Eukaryotic microorganisms Eukaryotic Pathogens Eukaryotic microorganisms Plantae Animalia Fungi Monera Protista Fungi cell wall composed of chitin absorptive nutrition (produce exoenzymes) many saprophytes but some parasites of plants or mammals ~30% of known fungi cause disease (MYCOSES) scientists who study fungi = mycologists Foothill Biol 41

Fungal anatomy: Thalli Eukaryotic Pathogens Fungal anatomy: Thalli hyphae thallus = nonreproductive, vegetative form can be single cells, globular shaped (as in yeasts) can be long, branched filaments called HYPHAE (as in molds) many hyphae intertwined = mycelium (pl. = mycelia) Dimorphic - organism that makes two kinds of thalli (both yeast and mold forms) in response to differing environmental conditions mycelium Foothill Biol 41

Fungal anatomy: Fruiting bodies Eukaryotic Pathogens Fungal anatomy: Fruiting bodies Sporangiospores (sac) Chlamydospores (walled in) Conidiospores (no sac) fruiting body = reproductive structure Sporangiospores - spores inside a sac on tips or side of hyphae the sac is called a sporangium stalk that bears the sporangium is called the sporangiophore in picture, the yellow-shaded micrograph Chlamydospores spores with a thickened cell wall inside hyphae in picture - the tan cells on white background Conidiospores - made at tip or sides of hyphae but not in a sac in picture, blue-green cells NOTE TO SELF: -phore = to bear -angium = vessel chlamys- = mantle conidio from Gr. Konis = dust Foothill Biol 41

Important yeasts: Saccharomyces cerevisiae Eukaryotic Pathogens Important yeasts: Saccharomyces cerevisiae Thallus Fruiting body: blastoconidia Remind: Yeasts thalli usually single globular cell S. cerevisiae essential to baking industry, alcoholic beverage industry also frequently used for research not usually a human pathogen in picture - fruiting body = blastoconidia a.k.a. bud type of conidiospore on agar, makes colony similar to bacterial colony do not make hyphae Foothill Biol 41

Important yeasts: Candida albicans Eukaryotic Pathogens Important yeasts: Candida albicans “Thrush” Diaper rash Important yeasts: Candida albicans part of normal flora (GI, respiratory tracts, female GU tract) opportunist: candidiasis can be local as in thrush (mouth) or skin (diaper rash) or ocular can be systemic Table 22.2 in text shows HUGE list of all possible manifestations of candidiasis buds, as S. cerevisiae Bauman Fig. 22.10 Foothill Biol 41

Important molds: Rhizopus spp. Eukaryotic Pathogens Important molds: Rhizopus spp. Important molds: Rhizopus spp. bread mold! often causes food spoilage opportunist - can cause “Zygomycosis” forms sporangiospores (inside a sac) Leboff & Pierce, Figs. 10-4 Foothill Biol 41

Important molds: Aspergillus spp. Eukaryotic Pathogens Important molds: Aspergillus spp. usually colored colony with white edge (color may be yellow, green or brown) Aspergillosis = several diseases r/t inhaling fungal spores VERY common in air!! usually just causes allergies but can cause serious infection in immunocompromised people respiratory infections can infect sinuses, conjunctiva, eye socket, brain systemic rare except in AIDS patients most disease caused by species A. niger, A. fumigatus & A. flavus Foothill Biol 41

Important molds: Penicillium spp. Eukaryotic Pathogens Important molds: Penicillium spp. conidiophores giveaway is radial furrows also distinctively green with white apron most known for production of penicillin some species also used for cheese production P. roquefortii - Roquefort cheese P. camemberti - Cambert and Brie Foothill Biol 41

Major Groups of “True” Parasites Eukaryotic Pathogens Major Groups of “True” Parasites Protozoans Single-celled eukaryotes Malaria, Giardia, Trichomonas vaginalis Helminths (The Worms) Multicellular animals Flukes, Tapeworms, Roundworms Ectoparasites Live outside the host Ticks, Lice, Fleas Remember that parasitologists only consider eukaryotic parasites in the definition. Bacteria and virus are pathogens, but not considered parasites. Other specialties in biology sometimes do refer to those groups as parasites. Foothill Biol 41

Protozoan Parasites Single-celled eukaryotes Can invade: Tissues- Trypanosomes, Toxoplasma, Plasmodium Intestinal lumen- Entamoeba histolytica, cryptosporidium

Protozoans general life cycles Eukaryotic Pathogens Protozoans general life cycles Trophozoite (active, feeding) Adverse environment Release of active cellular form Excystment Encystment Cyst formation Bauman p. 349 all free-living & pathogenic protozoa have motile feeding stage called trophozoite many have dormant protective state called cyst protect from harsh environmental conditions Moisture, nutrients Cyst (dormant, resting) Foothill Biol 41

Entamoeba histolytica Eukaryotic Pathogens Entamoeba histolytica Cyst Trophozoite model amoeba! no defined shape move, get food using pseudopodia ~10% population has as harmless member of normal flora! lots of human reservoirs most infection r/t ingestion of contaminated water (fecal contamination) that has cysts multiplies in intestine three types of amoebiasis (a-me-bi’a-sis) luminal - localized to intestines, little damage amoebic dysentery - more common, diarrhea, colitis, ulceration (can be fatal) invasive extraintestinal amoebiasis - MAJOR problem (can be fatal) Foothill Biol 41

