Canis ISSN: 2398-2942

Leishmania infantum

Synonym(s): Leishmania chagasi

Contributor(s): Gad Baneth, David Lindsay, Susan E Shaw

Introduction

Classification

Taxonomy

  • Kingdom: Protista
  • Phylum: Sarcomastigophora
  • Subphylum: Mastigophora
  • Class: Zoomastigophora
  • Order: Kinetoplastida
  • Family: Trypanosomatidae
  • Genus: Leishmania
  • Species: Infantum

Etymology

  • Leishmania infantum is in the Leishmania donovani complex. It is occasionally incorrectly referred to as L donovani.
  • The name, Leishmania chagasi is a synonym for L. infantum used in South America.

Active Forms

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Clinical Effects

Epidemiology

Habitat

  • Sand flies of the genera Phlebotomus and Lutzomyia.
  • Found mainly in tropics and subtropics, some species in temperate regions.
  • Habitats range from desert to savanna to rainforest with each species possessing specific ecological requirements.
  • Peridomestic species of sand flies vector Leishmania infections to man.

Lifecycle

  • Flagellated promastigotes Leishmania infantum: promastigote multiply asexually in the sand fly midgut by longitudinal binary fission.
  • Promastigotes inoculated into mammalian host while sand fly takes blood meal.
  • Promastigotes enter macrophages and transform into amastigotes Leishmania infantum: amastigotes .
  • Amastigotes divide by binary fission until the host cell ruptures and the parasites are released.
  • Amastigotes infect nearby macrophages or move through vasculature to infect other organs, eg spleen and liver.
  • Lifecycle completed when sand fly ingests amastigotes while blood feeding.

Transmission

  • Usual route of transmission between dogs and between dog and human is by competent sand fly species.
  • Direct transmission between dogs and humans has not been reported.
  • Alternative routes of transmission:
    • Infected blood transfusions.
    • Contaminated needles/syringes.
    • Direct transfer from dog to dog through close contact, exchange of body secretions.
    • Congenital transmission reported in dogs.
    • Venereal transmission reported between dogs especially if mucosal ulcerations.

Pathological effects

Host immunological response to infection

  • Cell-mediated immune responses (Th1 type) required for resistance.
  • Antibodies produced but are not protective.
  • Dogs that develop clinical leishmaniosis thought to have a genetic disposition to mount a humoral rather than cell-mediated immune response.
  • Cell-mediated response to Leishmania antigen and other antigens is decreased in dogs with leishmaniosis.
  • Dogs with clinical leishmaniosis have higher levels of IgG1 antibodies. Asymptomatic dogs have higher levels of IgG2 antibodies.

Host clinico-pathological response to infection

  • Most infected dogs are asymptomatic. In endemic areas, only 10% of infected dogs develop overt clinical disease.
  • Dogs with partial immunity may show only localized nodular/ulcerative lesions at site of sand fly bites.
  • Susceptible dogs may develop clinical signs referable to one body system or multiple systems:
    • Chronic porgressive weight loss, malaise, lethargy, variable appetite loss.
    • Cutaneous lesions.
    • Lymphadenopathy, splenomegaly.
    • Muscle wasting.
    • Ocular lesions.
    • Lameness.
    • Polyuria, polydipsia.
    • Epistaxis Epistaxis.
    • Anemia Anemia: overview.
    • Diarrhea Diarrhea: parasitic.

Control

Control via animal

Initial therapy

  • See Meglumine antimoniate Meglumine antimoniate.
    Meglumine antimoniate and miltefosine are licensed for the treatment of canine leishmaniosis in several European countries but may require importation and authorization in non-endemic countries.

Insecticide/repellent application to dogs

  • Synthetic pyrethroids including deltamethrin collars, permethrin or permethrin/imidocloprid combination spot-on products Control of canine leishmaniosis.

Control via environment

  • Destruction of sand fly habitat.

Vaccination

  • CaniLeish® - the first vaccine against Canine leishmaniosis registered by the European Medicines Agency in 2011 by Virbac.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from VetMedResource and PubMed.
  • Solano-Gallego L, Koutinas A, Miro G, Cardoso L, Pennisi M G, Ferrer L, Bourdeau P, Oliva G, Baneth G (2009) Directions for the diagnosis, clinical staging, treatment and prevention of canine leishmaniosis. Vet Parasitol 165 (1-2), 1-18 PubMed.
  • Tabar M-D, Francino O, Altet L, Sanchez A, Ferrer L & Roura X (2009) PCR survey of vectorborne pathogens in dogs living in and around Barcelona, an area endemic for leishmaniosis. Vet Rec 164, 112-116 PubMed.
  • Miro G, Cardoso L, Pennisi M G, Oliva G, Baneth G (2008) Canine leishmaniosis - new concepts and insights on an expanding zoonosis: part two. Trends Parasitol 24(8), 371-377 PubMed.
  • Baneth G, Koutinas A F, Solano-Gallego L, Bourdeau P, Ferrer L (2008) Canine leishmaniosis - new concepts and insights on an expanding zoonosis: part one. Trends Parasitol 24(8), 371-378 PubMed.
  • Baneth G & Shaw S E (2002) Chemotherapy of canine leishmaniasis. Vet Parasitol 106,315-324.
  • Lindsay D S, Zajac A M & Barr S C (2002) Canine leishmaniasis in the American Foxhounds: an emerging zoonosis? Comp Cont Ed Pract Vet 24,304-312.
  • Mauricio I L, Howard M K, Stothard J R & Miles M A (1999) Genomic diversity in the Leishmania donovani complex. Parasitol 119, 237-246.

Other sources of information


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