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Flashcards in Parasites Deck (9):

Giardia Lamblia

Zoonosis (beavers, raccoons); One of the common causes of travelers' diarrhea and is worldwide in distribution; second most common parasite infection in US after pinworm;
Ingestion of cysts in contaminated water or food (ventral sucking disc, release of trophozoites in prox small bowel);
symptoms include profuse and watery stools first, but then they become GREASY, foul-smelling, and float (steatorrhea); look for WEIGHT LOSS first



Coccidian with lifecycle similar to PLASMODIUM;
think community pools where it can be extremely resistant to chlorine;
think calves, young lambs, goats and diarrhea, or present in water (oocyts: need as low as FOUR!!);
if immunocompetent, can have self-limiting watery diarrhea, but in immunocompromised, can have more severe, chronic, incurable illness that's life-threatening;
Treat: fluids/electrolytes, along with nitazoxanide


Entamoeba Histolytica:

Look for disruption of protective mucus layer; get ulcerations and bleeding and possible colitis;
trophozoites penetrating intestinal wall go through body via portal circulation: amebic liver abscesses (can rupture into pleural space) b/c of toxin release and hepatocyte damage;
look for FEVER, bloody diarrhea, and RUQ pain


Intestinal Cestodes (Tapeworms)

Pts more likely to develop symptoms with T saginata than T solium (10 m vs 3 m); look for PROGLOTTIDS passing through anus and in feces; think about ingestion of the larva or cysticercus;

Saginata usually uses cow as intermediate host with larval cysts, and we eat the undercooked meat;

Solium: If we eat solium eggs, we can develop cysticercosis with cysts growing in the muscle or worse in the CNS (when we are the INTERMEDIATE HOST): look for seizures and intracranial HTN

D latum: freshwater fish containing parasite's cysts



Most common helminthic infection of humans: need male and female together in GI tract for infection;

ingest the egg, hatches in intestine, penetrates mucosa, goes to portal vessels to liver and then lungs; goes into alveolar air sac, coughed up and swallowed and sexually matures in the SI's;

look for possible intestinal obstruction, intussusception, volvulus, blockage of the biles ducts



the whipworm; think SE US in warm and humid months;
ingest eggs, and we see sometimes no symptoms or just peripheral blood eosinophilia;
heavy infections can lead to abdo pain, diarrhea, rectal prolapse, maybe growth retardation


Hookworm: Ancylostoma, Necator:

Rhabditiform larvae!! They can become filariform larvae in the soil;
they penetrate the skin and go to heart and lungs through veins; they also go up bronchial tree to pharynx to be swallowed and larvae reach SI to mature;
Symptoms: iron-deficiency anemia and protein energy malnutrition; look for chronic abdo pain and persistent eosinophilia,


Enterobius vermicularis:

Pinworm; most common of all heminthic infections in US;
think perianal and perineal pruritis and scratching, with possible vulvovaginitis;
can have retroinfection with newly hatched larvae from anal skin into rectum, or self-infection by moving eggs to mouth with hands after scratching perianal area;

Use scotch test to ID eggs collected in perianal area



The rhabditiform larva develop into filariform and they penetrate the skin and go to lungs via blood and can be swallowed, and they enter the intestinal mucosa and mature;
think larvae producing pneumonitis with cough, hemoptysis, and respiratory failure; also diffuse interstitial infiltrates;
maybe meningitis and brain abscesses if larvae in CSF fluid and tissue