Tissue Invasive Nematodes Flashcards by Donald Rees

How do we get Trichinella Spiralis?

Undercooked meat will give us this intestinal nematode

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Discuss the pathology and symptoms of Trichinella Spiralis

Sx: fever, vomiting, muscle pain/myalgia , abdominal cramps, periorbital edema, myocarditis, encephalitis, pneumonia

Path: larvae ingested → mature in intestine→ larvae shed into blood stream → deposit in striated muscle as new cysts (also in brain and heart)

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Discuss the lab values and how we diagnose Trichinella Spiralis

Labs: Eosinophilia
Dx: muscle biopsy (often insensitive); serology

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Treatment for Trichinella Spiralis?

Tx:Albendazole (disrupts microtubules)

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Discuss the pathology of Strongyloides stercoralis

intestinal nematode: (hookworm)
foot (skin)– blood –lungs – gi– feces
eggs laid in intestinal wall repenetrate and enter blood stream
intestinal nematode: (hookworm)
foot (skin)– blood –lungs – gi– feces
eggs laid in intestinal wall repenetrate and enter blood stream

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How does Strongyloides present?

sx: diarrhea, bloating

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Discuss the diagnosis and treatment for strongyloides

dx: larvae in stool
tx: Albendazole , ivermectin; steroids contraindicated

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Pathology and presentation of Enterobius vermicularis

intestinal nematode: (pinworm)
enterobiasis
ingestion of pinworm eggs, by hands, food, or water
sx: itching in the anal area where eggs are lain

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How to diagnose and treat enterobius vermicularis

dz: eggs on scotch-tape test
tx: Albendazole

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What the hell is Angiostrongylius cantonensis? Where do we get it from?

tissue trematode: (rat lungworm)

most common cause of eosinophilic meningitis worldwide

source: ingesting infected snails or slugs, prawns or crabs (paratenic hosts), or (snail) contaminated vegetables

Found in SE Asia and Caribean

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Discuss the pathology and presentation of Angiostrongylius cantonensis

In rats, adults develop in 2-3 weeks and migrate from brain surface to pulmonary arteries through venous system
In humans, adults develop and cause meningitis 1-2 weeks post infection

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How do we diagnose and treat Angiostringylius cantonensis?

Dx: CSF eosinophilia + meningitis + exposure history

Tx: corticosteroids may help

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Three presentation types of Filariasis

threadlike worms coming out of skin

Lymphatic filariasis (Wuchereria bancrofti and Brugia malayi)can be asymptomatic or cause lymphangitis ( acute filarial lymphangitis is inflammatory nodule with descending lymphangitis due to adult worms. Can cause dermatolymphngioadenitis (acute dermatolymphangioadenitis is ascending bacterial cellulits /lymphangitis). Can also cause lymphatic obstruction (lymphedema, elephantiasis, hydrocele)

pulmonary eosinophilia which manifests as paroxysmal nocturnal asthma, pulmonary infiltrates

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Discuss source and labs we see for filariasis in general

abs: blood eosinophilia, IgE elevation, and/ or filarial antibody titers
Source: spread by black flies (Simulium type) and mosquitoes.

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Treatment of Filariasis

Tx: elevation, hygiene, foot care, cutaneous fungal infections/ bacterial infections

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Discuss the source and location for Wuchereria

source: mosquito
lavae introduced to skin – invades lymphatics– blood
location: found in tropics

Discuss the disease progression of Wucheria bancrofti

Dz: Chronic Lymphatic filariasis → elephantiasis; also cough from filariasis in lungs
granulomas obstruct the lymphatic system → lymphedema

How do we diagnose and treat Wucheria bancrofti?

