Which protozoan have a flagellum at its one end?

The answer is Leishmania is a type of protozoa under the phylum Euglonozoa. This causes the disease leishmaniasis spread by sandflies. Vertebrates are their usual hosts and can infect canids, rodents, and even humans.

Its origin is not certain but some theories that it came from Africa then migrated to America and one proposes that it originated from America then migrated to other parts of the world via the Bering Strait in the Old World.

Their flagellum helps them to survive in their host’s body when the immune system is trying to destruct them. When they successfully infect their host, their victim experiences fever, anemia, and swelling of the spleen and the liver.