Fungi, Protozoa, and Helminthes

1. Fungi, Protozoa, and Helminthes

2. Fungi

3. Kingdom Fungi Divided into 2 groups: macroscopic fungi (mushrooms, puffballs, gill fungi) microscopic fungi (molds, yeasts) Majority are unicellular or colonial

4. Fungal Organization Mold Hyphae Mycelium Yeast Soft, uniform texture and appearance Thermal dimorphism grow as molds at 30�C and as yeasts at 37�C

6. Fungal Organization - Mold Fungal Cell Structure Cell walls contain chitin instead of cellulose Energy reserve is glycogen Nonmotile Produce wind-blown spores Grow toward food source Conidia / spores

7. Fungal Organization Yeasts Unicellular (bicellular) False hyphae Beta-glycan cell wall structure

8. Fungal Nutrition All are heterotrophic Majority harmless saprobes Some are parasites Live on the tissues of other organisms, but none are obligate

9. Fungal Reproduction Primarily through spores formed on reproductive hyphae Asexual reproduction spores are formed through: Budding or mitosis Sporangiospores Conidia Arthrospore Chlamydospore Blastospore Phialospore Microconidium or macroconidium porospore

12. Reproductive strategies Sexual reproduction Spores are formed following fusion of male and female strains and formation of sexual structure Sexual spores and spore-forming structures are one basis for classification Zygospores Ascospores Basidiospores

13. Zygospores

14. Ascospores

15. Basidiospores

16. Yeast Budding �cloning� Sometimes form pseudohypha

17. Opportunistic vs. Pathogenic Fungus is a secondary invader Animal has other pre-existing conditions However, the fungus may be there all the time Fungus is the primary problem Animal does not have to be immune suppressed to be affected by the fungus

18. Fungal Classification Yeast verse Mold Asexual verse Sexual (reproductive strategies) Terrestrial or water

19. Fungal Classification Subkingdom Amastigomycota Terrestrial inhabitants including those of medical importance: Zygomycota � zygospores; sporangiospores and some conidia Ascomycota � ascospores; conidia Basidiomycota � basidiospores; conidia Deuteromycota*** � majority are yeasts and molds; no sexual spores known; conidia

20. Fungal Classification Subkingdom Mastigomycota

21. Diagnosis and identification require: macroscopic and microscopic observation of: asexual spore-forming structures and spores hyphal type colony texture and pigmentation physiological characteristics genetic makeup culturing in selective and enriched media Reverse important!!!! Clinical signs Lesions of the skins Histology Look for hyphae

22. Roles of Fungi Adverse impact mycoses, allergies, toxin production destruction of crops and food storages Beneficial impact decomposers of dead plants and animals sources of antibiotics, alcohol, organic acids, vitamins used in making foods and in genetic studies

23. Characterization of Fungal Infections Systemic Subcutaneous Cutaneous Superficial Opportunistic

24. Systemic fungal infections by true pathogens

25. Histoplasma capsulatum Histoplasmosis typically dimorphic distributed worldwide most prevalent in eastern & central regions of US grow in moist soil high in nitrogen content inhaled conidia produce primary pulmonary infection may progress to systemic involvement of a variety of organs & chronic lung disease amphotericin B, ketoconazole

26. Coccidioides immitis Coccidioidomycosis distinctive morphology blocklike arthroconidia in the free-living stage arthrospores inhaled from dust Creates spherules and nodules in the lungs lives in alkaline soils in semiarid, hot climates endemic to southwestern US amphotericin B treatment

28. Blastomyces dermatitidis Blastomycosis dimorphic free-living species distributed in soil midwestern and southeastern US inhaled 10-100 conidia convert to yeasts & multiply in lungs symptoms include cough, chest pains and fever chronic cutaneous, bone, & nervous system complications amphotericin B

29. Blastomyces dermatitidis

30. Paracoccidioides brasiliensis Paracoccidioidomycosis distributed in Central & South America lung infection occurs through inhalation or inoculation of spores systemic disease not common ketoconazole, amphotericin B, sulfa drugs

