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United States Department of Agriculture

Agricultural Research Service


Location: Animal Parasitic Diseases Laboratory

Title: First isolation of Hammondia hammondi from a cat from Ethiopia

item Dubey, Jitender
item Tilahun, Getachew
item Boyle, Jon
item Schares, Gereon
item Verma, Shiv
item Ferreira, Leandra
item Solange, Oliveira
item Tiao, Nary
item Darrington, Courtney
item Gebreyes, Wondwossen

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2013
Publication Date: 9/1/2013
Publication URL:
Citation: Dubey, J.P., Tilahun, G., Boyle, J., Schares, G., Verma, S.K., Ferreira, L.R., Oliveira, S., Tiao, N., Darrington, C., Gebreyes, W. 2013. First isolation of Hammondia hammondi from a cat from Ethiopia. Journal of Parasitology. 99: 614-618.

Interpretive Summary: Toxoplasma gondii is a single-celled parasite of all warm-blooded hosts worldwide. It causes mental retardation and loss of vision in children, and abortion in livestock. Cats are the main reservoir of T. gondii because they are the only hosts that can excrete the resistant stage (oocyst) of the parasite in the feces. Humans become infected by eating under cooked meat from infected animals, as well as food and water contaminated with oocysts. Why some people become sick whereas most infected with toxoplasmosis remain asymptomatic is largely unknown. Parasite genetics is thought to be one factor determining the clinical outcome. Hammondia hammondi, is the closest relative of T. gondii but is non pathogenic, and is currently used to study the pathogenesis of toxoplasmosis. The authors report the first isolate of H. hammondi from the African continent. The results will be of interest to biologists, parasitologists, and public health workers.

Technical Abstract: Toxoplasma gondii oocysts are morphologically and antigenically similar to oocysts of another feline coccidian, Hammondia hammondi. The distinction between H. hammondi and T. gondii is important from an epidemiological perspective because all isolates of T. gondii are potentially pathogenic for humans and animals whereas H. hammondi is not known to cause clinical disease in any naturally infected host. In the present report, H. hammondi oocysts were found microscopically in the feces of 1 of 36 feral domestic cats (Felis catus) from Addis Ababa, Ethiopia. Oocysts were orally infective to Swiss Webster and gamma interferon gene knockout (KO) mice; the inoculated mice developed tissue cysts in their muscles. Laboratory-raised cats fed mouse tissues of infected mice shed H. hammondi oocysts with a prepatent period of 5 days. The DNA extracted from sporulated oocysts reacted with H. hammondi-specific primers, and sequences were deposited in Genbank (accession nos._). This is the first report of isolation of H. hammondi from a cat from the African continent.

Last Modified: 10/17/2017
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