04 - Parasitology Flashcards
Term: presence of an endoparasite in host
infection
Term: presence of an ectoparasite in host
infestation
Type of parasite that needs a host at some stage of life cycle to complete development and propagation.
Obligate parasite
Type of parasite that may exist in a free-living state but becomes parasitic when the need arises
Facultative parasite
This is a type of parasite that can establish itself in a host where it does not ordinarily live in.
Accidental or Incidental parasite
Type of parasite which successfully invades a host but merely passes through the GI tract without colonizing it.
Spurious parasite
Type of host in which the parasite attains sexual maturity.
Definitive (or Final) host
Type of host which only harbors the asexual or larval stage.
Intermediate host
Type of host in which the parasite does not develop further into later stage.
Paratenic host
Type of host in which the life cycle of the parasite is allowed to continue and which become additional sources of human infection
Reservoir host
What are vectors?
2 types of vectors, and describe.
Vectors transmit parasites from one host to another.
- Biologic vector - transmits a parasite only after it has completed its development (thus, also a host)
- Mechanical (or Phoretic) vector - only transports the parasite
Term: infection wherein an infected individual is further infected with the same species, leading to massive infection
Hyperinfection, a.k.a. Superinfection
What is the cause/origin of congenital toxoplasmosis?
Exposure of mother to cats during pregnancy
enumerate: virulence factors of Entamoeba histolytica, and their functions
- lectin - mediates adherence
- amebapores - for penetration
- cysteine proteases - most important virulence factor, which produces ulceration with bleeding
flask-shaped colon ulcers
Amebic colitis
anchovy sauce-like aspirate
Amebic liver abscess
Identify: most invasive among the Entamoeba genus.
Entamoeba histolytica
These amebicides act on organisms in the bowel wall and the liver. Give examples
- Tissue amebicides
- chloroquine, emetines, metronidazole, tinidazole
These amebicides act only in the lumen of the bowel. Give examples
-Luminal amebicides -diloxanide furoate, iodoquinol, paromomycin
Drug of choice for asymptomatic luminal cysts of E. histolytica:
Diloxanide furoate
Drug of choice for severe intestinal and extraintestinal amebiasis:
Metronidazole
Pathologic effect of Giardia infection:
acute effects
chronic effects
- attach and causes pathologic changes to the intestinal villi (villous flattening, crypt hypertrophy, and disruption of cytoskeleton), causing malabsorption
- Acute infection: flatulence, abdominal pain, diarrhea
- Chronic infection: steatorrhea, constipation, weight loss
Treatment of Giardiasis:
Metronidazole
How is Giardia lamblia transmitted?
Ingestion of food/water from sources contaminated with feces containing cysts
Gold standard for diagnosis of Giardia lamblia
direct fluorescent antibody testing
This parasite cause Gay bowel syndrome. Why is this so?
Giardia lamblia - high prevalence in homosexuals due to to their oro-anal practices
- Manifestation of cryptosporidiosis
- Cryptosporidiosis is life-threatening in what condition: and why?
- self-limited non-bloody diarrhea
- CD4 < 200, due to autoinfection
Treatment of cryptosporidiosis:
Usually self-limiting; DOC is Nitozoxanide, but in HIV patients, treatment with antiretrovirals may help the patient fight the pathogen on his own
Identidy: characterized by foul-smelling, greenish vaginal discharge, accompanied by itching and burning; with a characteristic strawberry cervix; What is the pathogen?
Trichomoniasis - cause by Trichomonas vaginalis
The only protozoal form of Trichomonas vaginalis
Trophozoite
How is trichomoniasis transmitted?
sexual intercourse (ping-pong transmission)
Treatment for trichomoniasis
Single dose 2 g oral metronidazole
most important parasitic disease in man
Plasmodium
What is the vector for Plasmodium?
Anopheles flavirostris minimus (infected female)
Two processes in the asexual life cycle of Plasmodium
- shizogony - occurs inside the RBCs
- gametogony
Process in the sexual life cycle of Plasmodium. Where does it occur?
sporogony - occurs inside the female mosquito (Anopheles flavirostris minimus)
What conditions are said to be protective against Plasmodium infection? (immune to malaria)
defects in RBC morphology (G6PD deficiency, sickle cell disease)
Term: recurrence of symptoms after a temporary abatement. Which Plasmodium species exhibit this?
- Recrudescence
- P. falciparum and P. malariae
- Term: return of a disease after its apparent cessation.
- Which Plasmodium species exhibit this?
- In Plasmodium, how does this happen?
