Leishmania Flashcards
What DIVA stands for
-differentiate between infected and vaccinated
-DIVA vaccine doesn’t elicit Ab response or Ab produced are different from natural infection
What does DAT stands for?
-direct agglutination test
-serology that directly detect Ab to whole promastigotes
-no intermediate steps
What is FAST?
-fast agglutination screening test
-similar with DAT
-faster reading
What does ELISA detect?
-serology that detects Ab to soluble, purified or recombinant Ag of Leishmania
What does IFAT detect?
-serology indirectly detects Ab to whole promastigotes of Leishmania
What does LPA stand for?
Leishmania promastigote Ag: whole parasite
-detect Ab specific to Lesihmania
What is Leishmanin skin test?
-Intradermal test
-may induce delayed type hypersensitivity
What are vectors ?
Old world- Phlebotomus L.infantum
-New world- Lutzomya L.chagasi
Which other vectors of leishmania have been recognised?
-tick
-flies
What else do sand flies transmit ?
-Bartonella baciliformis (Orayo fever )
-Lyme
-Toscana virus
What is Kala-azar?
visceral Leishmaniasis in people caused by L.donovani
What sources of infection?
-dog (main reservoir)
-wild dogs
-rodents
-wild mammals
What are the types of leishmania in people and dogs?
People:
1. Cutaneous
2. Mucocutaneous
3. Visceral
Dogs:
1. visceral - always cause both cutaneous and visceral disease
What is definition of clinical leishmaniosis ?
-clinical signs and/or clinicopathological abnormalities and confirmed L.infatnum infection
What is subclinical leishmaniosis
-no clinical signs, no clinicopathological abnormalities but confirmed leishmania infection
-self-limited disease
What is the prevalence of infection in endemic areas ?
> 50%
-disease prevalence 3-10%
What are the 2 major patters of progression?
- Acute- severe
-shortly after infection
-unable to develop effective cellular immune response
-develop strong humoral response - Chronically infected
-no lesions, no clinical disease
-but change in health status or immunosuppressive drug/disease can activate infection
What are the ways or transmission in non endemic ares?
- travel dogs
- no travel history but live with imported dogs
- Pups born from infected queens
- Blood transfusion
- Climate changes?
- shared syringes
- licking of wounds by an infected animal
What is life cycle of Leishmania
DIPHASIC parasite-2 host to complete life cycle
1. Sand fly-harbours flagellated extracellular promastigotes (infective)
2. Mammal-intracellular amastigote form develops and replicate
Incubation?
3 months to 7 years
How do sand flies infect mammals /pathogenesis
-they inoculate promastigotes from gut via proboscis (only females feed with blood, males on plants)
-enter dermis and phagocytosed by macrophages
-in phagosome vacuoles and try to eliminate it by NO, lysosomal hydrolyses
-if leishmania escapes , multiplies in macrophages
+ has SUPEROXID DISMUTASE
-progress of infection depends on host immune response
What systemic lesions are found in diseased animals
- poor body condition
- generalised muscle atrophy -myositis / masseter
- lymphadenomegaly
- renal disease: interstitial nephritis, glomerular deposition of parasite Ag, amyloidosis , deposition of immune complexes
- increased blood pressure - due to increased proteinuria, reduce GFR
- splenomegaly -increase in monocytes and macrophages
- joint and bone lesion- erosive/non-erosive poly arthritis, osteolysis, joint swelling, osteoporosis-proliferative bone lesion
- ocular lesion- anterior uveitis, kcs, blepharitis
- homeostatic disorder- platelet aggregation abnormalities, low plt, decrease coat factors, fibrinolysis, nose bleeding, hematuria, hemorrhagic diarrhoea
- anemia- renal disease or decreased erythropoietin + blood loss, immune mediated blood loss
- ch hepatitis, colitis, neurological disease (meningitis), autoimmune disorder , pericarditis, vasculitis, thromboembolism, hyper viscosity syndrome
Histopathologic changes ?
- Periadnexal nodular to diffuse pyogranulomatous/granulomatous dermatitis (+ orto/para HK, acanthosis, crusting, ulceration, macrophages and amastigotes, obliteration of sebaceous glands (SA dDX), decrease in col I, III
- Suncorneal pustular dermatitis
- Lichenoid dermatitis
- Vasculitis
- Panniculitis
Genetic susceptibility is seen ?
- Age: <3, >8
- breed: boxer, Rotweiler, cocker, GSD, foxhound
- Sex: maybe male
Which breed is resistant to lesihmania?
Ibizan hound
Which genes are involved in resistance/susceptibility?
- NRAMP1=Slc11a1
- certain alleles of MHC II genes (DLA-DRB1)
- TAG-8-141 (boxer predisposed to CanL)
Which type of immune response is protective?
