lab parasites sections 1 xbc-!xcs
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Selected fungi, parasitic helminths, and protozoa
Opportunistic pathogen Attaches to human epithelial cells as a yeast Usually it requires pseudohyphae to invade deeper tissues
Buds form a short chain of cells called a pseudohypha
Candida albicans
Pityriasis in a Caucasian patient
Pityriasis in an African-american patient
Malassezia furfur and pityriasis versicolor
Malassezia furfur and pityriasis versicolor
10% KOH, glycerol, and Parker ink solution
Diagnostic: Stained skin scrapings from patients reveal thick-walled, round yeast cells that reproduce by budding, and hyphae
Encapsulated yeast
Inhalation of dried,
contaminated droppings (pigeon/chicken)
Cryptococcal meningitis
Cryptococcus neoformans
Dimorphic fungi Histoplasma capsulatum
Pathogenic dimorphic fungi and systemic mycoses (diseases caused by fungi that can spread throughout the body)
Endemic of North America Coccidioides immitis - Coccidioidomycosis Histoplasma capsulatum – Histoplasmosis Blastomyces dermatitidis - Blastomycosis
Arthroconidia inhaled from soil
germinate in the alveoli
Coccidioides immitis causes coccidioidomycosis
Diagnosis Identification of spherules in clinical specimens
Mild respiratory symptoms More severe infections
involving Coughing up blood Pneumonia/Meningitis
Schistosoma mansoni Blood fluke
Flukes are given names according to the tissue of the definitive host in which the adults lives
Lung fluke Liver fluke Blood fluke
Cause progressive damage to tissues and organs
Trematodes
Schistosoma mansoni
Egg
Eggs lodge in tissues causing damage to several organs
Tapeworms - Cestodes
Taenia saginata Taenia solium
Ingestion of undercooked measly meat or Eggs that leads to
cysticercosis in humans
Diagnosis in clinical specimens Proglottids Eggs
Proglottid
Egg
Taenia species
Ascaris lumbricoides Nematode-round worm Infects over one billion people worldwide
Small intestine Feeds on partially digested foods Eggs excreted with feces can survive for long periods
Ascaris lumbricoides
Ascaris lumbricoides
Unfertilized egg
Fertilized egg
DPDX Parasite Image Library – University of South Carolina School of Medicine
Enterobius vermicularis (nematode) Pinworm
Eggs infective for humans
Enterobius vermicularis
Eggs
The female migrates to the anus to deposit eggs on the perianal skin at night (Diagnosis: Graham sticky-tape method)
Hookworms (nematode)
Necator americanus Ancylostoma duodenale
Larvae infective for humans by penetrating the
host’s skin
Live in the small intestine of humans
Feed on blood and tissue leading to anemia
Ancylostoma duodenale
Necator americanus
Clinical specimen: Feces/Eggs
Fertilized egg
Trichinella spiralis
Larva
Cysts within muscles
Plasmodium
species cause malaria
Ring-stage Trophozoites within red blood cells
Giardia intestinalis
Trophozoites
Adheres to small intestine causing diarrhea Trophozoite is the feeding/growing stage Cyst is the survival stage
Diagnosis: identification of cysts in feces
Pathogenic amoeba
Human intestine, causes amebic dysentery
Ingestion of cysts
excreted in the feces of infected person
Presence of ingested red blood cells is diagnostic of Entamoeba
Trypanosoma cruzi causes the Chagas’ disease
Bloodsucking “kissing bug”
Trichomonas vaginalis
Protozoan transmitted
through sexual intercourse
Worldwide Prevalence of Helminthic Diseases