Nematodes

What is the specimen of choice for nematode?

Stool

• eggs (most common)

• larva

• rarely adults

Which larval stage is usually the infective stage for nematodes?

Filariform larvae

What two species are the hookworms?

Ancylostoma duodenale
Necator americanus

How is the method of infection different for hookworms and Strongyloides compared to other nematodes?

Penetration of skin via filariform larvae

Besides the intestines, named two alternative body sites for infection and the parasite(s) associated with each.

Lungs

• Ascaris lumbricodes

• Hookworms

• Strongyloides

Tissue

• Trichinella spiralis

Common name for Enterobius vermicularis?

Pinworm

Infective stage of pinworm/E. vermicularis

Egg - ingestion (dirty hands, toys, bedding, etc.)

Diagnostic stage of pinworm/E. vermicularis

Eggs, larvae, adults in stool

What is pruritis and which parasite is it associated with?

Intense anal itching
E. vermicularis

Laboratory diagnosis of E. vermicularis

Wet mount
Scotch tape test

Common name for Trichuris trichiura

Whipworm

Infective stage of whipworm/T. trichiura

Eggs - ingestion

In heavy whipworm infection, what rectal symptoms might manifest?

Rectal prolapse

Laboratory diagnosis of T. trichiura?

Wet mount

Common name for Ascaris lumbricoides

Giant intestinal worm

Infective stage of A. lumbricoides

Eggs - ingestion

Diagnostic stage of A. lumbricoides

Eggs in feces
Larvae in sputum

What alternative body site does A. lumbricoides infects?

Lungs

Symptoms of A. lumbricoides infection

Intestinal

• usually asymptomatic unless the load is heave

• Abdominal pain

• Vomiting, nausea

Lungs

• Pneumonia

• Asthma

• Eosinophilia

Laboratory diagnosis of A. lumbricoides

Wet mount
Sputum

ELISA also available

Common name for Ancylostoma duodenale

Old World hookworm

Common name for Necator americanus

New World hookworm

Infective stage of hookworm

Filariform larvae - penetration of skin

Diagnostic stage of hookworm

Eggs in feces

What alternative body site can hookworm infects?

Lungs

How to differentiate btw. Ancylostoma and Necator?

Eggs are identical

Ancylostoma - teeth

Necator - cutting blades

Symptoms of hookworm

Pulmonary issues
Vomit, nausea, diarrhea
Iron deficiency anemia
Larval dermatitis (serpiginous tunnels)

What causes cutaneous larval migrans?

Ancyclostoma & Necator

What causes creeping eruption?

Ancyclostoma & Nector

Laboratory diagnosis of hookworm

Wet mount

Common name for Strongyloides stercoralis

Threadworm

Infective stage of Strongyloides

Filariform larvae - penetration of skin

Diagnostic stage of Strongyloides

Rhabiditiform larvae in feces

What alternative body site can Strongyloides infects?

Lungs

Symptoms of Strongyloides

Pulmonary issues
Vomit, nausea, diarrhea
Erythema
Can be fatal in IC patients

Laboratory diagnosis of Strongyloides

Wet mount
Sputum or bronchial samples
Enterotest (string test)
Antibody detection

How to acquire Trichinella spiralis?

Ingestion of undercooked meat (pork, bear, walrus)

Infective stage of Trichinella

Encysted larva - ingestion

Diagnostic stage of Trichinella

Encysted larva in tissues/muscles

Symptoms of Trichinella

Intestinal issues
Fever, eosinophilia
Muscle pain
Eye edema

Laboratory diagnosis of Trichinella

Muscle biopsy
Serology

What can cause visceral and ocular larval migrans?

Toxocara cati/canis

Infective stage of Toxocara

Eggs - ingestion

Diagnostic stage of Toxocara

Larvae - biopsy

How to acquire Toxocara?

Ingestion of eggs from cat/dog feces

Symptoms of Toxocara

Generally not severe
Fatigue, weight loss
Ocular problem
Eosinophilia

Laboratory diagnosis of Toxocara

Biopsy
Serology