Entamoeba histolytica Epidemiology: Worldwide distribution- Mexico, India, West and South Africa, South America 10% of the world’s population is infected Most are asymptomatic (carriers) 50-100,000 deaths per year Vector: Flys carry cysts from human feces to human food or water or humans self-infect after touching fecally contaminated items, can be sexually transmitted

Entamoeba histolytica Reservoir: Humans are the only hosts Pathologies: Mild to severe intestinal discomfort Dysentary (bloody diarrhea) Can invade and destroy the liver Treated with Metronidazole (flagyl)

Trypanosoma brucei African sleeping sickness Eukaryotic Pathogens a flagellate - moves via flagella insect vector: tsetse flies several animal reservoirs - domestic animals and wild can also be transmitted from human to human via tsetse flies complex life cycle disease: wound becomes necrotic parasites in blood cause fever, headaches, swelling of lymph nodes if invade CNS cause meningoencephalitis - comes with HA, extreme drowsiness, coma, death Foothill Biol 41

Trypanosoma cruzi Epidemiology: Eukaryotic Pathogens Trypanosoma cruzi Epidemiology: Mexico to S. America 16-18 million people are infected (45,000 die per year) Vector: Reduviid bug (aka. kissing bug) Bugs live in rafters of thatched hut houses Come down at night and bite while people are asleep Often bite near corners of mouth (why nicknamed “kissing bug”) Bug defecates on wound after biting victims Parasites are in bug feces and enter host through wound when victim scratches at bite Foothill Biol 41

Trypanosoma cruzi (Chagas Disease) Eukaryotic Pathogens Trypanosoma cruzi (Chagas Disease) Reservoir: rodents, armadillos, dogs, cats Pathologies: Inflammation at bite Swelling of the eyes Fever, malaise Enlarged Heart Heart Failure Hallmark symptom is the swelling of the eye called “kalabar” swelling Deaths occur primarily as a result of heart failure Foothill Biol 41

Plasmodium spp. malaria schizont Infected RBC Eukaryotic Pathogens [ in group Apicomplexans characterized by a complex of organelles at apical end of cell] complex life cycle four different species of Plasmodium cause malaria in humans endemic in more than 100 countries! vector = mosquito kills 2-3 million people annually (usually kids) schizonts - multinucleate cell involved in asexual reproduction schizont Infected RBC Foothill Biol 41

MALARIA Kills 1-2 million/year Loss of productivity Vaccines slow Eukaryotic Pathogens MALARIA Kills 1-2 million/year Loss of productivity Vaccines slow Mosquito abatement Swamps Vectored by mosquitos which must breed in standing water Mosquito also considered an intermediate host b/c the parasite matures in the mosquito “Mal” “aria” means bad air---people knew association with swamps before agent was found ~200million cases per year 4 kinds of plasmodium affect humans P. falciparum is very deadly, causes blood clots in the brain resulting in coma and death Foothill Biol 41

Plasmodium Life Cycle Eukaryotic Pathogens Organisms enter from mosquito saliva Travel to liver and enter cells-multiply Burst out and move into blood stream-enter RBCs-multiply As parasites bursts out of RBCs-antigenic and extremely pyrogenic (cause high fever) Fever so high that non-deadly strain of plasmodium was used to treat syphilis in the early 1900’s (syphilis bacteria is very heat labile) Parasites enter new RBC’s fever goes away, organisms multiply then burst out of RBC’s causing fever to return This causes the cycles of high fevers Foothill Biol 41

Co-Incidence Eukaryotic Pathogens Sickle cell is a genetic disease caused by a single point mutation (base-pair substitution) on the hemoglobin gene which causes a missense mutation This genetic condition affords protection from malaria in heterozygotes Homozygotes for the condition have sickle cell disease and don’t live long Homozygotes for normal hemoglobin have no protection and often die of malaria Selection is directed towards heterozygotes- regions with high malaria rates also tend to have high sickle cell rates Foothill Biol 41

Toxoplasma gondii Toxoplasmosis Bow-shaped cells Eukaryotic Pathogens Life cycle is between felines and their prey and other intermediate hosts (parasite MUST travel through felid intestine to mature) Intermediate hosts include birds (incl. poultry), rodents, pigs, humans Typically sub-clinical in intermediate hosts Primary danger to humans is for pregnant women Main risk of clinical sx is if infection occurs during first trimester. Fetus is vulnerable and toxo can cross placenta. Can result in mental retardation and other developmental abnormalities About 50% of human infections are the result of eating contaminated & undercooked meat (poultry, pork) The rest are from exposure to cysts in cat litter, sandboxes and from contact with soil (gardening) No risk from contact with cats directly Bow-shaped cells Foothill Biol 41

Giardia lamblia a.k.a. Giardia intestinalis Eukaryotic Pathogens Giardia lamblia a.k.a. Giardia intestinalis giardiasis called “the most photogenic parasite” water-borne diarrheal disease Sx: yellow, frothy, sulfur smelling diarrhea very hardy - can survive for long periods of time outside host if dog drinks water from stream, can later pass to owner (don’t let your dog lick your face!!) life cycle similar to Entamoeba infection (giardiasis) severity ranges - fluid loss can be life threatening usually treated with drug Metronidazole Foothill Biol 41