KINGDOM: PROTISTA SUBKINGDOM: PROTOZOA (“first animal”)
CHARACTERISTICS OF PROTOZOA • 1. Unicellular • 2. Chemoheterotrophs (get their energy by breaking down organic matter). • 3. Most ingest their food; thus, they have special structures for this. • 4. Trophozoites: any stage in a protozoa’s life cycle which can ingest food. In practice it refers to the motile form (pseudopods, cilia, flagella). • 5. Cyst: Non-motile form, protected by a membrane. This is usually the infective stage. Cysts have a thick cell wall that allows for survival in harsh environments better than the trophozoite form. Excystation: process of emergence of the trophozoite from the cyst. • 7. Capable of reproduction A. Asexual: fission, budding, or schizogony (produces a large number of trophozoites) B. Sexual: conjugation
PROTOZOA CYSTS • Cysts are not as resistant as a bacterial endospore. • You can kill cysts by boiling them. • They can live in the soil or water for months. • A cyst is not motile, so it is not trophozoic. • A cyst does not go and seek its nutrients or ingest food, but it can absorb nutrients. • It has no organelles to ingest food.
Classification Domain: Eukaryotes Kingdom: Protista
Kingdom ProtistaSubkingdom: Protozoa • Phylum: Sarcomastigophora • Subphylum: Sarcodina (amoebas) • Amoeba spp. • Entamoeba histolytica • Subphylum: Mastigophora (flagellates) • Giardia lamblia • Trichomonas vaginalis • Trypanosoma spp. • Phylum: Ciliata (ciliates) • Paramecium spp • Balandtidium coli • Phylum: Apicomplexia (Sporozoa; non-motile obligate parasites) • Plasmodium spp • Toxoplasma gondii • Cryptosporidium
Phylum: Sarcomastigophora(amoebas and flagellates) • Amoebas (move by pseudopods) • Flagellates (move by flagella)
Subphylum: Sarcodina (amoebas) • Amoeba spp (free living; not parasitic) • Nucleus • Pseudopods (false foot) • Entamoeba histolytica • Nucleus • Food vacuoles • Do you see a cyst (4 nuclei) or trophozoite (1 nucleus)?
Pseudopods • Nucleus • Food vacuole Amoeba
Pseudopods • Nucleus • Food vacuole Amoeba p
Pseudopods • Nucleus • Food vacuole Amoeba
Entamoeba histolytica • Disease: Amoebiasis • This is a global disease that any traveler can get. As soon as you cross the border into Mexico, you are exposed to it. • Entamoeba histolytica consume red blood cells. • In a fresh diarrheal specimen, you can see RBCs in the cytoplasm of the amoebas.
Entamoeba histolytica • Entamoeba histolytica, as its name suggests, can actually bore through the enteric walls (histolysis = destroying tissue) and reach the blood stream. • From there, it can reach different vital organs of the human body, like the liver, lungs, brain, eyes etc. • A typical effect is a liver abscess caused by such migrating Entamoeba histolytica, which can be fatal.
Entamoeba histolytica • Entamoeba histolytica infection can lead to amoebiasis or amoebic dysentery. Symptoms include dysentery (diarrhea), weight loss, fatigue, and abdominal pain. • It can be diagnosed by stool samples. Trophozoites should be seen in a fresh fecal smear and cysts in an ordinary stool sample.
Entamoeba histolytica • Treatment • Metronidazole • Diagnostic Features • Ingested RBC • Bull’s eye Karyosome
Entamoeba histolytica Trophozoites of Entamoeba histolytica with ingested erythrocytes
Entamoeba histolytica • Cysts
Subphylum: Mastigophora (Flagellates) • Giardia lamblia (intestinal parasite) • Nuclei • Flagella • Do you see a cyst (4 nuclei) or trophozoite (1 nuclei)? • Trichomonas vaginalis (urogenital parasite) • Nucleus • Flagella • No cyst stage • Trypanosoma spp (blood parasite) • Flagella (for movement) • Undulating membrane (for movement) • Nucleus • Kinetoplast (circular mass of DNA)
Mastigophora: Flagellates • Giardia lamblia • Disease: Giardosis • Trichomonas vaginalis • Disease: Trichomoniasis (an STD) • Trypanosoma brucei • Disease: African Trypanosomiasis • Sleeping sickness • Trypanosoma cruzi • Disease: American Trypanosomiasis • Chaga’s disease
TERMS • Mastigote = flagella • Promastigote: has single flagella • Amastigote: has no flagella • Kinetoplast: round mass of circular DNA
Giardia lamblia • Disease: Giardosis • Cysts are resistant forms and are responsible for transmission of giardiasis. • Both cysts and trophozoites can be found in the feces. • Infection occurs by the ingestion of cysts in contaminated water, food (includes undercooked meat), or by the fecal-oral route.
