Post Exam Parasitology

Parasitology Study Notes

Classification of Microorganisms

• The most specific and exclusive taxon used in classification is the species (d. Species)

Epidemiology

• An epidemic that spans the world is called a pandemic (c. Pandemic)

Ova and Parasite Examination

• 3 samples should be collected when following typical O&P protocol (c. 3)
• Visceral larva migrans is associated with Toxocara – serology (a. Toxocara – serology)

Stool Specimen Collection and Transport

• A formed stool received at 3 am should be preserved in formalin until examined (d. Preserve the specimen in formalin)
• Cysts are most affected by length of time from collection to examination (a. Cysts)

Artifacts in Stool Specimens

• Partially digested meat fibers, dried chemical crystals, degenerated cells from the gastrointestinal mucosa, and pollen grains can be confused with ova or cysts (a., c., b., d.)

Measuring Specific Gravity of Parasites

• A hydrometer is used to measure specific gravity of parasites (b. Hydrometer)

E. coli Cysts

• If an E. coli cyst is found, request a second specimen and look for additional E. coli cysts (a., b.)

Malarial Parasites

• Thick blood smears improve detection of malarial parasites (b. Improve detection of the organisms)

Intestinal Amebic Infection

• The most dependable procedure for accurate diagnosis of intestinal amebic infection is a formalin-ethyl acetate sedimentation (d. Formalin-ethyl acetate sedimentation)

Autofluorescence

• Autofluorescence is recommended for the identification of Cyclospora cayetanensis oocysts (d. Cyclospora cayetanensis oocysts)

Trophozoite Forms of Amoebae

• Trophozoite forms of amoebae are found in watery stool specimens (d. Watery)

Preservation Methods

• Formalin-ethyl acetate is a suitable preservation method for subsequent fixed smear preparation (a. Formalin-ethyl acetate)

... (rest of the notes truncated due to character limit)Here are the study notes in bullet points:

