1. EUKARYOTIC MICROORGANISMS AND PARASITES
CHAPTER 11

2. Parasitology Historical groupings Protozoa Helminths Arthropods
Ecto/Endoparasites
Obligate/Facultative parasites
Permanent/Temporary parasites
Accidental parasites

3. Vectors
Hyperparasitism
Biological vectors
Mechanical vectors

4. Host Types Definitive host
Host for the sexually mature, egg-laying worm
Intermediate host
Host for larval stages

5. Parasite Evasion Strategies
Encystment
Larvae buried in animal tissues
Protozoans with outer tough coat
Immunological challenges
Changing surface antigens (Ag)
Triggering antibody which cannot react to parasite Ag
Host cell invasion to escape Immune system

6. Damage Caused by Parasites
Nutritional deprivation
Compete for available nutrition
Direct trauma/obstruction
Lymphatic capillaries may be obstructed (Wuchereria bancrofti)
Intestine may be blocked (Ascaris lumbricoides)
Inflammation
Chronic inflammation around resident worms, alive or dead (Liver flukes, Trichinella)

7. Plant-like Protozoan Phyla
Algae
Euglenoids
Facultative chemoheterotrophs
Diatoms
Hydrocarbons and abrasives
Dinoflagellates
Toxin producers
PSP (Gonyaulax)
Ciguatera (Gambierdiscus)

8. Fungus-like Protozoan Phyla
Water molds – related to brown algae and diatoms
Non-photosynthetic algae!
Irish potato famine, other plant diseases
Slime Molds
Plasmodial
Fruiting bodies containing spores may form from plasmodial slime mold
Pseudoplasmodial (Cellular)
Produce free-living ameboid cells until conditions become unfavorable when an aggregate will form again

9. Animal-like Protozoan Phyla
Mastigophorans (Flagellae)
Hemoflagellates are pathogens
Trypanosoma brucei
African sleeping sickness
Tse-Tse fly
Progressive CNS damage
Trypanosoma cruzi
Chagas disease
Kissing bug
CNS and cardiovascular damage

10. Animal-like Protozoan Phyla
Amebozoa
Ameboid movement with pseudopods
Entamoeba histolytica
Causes “amoebic dysentery”

11. Animal-like Protozoan Phyla
Apicomplexans
Apical enzyme complex assists host cell penetration
Plasmodium falciparum
Malaria
Symptoms match invasion cycle
Toxoplasma gondii
Cat borne
Damages unborn babies

12. Animal-like Protozoan Phyla
Ciliophora
Move with cilia
Mostly free-living
Balantidium coli
Rare but serious diarrhea

13. Fungi Mycology Chitin in cell wall Single celled and multicellular
Thallus
Mycelium
Vegetative
Reproductive
Hyphus
Septae
Coenocytic

14. Fungal Reproduction Cycles

15. Fungal Significance Brewing, baking Decomposers Antibiotic producers
Pathogens (Plant and Animal)
Superficial mycosis
Cutaneous mycosis
Subcutaneous mycosis
Systemic mycosis
Opportunistic mycosis
Symbioses
Mycorrhizae
Dimorphism - Coccidioides

16. Phylum Zygomycota Hyphae which frequently join to form zygospores
Coenocytic hyphae
Includes bread molds
Starch and sugar digestion, no cellulose
May be opportunistic pathogens
Severe disease in diabetics

17. Phylum Ascomycota Sac Fungi (spore containers) Yeasts included
Septate hyphae with pores
Antibiotic producers
Penicillium
Pathogens
Saccharomyces
Candida
Trichphyton
Aspergillus
Blastomyces

18. Phylum Basidiomycota Club Fungi (spore containers) Septate hyphae
Mushroom, toadstools, rusts and smuts
Toxins/ Pathogens
Claviceps purperia
Cryptococcus
PHYLUM DEUTEROMYCOTA
Sexual forms not (yet?) observed
Likely to be Ascomycota when classification is completed

19. Parasitic Helminth Phyla
Nematodes
(Roundworms)
Platyhelminths
(Flatworms)
Size range: up to 10m
No tubular digestive tract
Absorb nutrients and oxygen through epithelium
Hermaphrodites
Parasitic classes
Flukes
Tapeworms
Size range: 1mm – 1m
Pseudocoelom and digestive tract
Male / female individuals
Intestinal/circulatory parasites
Parasitic adult/larval forms

20. Platyhelminths - Flukes
Class of parasitic flatworm
Trematodes
Tissue flukes
Blood flukes
Life cycle with multiple hosts

21. Blood fluke life cycle Schistosoma japonicum
Adult worms lay eggs in hepatic portal blood vessels
Eggs shed in human feces used as fertilizer
Eggs hatch in water
Life cycle stage in water snails
Larvae then burrow through human skin and enter the blood stream

22. Platyhelminths - Tapeworms
Class of parasitic flatworm
Cestodes
Scolex
Proglottids
Generalized life cycle involved intermediate and definitive hosts

23. Tapeworms affecting Humans
Taenia saginata
Adult worm in human intestine
Eggs/proglottids in feces
Eggs eaten by grazing cows
Encysted larvae in beef
Undercooked meat consumed by humans
Scolex attaches to human intestine

24. Additional Cestodes Taenia solium Can also encyst in human tissues
Hymenolepis
Rat tapeworm
Dipylidium
Dog tapeworm
Diphyllobothrium
Fish tapeworm
Echinococcus
Human is an intermediate host

25. Adult Roundworms Digestive system parasites at some stage Trichinella
Ascaris
Guinea worms
Pinworms
Hookworms

26. Trichinella Life Cycle
Trichinella spiralis
Worms can encyst in human or pig muscle
Humans contract from eating infected pork
Pigs are infected if they eat contaminated pork from garbage

27. Larval Roundworms Located in organs other that the digestive tract
Wuchereria bancrofti
Mosquito borne
Elephantiasis
Dracunculis medinensis
Larvae in abdomen
Skin location of adult worms

28. Arthropods as Vectors Arachnids Ticks as Vectors
Ixodes for B. burgdorferi
Viral encephalitis
Insects
Mosquitoes - Plasmodium and Wuchereria
Fleas can carry Yersinia pestis bacteria
Crustaceans
Guinea worms