Paracytology Flashcards
Define symbiosis
symbiosis permanent association of two organisms that can’t exist independently
Define Mutualism
both organisms benefit
Define Commensalism
One organism benefits the other is unharmed
Define Facultative Parasite
live both a free living and a parasitic existence during their life cycles
Define Obligate Parasite
completely dependent upon a host for existence
What do ectoparasites cause?
infestations (fleas, lice)
What do endoparasites cause?
infections (worms)
definitive host
host in which the sexual stage of the life cycle occurs
intermediate host
host in which the asexual stage of the life cycle occurs
reservoir host
animals other than man which harbor human parasites
What are the requirements for transmission of a parasitic infection?
source of infection, mode of transmission, the presence of a susceptible host
What are the functions of ectoplasm of protozoan?
excretion, movement, obtaining food/phagocytize, protection
What are the functions of endoplasm of protozoan?
reproduction, digestion
Classes of protozoa and their means of motility:
- sarcodina (amoeba)
- pseudopods (extension of ectoplasm)
- ciliate: cilia
- Mastigophora:flagella
- Sporozoa: non motile
What is a trophozoite?
(troph) the actively reproducing motile feeding stage
What is a cyst?
inactive, nonmotile, nonfeeding stage with protective cell wall (infective stage)
What is the most important parasitic amoeba?
Entamoeba histolytica
Where does Enatmoeba histolytica live?
in the large intestine (colon)
Describe the troph and cyst forms of Entamoeba histolytica
Troph: progressive movement, contains one nucleus with a central karyosome and even-staining peripheral chromatin and may contain ingested RBC’s
Cyst: contains up to 4 nuclei and has cigar-shaped chromotoidal bars
What makes Entamoeba gingivalis different from Entamoeba histolytica?
E. gingivalis lives in the mouth and has no cyst stage
Where does Enatmoeba coli live?
large intestine (colon)
Describe the troph and cyst forms of Entamoeba coli
Troph: sluggish random motility, contains one nucleus with an eccentric karyosome and uneven peripheral chromatin and contains ingested bacteria
Cyst: contains up to 8 nucle, chromatoid bars (if present) are irregular with splintered cells
Where does Endolimax nana live?
large intestine (colon)
How is Endolimax nana recognized?
by characteristic nuclear structure (has a large irregular eccentric karyosome “lump of coal”) seen in both the troph and cyst stages
Cyst: can be somewhat ovoid, contains up to 4 nuclei and no chromatoidal bars
What does Entamoeba hartmanii look like?
Entamoeba histolytica only smaller
Is Entamoeba hartmanii a pathogen?
no
What non-pathogen looks exactly like Entamoeba histolytica?
Entamoeba hartmanii
How is Iodamoeba butschlii most easily recognized?
in cyst form by the presence of a large glycogen body which will stain a golden brown with iodine
This parasitic amoeba can be a slight intestinal pathogen and causes mild diarrhea
Dientamoeba fragilis
How is Dientamoeba fragilis characterized?
by the fact that it is the only amoeba with two nuclei in the troph stage and by the fact that there is no cyst stage
Name the parasites without a cyst stage
Dientamoeba fragilis, Entamoeba gingivallis, and Trichomonas vaginalis
What are Charcot-Leyden crystals?
refractile, long spicules produced by trauma to the GI tract that are indicative of the presence of intestinal parasites, particularly Entamoeba histolytica (causative agent of amebiasis)
What are composed of the granules of ruptures eosinophils?
Charcot-Leyden crystals
Name a species of free living amoeba that can cause a rapidly fatal form of meningitis in patients who have gone swimming and/or diving in stagnant water ponds
Naegleria fowlerii
How are Naegleria fowlerii best observed?
by examining the CSF in a hemocytometer
Name the only parasitic member of the ciliate class
Balantidium coli
Balantidium coli is normally a parasite of what animal?
hogs
Describe the troph and cyst forms of Balantidium coli
Troph: large organism with cilia, containing a funnel shaped depression, a kidney-bean shaped macronucleus and smaller pear shaped micronucleus
Cyst: also large but is more rounded and lacks external cilia
Name the most important parasitic flagellate
Giardia lamblia
What is the usual habitat of Giardia lamblia?
doudenum
Describe the troph and cyst forms of Giardia lamblia
Troph: bilaterally symmetrical, pear shaped with an oval concave ventral sucking disc, 2 nuclei, a rod-like axostyle and numerous flagella. It moves with characteristic falling-leaf motility
Cyst: oval with up to 4 nuclei
Chilomastix mesnili is what kind of flagellate?
commensal
Describe the troph and cyst form of Chilomastix mesnili
Troph: distinct lateral curve to its body, a single nucleus, and a cytostome
Cyst: lemon-shaped and also has a single nucleus and a cytostome
What is the most common species of Trichomonas?
