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Chapter 39 Human Disease caused by Fungi and Protists

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1 Chapter 39 Human Disease caused by Fungi and Protists
Pathogenic Fungi and Protists - Medical mycology - Mycoses : fungal disease Table 39.1, ∙ superficial ∙ cutaneous ∙ subcutaneous ∙ systemic ∙ opportunistic - Protozoa : single-celled eucaryotic chemoorganotrophs - Protozoan Diseases Table 39.2, Table 39.3

2 Table 39.1

3 Table 39.2

4 Table 39.3

5 2. Airborne Diseases - Blastomycosis ∙ caused by Blastomyces dermatitidis : grows as a budding yeast in human but a mold in the environment ∙ three clinical forms - cutaneous - pulmonary - disseminated ∙ blastospores are inhaled into the lungs spread to the skin cutaneous ulcers and abscess occur Figure 39.1 ∙ Treatment : Amphotericin B Itraconazole Ketoconazole

6 Figure 39.1

7 Coccidioidomycosis ∙ caused by Coccidioides immitis ∙ In humans, the fungus grows as a yeast-forming, thick- walled spherule filled with spores Figure 39.2 ∙ most cases asymptomatic ∙ A few infection progressive chronic pulmonary disease

8 Figure 39.2

9 - Cryptococcosis · caused by Cryptococcus neoformans · This fungus always grows as a large budding yeast Figure 39.3 · Aged, dried pigeon droppings are an apparent source of infection · Cryptococcosis is found in approximately 15% of AIDS patients · Infection in the respiratory track - Histoplasmosis · caused by Histoplasma capsulatum var. capsulatum, a facultative parasitic fungus that grows intracellularly in phagocytic cells Figure 39.4 · Human acquire histoplasmosis from airborne microconidia · most cases : mild symptom such as coughing, fever, joint pain · some cases : in the lung ⇒ calcification : may resemble tuberculosis minor pulmonary infection skin, bones, viscera, central nervous system cryptococcal meningitis

10 Figure 39.3

11 Figure 39.4a

12 Figure 39.4b

13 3. Arthropod-Borne Diseases
Malaria - The most important human parasite among the protozoa is Plasmodium, the causative agent of malaria · 350~500 million people infection annualy · 1 million people death - Human malaria is caused by Plasmodium falciparum Figure 36.5 malariae vivax ovale - The mosquito injects a small amount of saliva containing an anticoagulant along with small haploid sporozoites Figure 39.6 → enter hepatic cells of the liver → production of schizont → the schizont attach to erythrocytes and penetrate these cells → production of trophozoites infection of RBC

14 Figure 39.5

15 Figure 39.6

16 - The sudden release of merozoites, toxins, erythrocyte debris
⇒ chills and fever normal relapse (malaria paroxysms) - anemia can result from loss of erthrocytes, the spleen and liver often hypertrophy - children and nonimmune individuals can die of cerebral malaria - Diagnosis : Wright or Giemsa-stained erythrocytes Figure 39.7 - Treatment : chloroquine, amodiaquine, melfloquine primaquine, Fansidar (a combination of primethamine and sulfadoxine) - Individuals who are traveling to areas where malaria is endemic should receive chemoprophylactic treatment with chloroquine - Various vaccines has been developed Figure 39.8

17 Figure 39.7a

18 Figure 39.7b

19 Figure 39.8

20 Leishmaniasis - Leishmanias are flagellated protists - 2 million new cases each year, 60,000 deaths - transmitted by sand flies → introduce promastigotes into the skin → engulfed by macrophages → multiply → a mastigotes Figure 39.10 → destroy host cells - Leishmania braziliensis ⇒ mucocutaneous leishmaniasis Figure 39.9(a) - L. tropica and L.mexicana ⇒ cutaneous leishmaniasis Figure 39.9(b) → small red papule → crustated ulcers - Leishmania donovani infection into the reticuloendothelial system → fever, enlargement of spleen, liver ⇒Visceral Leishmaniasis