Cell mediated
-production of CD4+ Th1
-release of IFN-gamma, TNF-alpha, IL-2
-macrophage secrete NO and intracellular killing of Leishmania
-apoptotic cell death controlled by proteasome inhibitors
Which test are used for evaluation of cellular immunity?
- Leishmanin skin test
- Lymphocyte proliferation test + clinical evaluation
Mild papular dermatitis represent which type of Th response?
-mix of Th1 and Th2
-early infection: IFNgamma produced by NK cels and phagocytes
-Later: balance between Th1 and Th2 , inhibit bacterial activity of infected macrophages (spleen cells from infected dogs have increased IL-10)
TLR: decrease expression / associated with disease progression/ parasites down regulate expression?
Name diagnostic methods ?
- PCR- based on kinetoplast DNA more reliable (RT-PCR detects extreme low levels of parasites)
- Culture
- Serology: IFAT, ELISA; DAT, western blot, immunochromatography (may cross react with T.cruzi)
- Cytology
- Histopathology/IHC (biopsies not from chronic lesions)
What is the % of asymptomatic dogs to have leishmania in clinically normal skin?
20%
Serology is usually when performed?
- To confirm the disease
- investigate presence of infection (epidemiological status, blood transfusion, import of infected dogs, monitor response to treatment )
- Negative status- repeat after 3 months
What are ddx ?
- DLE
- SLE
- PF
- PE
- dermatophytosis
- SA
- Zn- resposnive dermatitis
What are the steps in diagnosing leishmania ?
- Detection of specific Ab by serology (IgG)- quantitative serology: IFAT, Elisa
- Demonstration of parasite DNA in tissue by molecular techniques: parasitological diagnosis
-conventional, nested, real time PCR - Conclusive- microscopic finding of parasite
How to diagnose leishmania in vaccinated dogs?
- compatible clinical signs, clinicopathological abnormalities
- no serology alone, combined with detection of DNA parasite by PCR or cytology
Explain T cell exhaustion?
-limited T cell response to produce IFN-gamma
-deficit of immune cells due to ch exposure to infection
-related with inhibitory receptor Programmed-death-1
-we can use TLR7 agonist to reverse responses in clinically affected and infected dogs
How to dress healthy infected dogs in endemic areas?
- Leishmania DNA in blood or other tissue means they harbour infection, may never develop disease
- Higher Ab titer means they can develop disease or be in early stage of disease
- Best to use serology alone or plus PCR for screening of healthy dogs
- Avoid screening clinically healthy dogs by PCR (expect: travel in non-endemic areas, blood donors)
- Clinically healthy, PCR +, serology -: monitor every 6-12 months
What are the treatment goals ?
- decrease parasite load
- treat organ damage
- improve immune response against parasite
No treatment available to achieve 100% cure!
Name leishmanicidal and leishmanistatic drugs
- Meglumine antimonate
- Miltefosine
- Allopurinol
- Combination 1/2 + 3
- Aminosidine (paraomycine)
- Amphotericin B
- Marbofloxacin
MOA of meglumine antimonate?
-inhibits leishmanial glycolysis and fatty acid oxydation
-neprhotoxic, sc abcesses, cellulitis
-75-100 mg/kg SID or 40-75 mg/kg BID 4 weeks
MOA of allopurinol ?
- inhibits protein translation, interfere with RNA synthesis
- xanthine urolithiasis- C,D
-cutaneous and kidney adverse reactions, coprostasis, elevated liver enzymes - C
MOA of amphotericin B
=bind to ergosterol in parasite cells memebrne
-alters its permeability
-neprhotoxic
-IV ROUTE!
Name imunomodulators?
- Domperidone
- P-MAPA
- Impromune
+ anti IL-10 monoclonal Ab, TLR agonist
Domperidone
= dopamine D2 receptor anatgonist
-limited efficacy in clinically ill dogs, with exhausted T cell and parasite load high
-stimulates the prolactin secretion which acts as PRO-INFLAMMATORY cytokine
+induces phagocytic activation of neutrophils in healthy dogs
-1 mg/kg bid 30 days
-LEISHGUARD
What was the effect of domperidone on Ab titers, inflammatory markers and creatinine in dogs with leishmania and CKD (Cavalera, 2021)
-improved serum Crea
-reduced Ab titers, globulins, gamma-globulins and CRP
What is P-MAPA
= protein aggregate of magesium -ammonium phospholinoleate -palmitoleate anhydride
-limited efficacy in clinically ill dogs, with exhaused T cells and parasite high load
-by fermenting Aspergillus oryzae
What is P-MAPA immunomodulatory activity?
-induction of TLR2 in HEK (human embriotic kidney) cells
-stimulation of marrow myelopoiesis
-antimicrobial and antitumoral activities
-increase spleen cell proliferation and priduction of IL-2, IFN-gamma, NK cell activity which promotes greater stimulation of cellular immunity
What are the aims of vaccination?
