Parasitology: Parasitic Worms

Question 1

A patient presents with anal pruritis.

The Scotch Tape test is positive.

Diagnosis? How is it spread?

Answer 1

Enterobius vermicularis (pinworm, subset of roundworm)

Fecal-oral spread.

Question 2

How to treat Enterobius vermicularis (pinworm)

Answer 2

Bendazoles or pyrantel pamoate

(because worms are bendy)

Question 3

Patient presents with intestinal discomfort.

Microscopic examination of the feces reveals eggs.

Diagnosis and spread?

Answer 3

Ascaris lumbricoides (giant roundworm)

Fecal-oral spread.

Question 4

How would you treat Ascaris lumbricoides (giant roundworm)?

Answer 4

Bendazoles or pyrantel pamoate

(because worms are bendy)

Question 5

A landscaper presents with vomiting, diarrhea, and epigastric pain. He says he usually works barefoot.

You’re suspicious of a parasitic disease.

Likely diagnosis and spread?

Answer 5

Strongyloides stercoralis, a roundworm

Larvae in soil penetrate the skin.

Question 6

Treatment for Strongyloides stercoralis?

Answer 6

Ivermectin or albendazole.

Question 7

Patient presents with fatigue and abdominal discomfort.

A CBC confirms microcytic anemia.

What are some parasitic worms that can cause these symptoms?

How are they spread?

Answer 7

Hookworms (a subset of roundworm):

• Ancylostoma duodenale*
• Necator americanus*

Larvae penetrate skin.

Question 8

How to treat hookworm infections? (Ancylostoma duodenale, Necator americanus)

Answer 8

Bendazoles or pyrantel pamoate.

Question 9

A patient presents with blindness and black skin nodules.

He confirms a recent black fly bite.

Diagnosis?

Answer 9

Onchocera volvulus, a roundworm

Causes hyperpigmented skin and river blindness (black flies, black skin nodules, “black sight”)

Allergic reaction to microfilaria possible.

Question 10

Treatment for Onchocera volvulus?

Answer 10

Ivermectin (ivermectin for river blindness)

Question 11

Patient presents complaining of seeing “something floating in his eye”.

Upon examination, you see small worms in her conjunctiva.

Diagnosis? Spread?

Answer 11

Loa loa, a roundworm

Either a swollen skin infection or worms in conjunctiva.

Spread by deer fly, horse fly, or mango fly.

Question 12

How to treat loa loa?

Answer 12

Diethylcarbamazine

Question 13

Patient presents with elephantitis.

You suspect a roundworm infection.

Diagnosis? Spread?

Answer 13

Wuchereria bancrofti

Spread by female mosquito. Can take 9 months-1 year to become symptomatic.

Question 14

Treatment for Wuchereria bancrofti?

Answer 14

Diethylcarbamazine

Question 15

A young child presents with infection of several organs with a roundworm.

Diagnosis? Spread?

Answer 15

Toxocara canis, a roundworm.

Disseminated infection called Visceral larva migrans

Spread by fecal-oral route.

Question 16

How to treat Toxocara canis?

Answer 16

Albendazole or mebendazole.

Question 17

What are the roundworms that cause infection when ingested?

Answer 17

Enterobius - Anal pruritis, Scotch Tape test

Ascaris - Intestinal infection

Toxocara - Cisceral larva migrans

“You’ll get sick of you EAT these!”

Question 18

What are the nematodes/roundworms that cause infection when exposed to the skin?

Answer 18

Strongyloides - Vomiting, diarrhea, epigastric pain

Ancylostoma - Anemia, hookworm

Necator - Anemia, hookworm

“These get in your feet from the SANd.”

Question 19

What nematodes that cause infection when spread by insect bites?

Answer 19

Loa loa: Worm in conjunctiva, deer, horse, and mango flies

Onchocerca: Black flies, black nodules, black sight

Wuchereria bancrofti: Female mosquito, elephantitis

“Lay LOW to avoid getting bitten”

Question 20

Patient presents with intestinal discomfort.

He ate at a pig roast recently.

Most likely parasitic worm? How is it spread?

Answer 20

Taenia solium - a cestode/tapeworm

Causes intestinal infections when larvae cysts are eaten from uncooked pork.

Question 21

Patient presents with numerous seizures.

MRI finds several brain cysts.

Possible infectious worm? Spread?

Answer 21

Taenia solium - a cestode/tapeworm

This syndrome is called cystericerosis (neurocystericosis when in brain)

Ingestion of eggs can result in this syndrome.

Question 22

How to treat Taenia solium?

Answer 22

Praziquantel

Albendazole for neurocystericerosis.

Question 23

A patient presents with fatigue.

A CBC shows macrocytic anemia.

He admits to loving sushi.

Possible worm infection? Route of transmission?

Answer 23

Diphyllobothrium latum, a cestode/tapeworm.

Ingestion of larvae from raw freshwater fish. Vitamin B12 deficiency induced from tapeworm competition in intestine.

Question 24

How to treat Diphyllobothrium latum?

Answer 24

Praziquantel.

Question 25

A dog handler presents with unrelenting abdominal pain.

An abdominal CT shows multiple cysts in the liver.
The surgeons preinject the patient with ethanol before beginning a removal procedure.

Diagnosis? What’s with the ethanol?

Answer 25

Echinococcus granulosus

Caused by ingestion of eggs from dog feces.

Hydatid cysts in liver - anaphylaxis can result if antigens are released (ethanol kills cysts before removal to avoid this complication).

Question 26

How to treat Echinococcus granulosus?

Answer 26

Albendazole.

Question 27

Patient presents with abdominal pain and splenomegaly.

Biopsy of the liver shows granulomas, fibrosis, and inflammation.

Possible parasitic infectious agent? Spread?

Answer 27

Schistosoma - a trematode (fluke)

Snails are host; cercariae penetrate skin of humans

Chronic infection can cause squamous cell carcinoma of the bladder (painless hematuria)

Question 28

How to treat Schistosoma?

Answer 28

Praziquantel.

Question 29

Patient presents with horrible RUQ pain.

He admits to enjoying undercooked fish. You diagnose cholelithiasis.

Diagnosis? Source? Important association?

Answer 29

Clonorchis sinensis, a trematode (fluke)

Acquired from undercooked fish.

Causes biliary tract inflammation -> pigmented gallstones

Associated with cholangiocarcinoma.

Question 30

How to treat Clonorchis sinensis?

Answer 30

Praziquantel.