SUBKINGDOM: PROTOZOA (“FIRST ANIMAL”) KINGDOM: PROTISTA

SUBKINGDOM: PROTOZOA (“FIRST ANIMAL”)

KINGDOM: PROTISTA

CHARACTERISTICS OF PROTOZOA

1. Unicellular2. 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 reproductionA. 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.

ClassificationDomain: 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)?

AmoebaPseudopodsPseudopods

NucleusNucleus

Food vacuoleFood vacuole

Amoeba

p

PseudopodsPseudopods

NucleusNucleus


AmoebaPseudopodsPseudopods

NucleusNucleus


Entamoeba histolytica

Disease: AmoebiasisThis 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, 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 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.


Treatment Metronidazole

Diagnostic Features Ingested RBC Bull’s eye Karyosome

Entamoeba histolyticaTrophozoites


Trophozoites of Entamoeba histolytica with ingested erythrocytes


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 lambliaDisease: Giardosis

Trichomonas vaginalisDisease: Trichomoniasis (an STD)

Trypanosoma bruceiDisease: African Trypanosomiasis

• Sleeping sickness Trypanosoma cruzi

Disease: American Trypanosomiasis• Chaga’s disease

TERMS

Mastigote = flagellaPromastigote: has single flagellaAmastigote: has no flagellaKinetoplast: 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 painDiarrheaGas or bloatingHeadacheLoss of appetiteLow-grade feverNauseaSwollen or distended abdomenVomiting

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.


Trophozoite

Undulating membrane


Trichomoniasis

Usually asymptomatic in men, or mild itchingIn 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.

Winterbottom’s Sign

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

Trypanosoma brucei

Trypomastigote

Trypanosoma

Tsetse Fly

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.


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.


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 cruzi

Trypanosoma brucei and cruzi

Trypanosoma bruceiSmaller posterior kinetoplast

Trypanosoma cruziLarger posterior kinetoplast

African Trypanosomiasis“Sleeping sickness”

American Trypanosomiasis“Chaga’s Disease”

Trypanosoma cruzi

Trypanosoma cruzi

large kinetoplast

Trypanosoma cruzi

Triatomine bug, Trypanosoma cruzi vector, defecating on the wound after taking a blood meal.

Kissing Bug

Romana’s sign

Swollen eye, seen in Chaga's disease.

Phylum: Ciliata (ciliates)

Paramecium spp (free living; non-parasitic) Oral groove Macronucleus Food vacuole Cilia

Balantidium coli (intestinal parasite) Cytostome Contractile vacuoles Cilia

Phylum: Ciliata(Ciliates)

Ciliates (move by cilia)

Paramecium

Balantidium coli

Disease: Balantidiosis The animal reservoir is the pig. Its

geographical distribution is world-wide, wherever humans and pigs live nearby each other.

This is the only ciliated protozoan that causes disease in humans.

Balantidiosis

This is almost identical to Entamoeba histolytica. The cyst form is infective. It has a thick wall to protect it from stomach

acid. It enters the human (and dogs) by ingestion of

fecal contaminants on food, water, and hands.In the trophozoite form, they reproduce in the

large intestine, invade the colon wall, and cause ulcerations in the colon.

Like Entamoeba, it leaves a flask-shaped ulcer. Symptoms include diarrhea and GI discomfort.

Balantidium coli

Trophozoites characterized by: Large size (40 µm to more than 70 µm). Presence of cilia on the cell surface A cytostome (where they take in food) A bean shaped macronucleus which is often

visible and a smaller, less conspicuous micronucleus.

Balantidium coli

Trophozoites

Cytostome

Balantidium coli

Trophozoites

Balantidium coli Trophozoite

Balantidium coli Cyst

Balantidium coli

Cysts

APICOMPLEXA

Characteristics: has an organelle called an apical complex which allows the organism to attach to the host.

They all require a biological vector for transmission (to get into the blood of the host).