Trichomonas vagilis
What is the largest species of Trichomonas?
Trichomonas vagilis
Where does Trichomonas vagilis inhabit?
urogenital system of both males and females
Describe the troph and cyst forms of Trichomonas vagilis
Troph: comparable in size to a seg, and has a prominent undulating membrane
Cyst: no cyst stage
How is Trichomonas vaginalis transmitted?
sexual contact
What are some problems associated with Trichomonas vaginalis if left untreated?
sterility
What specimen is Trichomonas vaginalis most often isolated from?
urine- NOT feces
What is an axostyle?
“backbone” of cell, gives support
What is a blepharoplast?
controls movement of flagella
What is a cytostome?
cell “mouth” - where particulate matter enters
What is an undulating membrane?
motion of UM can direct particulate matter into cytostome
In what class is Isospora belli? What is another name for an organism found in this class?
Sporozoa
AKA a cocidian
Where does Isospora belli live?
intestine of man and other animals
Review the structure and characteristic host of the 4 morphological forms of blood flagellates
Insects: crithidial form & leptomonad form.
Vertebrates: leishmanial form-no flagella (intracellular)
Trypanosomal form-long anterior flagella with a central nucleus
Which form is also known as the Donovan (or L-D) body?
Leishmanial form
All Leishmanial occur in man as?
Intracellular inclusions in macrophages
This organism also occurs in man as an intracellular inclusion in macrophages
Trypanosoma cruzii
What is the main invertebrate host of Leishmania?
several species of sand flies (Genus Phlebotomas)
insect vectors
What parasite causes African sleeping sickness?
Trypanosoma gambiense-West African sleeping sickness
Trypanosoma rhodesiense-East African sleeping sickness
How is African sleeping sickness transmitted?
tsetse fly
African sleeping sickness affects…
the CNS, in the chronic form
Trypanosoma gambiense
sleeping sickness
Tsetse fly
Trypanosoma cruzii
Chagas disease
Kissing bug
Leishmania donovani
Kala-azar, visceral Leishmaniasis LD bodies Genus phlebotomis (sand flies)
Leishmania braziliensis
Espundia Genus phlebotomis (sand flies)
Leishmania tropica
Oriental sore, Baghdad?Deli boil Genus phlebotomis (sand flies)
Plasmodium vivax
prefers retics
RBC’s enlarged
Shuffner’s granules
Plasmodium falciparum
applique forms and crescent shaped gametocytes
multiple infected cells are common
Blackwater fever
Plasmodium ovale
cells are oval and fimbriated (irregular)
Plasmodium malariae
rosette appearance of merozoites and band trophozoites
When is Plasmodium motile?
when the microgametocytes undergo exflagellation-the sperm produced possess flagella for a brief period until fertilization occurs
In Plasmodium falciparum infections, complications of malaria are due to what? What is this form of malaria called and why?
vascular obstruction caused by the “sticky” parasites in the capillary beds. This is called “Blackwater fever” due to the severe hematuria that occurs
What are some general symptoms of malaria?
cyclic chills and fever, headache, muscular aches, nausea
What other protozoan can be confused with Plasmodium falciparum? Why are they easily confused? Why must they be differentiated?
Babesia microti due to its appearance in a peripheral blood smear
Troph form of falciparum appears in a ring form and Babesia appears as a maltese cross that looks similar to the ring form
must be differentiated because malarial drugs are toxic and are of no benefit in the treatment of infections due to Babesia
How can Toxoplasma gondii be contracted?
contact with infected cat feces
How is Toxoplasma gondii diagnosed?
serological techniques
classic test is Sabin-Feldman dye test
What is the causative agent of a leading cause of death among AIDS patients?
pneumocystis carinii (PCP pneumonia)
Pneumocystis carinii is likely to infect..
immunocompromised patients
This intestinal sporozoan can cause mild GI disturbances in man and other vertebrates
cryptosporidium which can not be killed by chlorination
What is the best identification test for Cryptosporidium?
acid fast stain
