Helminths and Ectoparasites

Question 1

Enterobius vermicularis (pinworm)

NEMATODE (roundworm)

Answer 1

MC in US
fecal- oral transmission
female lays eggs at night, causing anal pruritis. Child scratches and re-infects.

Tape test and microscopy for diagnosis

albendazole, mebendazole for treatment

Question 2

ascaris lumbricoides (giant roundworm)

NEMATODE (roundworm)

Answer 2

2nd MC in US
fecal- oral transmission. eggs visible in feces under microscope

intestinal infection
possible obstruction at ileocecal valve

treat with bendazoles

eggs are released in stool. They hatch 2-3 weeks later. Ingested eggs hatch in the intestine.
Larvae enter the bowel wall, going into the veins, which lead to the lungs. They travel through alveoli to the trachea and oropharynx, are swallowed and then mature in the intestine. They lay eggs in the stool, and the cycle begins again.

Question 3

Trichonella spiralis

NEMATODE (roundworm)

Answer 3

from eating undercooked meat
larvae migrate from GI tract to muscles causing
-myositis
-fever
-eosinophilia
-periorbital edema

on biopsy, cysts are visible in the muscle tissue

Question 4

ingested worms (EAT)

NEMATODE (roundworm)

Answer 4

Enterobius
Ascaris
Trichinella

Question 5

Strongyloides stercoralis

NEMATODE (roundworm)

Answer 5

larvae in soil penetrate skin of feet, enter bloodstream and travel to lungs, to oropharynx, swallowed, maturation and egg-laying in GI tract

Tx: ivermectin
albendazole

Question 6

Ancylostoma duodenale
Necator americanus (hookworms)

NEMATODE (roundworm)

Answer 6

larvae penetrate skin
travel via bloodstream to lungs, oropharynx, intestine, hook into intestinal wall and suck blook.
Abd pain, discomfort, anemia

Tx: albendazole
mebendazole
pyrantel pamoate

Question 7

Soil- transmitted worms (SANd)

NEMATODE (roundworm)

Answer 7

Strongyloides
Ancelostoma
Necator
D

Question 8

Taenia solium

CESTODE (tapeworm)

Answer 8

larvae, when ingested become adult tapeworms that live in the GI tract for YEARS. Tx: praziquantel

eggs, when ingested form cysts in human tissue (cysticercosis), in the CNS (neuocysticercosis) this can lead to seizures, behavioral changes. On imaging, the brain may look like swiss cheese. Tx: praziquantel, albendazole

Question 9

Diphyllobrothrium latum

CESTODE (tapeworm)

Answer 9

ingestion of larvae from raw freshwater fish

B12 deficiency (tapeworm eats B12), leading to megaloblastic anemia

Tx: praziquantel

Question 10

Echinoccus granulosus

CESTODE (tapeworm)

Answer 10

eggs from dog feces. Sheep are an intermediate host.

Hydatid cysts form in the liver. They leak fluid, possibly leading to anaphylaxis. Surgical removal and albendazole for treatment. The cyst is injected with ethanol or hypertonic saline to kill daughter cysts before removing them.

Question 11

Schistosoma

TREMATODE (fluke)

Answer 11

eggs release, larvae mature into cercaria in snails. Cercaria penetrate swimmers’ skin leading to “swimmer’s itch” (local inflammation). The cercaria travel to lungs/liver and then to

mesenteric vessels (s. mansoni)
vs
lower urinary tract (s. haematobium)

embolized eggs can get struck, causing portal htn, pulmonary htn, or splenomegaly

s. haematobium can cause squamous cell carcinoma of the bladder (painless hematuria)

Question 12

Paragonimus westermani

TREMATODE (fluke)

Answer 12

adult fluke lives in lung
sx: chronic bronchitis , hemoptysis

aquired from undercooked crab meat

treatment: praziquantel, off label

Question 13

Clonorchis sinensis
(liver fluke)
TREMATODE

Answer 13

undercooked fish
biliary tract inflammation (pigmented gallstones, cholangiocarcinoma)

treatment: praziquantel, albendazole

Question 14

Wuchereria bancrofti
(Filariasis)

NEMATODE (roundworm)

Not a GI tract parasite

Answer 14

larvae transmitted by mosquitos
larvae migrate to lymphatics, leading to inflammation and obstruction, leading to elephantiasis (9months to 1 year after the bite), hydrocele

tx: diethylcarbamazine

Question 15

Headlice treatment

Answer 15

permethrin, pyrethrin, malathion, ivermectin, spinosad, benzoyl alcoho

NOT lindane, which causes neurotoxicity and lice are resistant anyway

Question 16

pubic lice

Answer 16

pruritis
STD, screen for others
permethrin
pyrethrin

Question 17

Scabies

Answer 17

mite that burrows into skin
sexual or other close contest
webbing of fingers
penis, periumbilical area

look at interdigital webbing, linear burrows

permethrin
ivermectin

Question 18

bedbugs

Answer 18

hide in mattresses, suck blood
eat several times per day but can go months without food

pruritis at site of bloodmeal

Question 19

snail host, swimmer’s itch

Answer 19

schistosoma haematobium

Question 20

fluke associated with hematuria and bladder cancer

Answer 20

schistosoma haematobium

Question 21

contracted by eating undercooked fish and causes inflammation of the biliary tract

Answer 21

clonorchis (liver fluke)

Question 22

soil, enters through skin, venous blood supply, lungs, coughed into pharynx, intestines

Answer 22

strongyloides, ancylostoma, necator

Question 23

responsible for lymphatic filariasis

Answer 23

wuchereria bancrofti

Question 24

adult patient from mexico with new-onset seizures and brain calcifications

Answer 24

taenia solium eggs

neurocysticercosis

Question 25

treatment for giardia, entamoeba, trichomonas

Answer 25

metronidazole

Question 26

treatment for plasmodium vivax or ovale

Answer 26

chloroquine and primaquine

Question 27

chloroquine- resistant malaries

Answer 27

quinine+doxycycline
mefloquine
atovaquone-proguanil
artemether-lumefantrine

Question 28

treatment for most flukes (includine schistosoma, clonorchis)

Answer 28

praziquantel

Question 29

treatment for hookworm, pinworm, roundworm

Answer 29

benzimidazoles

pyrantel pamoate

Question 30

treatment for chagas disease

Answer 30

benznidazole, nifurtimox

Question 31

treatment for leishmaniasis

Answer 31

cutaneous- sodium stibogluconate

visceral- liposomal amphotericin B