21 Figure 39.9a

22 Figure 39.9b

23 Figure 39.10

24 Trypanosomiasis - Trypanosoma brucei gambiens and T.brucei rhodesience cause African trypanosomiasis - The parasites are transmitted through the bite of testse fly to humans - The protozoa → multiply in the blood → interstitial inflammation and necrosis Figure within the lymph nodes and small blood vessels of the brain and heart - T. brucei rhodesience infection death within a year - T. brucei gambiense infection CNS infection sleeping sickness death in 2~3 years - T.cruzi causes American trypanosomiasis (Chagas’ disease) the parasites in triatomine bug feces infection through Figure the wound invade the liver, spleen, lymph nodes, CNS destroy the cells

25 Figure 39.11

26 Figure 39.12a

27 Figure 39.12b

28 4. Direct Contact Diseases
• Superficial Mycoses - Infection in the outer surface of hair and skin - Piedras : infection of the hair shaft · black piedras caused by Piedraia hortae · white piedras caused by the yeast Trichosporon beigelii - Tineas : superficial fungal infection involving the outer layers of skin, nails and hair · Tinea versicolor caused by the yeast Malassezia furfur

29 Cutaneous Mycoses - also called dermatomycoses, ringworms or tinea - represent the most common fungal diseases in humans - Three genera of cutaneous fungi (dermatophytes) · Epidermophyton · Microsporum · Trichophyton - Diagnosis · microscopic examination · culture on Sabrouraud dextrose agar - Tinea barbae · an infection of the beard hair · caused by Trichophyton mentagrophytes or T. verrucosum · acquire the fungus from infected animals

30 Tinea captis · an infection of the scalp hair Figure 39.13 · characterized by loss of hair, inflammation and scaling · caused by Trichophyton or Microsporum species · person to person, animal to human transmission Tinea corporis Figure 39.14(a) · a dermatophytic infection that may occur on any part of the skin · The disease is characterized by circular, red, well-demarcated, scaly vesiculopustular lesions accompanied by itching · caused by Trichophyton rubrum, T. mentagrophytes or Microsporum canis · Transmission is by direct contact or indirect contact through formites

31 Figure 39.13a

32 Figure 39.13b

33 Figure 39.14a

34 Tinea cruris · a dermatophytic infection of the groin Figure 39.14(b) · The pathogenesis and clinical manifestations are similar to those of tinea corporis · caused by Epidermophyton floccosum Trichophyton mentagrophytes T.rubrum Tinea pedis Figure 39.14(c) · also known as athlete’s foot and tinea mannum · Clinical symptoms vary from a fine scale to a vesiculopustular eruption · Itching is frequently present · Most infections are caused by Trichophyton rubrum, T. mentagrophytes and Epidermophyton floccosum

35 Figure 39.14b

36 Figure 39.14c

37 - Tinea unguium Figure 39.14(d)
· a dermatophytic infection of the nail bed the nail plate rises and seperated from the nail bed · caused by Trichophyton rubrum and T.mentagrophytes Subcutaneous Mycoses - Transmission : the dermatophytes in soil infection by a puncture wound - Chromoblastomycosis Figure 39.15(a) · This disease is caused by the black molds Phialophora verrucosa Fonsecaea pedrosoi

38 Figure 39.14d

39 Figure 39.15a

40 Maduromycosis Figure 39.15(b)
(= eumycotic mycetoma, fungal tumor) - caused by Madurella mycetomatis Sporotrichosis Figure 39.16 - caused by the dimorphic fungus Sporothrix schenckii - The disease occurs throughout the world and is the most common subcutaneous mycotic disease in the US - Symptoms red papule ulcer extracutaneous sporotrichosis

41 Figure 39.15b

42 Figure 39.16

43 Toxoplasmosis - caused by Toxoplasma gondii - transmission Figure 39.17 oocysts nose or mouth intestinal infection blood transfusion - In pregnant women the protist might also infect the fetus, causing serious congenital defects or death - most cases of toxoplasmosis are asymptomatic - In immunocompromised individuals fatal disseminated disease with a heavy cerebral involvement · lymph node swelling · reticular cell enlargement · pulmonary necrosis · myocarditis · hepatitis · retinitis - Currently toxoplasmosis in the immunocompromised, such as AIDs or transplant patients, can produce a unique encephalitis with necrotizing lesions acompanied by inflammatory infiltrates

44 Figure 39.17

45 Trichomoniasis - caused by Trichomonas vaginals - sexually transmitted - female : a profuse purulent vaginal discharge, itching The cervical mucosa is covered with punctuate hemorrhage, papules and vesicles ⇒ “strawbery cervix” Figure 39.18 - male : asymptomatic, sometimes burning sensation