Giardia lamblia • Trophozoite form: piroform (pear or teardrop shape), looks like a happy face. • Discovered by Anton Van Leuwenhoek when he examined his own feces when he had this infection. • You won’t see the flagella in lab because you need a special stain for that. • Cyst form: oval shaped. Nuclei looks like two eyes.
Giardia lamblia • Trophozoite
Giardia lamblia • Trophozoites
Giardia lamblia • Trophozoites
Giardia lamblia trophozoite
Giardia lamblia • Cysts
Giardosis • Abdominal pain • Diarrhea • Gas or bloating • Headache • Loss of appetite • Low-grade fever • Nausea • Swollen or distended abdomen • Vomiting
Trichomonas vaginalis • Disease: Trichomoniasis • Trichomonas vaginalis resides in the female lower genital tract and the male urethra and prostate. • The parasite is a trophozoite only; it does not have a cyst form, and does not survive well in the external environment. • Trichomonas vaginalis is transmitted among humans, its only known host, primarily by sexual intercourse.
Trichomonas vaginalis • Trophozoite Undulating membrane
Trichomoniasis • Usually asymptomatic in men, or mild itching • In women, vagina is extremely pruritic, with vaginal odor and discharge.
Trypanosomiasis • African Trypanosomiasis • (African Sleeping Sickness) • American Trypanosomiasis • (Chaga’s Disease)
Trypanosoma brucei • Disease: African Trypanosomiasis “African Sleeping Sickness” • Trypanosomiasis has a biological vector, the tsetse (pronounced “set-see”) fly. • Wild animals may also be a reservoir (Zoonotic is when a disease is transmitted to animals as well as humans.) • The tsetse fly bites a human and injects the trypanomastigotes into the skin. • This causes a chancre (pronounced “shanker”), which is an ulcer on the skin. • Then it enters the lymphatic system.
Trypanosomiasis • It is characterized by Winterbottom’s Sign: swelling of the cervical lymph nodes in the head and neck area. • CNS symptoms include a shuffling gait (like a stroke victim), slurred speech, and malaise (needing to sleep longer and longer each day). • They are also restless at night.
Trypanosomiasis • CNS symptoms • Shuffling gait • Slurred speech • Malaise (sleeping all day) • Treatment • Melarsoprol: which has dangerous side-effects like chemotherapy. This drug requires administration with a substance called ethylene glycol, which will break down regular plastic tubing, so the drug must be administered with special plastic iv tubing.
Trypanosoma brucei • Trypomastigote stages are the only form found in patients. • Posterior kinetoplast • Centrally located nucleus • Undulating membrane • Anterior flagellum
Trypanosoma brucei • Trypomastigote
Trypanosoma cruzi • Disease: American Trypanosomiasis • “Chaga’s Disease” • A zoonotic disease (can infect animals) that can be transmitted to humans by blood-sucking bugs. • This organism is a little smaller than T. bruceii and has a larger kinetoplast.
“Chaga’s Disease” • This disease is NOT found in Africa. • This disease is also zoonotic; it can infect animals as well as humans. • The vector is a large bug called the “Kissing Bug”. • It is found in warm regions and crowded areas, especially in the cracks of adobe huts. • It comes out at night and crawls on a human while they sleep.
“Chaga’s Disease” • It prefers the lips because the blood supply is close to the surface. • It sucks the blood there, but they don’t transmit the organism this way. • When they suck the blood, they also defecate, and the organism is in the feces. • When the human wakes up to scratch the itch, feces get into the tiny wound. • This is a fecal blood route.
“Chaga’s Disease” • Symptoms include fever, anorexia, swollen lymph nodes, hepatosplenomegaly (enlarged liver and spleen), and myocarditis (inflammation of the heart), which usually causes death. • They also have megacolon (large colon) and megaesophagus (large esophagus).
Trypanosoma brucei and cruzi Trypanosoma brucei Smaller posterior kinetoplast Trypanosoma cruzi Larger posterior kinetoplast American Trypanosomiasis “Chaga’s Disease” African Trypanosomiasis “Sleeping sickness”