-keep infection to subclinical stage
-still can be source of infection
-adjuvant plays a major part
-ability of a vaccine to maintain low paarsite load is essential in order to limit transmission from dogs to humans
-THEY DO NOT PREVENT INFECTION!
Types of vaccines
- Killed leismania -inactivated promastigotes
- Purified leishmania freaction - components of whole cultured parasite or excretory - secretory macromolecules
-main representative fucose-mannose ligand- most succesful LEISHMUNE (Ab to Leishmania detected after <6 mo after first dose )
-proposed for immune therapy of sick dogs and as a transmission blocking - Recombinant antigens : immunogenic proteins from cloned lesihmania genes
- DNA vaccines - protein antigens : CANILEISH, LETIFEND
To wich drugs has resistance been noted (humans, limited in dogs)?
- Amphotercine B
- Aminosidine
- Miltefosine
When does the transmission of promastigotes happens?
Immediately after bite!
Topical insecticides and repellents!
Reccomended repellents?
- permenthrin, deltamethrin , flumethrin
-pyretroids
-imidacloprid
Name brand names that can be used to prevent sand flies ?
- Activyl Plus
- Advantix
- Duowin
- Effitix
- EX-spot
- Frontline Tri-Act
- Scalibor
- Seresto
- Vectra 3D
Several Leishmania spp. can affect cats (Garcia- Torres, 2024):
- L.infantum
- L.mexicana
- L.venezuelensis
- L.tropica
- L.major
- L.amazonensis
- L.braziliensis
What are most common presentations in cats (Garcia- Torres, 2024)?
- dermatological signs 69.8%
- Systemic 55.5%
- ocular 34.9%
- mucocutaneous 28.6%
- respiratory 12.7 %
Combination of clinical signs 58.7%
Is lymphadenomegaly always present (Garcia- Torres, 2024)?
No, only in 40 % of cases
-meaning that 60% have normal lymph nodes!!
Most common clinicopathological abnoramilites in cats (Gacia-Torres, 2024)
○ HYPERPROTEINEMIA 46.3%
○ hypergammaglobulinemia 71%
○ hypoalbuminemia 19.1%
○ Anemia 33.3 %
○ neutrophilia 18%, neutropenia 8.3%
○ thrombocytopenia 16.6%
○ proteinuria 15.2%
○ azotemia 14.9%
○ Eosinopenia 6.25%
○ Pancytopenia 2%
Increased ALT 4.1%
Why usage of miltefosine in cats should be under close monitor (Garcia-Torres, 2024) ?
-contains PROPYLENE GLYCOL
-causes decreased life span of feline RBC due to formation of Heinz bodies
What is the correlation of FIV and FeL (Priolo, 2022)
-FIV seropositve cats are more prone to be L. infantum seroreactive by IFAT in endemic areas
-pale MM, low BCS and oral lesions, but no CBC abnormalities were significantly associated with coinfection
-FIV serepositve cats should be testes for L.Infantum Ab and treated by preventing sand fly bites
What is the correlation of Phlebotomus perniciosus and Leishmania infections in cats ?
-cats presenting with IgG Ab to P. perniciousus had a significantly higher risk of being positive for L. infantum infection
What is the prognosis in cats ?
-good (if no FIV+ or FeLV+)
-panleukopenia, AKI and lack of treatment associated with poor prognosis and short survival time
Which collar is recommended in cats ?
Seresto ( 10% imidacloprid, 4.5% flumethrin)
=75 % collar efficacy in preventing Leishmanian infection in cats (Brianti, 2017)
+ spot on fluralaner (causes long term mortality in sand flies after feeding on tretaed dogs, similar results in cats?
What is Impromune?
-active hexose correlated compund
-dietary nucleotides
-is safe, allows significant reduction in Ab and leads to lower disease progression (Segarra, 2018)
Which TLR receptors are connected with more robust Th1 CD4 + cell response in dogs (Schaut, 2016)?
TLR4 and TLR7 agonist
What did the Moreira study, 2016 proved with vaccination?
Vaccination against canL increase phagocytic activity, nitric oxide priduction and expression of cell activation/migration molecules in neutrophils and mononcytes
What does Lesimhmune cause?
-increased TLR expression (2,4,5,9)
-increased integral (CD29, CD49f)
-increased activation of MHC II and co stimulatory CD80, CD81 molecules
=by neutrophils and monocytes
-decrase in IL-4, increase in IL-8 production by monocytes and high IFN-gamma, IL-17 production by T cells
What are the examples of TLR agonist and treatmeni in sick animals?
