Parasites/helminths Flashcards
Giardias Etiology
G.lamblia
Giardias reservoir
beavers, dogs, cats, primates.
Giardias epidemiology
Common in children. Highly contagious. June-october. Common in the rocky mountains. Communicable as an STI.
Giardias Life cycle
Ingestion of cyst. Excystation in stomach. trophozoites pass to small bowel. Trophozoites encyst in the large bowel and then the cysts are excreted.
Giardias Symptoms
Intermittent episodes of watery diarrhea (no blood), cramps, abdominal distension, anorexia (malabsorption), vitamin B12 deficiency.
Giardias Diagnosis
O/P examination of multiple stool samples. ELISA for GSA65.
Giardias treatment
metronidazole.
Amebiasis etiology
Entamoeba Histolytica
Giardias trophozoites
exist freely in the intestine. bilobed adhesive disc with flagella and 2 nuclei. Feeds on the mucous and flattens the villi.
Giardias Cysts
Passed into the environment. Hyaline wall with 4 nuclei.
Amebiasis trophozoite
1 nucleus, non-flagellated, pseudopod, invasive and pathogenic.
Amebiasis Cysts
round with 4 nuclei. infectious.
Amebiasis Life cycle
ingestion of cysts. excystation in the colon. Highly motile. colonizes colon mucosa. encyst and are passed into the environment or invade the mucose to enter the blood stream and disseminate.
Amebiasis Epidemiology
Common in tropical/subtropical areas.
Amebiasis symptoms
Can range from asymptomatic to dysentery to extraintestinal manifestions. Acute amoebic colitis: cramps, tenderness, bloody stools, fever, vomiting, weight loss. Ulcers and right upper quadrant pain.
Amebiasis Mortality causes
peritonitis, cardiac failure and exhaustion
Amebiasis Lectin
adhesion
Amebiasis Phospholipases
Disrupt the cell membrane.
Amebiasis amebapore
peptide released that inserts ion channels into the host lipid structure causing lysis.
Amebiasis cyestein proteases
degrade mucus, antibodies, complement and cellular matrix.
Amebiasis Diagnosis
ELISA; differentiates between E. hystolitica and E. dispar (Commensal). Radiology will detect ascesses extraintestinal.
Amebiasis Treatment
Metronidazole and surgery for large abcesses.
Cryptosproridiosis etiology
Cryptosporidium hominis (humans) and C. parvum (bovine and human).
Cryptosproridiosis Oocyst
Infectious. Contains 4 sporozoites.
Cryptosproridiosis Sporozoites
motile. bind receptors on the surface of intestinal epithelium. Ingested into parasitophorous vacuole (near surface but still separated from the cytoplasm).
Cryptosproridiosis life cycle
Asexual and sexual reproduction inside the host
Cryptosproridiosis thin oocyst
Asexual. reinfect the host.
Cryptosproridiosis thick oocyst
Sexual. Shed into the environment. Highly infectious immediately after being released. Shedding can continue for weeks after the patient improves.
Cryptosproridiosis epidemiology
Person-to-person. Resistant to chlorine. Commonly associated with AIDS.
Cryptosproridiosis symptoms
watery (not bloody) diarrhea, dehydration, weight loss, fever, abdominal pain. Lasts for 2 weeks.
Cryptosproridiosis Diagnosis
Isolate oocysts from the stool (zinc sulfate centrifugal flotation) then use immunoflourescence or ELISA.
Cryptosproridiosis treatment
nitazoxanide or paroromycin.
Cyclosporiasis etiology
cyclospora cayetanensis
Cyclosporiasis epidemiology
common in latin america. contaminated water and imported food. Resistant to chlorine.
Cyclosporiasis description
Large oocyst that is autofluorescent. Acid-fast.
Cyclosporiasis life cycle
oocysts are shed in the feces and must sporulate in the environment which can take days to become infectious.
Cyclosporiasis symptoms
Low grade fever, chills, cramps, nausea, vomiting, explosive (not bloody) diarrhea, rapid weight loss, profound fatigue.
Cyclosporiasis treatment
bactrim.
Blastocystis hominis description
polymorphic. large central vacuole with multiple nuclei around the rin.
Blastocystis hominis epidemiology
comes from animal feces.