31. Subcutaneous Mycoses

32. Sporothrix schenckii Sporotrichosis (rose-gardener�s disease) dimorphic very common saprobic fungus that decomposes plant matter in soil infects appendages and lungs Lymphocutaneous variety occurs when contaminated plant matter penetrates the skin pathogen forms a nodule spreads to nearby lymph nodes Potassium iodide orally Amphotericin B in unresponsive cases

33. Lymphocutaneous Sporotrichosis

34. Mycetoma when soil microbes are accidentally implanted into the skin progressive, tumorlike disease of the hand or foot due to chronic fungal infection may lead to loss of body part caused by Pseudallescheria or Madurella

35. Cutaneous Mycoses

36. Cutaneous Mycoses Dermatophytoses infections strictly confined to keratinized epidermis (skin, hair, nails) ringworm & tinea 39 species in the genera Trichophyton, Microsporum, Epidermophyton communicable among humans, animals, & soil infection facilitated by moist, chafed skin

38. Dermatophytoses Ringworm of scalp tinea capitis affects scalp & hair-bearing regions of head hair may be lost Ringworm of body tinea corporis occurs as inflamed, red ring lesions anywhere on smooth skin Ringworm of groin tinea cruris �jock itch� affects groin & scrotal regions Ringworm or foot & hand tinea pedis & tinea manuum spread by exposure to public surfaces; occurs between digits & on soles Ringworm of nails tinea unguium persistent colonization of the nails of the hands & feet that distorts the nail bed

39. Ringworm Treatment Topicals: ointments containing tolnaftate, miconazole or menthol & camphor lamisil or griscofulvin 1-2 years

40. Superficial Mycoses

41. Superficial Mycoses Tinea versicolor causes mild scaling, mottling of skin Malassezia furfur White piedra is whitish or colored masses on the long hairs of the body Trichosporan beigelli Black piedra causes dark, hard concretions on scalp hairs Piedraia hortae

42. Hortaea werneckii Tinea nigra Dematiaceous yeast-like hyphomycete found in tropical and subtropical areas Extremely halophilic environments Slow growing Pale colonies that turn olive black Reverse is black also Leathery culture

43. Opportunistic Pathogens

44. Candida albicans Candidiasis widespread yeast infections can be short-lived, superficial skin irritations to overwhelming, fatal systemic diseases budding cells of varying size may form both elongate pseudohyphae & true hyphae forms off-white, pasty colony with a yeasty odor

45. Candida albicans Normal flora of oral cavity, genitalia, large intestine or skin 20% of humans Account for 80% of nosocomial fungal infections Account for 30% of deaths from nosocomial infections

46. Candida albicans Thrush occurs as a thick, white, adherent growth mucous membranes of mouth & throat Vulvovaginal yeast infection painful inflammatory condition of the female genital region causes ulceration & whitish discharge Cutaneous candidiasis occurs in chronically moist areas of skin and burn patients

48. Cryptococcus neoformans Crypotcoccosis widespread encapsulated yeast inhabits soils around pigeon roosts common infection of AIDS, cancer or diabetes patients

49. Cryptococcus neoformans infection of lungs leads to cough, fever, and lung nodules dissemination to meninges and brain causes severe neurological disturbance death

50. Pneumocystis (carinii) jiroveci causes pneumonia (PCP) most prominent opportunistic infection in AIDS patients forms secretions in the lungs that block breathing can be rapidly fatal if not controlled with medication small, unicellular fungus pentamidine & cotrimoxazole

51. Aspergillus Aspergillosis very common airborne soil fungus 600 species 8 involved in human disease inhalation of spores causes fungus balls in lungs and invasive disease in the eyes, heart, & brain amphotericin B & nystatin

53. Zygomycosis Zygomycota are extremely abundant saprobic fungi found in soil, water, organic debris, & food Genera most often involved are Rhizopus, Absidia, & Mucor usually harmless air contaminants invade the membranes of the nose, eyes, heart, & brain of people with diabetes, malnutrition with severe consequences

54. Mycotoxicoses Fungal toxins lead to mycotoxicoses usually caused by eating poisonous or hallucinogenic mushrooms aflatoxin toxic and carcinogenic grains, corn peanuts lethal to poultry and livestock Stachybotrys chartarum sick building syndrome severe hematologic and neurological damage

