Nematodes Flashcards
What is the definitive host?
Harbors adult and sexual stage of parasite
What white cells increase during parasitic infection?
Eosinophils = eosinophelia
What stimulates eosinophilia?
granulocyte-macrophage colony stimulating factor (GM-CSF)
IL-3
IL-5
What other diseases can cause eosinophelia?
“NAACP”
Neoplastic syndromes i.e. leukemia, lymphoma
Allergic diseases
Addison’s disease= hypoadrenalism
Collagen vascular disease = lupus
Parasitic diseases: helminths + fungal infection
Why are parasitic infections associated with eosinophilia?
During the migration stage of parasites through tissue
Chronic parasitic infections is not associated with eosinophilia
What is a nematode?
Round worm
In a stool sample, “nematodes have structures, celerty doesnt” - digestive/nervous system
moving, patchy infiltrates wtih eosinophils
How can nematodes infect a person?
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
What is pinworm? How is it transmitted? Diagnosis? Treatment?
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
What is strongly associated with pinworm?
Dientamoeba fragilis = protozoa; if you have this, you almost always have pinworm!!! check for pinworm if you have this.
How does albendazole work?
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
How do you prevent pinworm?
Clip nails
have baby wear a onesie to sleep
Treat family
What is whipworm? How is it transmitted?
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
What is the pathogenesis of whipworm?
How is it diagnosed?
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
What is Trichuris Dysentery syndrome?
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
What is azcaris lumbricoides? Transmitted? Diagnosed? Clinical presentation? Treatment?
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
What is hookworm? How is it transmitted?
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
What is strongyloides stercoralis?
How do you diagnose?
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
What should you think when you see gram neg meningitis?
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
What is HTLV-1?
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!
What is ivermectin?
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
