Parasites

Question 1

Giardia Lamblia

Answer 1

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

Question 2

Cryptosporidiosis:

Answer 2

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

Question 3

Entamoeba Histolytica:

Answer 3

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

Question 4

Intestinal Cestodes (Tapeworms)

Answer 4

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

Question 5

Ascariasis:

Answer 5

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

Question 6

Trichuriasis:

Answer 6

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

Question 7

Hookworm: Ancylostoma, Necator:

Answer 7

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,

Question 8

Enterobius vermicularis:

Answer 8

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

Question 9

Strongyloidiasis:

Answer 9

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