-TLR2 agonist (Pam3CSK4) in L.major in mice have shown to decrase pathology
-topical resiquimod (TLR7/8 agonist) protects against visecral infection with L. infantum in mice
-Pam3Cys (a TLR-2/1 ligand) + miltefosine- lower dosage of miletfosine in mice to promtote decrased parasite load
What did the study from Roatt, 2017 demonstrated with vaccination with L.braziliensis antigen and MPL (TLR4 agonist)?
-dogs showed clinical improvement
-low parasite load
-restrore T cell mediated immunity
-blocking transmission only in 3 dogs
In a study by Santiago, 2013 - P-MAPA had was results?
-induced stimulation of cellular immunity
-no toxic side effects
-clinical signs improved
-decreased parasite load
-dogs had decreased IL-10 serum levels with incerased IL-2, IFN gamma
= 2 mg/kg IM in dosral region EOT for 45 days
Does Wolbachia in CanL has a protective or detrimental role (Tabular, 2013)?
-protective
+ greatest severity of clinical signs occurs with Lesihmania-filaria coinfection
In a study by Mylonakis, 2014- did Bartonella with CanL had impact on arthritis ?
-no significant difference was obtained in frequency of infection of Bartonella spp. between dogs with arthritis (19%) and without artritis (29%)
In a study by Attipa, 2018 did association with Ehrlichia canis in canL had impact on disease ?
-dogs with CanL were 12 times more likely ro be coinfected with E.canis than clinically heatly dogs
In Attipa study, 2019 what we results about coinfection with CanL?
-dogs with CanL were 3 times more likely to have been exposed to E.canis/E.ewingii when compared to control dogs
-CanL were 5 times more likely to have been exposed to A.phagocytophilum/A.platys when compared to healthy dogs
Baxarias, 2018 does co-infection with vector bourne plays a role in canL?
-dogs with canL were 4 times more likely to be sero+ for Rickettsia conorii
-and 14 times more likely to be sero+ for A.phagocytophilum
-when compared to heatly dogs
From wich species has been L.tarentolae been isolated?
-dogs
-sand flies
-lizards
What are UNCOMMON lab findings in CanL
HEMATOLOGY
1. thrombocytopenia
2. pancytopenia
3. neutropenia
4. reactive lymphocytosis
5. regeneraive anemia- likely due to hemolysis
BIOCHEMISTRY
1. high TP (above 10 g/dl)
2. marked polyclonal gammapathy
3. marked hypalbuminemia,
4. marked proteinuria?
When we suspect co-infection in dogs with canL?
-presence of clinicopathological
In a peper by Patino, 2021 they developed an amplicon based next generation sequencing protocol for what?
-targets heat shock protein 70 (HSP70)
-to detect and identify leishmania and other trypanosomid species in humans and mammalian reservoirs
What are limits of serology?
- positive serology= contact with infectious agent
- negative serology does NOT exlude that the dog is infected
- cross seroreaction between pathogens of the same genus Ehrlichia, Babesia, Rickettsia …
- DOES NOT differentiate between vaccinated and naturally infected animals
In acute phase of the disease seroconversion form seronegative to seropositve happens in which time frame?
After 2-4 weeks
-incerased antibody levels> 4 fold incersase
What are comorbidities in FeL
-significant association between L.infantum and FIV co infection
-66% of cats had comorbities: corticosteroid treatment, diabetes mellitus, epidermoid carcinoma, squamous cell carcinoma, pemphigus, or co- infections such as FIV, feline leukemia virus, Bartonella henselae, ‘Candidatus Mycoplasma haemominutum,’ feline coronavirus, Toxoplasma spp. and Hepatozoon spp
What where the most common cutaneos symptoms (69.8%) in cats (Garcia- Torres, 2022)
- Ulcerative dermatitis 31.7%
- Nodular dermatitis 22.2%
- Alopecia 14.3%
What were the most common systemic signs (55.5%) in FeL (Garcia Torres, 2022) ?
- LN enlargement (28.5%)
- anorexia/hyporexia 22.2%
- Weight loss 22.2%
What were the most common ocular signs 34.9% in Fel ( Garcia -Torres 2022)
- Uveitis 20.6%
- Conjunctivitis 11.1 %
3 Nodular blepharitis 9.5%
What were the most common mucocutaneous signs in FeL (Garcia-Torres, 2022)
- stomatitis/gingivostomatitis 17.4%
- Glossitis 4.7%
Which form of CanL has better prognosis and why?
Nodular dermatitis
-lesion is localized and has good response to treatment
What where the most common respiratory symptoms 12.7% in FeL (Garcia- Torres, 2022)
- Nasal discharge 6.3%
- Stridor 4.7%
How many biopsy samples are recommended and why?
3
1. histo
2. sterile one for culture and PCR
3. snap-frozen for immunohistochemistry