55. Parasites

56. Parasitology Study of eucaryotic parasites, protozoa and helminths Cause 20% of all infectious diseases Less prevalent in industrialized countries Increasingly common in AIDS patients

58. Kingdom Protista Algae Protozoa

59. Protozoa 100,000 species @ 25 are important pathogens Vary in shape, lack a cell wall Most are unicellular Colonies are rare Most are harmless, free-living in a moist habitat Some are animal parasites Spread by insect vectors All are heterotrophic Feed by engulfing other microbes and organic matter

60. Protozoa Most have locomotor structures flagella, cilia, or pseudopods. Exist as trophozoite motile feeding stage cyst Dormant resting stage when conditions are unfavorable for growth and feeding All reproduce asexually, mitosis or multiple fission Many also reproduce sexually conjugation

61. Protozoan Classification Difficult because of diversity Simple grouping is based on method of motility, reproduction, and life cycle

62. Protozoan Classification Mastigophora primarily flagellar motility some flagellar and amoeboid sexual reproduction cyst and trophozoite

63. Protozoan Classification Sarcodina primarily ameba asexual by fission most are free-living

64. Protozoan Classification Ciliophora Cilia trophozoites and cysts most are free-living, harmless

65. Protozoan Classification Apicomplexa motility is absent except male gametes sexual and asexual reproduction complex life cycle � all parasitic

66. Protozoan Classification Phyla grouping based on method of motility, reproduction, and life cycle:

67. Hemoflagellates: Vector-Borne Blood Parasites Obligate parasites that live in blood and tissues of human host Spread in specific tropical regions by blood-sucking insects that serve as intermediate hosts Categorized according to cellular and infective stages

68. Protozoal Diseases

69. An Intestinal Ciliate: Balantidium coli An occupant of the intestines of domestic animals such as pigs and cattle Acquired by ingesting cyst-containing food or water Trophozoite erodes intestine and elicits intestinal symptoms Healthy humans resistant Rarely penetrates intestine or enters blood Treatment � tetracycline, iodoquinol, nitrimidazine or metronidazole

71. Leishmania species Leishmaniasis Endemic to equatorial regions Promastigotes are injected with sand fly bite convert to amastigote and multiply if macrophage is fixed the infection is localized systemic if macrophage migrates L. major

72. Entamoeba histolytica Amebiasis Alternates between a large trophozoite Motile by means of pseudopods and a smaller nonmotile cyst Humans are the primary hosts Ingested Carried by 10% of world population

74. Entamoeba histolytica Cysts swallowed and travel to small intestine alkaline pH and digestive juices stimulate cysts to release 4 trophozoites Trophozoites attach, multiply, actively move about and feed Asymptomatic in 90% of patients Ameba may secrete enzymes that dissolve tissues and penetrate deeper layers of the mucosa Causing dysentery, abdominal pain, fever, diarrhea and weight loss

75. Entamoeba histolytica Life-threatening manifestations are Hemorrhage Perforation Appendicitis Amebomas Tumor-like growths May invade liver and lung Severe forms of disease result in 10% fatality rate Effective drugs are iodoquinol, metronidazole, and chloroquine

76. Giardia lamblia Giardiasis Pathogenic flagellate Cysts are small, compact, and multinucleate Reservoirs include beavers, cattle, coyotes, cats, and humans Cysts can survive for two months in environment Usually ingested with water and food 10 to 100 cysts

77. Giardia lamblia Cysts enter duodenum, germinate, travel to jejunum to feed and multiply Diagnosis difficult because organism is shed in feces intermittently Treatment: quinacrine or metronidazole Agent is killed by boiling and iodine

78. Trichomonads: Trichomonas species Small, pear-shaped 4 anterior flagella and an undulating membrane Exist only in trophozoite form 3 infect humans: T. vaginalis T. tenax T. hominis

79. Trichomonas vaginalis Causes an STD called trichomoniasis Reservoir is human urogenital tract Strict parasite 3 million cases yearly Female symptoms foul-smelling, green-to-yellow discharge; vulvitis; cervicitis; urinary frequency and pain Male symptoms urethritis, thin, milky discharge, occasionally prostate infection Metronidazole Ping-pong effect!

