Worms Flashcards
Name and describe the three large groups of helminths.
Nematodes: aka roundworms - cause both intestinal and tissue infections
Trematodes: aka flukes - have characteristic hookers/suckers
Cestodes: aka tapeworm
Describe an infection from pinworms and state how it is transmitted.
Mate in colon and migrate to the anus to deposit eggs
Transmitted fecal-oral or by inhalation
What is the test used to diagnose pinworms?
Tape test
Describe the treatment after a diagnosis of pinworm infection is made.
Two doses albendazole given 2 weeks apart
Treat the entire household s/p easy transmission
Describe an infection from roundworm and state how it is transmitted.
Reproduce in the SI then eggs are transmitted in the feces
Transmission by fecal-oral or contaminated soil
What is the most common nematode infection?
Roundworm
What is the drug of choice for treatment of roundworm?
Albendazole
Describe an infection from hookworm and state how it is transmitted.
Infection of small intestine transmitted from contact with infected soil –> walking barefoot through soil is most common method of transmission.
In what part of the US is hookworm most common and why has the infection rate decreased in recent years?
Southeastern US –> improved sanitation has decreased infection rates
What is the significant AE associated with hookworm infection?
Anemia in children and pregnant women
What is the drug of choice for treatment of hookworm?
Albendazole
Describe how an infection from strongyloidiasis (threadworm) is transmitted and in what regions it is most common.
Transmitted cutaneously from infected soil or person to person. Common in areas with warm, moist soil - tropical regions.
What is the drug of choice for treatment of strongyloidiasis (threadworm)?
Ivermectin
Describe an infection from tapeworm and state how it is transmitted.
Very long (3-10 m) nematode with a hook that attaches itself to GI wall. Transmitted by eating undercooked meat.
What is a dangerous sequelae that can form from tapeworm infection?
Development of a solium that can lead to cysticercosis (muscle/eye damage from cysts) and neurocysticersosis (cysts in the brain causing seizures)
What is the drug of choice for treatment of simple tapeworm?
Praziquantel
Describe the treatment of a Taenia Solium infection.
Cysticercosis: albendazole
Neurocysticercosis: albendazole, praziquantel, and dexamethasone
Describe an infection from the tissue nematode filariasis (worm that causes river blindness) and state how it is transmitted.
Vector borne (black flies) larvae introduced into skin and grow to adult worms in subcutaneous tissue.
What causes river blindness from a filariasis infection?
Reversible lesions on the optic nerve.
Describe the treatment of a tissue nematode infection (river blindness).
Drug of choice is ivermectin –> only kills larvae. May add doxycycline.
Describe an infection from schistosomiasis and state how it is transmitted.
Vector borne (snails) through contaminated fresh water. Larvae enter human skin and grow into adults in the blood vessels.
What is the drug of choice in the treatment of schistosomiasis?
Praziquantel
Describe an infection from Hydatid Disease (echinococcosis) including the main areas of the body where the disease manifests.
Fecal-oral transmitted worm that creates cysts that can grow asymptomatically for years in the lungs, liver, and CNS
What more common infection does Hydatid Disease mimic?
Streptococcal Abscess
What is a life threatening potential complication of Hydatid Disease?
Cystic rupture releases larval organisms that can cause anaphylaxis.
Describe the treatment of Hydatid Disease.
Can be medical or surgical. Drug of choice is albendazole with praziquantel added if surgery is needed.
What are the two broad mechanisms by which antihelminth medications work?
Paralysis of the worm
Damage to the worm altering its metabolism or allowing the immune system to eliminate it.
What is the mechanism of action of albendazole?
Paralysis of the worm
Differentiate administration of albendazole for an intestinal parasite vs a tissue parasite.
Intestinal: administer on an empty stomach
Tissue: administer with a fatty meal
Differentiate use of mebendazole vs albendazole.
Mebendazole is mostly used for intestinal infections.
What are the concerns with mebendazole regarding other medications?
Can’t be administered with metronidazole and interacts with anti-seizure medications
What is the mechanism of action of ivermectin?
Paralysis of the worm
How is ivermectin administered?
Given on an empty stomach
T/F: Ivermectin is indicated in pregnancy and nursing mothers.
False: cannot be given in pregnancy or nursing mothers
Name a describe a reaction that is an AE of ivermectin.
Mazzotti reaction: fever, hives, tachycardia, hypotension –> key sign is ophthalmic reactions
What drug interaction is common with ivermectin?
Enhances the anticoagulant effect of warfarin.
What is the mechanism of action of praziquantel?
Paralysis of the worm
How is praziquantel administered?
Take with food because it increases the drug level.
What results if praziquantel is administered within 24 hours of dexamethasone?
Bioavailability of praziquantel is decreased by 50%
What is the mechanism of action of pyrantel pamoate?
Paralysis of the worm –> MOA similar to succinylcholine
In what patients is there a precaution in administering pyrantel pamoate?
Patients with liver disease.
Name two drugs not available in the US unless specifically approved by the CDC.
Diethylcarbamazine and niclosamide
