Ribosomes similar to prokaryotes Ex. Diplomonadida Diplomonads are small heterotrophic protists with no mitochondria. Individuals may be infected and show no disease, some have acute diarrheal disease periodically. They have two haploid nuclei. Outbreaks have occurred among travelers to Russia, skiers in Rocky Mountain resorts, and parts of Pennsylvania.
Cysts are the infective stage.
They are passed periodically in solid stools. The wall of the cyst resists the deleterious effects of various physical and chemical agents such as chlorine. The only sure methods to render contaminated water safe are boiling water or the physical removal of the cysts by filtration. The euglenid cell is covered by a flexible coat, the pellicle, that allows the cell to change shape. Exhibit positive phototaxis.