EUKARYOTIC MICROORGANISMS AND PARASITES CHAPTER 11

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

Vectors Hyperparasitism Biological vectors Mechanical vectors

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

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

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)

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

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

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

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

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

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

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

Fungal Reproduction Cycles

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

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

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

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

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

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

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

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

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

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

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

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

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

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