Organisms Plasmodium

Disease: Malaria Toxoplasma gondii

Disease: toxoplasmosis Cryptosporidium parvum

Disease: Cryptosporidiosis

Phylum: Apicomplexia(Non-motile obligate parasites)

Plasmodium spp (blood and liver parasite)

Erythrocyte Leukocyte Parasite Identify the stage:

Hepatic stage: Merozoites Blood stage: Ring stage trophozoites

Plasmodium spp

Disease: Malaria200-300 million infections a year2-3 million deaths a yearAffects mostly young people and teenagers2/3 of the cases are in Africa

Malaria

The term “malaria” comes from “mal air”, which means “bad air”. They used to think malaria was cause from the bad air of a foul-smelling swamp. Later it was discovered that the disease was caused by the protozoa inside the mosquito.

Sporozoites migrate into the salivary gland of the mosquito, and they are injected into the blood of the human. They immediately go to the liver. This is the only way to get malaria; you can’t get it from a blood transfusion because the transmission form is the sporozoite. They go right to the liver quickly to begin their next cycle.

Plasmodium

The malaria parasite life cycle involves two hosts. Sporogenic Stage

During a blood meal, a malaria-infected female Anopheles mosquito inoculates sporozoites into the human host.

Hepatic Stage Sporozoites infect liver cells and mature into schizonts, which

rupture and release more merozoites into the bloodstream. Blood Stage

Merozoites infect red blood cells The parasites undergo asexual multiplication in the

erythrocytes. The ring stage trophozoites mature into schizonts, which

rupture releasing merozoites. Some parasites differentiate into male and female gametocytes. Blood stage parasites are responsible for the clinical

manifestations of the disease.

Malaria

Symptoms Fever, chills, sweating, headaches, muscle pains Severe complications (cerebral malaria, anemia,

kidney failure) can result in death.

Anopheles Mosquitoes

Female mosquitoes need blood meals to nourish their eggs.

Hepatic Stage: merozoites mature into schizonts

Schizonts: Hepatic Stage

Blood Phase: Rings 0f trophozoites in RBCs

Blood Phase: Rings

Malaria

Merozoites being released from lysed RBC.

Gametocyte: Blood Stage

Gametocyte: Blood Stage

Toxoplasma gondii

Disease: Toxoplasmosis Infects most species of warm blooded animals, including

humans.Cats are the only known definitive hosts for the

sexual stages of T. gondii and thus are the main reservoirs of infection.

Cats become infected by eating infected wild animals (e.g. birds)

Tissue cysts or oocysts are excreted in the feces.Oocysts can survive in the environment for several

months and are remarkably resistant to disinfectants.

Pregnant women who clean the litter box can catch the mild disease, but the fetus has severe symptoms.

Toxplasmosis

Most primary infections produce no symptoms. The time between exposure to the parasite and symptom development is 1 - 2 weeks. The disease can affect the brain, lung, heart, eyes, or liver.

Symptoms are mild illness with fever, muscle pain, sore throat, headache, enlarged lymph nodes.

This organism prefers nerve tissue, so it travels to the CNS.

Pregnant women should avoid cleaning cat litter boxes, because the fetus can develop mental retardation, blindness and epilepsy, and stillbirths.

Toxplasmosis Cyst

Cyst in brain tissue

Toxplasmosis Trophozoites

Trophozoites

Toxoplasmosis Trophozoites

Toxoplasma Trophozoites sometimes form rosettes

Toxplasmosis

Oocyst

Toxplasmosis

Ocular toxoplasmosis

Cryptosporidium parvum

Disease: Cryptosporidiosis Spread through the fecal-oral route, often

through contaminated waterCauses self-limiting diarrhea in people with

intact immune systems. In immunocompromised individuals (such as

AIDS patients), symptoms are severe and often fatal. AIDS patients have been known to have 50 stools a day, with tremendous water and weight loss. In these patients, the disease may persist for years.

Documents

SUBKINGDOM: PROTOZOA (“FIRST ANIMAL”) KINGDOM: PROTISTA