- Relapse
- P. ovale and P. vivax
- due to reactivation of hypnozoites
Identify: Plasmodium: intermediate host / definitive host
humans / Anopheles flavirostris minimus
Gold standard for diagnosis of Plasmodium:
Giemsa stain:
- Thick smear - to screen for presence of organisms
- Thin smear - to identify the species of the infecting organism
- Identify: Punctate granulations present in red blood cells that contain hypnozoites.
- What Plasmodium species causes these changes?
- Schuffner dots
- Plasmodium ovale and Plasmodium vivax
- Identify: coarse granulations present in red blood cells.
- What Plasmodium species causes these changes?
- Maurer dots
- Plasmodium falciparum
- Identify: fine dots present in red blood cells.
- What Plasmodium species causes these changes?
- Ziemann dots
- Plasmodium malariae
Ziemann is a Fine Man
A severe complication of P. falciparum malaria, characterized by intravascular hemolysis, massive hemoglobinuria, and acute renal failure
blackwater fever
A severe form of malaria that is accompanied by septic shock.
Algid malaria
Enumerate: Usual symptoms of malaria (5)
- malaise
- joint pains
- hemolytic anemia
- jaundice
- splenomegaly
Term: These antimalarial drugs kill schizonts in the liver. Give some examples
- Tissue Schizonticides
- primaquine
Term: These antimalarial drugs kill the parasitic forms only in the RBCs. Give some examples
- Blood schizonticides
- chloroquine, quinine
Term: These antimalarial drugs kill gametocytes in human blood. Give some examples
- gametocides
- primaquine
Term: These antimalarial drugs prevent sporogony and multiplication in the mosquito. Give some examples
- sporonticides
- proguanil, pyrimethamine
Per Plasmodium species, in terms of erythrocyte age, what erythrocytes do they target? (young vs old)
- vivax - young RBCs
- ovale - young RBCs
- malariae - old RBCs
- falciparum - all ages
Vata, oVata, Matanda, Futa
Form of heme that is non-toxic to the Plasmodium cell
Hemozoin
- Definitive host of Toxoplasma gondii
- DOC
- domestic cat
- sulfadiazine and pyrimethamine
How is Toxoplasma transmitted?
- ingestion of food/water with fecal oocysts
- transplacentally
Two types of trophozoites of Toxoplasma
- Tachyzoites - rapidly multiplying
- Bradyzoites - slowly multiplying
Enumerate: signs of Congenital toxoplasmosis
- hydrocephalus
- encephalitis
- chorioretinitis
- hepatosplenomegaly
vector of Trypanosoma cruzi
reduviid (Triatoma) bug bite
Tissue that is the most frequently and severely affected by T. cruzi
cardiac tissue
What is the Romana sign?
- periorbital edema in acute Chagas disease
What is a chagoma?
inflammatory nodule near the bite, in acute Chagas disease
Enumerate: manifestations of chronic Chagas disease:
- myocarditis
- megacolon
- megasesophagus (achalasia)
Treatment for Chagas disease
Nifurtimox
Causative agent of West African sleeping sickness
Trypanosoma brucei gambiense
Causative agent of East African sleeping sickness
Trypanosoma brucei rhodesiense
Which is more rapid and fatal, gambian or rhodesian sleeping sickness?
Trypanosoma brucei rhodesiense
Rapid Rhodesian! Fatallll
- spectrum of disease caused by Trypanosoma brucei:
- indurated skin ulcer (trypanosomal chancre)
- enlargement of posterior cervical LN (winterbottom sign)
- hyperesthesia (Kerandel sign)
- encephalitis - Mott cells
- somnolence
DOC for advanced West African sleeping sickness
Eflornithine
WE - PESM
West / East
Pentamidine, Eflornithine / Suramin-Melarsoprol
It SUR is nice to sleep because of MELAtonin -> Suramin-Melarsoprol
DOC for advanced East African sleeping sickness
Melarsoprol
WE - PESM
West / East
Pentamidine, Eflornithine / Suramin-Melarsoprol
It SUR is nice to sleep because of MELAtonin -> Suramin-Melarsoprol
DOC for early West African sleeping sickness
Pentamidine
WE - PESM
West / East
Pentamidine, Eflornithine / Suramin-Melarsoprol
It SUR is nice to sleep because of MELAtonin -> Suramin-Melarsoprol
DOC for early East African sleeping sickness
Suramin
WE - PESM
West / East
Pentamidine, Eflornithine / Suramin-Melarsoprol
It SUR is nice to sleep because of MELAtonin -> Suramin-Melarsoprol
How is African sleeping sickness transmitted?
bite of the tsetse fly (Glossina)