protozoa and parasites quick quiz Flashcards
Organism in which parasite lives
host
Host which maintains the parasite in nature as a source for continued transmission
resevoir
Host in which sexual reproduction takes place
definitive host
Host in which development occurs, possibly asexual reproduction, but not sexual reproduction
intermediate host
Host in which parasite cannot complete life cycle (dead-end)
accidental host
what egg morphology
which location?
S. mansoni
Africa, Middle East, Suriname, Brazil, Venezuela
which egg form?
what disease caused?
where?
S. haematobium - bladder granulomas, hematuria, associated with bladder cancer.
Africa, Middle East
which form?
what disease caused?
where found?
China, Indonesia, the Philippines
S. japonicum - periportal fibrosis, portal hypertension with hepatosplenomegaly. Hypersensitivity to eggs major cause of pathology. Eosinophilia common
life cycle of entaemoeba histolytica
- Mature cysts are ingested in fecally contaminated food, water, hands
- Excystation occurs in small intestine
- Released trophozoites migrate to large intestine
- Trophozoites produce cysts, passed in feces - can survive outside the body
- Can have (A) asymptomatic infection, (B) intestinal disease, or (C) extra-intestinal abscesses
anchovie paste absess?
entamoeab histolytica life cycle
morphology of entamoeba histolytica
morphology?
what do the cysts look like?
what do the trophozites look like?
signs and symptmoms?
pathology: buzz word here
dx:
rx: what do you use for sympotmatic infection? how about to eradicate luminal carriage?
- *Morphology:** Trophozoite (active form) - single nucleus, often contains ingested RBCs.
- *Cyst:** Excreted, durable form. May contain up to 4 nuclei
Signs & Symptoms: Acute- dysentery with abdominal pain. Chronic- recurrent episodes with blood and mucus in feces. Can disseminate to liver, lung, brain - forms abscesses
Pathology: Flask-shaped ulcers in large intestine. No protective immunity
Dx: Symptoms, history, and epidemiology - lab looks for cysts in stool; serology, Amoeba antigen and DNA [PCR] tests
Rx:** **Metronidazole for symptomatic infection, Paromomycin for eradication of luminal carriage
where do outbreaks of N. fowleri occur?
waht do you use to tx?
Outbreaks of N. fowleri have been associated with diving in fresh water and use of tapwater in neti pots
Amphotericin B is effective against N. fowleri in vitro, but the prognosis remains bleak for those that contract PAM, and survival remains less than 1%.
what is the morphology of trichomoniasis?
symptoms in men and wmen?
pathology: buzzword
dx: ?
rx?
Morphology: Trophozoite, single nucleus, 4 anterior flagella. Undulating membrane, symmetrical axostyle. No cyst form.
Symptoms: Asymptomatic in men (can transmit). In women, prefers pH >4.5, with copious, frothy discharge.
Pathology: Contact-dependent, vaginal epithelium damage, strawberry cervix
Dx: Clinical suspicion confirmed by finding trophozoites in discharge - PCR
Rx: Metronidazole. Safe sex practice is prophylactic
what is the life cycle of t. vaginalis?
what life cycle lacking?
- Organism resides in female lower genital tract and male urethra
- Multiplies by binary fission (mainly in female genital tract) - no cyst stage.
- Transmitted by sexual contact. Does not survive outside of the host, no known reservoir hosts.
who gets giradia?
morpohlogy?
symtpoms?
dx:
tx?
Epidemiology: World-wide distribution. Most common protozoan intestinal disease in US-often transmitted via water, also common in day care centers
Morphology: Flagellated protozoan. Trophozoite with 2 nuclei and bilateral symmetry of axostyles and suction discs. Cyst with 4 nuclei and a well-defined wall
** Symptoms:** Uncontrollable flatulence, abdominal distension, foul-smelling, bulky diarrhea. Stool often contains excess lipids, but rarely blood or necrotic tissue. Trophozoites cover and flatten intestinal epithelium, may lead to malabsorption of nutrients.
- *Dx:** Symptoms, history, epidemiology - find cysts and trophs in stool
tx: Treatment: Metronidazole
giardia life cycle?
Cysts in contaminated water, food, or fecal-oral route are (2) ingested.
Trophozoites multiply by longitudinal binary fission (4) in small bowel.
Encystation occurs as parasites move toward colon.
Note: animals may serve as a reservoir (think camping)
where is T.b. gamiense? Tb rhodesiense?
morphology?
symptoms?
pathology?
Dx?
Rx? what do you use for the CNS stage? Blood stage?
Epidemiology: T.b. gambiense in West Africa; T.b. rhodesiense in East Africa
Morphology: Trypomastigote with kinetoplast and undulating membrane
Symptoms: bite reaction (chancre), parasitemia/LNs (fever) CNS (coma and death) – East African form rapidly progressive
Pathology: Not clear, partially immunologic due to antigenic variation
Dx: Dx: Card agglutination test, detection of parasite in blood or LN
Rx: Blood stage - pentamidine, suramin. CNS stage - Melarsoprol [arsenic cmpd = toxic], nifurtimox/eflornithine. Avoid tsetse flies.
