parasitology

• The appropriate procedure for the diagnosis of

  E. granulosus (hydatid disease) would involve the

  microscopic examination of hydatid fluid aspirated

  from a cyst
• When eosinophils disintegrate, the granules reform

  into Charcot–Leyden crystals
• East and West African trypanosomiasis (T. b. rhodesiense

  and T. b. gambiense) are caused when infective forms

  are introduced into the human body through the bite

  of the tsetse fly
• C. belli oocysts would stain

  positive with modified acid-fast stains
• E. gingivalis tends to ingest PMNs, whereas

  Entamoeba histolytica/E. dispar do not
• An Entamoeba histolytica trophozoite has the

  following characteristics: Central karyosome in the nucleus, ingested

  RBCs, and clear pseudopodia
• N. fowleri are free-living soil and water amoebae that

  cause primary amoebic meningoencephalitis, or PAM.
• The rhabditiform larvae of S. stercoralis are

  characterized by the short buccal capsule (mouth)

  and large genital primordium
• Toxocara spp. are the cause of visceral larva migrans

  and occur when humans accidentally ingest the

  infective eggs of the dog or cat ascarid
• P. westermani adult worms are found in the lung,

  and eggs may be coughed up in the sputum.
• Both T. solium (pork tapeworm) and T. spiralis can

  be acquired from the ingestion of raw or poorly

  cooked pork.
• D. latum is the only operculated cestode egg that is

  found in humans; the infection is acquired from the

  ingestion of raw freshwater fish.
• Although the hydatid cysts are found in sheep or in

  humans (accidental intermediate host), the adult

  tapeworms of E. granulosus are found in the intestine

  of the dog
• Babesia is an intracellular parasite that closely

  resembles the ring forms (early trophozoites) of

  P. falciparum
• Infection with T. gondii is acquired through the

  ingestion of rare or raw meats, infective oocysts

  from cat feces, or as a congenital transmission
• The oocysts of Cryptosporidium spp. examination of fecal

  smears stained with modified acid-fast stains
• The microfilariae of O. volvulus are normally found in

  the fluid right under the outer layer of skin
• P. falciparum are the most severe. They can include massive hemolysis, blackwater fever, and multiple organ involvement,

  including the central nervous system (cerebral

  malaria).
• G. lamblia, D. fragilis, and Cryptosporidium have been

  implicated in nursery school outbreaks
• Infections with E. vermicularis (the pinworm) may

  cause anal itching, sleeplessness, and possibly some

  vaginal irritation or discharge
• The ova and parasite examination contains three

  components: the direct wet film (demonstrates

  protozoan trophozoite motility), the formalin–ethyl

  acetate concentration (demonstrates protozoan

  cysts, coccidian oocysts, and helminth eggs), and the

  trichrome or iron hematoxylin–stained smear

  (confirms protozoan cysts and trophozoites).
• The cyst of I. bütschlii is characterized by a large

  glycogen vacuole
• the miracidial hatching

  test is helpful in demonstrating the egg viability of

  Schistosoma species
• Rapid fecal immunoassays have become more widely

  used for the diagnosis of infections with G. lamblia

  and Cryptosporidium
• the most sensitive method for the recovery

  of Acanthamoeba spp. from clinical specimens is the

  non-nutrient agar culture seeded with E. coli
• H. nana has a thin eggshell containing a six-hooked

  embryo (oncosphere) and polar filaments
• The Knott concentration is designed to allow the

  recovery of microfilariae from a blood specimen
• The egg of S. mansoni is characterized by a large

  lateral spine; S. haematobium has the characteristic

  terminal spine
• A latent infection with S. stercoralis acquired years

  before may cause severe symptoms in the

  immunosuppressed patient
• Eosinophilic meningoencephalitis is a form of larva

  migrans and is caused by A. cantonensis
• The accidental ingestion of T. solium eggs can result

  in the disease called cysticercosis
• T. cruzi, the cause of Chagas disease, has two forms

  within the human: the trypomastigote in the blood

  and the amastigote in the striated muscle (usually

  cardiac muscle and intestinal tract muscle
• Both P. vivax and P. ovale infect young red cells, have

  true stippling (Schüffner’s dots), contain malarial

  pigment, and have a true relapse stage in the life

  cycle.
• Cryptosporidium and S. stercoralis have an

  internal autoinfection capability in their life cycles
• Confirmation of an infection with microsporidial

  spores can be achieved by seeing evidence of the

  polar tubule within the spores
• The early ring stages of Plasmodium knowlesi

  resemble those of P. falciparum
• The older developmental stages of Plasmodium

  knowlesi (trophs, schizonts) resemble those seen in

  infections with P. malariae
• Autofluorescence requires no stain and is often

  recommended for confirmation of Cyclospora

  cayetanensis oocysts
• Plasmodium

  knowlesi include a rapid life cycle (24 hr), the potential

  to infect all ages of RBCs, and the possibility of serious

  symptoms similar to those seen with P. falciparum

  infections.
• An infection with microsporidia can be confirmed

  using modified trichrome stains (10X the normal dye

  content found in routine trichrome stains) and light

  microscopy