46 Figure 39.18

47 5. Food-Borne and Waterborne Disease
∙ Amebiasis - Entamoeba historica is responsible for amebiasis (amebic dysentery) - Infection occurs by ingestion of mature cysts Figure 39.19 - The invading trophozoites destroy the epithelial lining of the large intestine by producing cysteine proteinases a virulence factor ulcer liver hepatic amebiasis - Symptoms : fulminating dysentery (exhaustive diarrhea) appendicitis, abscesses in the liver, lung or brain

48 Figure 39.19a

49 Figure 39.19b

50 Figure 39.19c

51 Amebic Meningoencephalitis and Keratitis
- Free-living amoebae of Naegleria fowleri causes primary amebic meningoencephalitis in humans ⇒ typically fatal in 3 to 10 days after infection - several Acanthamoeba spp. are known to infect the eye causing a chronically progressive ulcerative Acanthamoeba keratitis may result in blindness Cryptosporidiosis - caused by Cryptospodium parvum - If a human ingests food or water that is contaminated with the oocysts infection - Symptoms : cholera like diarrhea, abdominal pain, nausea, fever and fatigue

52 - Cycloporiasis is caused by the unicellular coccidian protist
Cyclosporiasis - Cycloporiasis is caused by the unicellular coccidian protist Cyclospora cayetanensis - oocysts sporozoites food chain infection by ingestion Figure 39.20 - Symptoms : explosive diarrhea, gas production, nausea, vomitting fever, fatique and substantial weight loss Giardiasis - Caused by a flagellated protist, Giardia intestinalis Figure 39.21 - Transmission is most frequent by cyst-contaminated water supplies - The disease can be acute or chronic - Acute giardiasis is characterized by severe diarrhea, epigastric pain, cramps, voluminous flatulence (“ passing gas ”) and anorexia - chronic giardiasis is characterized by intermittent diarrhea in the enviroment

53 Figure 39.20

54 Figure 39.21

55 6. Opportunistic Diseases
- An opportunistic microorganism is generally harmless in its normal environment but becomes pathogenic in a immunocompromised host (malnutrition, alcholism, cancer, diabetes, leukemia…) • Aspergillosis - caused by Aspergillus fumigatus and A. flavus Figure 39.22 - Inhalation of conidiospores can lead to several types of pulmonary aspergillosis ∙ allergic aspergillosis asthmatic attack ∙ bronchopulmonary aspergillosis bronchitis ∙ colonizing aspergillosis within the lungs “fungus balls” (aspergillomas) ∙ disseminated aspergillosis - treatment : voriconazole and itraconazole

56 Figure 39.22a

57 Figure 39.22b

58 • Candidiasis - caused by dimorphic fungus Candida albicans or C.glabrata - C. albicans and C.glabrata are members of the normal microbiota within the GI tract, respiratory track, vaginal area and mouth if anything upsets the normal microbiota, Candida may multiply rapidly candidiasis : important nosocomial pathogens - Most infection involve the skin or mucous membrane oral candidiasis (thrush) Figure 39.23 - Paronychia and onychomyosis digits nails - Intertriginous candidiasis : axillae, groin, skin folds - Napkin (diaper) candidiasis - Candidial vaginitis - Balanitis : infection of the male glans penis

59 Figure 39.23a

60 Figure 39.23b

61 Figure 39.23c

62 - Microsporidia is a term used to describe obligate, intracellular
fungi that belong to the phylum Microspora - Microsporidosis is an emerging infectious disease, found mostly in HIV patients - Microsporidia posses a unique organelle known as the polar tubule which is coiled within the spore Figure 39.24 - Infection : sporoplasm (cytoplasm-like contents) the host cell multiplication - Symptoms : hepatitis, pneumonia, skin lesions diarrhea, weight loss, wasting syndrome Via polar tubule

63 Figure 39.24

64 • Pneumocystis pneumonia
Figure 39.25 - caused by Pneumocystis jiroveci (renamed in 1999) - The disease that this fungus causes has been called pneumocystis pneumonia or pneumocystis carninii pneumonia (PCP) - This pneumonia occurs in more than 80% of AIDS patients

65 Figure 39.25

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