American trypanomiasis:
what is vector?
morphology?
symptoms: primary lesion vs. chronic stage?
pathology:
dx:
Rx:
- Epidemiology: Central and South America
Morphology: Trypomastigote in blood, amastigote (intracellular) in tissue
Symptoms: Primary lesion (chagoma) at site of infection-usually on face [Romaña’s sign]; acute stage-non-specific symptoms [e.g. fever, myalgia, rash]
Parasitemia and lymphocytosis.
Chronic stage (10-20% of infected) involves heart, esophagus, colon
Pathology: Direct damage to infected cells (cardiomyopathy), destruction to autonomic nerve ganglia (mega-esophagus, megacolon)
Dx: Clinical dx in endemic area, blood smear, tissue histology
Rx: Complex Benznidazole, nifurtimox
what is the morphology of Leishmaniasis?
epidemiology?
symtpoms: 3 types?
pathology:
dx:
rx?
Epidemiology: Asia, India, Mediterranean, N. and C. Africa, S. and C. America
Morphology: promastigote taken up by macrophages, differentiates into amastigote, infection propagated by amastigotes
Symptoms: Visceral - organisms multiply in phagocytes of spleen, liver, nodes, etc. hyperpigmented skin. Superinfections. Mucocutaneous - organisms in skin metastasize to mucoid tissue leading to severe deformity. Cutaneous - ulcer develops at site of lesion.
Pathology: mainly immunologic; leukopenia, anemia, thrombocytopenia but elevated immunoglobulins
Dx: History, blood or tissue exam
Rx: sodium stibogluconate (antimonial), miltefosine, vector control
describes what:
Human infection through undercooked meat containing cysts or water contaminated with parasite oocyts
Parasite differentiation due to selective pressure (adaptive immune response) cuases differentiation to bradyzoites (tissue forms as cysts)
Embryonation in cat litter, cat as definitive host
Toxoplasma gondii life cycle
what is the morphology of toxoplasmosis?
how do you tx toxoplasmomis?
how do you prevent it?
Morphology: Intracellular replication - cat definitive host, pseudocysts form in intermediate hosts
- *Rx:** Pyrimethamine and sulfadiazine
- *Prevention:** Avoid cat litter (especially from scavenger cat); Watch out for rare meat
which disease?
Mild flu-like illness occurs while tachyzoites disseminate throughout body
Reactivation in Immunocompromised hosts
Don’t test pregnant women unless you know what you’ll do with the result…
vertical transmission (acute infection in pregnancy)
Present as brain mass in HIV
toxoplasma
Thick-walled oocyst released as infectious form.
Many outbreaks are associated with water parks, swimming pools and even reservoir sources.
Oocyst ingested, sporozoites released to infect gastric epithelial cells. Differentiate into merozoites, which grow via asexual cycle.
Some merozoites differentiate into male and female gametes that fuse to form a zygote.
5. Reduction division occurs within the walled zygote resulting in oocysts containing sporozoites
which bug?
Cryptosporidium parvum life cycle
how do you contract C. parvum? what is this infection not killed by?
what is the morphology of cyrptosporidiosis? how many sporozite in each oocsyst?
symptoms?
pathology?
dx?
rx?
Epidemiology: Outbreaks of diarrhea most often through contaminated water source. Not killed by chlorine
Morphology: Oocysts, sporozoites and merozoites. Oocysts contain 4 sporozoites, which differentiate into merozoites in GI tract. Some merozoites differentiate into sex cells (gametocytes); join to form oocyst.
Symptoms: Severity of diarrhea depends on dose ingested. Disease can be severe in immunocompromised (disseminate to gall bladder, biliary tract, lung)
Pathology: No dramatic pathology, dehydration from chronic diarrhea, progressive disease in compromised
Dx: Antigen testing, stool microscopy.
Rx: Nitazoxanide (?); Prevent by boiling or filtering water (<1um)
P. falciparum:
classic cycle?
distinguishng marks?
distribution?
48 hours
deadlies
widespread (tropics/subtropics)
P vivax + P. ovale
cycle?
distinguishing marks?
distribution?
48 hrs
Hypnozoites relapse
Widespread (tropics/subtropics, but extends to temperate zones), less in Africa
P. ovale: Tropical Africa, particularly W. coast
P. malariea
classic symtoms
where?
Tropical Africa, particularly W. coast
distribution: broad range, but lower incidence
how do you dx malaria?
Diagnosis
Giemsa stained blood smear (thin/thick)
Identify parasites by morphology
Estimates parasitemia (%)
**Antigen detection by rapid antigen tests (all/ P. falciparum) **
5 flagellate prozoans(mastigophora)
Leishmania spp.
Trypanosoma brucei,
Trypanosoma cruzi
Giardia lamblia
Trichomonas vaginalis
amoebas (sarcodina)
Amoebas (sarcodina)
Entamoeba histolytica
Naegleria fowleri
sporozea
Sporozoea (apicomplexa)
Cryptosporidium parvum
Plasmodium spp.
Toxoplasma gondii
Morphology: Trypomastigote with kinetoplast and undulating membrane
which bug?
African tryponosma brucei
Pathology: Flask-shaped ulcers in large intestine. No protective immunity
entaoemeba histolytica
Morphology: promastigote taken up by macrophages, differentiates into amastigote, infection propagated by amastigotes
leischmaniasis