Dx: see microfilariae in nightime blood smear, or detection of antigen, or adult worm (biopsy or U/S)
tx: diethylcarbamazine (DEC)

Discuss the source and pathogenesis of onchocerca volvulus

source: blackfly
location: Africa, Americas
larvae introduced to skin– adults mate in subcutaneous fat layer of the skin– microfila enter lymph and blood – accumulate in skin and eye

Sympoms for onchocerca volvulus

dz: Subcutaneous filariasis and river blindness
sx: nodules under the skin, hyper/hypopigmented spots, severe itching, hanging groin, and blindness (begins as punctate keratitis)

Discuss the diagnosis and treatment for onchocerca volvulus

dx: microfilariae on microscopy of skin punch biopsy, serology, nodulectomy
tx: ivermectin

Discuss Loaloa

“african eyeworm”
Vector: deer fly
host: human only (no reservoir)
blood borne microfilariae
adult worms live in subcutaneous tissue
found in Africa

Symptoms for Loa loa

Sx: may be asymptomatic, non-specific (fatigue, urticaria, arthralgia, myalgia)
subcutaneous angioedematous swelling (calabar swelling), eyeworm (does not cause blindness)

Diagnosis and treatment for Loa loa

Dx: ID adult worm in conjunctiva, microfilaria seen in noon blood smear, or clinical picture + antifilarial antibodies
Tx: DEC

What causes heartworm?

Dirofilaria Immitis (Heartworm)

What type of bug is Toxocariasis and how do we get it?

tissue nematodes Humans acquire infection by ingestion of eggs in dog/cat feces. Larvae hatch in intestine and travel to liver, spleen, lungs, brain, and/ or eye

Symptoms of Toxocriasis

Sx: visceral larva migrans in 2-5 y.o.: fever, eosinophilia, hepatomegaly, wheezing, pneumonia, splenomegaly 10-15 y.o.: ocular larva migrans- retinal lesions that appear as solid tumors near macula (can cause blindness)

Diagnosing and treating Toxocariasis

Dx: clinical picture + serology Tx: self-limited or albendazole for acute

Typical clinical vignette for Toxocariasis

kid in sandbox with dogs

Source and pathogenesis for Anisalkis simplex

tissue nematodes source: ingestion of raw or undercooked seafood (worldwide but many cases in Japan and Spain) Inhabits stomach of final host. The parasite will bury head in gastric mucosa causing intra-abdominal abscess. Worm eventually dies.

Symptoms and treatment for Anisakis simplex

Sx: Pain, vomiting, allergic rxn (urticaria, itchy throat, anaphylactic shock) Tx: endoscopic removal

Pathogenesis and risk factors for getting schistosomiasis

Trematodes (flat flukes) risk: swimming in feces water snail-- free worms -- penetrate human skin-- blood-- liver --eggs in bowel/bladder migrates against venous blood flow to liver patho: granulomas (eggs and eosinophils) → fibrosis of liver and urinary tract → obstruction and portal HTN

Symptoms for Schistosomiasis

sx: swimmer’s itch, portal htn, liver problems, hematuria, squamous cell carcinoma of bladder

Histology and treatment for Schistosomiasis

histo: eggs in stool: spines look different: mansoni =large lateral spine; japonicum= small lateral spine; haematobium= large terminal spine tx: praziquantel

Discuss the presentation and treatment of Taenia solium if obtained from infected meat

source: worm infected meat (pig) worm has hooks unlike saginata (beef tapeworm) dz: taeniasis- GI sx; attaches to intestinal wall, consumes food ingested by host, eggs are then passed in feces tx: praziquantel

If Taenia solium is obtained from eggs in feces water, how does it present? How do we treat it?

dz: eggs hatch in intestines, penetrate intestinal wall and travel to other tissue: cysticercosis- cysts in skin and neurocysticercosis- cysts in brain = sz and hydrocephalus patho: hooklets attach to GI tract → auto-reproduce--> brain/muscle/skin tx: albendazole

How do we get Echinococcus granulosis and what is it?

cestodes (tapeworms) | source: dogs through feces; sheep are intermediate host

Symptoms of tape worm

sx: echinococcal cyst in liver (also lung, brain, bones) with egg shell calcifications cyst rupture may have anaphylactic rxn and acute abdomen

How do we diagnose and treat tapeworm?

dx: imaging tx: albendazole