

Microscopic agglutination test
Detects AB in serum sample
Relatively inexpensive
Can get false -ves as takes 7-9d to make the ABs, or the patient may be immunocompromised, the serovar may not be included in the test
Can get false +ves if the pet has been recently vaccinated

Therefore best way to confirm is to 2 tests 1-2 weeks apart
Want to see a 4 fold increase
If >800 suggestive

22
Q

Outline the use of PCR

A 
On blood, u+, tissue
Useful early in the disease process
Good if the pet has been vax
No info on serovar given
Only in blood in first 10d infection, best to test both blood and u+ at the same time, BEFORE AB TX
23
Q

Why may a pet have a -ve PCR but +ve infection?

A

Leptospiraemia is transient
Prev AB tx
U+ shedding is delayed after acute infection

24
Q

What is the test to use to detect a renal carrier?

A

Urine PCR

25
Q

Outline the use of ELISAs

A

For IgM and IgG
IgM - increases in the first week, peak 14d
IgG - increases after 2-3 weeks, peak 1 m, remains high for a while
Very quick but has the same limitations as MAT
If -ve but still suspected, repeat test after a few days
Ideally use in conjunction with MAT titres

26
Q

Outline AB tx

A

Needs 14d doxy to clear kidneys
If GI signs, not eating initially, use IV penicillin derivative
If stage 4 AKI - double the dosing interval
Give prophylactic doxy for 14d for all other dogs (not cats) in the house

27
Q

How do you treat the AKI component

A

Standard AKI - if using antiemetics, ensure there is no intussusception as these can be seen

28
Q

When should renal replacement be considered?

A 
Oliguria or anuria
Life threatening high K
Severe volume overload
Advanced uraemia refractory to medical management
Ideally refer early!
29
Q

How do you treat LPHS

A

Reduce stress and manipulation
Avoid over hydration
02 tx/ mechanical ventilation
Plasma/ whole blood transfusion

30
Q

What is the Px?

A

Excellent with early aggressive tx
Success = normalisation of biochem parameters in 14d
50% survivors have renal imparement 12m after - so need to monitor

31
Q

When should you RC the patient?

A

1 week post dc, then 1-3w, then 1-6m, then 12m

RC bloods, urine, BP as needed

32
Q

Outline lepto in cats

A 
Poss reservoirs?
No Vax - therefore MAT more useful poss
Incubation period longer
Hepatic injury less frequent
Dx serology or urine PCR
Tx doxy
33
Q

What occurs in the kidneys?

A

acute interstitial nephritis and tubular dysfunction, although acute tubular necrosis can occur

34
Q

How do MAT titres change in non-infected dogs

A

Titers can persist for at least 1 year after natural infection, and in 1 study, generally declined by 4 months after vaccination

35
Q

Can PCR be affected by recent vaccination?

A

No

SAM Module C infectious diseases (20 decks)

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