Phylum: Sarcomastigophora

Sub-phylum: Mastigophora

Class: Zoomastigophora

Order: Trichomonadida

Family: Monocercomoriadidae

Genus: Histomonas

Trichomonadida

• Flagellate protozoa under this order are characterized by presence of 4-6 flagella, one of which may be a trailing flagellum attached to undulating membrane
• Multiplication occurs by binary fission
• Cyst are produced by some forms
• Most of species are non-pathogenic and found in alimentary canal of animals
• Pathogenic forms are classified under two families ‘Monocercomonadidae’ and ‘Trichomonadidae’.

Family: Monocercomonadidae

• Species of this family have three to five flagella directed toward and one trailing flagellum which is usually free

Genus: Histomonas

• Organism is amoeboid with single nucleus
• Shape is spherical or elongated with one flagellum
• A single species ‘Histomonas meleagridis’ is recognized.