Canis ISSN: 2398-2942

Giardia spp

Contributor(s): Dwight Bowman, Ibulaimu Kakoma

Introduction

Classification

Taxonomy

  • Within the Excavata. phylum Metamonada, and the order Diplozoa.
  • Giardia taxonomy remains in a state of flux. There are several species recognized: 3 in mammals, 2 in birds, and one in amphibians.
    • Giardia duodenalis (syn.Giardia lambliaGiardia intestinalis) in humans, livestock, other domestic animals, and wildlife.
    • Giardia microti and Giardia muris in rodents.
    • Giardia psittaci and Giardia ardeae in birds.
    • Giardia agilis in amphibians.
  • The species G. duodenalis is broken into 8 groups called assemblages based on various molecular genetic markers. These Assemblages are designated by letters:
    • The ones most commonly found in dogs are Assemblages C and D.
    • The one most commonly found in cats is Assemblage F.
    • Ungulates and pigs tend to be infected with E, rats are infected with G, and seals are infected with H.
    • Assemblage B is found mainly in people.
    • Assemblage A has been reported from a number of different animal types and is the only Assemblage that appears to be readily shared by hosts in disparate mammalian groups.

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Clinical Effects

Epidemiology

Habitat

  • Inhabit the intestines of mammalian hosts.
  • Cysts may be found in water sources.

Lifecycle

  • Direct lifecycle.
  • Cysts ingested.
  • Excystation occurs in the small intestine → release 2 trophozoites.
  • Trophozoites mature and divide.
  • Encystation may be stimulated by intraluminal bile acids or fatty acids.
  • Pre-patent period varies from 5-16 days.

Transmission

  • Ingestion of cysts. Inadequate treatment (filtration) at water treatment plants → epidemics.
  • Prevalence in humans varies from 2-60%.

Pathological effects

  • Immunodeficient and immature animals are predisposed.
  • See giardiasis Giardiasis.
  • Inhibition of host intestinal enzymes; blunting intestinal villi and microvilli.
  • Severe (may be profuse) chronic diarrhea (often young or immuno-deficient animals).
  • Chronic diarrhea (continuous or sporadic).

Other Host Effects

  • Often subclinical infection, 'carrier' status.

Control

Control via chemotherapies

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Mohamed A S, Levine M, Camp W Jr et al (2014) Temporal patterns of human and canine Giardia infection in the United States: 2003-2009. Prev Vet Med 113, 249-256 PubMed.
  • Gruffydd-Jones T, Addie D, Belak S et al (2013) Giardiasis in cats: ABCD guidelines on prevention and management. J Fel Med Surg 15, 650-652 PubMed.
  • Ryan U, Caccio S M (2013) Zoonotic Potential of Giardia. Int J Parasitol 43, 943-956 PubMed.
  • Payne P A & Artzer M (2009) The Biology and Control ofGiardiaspp andTritrichomonas foetusVet Clin N Am Sm Anim Pract 39, 993-1006 PubMed.

Other sources of information

  • Little S E & DeBess E (2013) Canine protozoa recommendations from the Companion Animal Parasite Council. Today's Vet Pract 3, 43-47.
  • Lund C & Blagburn B (2013) Feline protozoa recommendations from the Companion Animal Parasite Council. Today's Vet Pract 3, 74-79.

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