Life Cycles - Human Parasites

Human

Cysts and trophozoites passed in feces

Mature cysts ingested

Entamoeba histolytica

Trophozoite

Cyst

Flagellated form

Humans

Swimming/ water sports (resulting in water going up the nose)

Naegleria fowleri

Also undergoes promitosis

Human

Trophozoites/ Cysts

Trophozoites reproduce to form cysts (trophozoites cannot survive in environment)

Cyst

Giardia lamblia

Contamination of water, food or hands with infective cysts

Human (female)

Human (male)

Trichomonas vaginalis

Trophozoite multiplies by longitudinal binary fission (in male or female)

Sandfly takes blood meal (passes promastigote to human)

Promastigotes are phagocytized by macrophages

Promastigotes transform into amastigotes inside macrophages

Amastigotes multiply in cells of various tissues

Sandfly takes a blood meal (ingests macrophages infected with amastigotes)

Ingestion of parasitized cell

Amastigotes transform into promastigote stage in midgut

Divide in midgut and migrate to proboscis

Sandfly Stages

Human Stages

Leishmaniasis

Tsetse fly takes a blood meal (injects metacyclic trypomastigotes)

Injected metacyclic trypomastigotes transform into bloodstream trypomastigotes, which are carried to other sites

Trypomastigotes multiply by binary fission in various bodily fluids

Trypomastigotes in blood

Tsetse fly takes a blood meal (bloodstream trypomastigotes are ingested)

Procyclic trypomastigotes leave the midgut and transform into epimastigotes

Bloodstream trypomastigotes transform into procyclic trypomastigotes in tsetse fly's midgit. Procyclic trypomastigotes multiply by binary fission

Epimastigotes multiply in the salivary gland. They transform into metacyclic trypomastigotes

Tsetse fly stages

Human Stages

Trypanosoma (sleeping sickness)

Triatomine Bug takes a blood meal

Metacyclic trypomastigotes penetrate various cells at bite wound site. Inside cells they transform into amastigotes

Amastigotes multiply by binary fission

Intracellular amastigotes transform into trypomastigotes then burst out of the cell and enter the bloodstream

Triatomine bug takes a bloodmeal

Epimastigotes in midgut

Multiply in midgut

Metacyclic trypomastigotes in hind gut

Triatomine Bug Stages

Human Stages

Trypanosoma cruzi (Chagas Disease)

Infected liver cell

Schizont

Ruptured schizont

Human blood cell

Immature trophpzoite (ring stage)

Mature trophozoite

Schizont

Ruptured schizont

Gametocytes

Gametocytes (male and female)

Mosquito takes a blood meal

Macrogametocyte

Ookinete

Oocyst

Ruptured oocyst

Mosquito takes a blood meal

Liver cell

Enthrocytic Cycle

Exo-erythrocytic cycle

Sporogonic Cycle

Malaria

Human

Oocysts in feces

Immature oocyts with sporoblasts

Immature oocysts with sporocysts

Mature oocysts with sporozoites

Isospora belli

Human

Excretion of unsporulated oocysts in the stool

Environmental contamination

Oocyst sporulation in the environment

Sporulated oocysts enter the food chain

(Raspberries, water, basil)

Sporulated oocysts

Cyclospora cayetanensis