Protozoa Unicellular organisms. Grouped by how they are motile. - Amoebae - pseudopods - Flagellates – flagella - Ciliates – cilia - Apicomplexans – not motile

Protozoa May have two life stages: Trophozoite - motile stage that causes symptoms Cyst - dormant stage that protects; usually stage that infects us

Entamoeba histolytica Get infected by drinking contaminated water or food Causes amoebic dysentery Organism very invasive – causes ulcers in large intestine and liver abscesses Symptoms: bloody diarrhea, dehydration Diagnose by presence of cysts or trophs in feces

Entamoeba histolytica

Trophozoite

Entamoeba histolytica Cyst

Entamoeba histolytica

Rare, but if gets in the brain, almost always fatal – Primary Amoebic Meningoencephilitis Get infected by swimming in warm, fresh water – water gets up into the nose Organism very invasive – passes into brain via the olfactory nerve 33 cases in 10 years in U.S. – 5 of those in Arizona Naegleria fowleri

Troph in brain tissue Troph in spinal fluid Naegleria fowleri - trophozoites

Acanthamoeba Most people exposed to it in their lifetime Causes three kinds of infection: - Keratitis in contact lens wearers - Granulomatous Amoebic Encephalitis in immunocompromised - Disseminated infection in immunocompromised

Acanthamoeba Follow directions for lens use, wear, storage Don’t use saline to disinfect lenses Wash hands Remove lenses before water activity

Trichomonas vaginalis Flagellate Causes vaginitis, urethritis – often no symptoms “Ping-pong” vaginitis No cyst stage Sexually transmitted

Trichomonas vaginalis Trophozoite

Trichomonas vaginalis

Giardia lamblia Get infected by drinking contaminated water Called “back-packer’s” parasite; also in day care centers; traveler's diarrhea Symptoms – severe cramps and diarrhea proceeded by “sulfur burps” Must boil water – organism survives chlorine and iodine tablets

Giardia lamblia TrophozoiteCyst

Giardia lamblia SEM of nucleiSEM of sucking disc

Giardia lamblia Giardia attached to mouse intestine

Trypanosoma Organism needs a vector Multiplies at bite site and gets into the blood and lymph and causes fever, nausea, vomiting, CNS involvement, heart problems

Trypanosoma

Needs an insect vector T.brucei gambiense and T. brucei rhodesiense cause African Sleeping Sickness – tsetse fly is vector T. cruzi causes Chagas Disease or South American Trypanosomiasis - Reduviid bug or “kissing bug” is vector

Trypanosoma - Vectors Tsetse Fly Reduviid Bug “Kissing Bug”

Leishmania Causes Leishmaniasis Infected by bite of sand fly Endemic in southern Texas; Found predominantly in Central and South America, Asia, Africa, Europe, and Middle East Diagnosed in soldiers returning from Iraq and Afghanistan – called “Baghdad boil”

Leishmania Sand fly Rosettes of Leishmania Flagellate

Leishmania Three forms: - Cutaneous – skin ulcers around bite - Mucocutaneous – skin ulcer spreads to mouth, nose and soft palate - Visceral – macrophages spread to liver, spleen, bone marrow and lymph nodes - fatal if not treated

Leishmania Mucocutaneous Visceral Cutaneous

Motile by cilia Has both a micro and macro nucleus Causes large intestine infection Common in areas of crowding – rest homes, prisons, mental hospitals, day care centers Food and water contamination Balantidium coli

Balantidium coli - trophozoite

Balantidium coli Trophs in intestinal tissue

Balantidium coli - cysts

Apicomplexa No protective cyst stage Not motile Definitive host – sexual reproduction Intermediate host – asexual reproduction

Plasmodium Causes malaria Several species (P. falciparum is most lethal, P. vivax is most common) Man is intermediate host Anopheles mosquito is the definitive host

Plasmodium Figure Infected mosquito bites human; sporozoites migrate through bloodstream to liver of human Sporozoites undergo schizogony in liver cell; merozoites are produced Merozoites released into bloodsteam from liver may infect new red blood cells Merozoites are released when red blood cell ruptures; some merozoites infect new red blood cells, and some develop into male and female gametocytes Asexual reproduction Intermediate host Merozoite develops into ring stage in red blood cell Ring stage Merozoites Another mosquito bites infected human and ingests gametocytes 7 5 Ring stage grows and divides, producing merozoites Definitive host In mosquito’s digestive tract, gametocytes unite to form zygote 8 Male gametocyte Female gametocyte Zygote Sexual reproduction Resulting sporozoites migrate to salivary glands of mosquito 9 Sporozoites in salivary gland

Plasmodium Oocysts in gut of mosquito hatch into sporozoites Sporozoites migrate to salivary glands and are injected into host when mosquito bites. Sporozoites go to liver and become merozoites through asexual reproduction. These merozoites infect red blood cells.

Plasmodium Oocysts in gut of mosquitoSporozoites Anopheles Mosquito Definitive Host

Plasmodium Symptoms of malaria caused by destruction of the red blood cells - anemia occurs because merozoites rupture red cells - fever and chills occur because waste products from merozoite reproduction are released into the blood stream when red cells lyse

Plasmodium Merozoites in red blood cells

Plasmodium

Eventually the merozoites become male and female gametocytes Mosquito sucks up gametocytes when they bite Gametocytes mate in the gut of the mosquito and produce oocysts that hatch into sporozoites

Plasmodium Merozoites in red cellsGametocytes

Toxoplasma gondii Causes Toxoplasmosis Infected from cat feces, litter boxes, sand boxes Infected from eating raw meat Infected fetus from mother

Definitive Host Cat Intermediate Host Man,mammals, Birds Torch Test Done on babies with severe birth defects

Toxoplasma gondii

Oocysts from cat or litter box or from rare beef are ingested. Trophozoites are released into GI tract. Migrates into tissue from GI tract.

Toxoplasma gondii Cyst with trophozoites in host cellTrophozoites in tissue

Toxoplasma gondii Trophozoites from bronchial washing of HIV patient

Cryptosporidium parvum Transmitted by food and water Danger to immunocompromised host Resists chlorination – must be filtered from water Thick wall surrounds organism – resists most disinfectants Organism is detected with acid-fast stain

Cryptosporidium parvum Acid-fast stain of oocysts in fecesOocyst

Cyclospora Infections have occurred from eating imported raspberries (Guatemala) and strawberries (Mexico) Cyclospora presence can be demonstrated with an acid-fast stain Man may be only true host

Cyclospora Acid-fast Stain