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Scientific classification
Domain: Eukaryota
(unranked): Sar
(unranked): Alveolata
Phylum: Apicomplexa
Class: Conoidasida
Subclass: Coccidiasina
Order: Eucoccidiorida
Suborder: Eimeriorina
Family: Sarcocystidae
Subfamily: Toxoplasmatinae
Genus: Hammondia

Hammondia hammondi
Hammondia heydorni
Hammondia triffittae

Hammondia is a genus of parasitic alveolates in the phylum Apicomplexa.


This genus was created in 1975. Before this date the species of this genus were confused with Toxoplasma gondii to which they are closely related.[1]

Life cycle[edit]

The species in this genus have two vertebrate hosts in their life cycle: a carnivore (the definitive host) and prey species (the intermediate host). Both H. heydorni and H. triffittae use canids as their definitive host and H. hammondi uses felids as its definitive host. The prey species vary and depend on the local fauna but include mice, deer and others.

In the gastrointestinal tract of the definitive host the parasite undergoes sexual reproduction, forms and zygote which after some divisions forms a cyst that is excreted. The cyst is subsequently ingested by the prey species in whom the parasite decysts and invades its tissues wherein it again multiplies and encysts. After ingestion of the tissues of the prey species by the definitive host the parasite again decysts and multiplies. It also undergoes sexual reproduction before encysting again.


The genome of Hammondia hammondi has been sequenced.[2]


  1. ^ Dubey JP, Sreekumar C (2003) Redescription of Hammondia hammondi and its differentiation from Toxoplasma gondii. Int J Parasitol 33(13):1437-1453
  2. ^ Walzer KA, Adomako-Ankomah Y, Dam RA, Herrmann DC, Schares G, Dubey JP, Boyle JP (2013) Hammondia hammondi, an avirulent relative of Toxoplasma gondii, has functional orthologs of known T. gondii virulence genes. Proc Natl Acad Sci USA