Eukaryotic Pathogens: Algae and ProtozoansWhat types of eukaryotic organisms are pathogenic, and how do they differ from bacteria?

• Algae: dinoflagellates and saxitoxin

• Protozoans

• Classification and special structures

• Pseudopodia, flagella, cilia

• Pellicles, cysts

• Important protozoan pathogens

• Amoebic dysentery

• Balantidiasis (Balantidium dysentary)

• Giardia, Trichomoniasis, Trypanosomiasis

• Malaria, CryptosporidiumEukaryotic pathogens are mostly parasitic and are difficult to target selectively with drugs since their cells are so similar to human cells.

Algae:”Plant-like Protists” Based on Nutrition

Table 12.1

• Cellulose in plasma membrane

• Unicellular

• Algal “blooms” cause “red tides”

• Shellfish ingest dinoflagellates; toxin concentrated through food chain

• Neurotoxin (saxitoxin) causes paralytic shellfish poisoning

Toxic Algae: Photosynthetic Dinoflagellates

Eukaryotic Pathogens: Algae and ProtozoansWhat types of eukaryotic organisms are pathogenic, and how do they differ from bacteria?

• Algae: dinoflagellates and saxitoxin

• Protozoans

• Classification and special structures

• Pseudopodia, flagella, cilia

• Pellicles, cysts

• Important protozoan pathogens

• Amoebic dysentery

• Balantidiasis (Balantidium dysentary)

• Giardia, Trichomoniasis, Trypanosomiasis

• Malaria, CryptosporidiumEukaryotic pathogens are mostly parasitic and are difficult to target selectively with drugs since their cells are so similar to human cells.

The Protozoa: Kingdom Protista

Table 12.1

• Eukaryotic

• Unicellular

• Chemoheterotrophs

• Vegetative form is a trophozoite

• Some produce cysts, or dormant forms (often the infective agent)

• Some have an outer support layer: pellicle

• Asexual reproduction by fission, budding, or schizogony;

• Sexual reproduction by conjugation

Protozoa: “Animal-like Protists” Based on Nutritional Mode

Figure 12.16

Pathogenic Protozoans

Protozoans can be studied according to their type of locomotion:• Amoebas (sarcodines) move using pseudopodia

• Ciliates (ciliates) move using beds of cilia

• Flagellates (mastigophorans) move using one or more flagella

• Apicomplexans are non-motile, intracellular parasites

Eukaryotic Pathogens: Algae and ProtozoansWhat types of eukaryotic organisms are pathogenic, and how do they differ from bacteria?

• Algae: dinoflagellates and saxitoxin

• Protozoans

• Classification and special structures

• Pseudopodia, flagella, cilia

• Pellicles, cysts

• Important protozoan pathogens

• Amoebic dysentery

• Balantidiasis (Balantidium dysentary)

• Giardia, Trichomoniasis, Trypanosomiasis

• Malaria, CryptosporidiumEukaryotic pathogens are mostly parasitic and are difficult to target selectively with drugs since their cells are so similar to human cells.

Important Pathogenic Protozoans

• Amoebas• Entamoeba histolytica - amoebic dysentery

• Ciliates• Balantidium coli - Severe colitis/dysentery

• Flagellates• Giardia lamblia - giardiasis/beaver fever• Trypanosoma brucei -trypanosomiasis/African sleeping sickness• Trichomonas vaginalis - trichomoniasis

• Apicomplexans• Plasmodium vivax - malaria• Toxoplasma gondii - toxoplasmosis

Amoebic dysentery(Entamoeba histolytica)

Amoebic protozoan

Pathogenic Protozoans

• Amoebas• Entamoeba histolytica - amoebic dysentery

• Ciliates• Balantidium coli - Severe colitis/dysentery

• Flagellates• Giardia lamblia - giardiasis/beaver fever• Trypanosoma brucei -trypanosomiasis/African sleeping sickness• Trichomonas vaginalis - trichomoniasis

• Apicomplexans• Plasmodium vivax - malaria• Toxoplasma gondii - toxoplasmosis

Severe colitis/dysentery( Balantidium coli)A Ciliate

Parasite primarily of cows, pigs and horses

Seen mostly in farm workers and other rural dwellers by ingestion of cysts in fecal material of farm animals

Symptoms similar to amoebic dysentery but milder.

Only known pathogenic ciliated protozoan

Pathogenic Protozoans

• Amoebas• Entamoeba histolytica - amoebic dysentery

• Ciliates• Balantidium coli - Severe colitis/dysentery

• Flagellates• Giardia lamblia - giardiasis/beaver fever• Trypanosoma brucei -trypanosomiasis/African sleeping sickness• Trichomonas vaginalis - trichomoniasis

• Apicomplexans• Plasmodium vivax - malaria• Toxoplasma gondii – toxoplasmosis•Cryptosporidium

• No mitochondria

• Multiple flagella

• Giardia lamblia

• Trichomonas vaginalis (no cyst stage)

Archaezoa: Troublesome Flagellates

Figure 12.17b-d

Giardiasis -Beaver fever (Giardia lamblia)

Trophozoite stage

Cysts shed in feces

Flagellated protozoan

Trichomoniasis (Trichomonas vaginalis)

Flagellated protozoan

Unusual undulatingmembrane

Trypanosomiasis/African Sleeping Sickness(Trypanosoma brucei)

Tsetse fly (intermediate host)

Flagellated protozoan

Pathogenic Protozoans

• Amoebas• Entamoeba histolytica - amoebic dysentery

• Ciliates• Balantidium coli - Severe colitis/dysentery

• Flagellates• Giardia lamblia - giardiasis/beaver fever• Trypanosoma brucei -trypanosomiasis/African sleeping sickness• Trichomonas vaginalis - trichomoniasis

• Apicomplexans• Plasmodium vivax - malaria• Toxoplasma gondii – toxoplasmosis•Cryptosporidium

Malaria (Plasmodium vivax)An Apicomplexan

Anopheles mosquito

gametocytes in RBC

Apicomplexanprotozoan

ring stage in RBCs

nonmotile

Plasmodium: An Apicomplexan

Figure 12.19

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

1 2

3

4

6

Asexual reproduction

Intermediate host

Merozoite develops into ring stage in red blood cell

Ringstage

Merozoites

Another mosquito bites infected humnan 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

Sexualreproduction

Resulting sporozoites migrate to salivary glands of mosquito

9

Sporozoites in salivary gland

Toxoplasmosis(Toxoplasma gondii)

Apicomplexanprotozoan

Cryptosporidium (An Apicomplexan)

Causes watery diarrhea, dehydration, cramps and nausea

Shed in feces; spread easily by contaminated food and water, especially uncooked foods

Caused by Crytposporidium parvum

Eukaryotic Pathogens: Algae and ProtozoansWhat types of eukaryotic organisms are pathogenic, and how do they differ from bacteria?

• Algae: dinoflagellates and saxitoxin

• Protozoans

• Classification and special structures

• Pseudopodia, flagella, cilia

• Pellicles, cysts

• Important protozoan pathogens

• Amoebic dysentery

• Balantidiasis (Balantidium dysentary)

• Giardia, Trichomoniasis, Trypanosomiasis

• Malaria, CryptosporidiumEukaryotic pathogens are mostly parasitic and are difficult to target selectively with drugs since their cells are so similar to human cells.

Species Protozoan Category

Hosts Disease Name

Disease description

How transmitted

Sketch

Making a Table to Study and Associate Characteristics