1. Ch 12
The Eukaryotes: Fungi
Algae
Protozoa
Helminths

2. Student Learning Outcomes
List the defining characteristics of fungi.
Identify two beneficial and two harmful effects of fungi.
List the defining characteristics of protozoa.
Differentiate an intermediate host from a definitive host.
List the distinguishing characteristics of the two classes of parasitic helminths, and give an example of each.
Provide a rationale for the elaborate life cycles of parasitic worms.
Define arthropod vector.
Differentiate between a tick and a mosquito, and name a disease transmitted by each.

3. FUNGI
Chemoheterotroph, aerobic (molds) or facultatively anaerobic (yeasts)
Mycology: Study of fungi
Most decomposers, few parasites of plants and animals
# of serious fungal infections increasing

4. Characteristics
Hyphae: Cell filaments, mostly septate Mycelium: Mass of hyphae Molds: mostly filamentous Yeasts: non-filamentous, unicellular fungi Budding yeasts divide asymmetrically. Dimorphic fungi: yeast-like at 37C, mold-like at 25C. Fungal spores are reproductive spores (unlike bacterial spores). Used to differentiate fungi. Growth in acidic, low-moisture, high osmotic pressure environments.

5. Economic Effects of Fungi p. 341
The good:
Saccharomyces cerevisiae: Bread, wine, HBV vaccine
Trichoderma: Cellulase for clear fruit juice
Taxomyces: Taxol
Entomophaga: Biocontrol
Paecilomyces: Kills termites
The bad:
Mold spoilage
The ugly:

6. Fungal Diseases – Mycoses
p. 335
Systemic mycosis: infection deep within body, affects many tissues and organs. Histoplasmosis and coccidiomycosis.
Subcutaneous mycosis: Saprophytic fungi, e.g.: Sporotrichosis.
Cutaneous mycosis = Dermatomycosis: affects keratin-containing tissues (hair, nails, skin).
Superficial mycosis: localized on hair shafts and superficial skin cells.
Opportunistic mycoses:
caused by normal microbiota or fungi that are not usually pathogenic (E.g.: Candidiasis, Pneumocystis pneumonia, et.al.)
usually systemic.

7. Human eyelash with unknown fungus infection.
Minimal damage to skin or underlying tissues.
However, if IS impaired, can encourage infecting fungus to proliferate.

8. ALGAE Mostly Photoautotrophs in Ocean
Several forms of shellfish poisoning affecting fish, sea mammals and humans
Toxins are ingested and concentrated by shellfish (e.g.: mussels, oysters, clams, scallops)
Both may produce potent marine toxins

9. Diseases due to marine toxins
Domoic Acid Intoxication (1st reported case in Canada, 1987) Diatomes  Muscles  Ho Diarrhea and memory loss. Also sea lions and birds
Paralytic shellfish poisoning (PSP): Dinoflagellates of genus Alexandrium produce saxitoxins Diatomes  Muscles/clams  Ho
Red tide
Ciguatera poisoning: Dinoflagellate Gambierdiscus toxicus moves up food chain to large fish

10. See p. 351
PROTOZOA
Unicellular, eukaryotic chemoheterotrophs. Large and diverse group. Few are pathogenic. Found in soil and water and as normal microbiota in animals. Trophozoite: Vegetative form (feeding and growing). Asexual reproduction via fission, budding, or schizogony (multiple fission). Sexual reproduction via conjugation. Some protozoa can produce a cyst that provides protection during adverse environmental conditions.

11. Some Medically Important Protozoa
Giardia lamblia (G. intestinalis or G. duodenalis). In ho and mammals. Diagnosis via cysts in feces
Trichomonal vaginalis

12. Apicomplexa: not mobile, intracellular Plasmodium , Babesia, Toxoplasma, Cryptosporidium (Clinical Focus p.355 2 3
Plasmodium vivax Life Cycle 8 7 6
Fig 12.20

13. Euglenozoa: Hemoflagellates Trypanosoma
Move by flagella
Hemoflagellates
Sleeping sickness
Chagas’ disease

14. Amoebae Move by pseudopods
Entamoeba histolytica in human GI tract. ~ 10% carriers. Amoebic disentery.
Acanthamoeba in water. Can infect cornea.

15. HELMINTHS (Parasitic Worm)
Kingdom: Animalia
Phylum: Platyhelminthes (flatworms)
Class: Trematodes (flukes)
Class: Cestodes (tapeworms)
Phylum: Nematoda (roundworms)
few are human parasites
Anatomy and life cycle modified for parasitism
Adult stage in definitive host.
Each larval stage in specific intermediate host.

16. Life Cycle of Helminths
Monoecious (hermaphroditic)
Male and female reproductive systems in one animal
Dioecious
Separate male and female
Egg  larva(e)  adult

17. Platyhelminths Dorsoventrally flattened
Trematode, or fluke: Leaf-shaped; suckers attaches to host tissue
Cestode, or tapeworm: Scolex (head), proglottids
4 suckers and rostellum with hooks
Fig 12.27
Gravid proglottid with uterine branches

18. Taenia solium Taenia saginata
Human definitive host; pig or cattle intermediate host.

19. Echinococcus granulosus
Fig

20. Human is …. Taenia saginata Echinococcus granulosus __________ Host
Cysticerci in beef muscle
___________ Host
Echinococcus granulosus
Adult in dog

21. Nematodes Eggs infective for humans:
Roundworms have a complete digestive system
Eggs infective for humans:
Enterobius vermicularis (pinworm). Most common worm infection in US (30% of children, 16% of adults infected)
Ascaris lumbricoides: Ascariasis. 2nd most common worm infection in US. (Most common worldwide; > 1 bio infected)

22. Pinworm / Enterobius vermicularis
Fig12.29

23. ova
Pinworm (Enterobius vermicularis) in sigmoid colon

24. Diagnosing Pinworm Disease
Do test immediately after waking up. Several samples might need to be examined.
Since scratching of the anal area is common, samples taken from under the fingernails may also contain eggs.
pinworm paddle

25. Ascariasis Ascaris lumbricoides Soil transmitted – how do you get it?
Often no symptoms
Worldwide in warm, moist areas
Heavy infections can cause intestinal blockage and impair growth in children.
Coughing??

26. Larvae Infective for Humans
Fig 25.23
Larva penetrate host skin to blood and lymph to lungs, caughed up, swallowed , to intestine
Hookworms
Necator americanus and
Ancylostoma duodenale

27. The Heartworm Dirofilaria immitis
Primarily in dogs and cats  human heart failure, also in human lungs Spread via mosquitoes
Fig 12.30

28. ARTHROPODS AS VECTORS Kingdom: Animalia
Phylum: Arthropoda (exoskeleton, jointed legs, segmented body)
Class: Insecta (6 legs)
Lice, fleas, mosquitoes
Class: Arachnida (8 legs)
Mites and ticks
Arthropods that carry diseases are called vectors.
Elimination of vectorborne diseases best via control or eradication of vectors.
Fig 12.32

29. Arthropod Vectors The End Mechanical transmission
Biological transmission
Microbe multiplies in vector
Definitive host
Microbe’s sexual reproduction in vector
The End