• Dientamoeba fragilis and Giardia lamblia*
• Dientamoeba fragilis is a parasite that infects the gastrointestinal tract.
• Giardia lamblia is a protozoan that causes giardiasis, a diarrheal disease.
• Clonorchis and Fasciola*
• Clonorchis sinensis is a parasitic flatworm that infects the liver and causes clonorchiasis.
• Fasciola hepatica is a parasitic flatworm that infects the liver and causes fascioliasis.
• Malaria Smears*
• A malaria smear is a diagnostic test used to detect malaria parasites in the blood.
• Patient information required for malaria smears includes age, travel history, and date of return to homeland.
• Acanthamoeba spp.*
• Acanthamoeba spp. are parasites that cause keratitis, a corneal infection.
• Contaminated contact lenses can transmit Acanthamoeba spp.
• Hydatid cysts*
• Hydatid cysts are caused by the tapeworm Echinococcus granulosus.
• Ingesting contaminated food and water can transmit Echinococcus granulosus.
• Intestinal Parasites*
• Sanitary disposal of human feces is essential in preventing the spread of intestinal parasites.
• Examples of intestinal parasites include Ascaris lumbricoides, Taenia saginata, and Hookworm.
• Toxoplasma gondii*
• Toxoplasma gondii is a protozoan that causes toxoplasmosis.
• Toxoplasma gondii can cause congenital infections and is commonly found in cat feces.
• Babesia*
• Babesia is a protozoan that causes babesiosis, a tick-borne disease.
• Babesia is commonly found in ticks that feed on rodents and deer.
• Hookworms*
• Hookworms are parasitic worms that infect the small intestine.
• Hookworms can cause anemia, weakness, and digestive problems.
• Trichinella spiralis*
• Trichinella spiralis is a parasitic worm that infects the gastrointestinal tract.
• Trichinella spiralis is commonly found in undercooked meat, especially pork and wild game.
• Trypanosoma spp.*
• Trypanosoma spp. are protozoa that cause trypanosomiasis, a disease transmitted by the tsetse fly.
• Examples of Trypanosoma spp. include Trypanosoma brucei and Trypanosoma cruzi.
• Strongyloides stercoralis*
• Strongyloides stercoralis is a parasitic worm that infects the small intestine.
• Strongyloides stercoralis can cause strongyloidiasis, a disease characterized by gastrointestinal symptoms and skin lesions.### Parasitology
• Enterobius vermicularis: Most prevalent helminth to infect humans.
• Formalin: Mercury-containing fixative used to preserve parasites in stool specimens, but has disadvantages, such as inability to be used for concentration procedures, permanent stained slides, and direct microscopic examinations.
• Fleas: Move quickly due to the presence of pronotal ctenidia and extra long rear pair of legs.
• Giardia intestinalis: Parasite that should be quantitated in the parasitology report.
• WBCs vs. amebic cysts: Size and number of nuclei are distinguishing features, as well as absence of protozoan nuclear inclusions.
• Fasciolopsis buski: Infects the small intestine in humans.
• Wuchereria bancrofti: Diagnosis is best accomplished by examination of stained peripheral blood taken during the night.
• Polyvinyl alcohol: Used in preparation of permanently stained smears of fecal material to serve as an adhesive and enhance stain preparation.
• Ehrlichia phagocytophila: Causes a self-limiting infection characterized by a gradual onset of headache, chills, sweating, and fatigue that demonstrates no periodicity.
• Fasciolopsis vs. Fasciola: Can only be distinguished in the laboratory by the recovery of adults.
• Anopheles: Species of mosquito that serves as a vector for the genus Plasmodium.
• Parasite terminology:
  • Endoparasite: Parasite established inside a host.
  • Ectoparasite: Parasite living on the host's surface.
  • Accidental host: Host other than the normal one that harbors a parasite.
  • Incidental host: Host that is not essential for the parasite's life cycle.
• Angiostronglyus cantonensis: Has a Barber's pole appearance.
• Leishmaniasis: Types include visceral, mucocutaneous, and cutaneous.
• Malaria detection: Giemsa blood stain is the gold standard.
• Wandering larvae: Seen in Trichuris trichiura and Hookworm infections.
• Lugol's iodine: Emulsifies granules and stains parasites.
• Microsporidial infections: Can be confirmed using a modified trichrome stain.
• Toxoplasma gondii: Can be acquired through feline feces.
• N95: Should be worn snugly to fit the face, and the outer part should be wet but the inner part should be dry.
• Scabs: A sign of infestation, not infection.
• Loeffler's syndrome: Characterized by peripheral eosinophilia.
• Diphyllobothrium latum: Operculated with terminal knobs (abopercular knob).
• Paragonimus westermanii: Metacercaria is the infective stage.
• Trichomoniasis: Most common non-viral sexually transmitted infection.
• Ancylostoma duodenale: Can cause a heavy worm burden and requires characteristic larval migration in the life cycle.
• Strongyloides fuelleborni: Causes a severe life-threatening condition called "Swollen belly Syndrome".
• Cryptosporidium spp.: Oocysts can be detected in stool specimens using a modified Ziehl-Neelsen acid-fast stain.
• Wuchereria bancrofti: Lymphatic vessel involvement within the retroperitoneal region is associated with this parasite.
• Mansonella perstans: Microfilaria has a tail often referred to as a "Shepherd's crook".
• Onchocerca volvulus: Endosymbiont Wolbachia sp. is required for parasite reproduction.
• Dracunculus medinensis: Removal and gradual retraction of the adult gravid female worm is recommended.
• Gnathostoma sp.: Infection may resemble acute appendicitis.
• Entamoeba histolytica: Protozoan with a large karyosome, may be surrounded by refractile granules that are difficult to see (Basket Nucleus).
• Entamoeba histolytica diagnosis: Stool EIA has the highest sensitivity and specificity.
• Cryptosporidium: Organism found most commonly in the crypts of the duodenum.
• Xenodiagnosis: Used for Trypanosoma cruzi diagnosis.
• Plasmodium falciparum: Leading cause of death in malaria endemic areas; although the host can develop antibody protection, it is train-specific and short-lived.
• Toxoplasma gondii: Important cause of chorioretinitis, may be result of congenital or acquired infection.
• Cryptosporidium detection: Modified Ziehl-Neelsen acid-fast stain is used.
• Cyclospora cayetanensis: Protozoa causing diarrhea, associated with raspberries, strawberries, herbs, and some vegetables.
• Elements of plant origin: May resemble some parasites, including plant cells/fibers, pollen grains, starch granules, and vegetable spirals.
• Zinc sulfate solution: Preferred specific gravity for the flotation method is 1.18.
• Paratenic host: Host in which the parasite does not develop further to later stages, but remains alive and is able to infect another susceptible host.
• Malarial infections: Relapses are caused by reinvasion of the blood form from infected liver cells.
• Hermaphroditic parasites: Flukes, tapeworms, and some roundworms.
• Creeping eruption: Caused by Ancylostoma braziliense.
• Fasciolopsis buski: Acquired by eating contaminated vegetation.
• Enterobius vermicularis: Proper collection of a sample for recovery includes collecting a scotch tape preparation from the perianal region.
• Trichinella spiralis: Seen in muscle biopsy.
• Schistosoma spp.: Different species have distinct egg morphology.
• Cestode eggs: Different species have distinct egg morphology.
• Nematode eggs: Different species have distinct egg morphology.
• Plasmodium spp.: Different species have distinct macrogametocyte morphology.
• Trypanosomes: Suitable specimen for demonstration is CSF or fluid from a lymph node.
• Liquid stool collection: In infants, collect stool from a diaper or use a cotton swab.