Nematodes

Question 1

What is the definitive host?

Answer 1

Harbors adult and sexual stage of parasite

Question 2

What white cells increase during parasitic infection?

Answer 2

Eosinophils = eosinophelia

Question 3

What stimulates eosinophilia?

Answer 3

granulocyte-macrophage colony stimulating factor (GM-CSF)

IL-3

IL-5

Question 4

What other diseases can cause eosinophelia?

Answer 4

“NAACP”

Neoplastic syndromes i.e. leukemia, lymphoma

Allergic diseases

Addison’s disease= hypoadrenalism

Collagen vascular disease = lupus

Parasitic diseases: helminths + fungal infection

Question 5

Why are parasitic infections associated with eosinophilia?

Answer 5

During the migration stage of parasites through tissue

Chronic parasitic infections is not associated with eosinophilia

Question 6

What is a nematode?

Answer 6

Round worm

In a stool sample, “nematodes have structures, celerty doesnt” - digestive/nervous system

moving, patchy infiltrates wtih eosinophils

Question 7

How can nematodes infect a person?

Answer 7

Oral-fecal (Enterobias vermicularis, trichuris trichuria)

Oral-fecal migration to lungs (Ascaris lumbricoides)

Soil-migration to lungs: you walk with barefeet and it goes through your feet to your lungs (N americanis/A duodenales=hookworm, strongyloides)

All the ones in your lungs cause Loefflers syndrome = eosinophils in the lungs

All are treated with albendazole except Strongyloides is treated with ivermectin

Question 8

What is pinworm? How is it transmitted? Diagnosis? Treatment?

Answer 8

Enterobias vermicularis: you can see with naked eye (enteric verenal disease)

Person to person, oral/fecal, esp school aged children, indoor conditions

Pinworm season is during the winter

Diagnose via scotch tape test: put tape near anus, catch a sample, look under a microscope to look for eggs & worms; doesn’t normally cause eosinophilia bc it swims on top of the bowel, not invading tissue

Clinical presentation: vulvovaginitis (worm migrates to vagina) -looks like UTI, so always have it on your differential; migration to peritoneum via perforated appendix

Treat with albendazole (not good if pregnant), mebendazole (stays in intestine), pyrantel pamoate for oral suspension

Question 9

What is strongly associated with pinworm?

Answer 9

Dientamoeba fragilis = protozoa; if you have this, you almost always have pinworm!!! check for pinworm if you have this.

Question 10

How does albendazole work?

Answer 10

Binds to helminthic tubulin, blocks microtubule assembly; inhibits glucose uptake (only affects parasite, not humans)

Mebendazole is poorly absorbed- stays in GI tract

Increased absorption with fatty meal

If you give it at the same time as sterodis, increases levels by 50%

Side effects = bone marrow suppression, hepatotoxicity, alopecia

Question 11

How do you prevent pinworm?

Answer 11

Clip nails

have baby wear a onesie to sleep

Treat family

Question 12

What is whipworm? How is it transmitted?

Answer 12

Trichuris trichuria “trick you into getting whipped”

Think about it in immigrants, rural communities

Also hand to mouth transmission, but often from eating fruits and veggies fertilized with human feces

Question 13

What is the pathogenesis of whipworm?

How is it diagnosed?

Answer 13

Primarily affects children & causes growth retardation, diarrhea, anemia (from bleeding), rectal prolapse

Adults don’t get symptoms & can spread it more

Colonizes intestinal epithelial cells of colon, then lays eggs

Local eosinophilic response, edema, mucosa may bleed in heavy infections due to making the mucosa so thin

Stool sample to diagnose: football shaped eggs

Multiple infections can occur implying that immunity is incomplete

Treat with albendazole

Question 14

What is Trichuris Dysentery syndrome?

Answer 14

A complication of whipworm

Chronic dysentery, poor growth, rectal prolapse, clubbing of fingers, anemia (secondary to blood loss/apetite), elevation of acute phase proteins (plasma viscosity, systemic response to the infection)

Treat rectal prolapse not with surgery: just push the rectum in, give albendazole, and nutrition

Question 15

What is azcaris lumbricoides? Transmitted? Diagnosed? Clinical presentation? Treatment?

Answer 15

Giant worm: Causes acute infections in children due to immune hypersensitivity/Loffer’s syndrome: bronchospasm, urticaria (hives), pneumonia

Oral fecal transmission: intestine to lung vial liver which causes eosinophilia; lay eggs here

Diangose by seeing eggs in a stool biopsy

Complications include intestinal obstruction, peritonitis, biliary and pancreatic obstruction

Treat with albendazole, mebendazole and sometimes surgery to remove the worms

Question 16

What is hookworm? How is it transmitted?

Answer 16

There ar 2 different ones: Necator americanus and Ancylostoma duodenale

Through the feet (urticaria at site) to the heart, lungs, and intestine where it attaches and sucks blood; cause Loffler’s syndrome, coughing, wheezing

Related to malnutrition, impacts health of mother and child, causes iron deficiency and anemia because they suck our blood

Treat with albendazole or mebendazole

Question 17

What is strongyloides stercoralis?

How do you diagnose?

Answer 17

Lifelong infection! Can be bad if they are undiagnosed and then take steroids bc it suppresses the immune system & there can be an explosion of larvae

Larvae enters foot like hookworm (acute infection), goes to lungs, female lays eggs in intestine (different than hookworm, which lay eggs in soil); can also cause gram neg meningitis!!!

Autoinfection can occur, so you always have a low level of worm in your body. Most people are asymptomatic, so you have to take a travel history & check for mild eosinophilia with serology before you give steroids. Stool sample would show the worm, not the egg

Question 18

What should you think when you see gram neg meningitis?

Answer 18

Strongyloides!!

Very important bc you can’t give a patient with strongyloides steroids!

Also think HTLV-1, which is a virus associated wiht strongyloides coinfeciton

Question 19

What is HTLV-1?

Answer 19

Virus that infects T cells

It’s associated with strongyloides infection

If a patient has both, it affects the T cells & they can’t produce eosinophils!

Question 20

What is ivermectin?

Answer 20

Macrocyclic lactone produced by Streptomyces avermitilis
• Highly protein bound
• Activates the opening of gated chloride
channels

– Influx of chloride ions

– Paralysis of pharyngeal pumping mechanism
• 95% cure rate