80. Protozoal Diseases of the Blood and Nervous System The Plasmodium Parasite Infects the Blood Malaria affects 300-500 million people Four species of Plasmodium cause malaria P. vivax P. ovale P. malariae P. falciparum

81. Plasmodium: Malaria Dominant protozoan disease Obligate intracellular sporozoan Female Anopheles mosquito is the primary vector blood transfusions, mother to fetus 2 million deaths each year

82. Plasmodium Africans with sickle-cell anemia gene Resistant!!!

83. Trypanosoma species and Trypanosomiasis Distinguished by their infective stage trypomastigote elongate, spindle-shaped cell with tapered ends, eel-like motility 2 types of trypanosomiasis: T. brucei African sleeping sickness T. cruzi Chagas disease

84. Trypanosoma brucei African Sleeping Sickness Spread by tsetse flies Biting of fly inoculates skin with trypomastigotes Multiplies in blood and damages spleen, lymph nodes and brain Harbored by reservoir mammals Two variants of disease caused by 2 subspecies: T.b.gambiense � Gambian strain; West Africa T.b. rhodesiense � Rhodesian strain; East Africa

85. Trypanosoma brucei Chronic disease symptoms are sleep disturbances, tremors, paralysis and coma. Blood, spinal fluid or lymph nodes Treatment before neurological involvement with melarsoprol, eflornithine Control involves eliminating tsetse fly

86. Trypanosoma cruzi Chagas disease Endemic to Central and South America Reduviid bug (kissing bug) is the vector Bug feces is inoculated into a cutaneous portal Local lesion, fever, and swelling of lymph nodes, spleen, and liver Heart muscle and large intestine harbor masses of amastigotes Chronic inflammation occurs in the organs (especially heart and brain) Treatment nifurtimox and benzonidazole

87. Toxoplasma gondii Toxoplasmosis Intracelllular apicomplexan parasite with extensive distribution Lives naturally in cats harbor oocysts in the GI tract Acquired by ingesting raw meats or substances contaminated by cat feces Most cases go unnoticed Except in fetus and AIDS patients Can suffer brain and heart damage Treatment: pyrimethamine and sulfadiazine

88. Parasitic Helminths

89. Parasitic Helminths Multicellular animals Parasitize host tissues Organs for reproduction, digestion, movement, protection Mouthparts Attachment Digestion of host tissues Well-developed sex organs that produce eggs and sperm Fertilized eggs go through larval period in or out of host body

90. Helminths Flatworms (Phylum Platyhelminthes) do not have respiratory or circulatory structures, or a digestive tract Cestodes (tapeworms) Trematodes or flukes Roundworms (Phylum Nematoda)

91. Flatworms Cestodes have a head region called a scolex Fertilized eggs are produced in proglottids which break off and spread eggs Tapeworms generally live in host�s intestine, absorbing nutrients They have limited host range, but usually at least 2 hosts

92. Flatworms Trematodes have complex life cycles and often 2 hosts Eggs develop into larvae (miracidia) in water, which invade snails Trematodes evade the immune system by having a surface similar to host cells

93. Roundworms (Phylum Nematoda) Damage to the host often occurs by large worms burdens in vessels or intestines

94. Tapeworms Beef and pork tapeworm disease are caused by Taenia saginata and T. solium, respectively acquired by eating poorly cooked beef or pork scolex attached to the intestine, causing obstruction and mild diarrhea

95. Humans Host to at Least 50 Roundworm Diseases Pinworm disease is caused by Enterobius vermicularis Infection of the intestines leads to diarrhea and anal itching Reinfection can occur if contaminated hands contact food or the mouth Worms die in a few weeks, even without treatment

96. Trichinellosis caused by Trichinella spiralis T. spiralis lives in pig intestines and can encyst in skeletal muscles Transmission to humans occurs by eating raw or poorly cooked pork Symptoms include: pain vomiting nausea constipation Larvae can migrate to the tongue, eyes, and ribs

97. Hookworms have a set of hooks or suckers to attach to the upper intestine Hookworms suck blood from intestinal capillaries This cause blood loss and anemia Humans are the only host Larvae in soil penetrate the skin of bare feet and enter the bloodstream