Parasitology II: Helminths Flashcards
What is the most common worm infection in the United States?
Enterobius vermicularis
How is Enterobius vermicularis transmitted?
Fecal-orally
Pathogenesis of Enterobius vermicularis
Attaches to the wall of the colon and migrates through the anus where it hatches eggs
Symptoms of Enterobius vermicularis
Anal itching
Can lead to secondary bacterial infection
Diagnosis of Enterobius vermicularis
E. vermicularis worms stain orange with Papanicolau stain
Treatment of Enterobius vermicularis
Pyrantel pamoate
Mebendazole
Albendazole
What is the distribution of Trichuris trichiura?
Southern United States
What is the route of transmission of Trichuris trichiura?
Fecal-oral
What are the symptoms of Trichuris trichiura?
Heavy infections: Bloody diarrhea, rectal prolapse
What is the treatment of Trichuris trichiura?
Mebendazole
Albendazole
What is the distribution of Ascaris?
Uncommon in the U.S.
If seen, it is seen in the SE
What do the Ascaris eggs look like?
Rough coat
What are the symptoms of Ascaris?
Light infection: Asymptomatic
Heavy infection: Wheezing, SOB, malabsorption of food, intestinal obstruction
Diagnosis of Ascaris
ID of eggs in the feces
Finding of worms leaving the body
Treatment of Ascaris
Mebendazole
Albendazole
Ivermectin
Pyrantel pamoate (pregnant individuals)
What is the distribution of Necateur americanus?
Prevalent in Central and South America
What is the mechanism of infection of Necateur americanus?
Eggs hatch to larval stage in the environment. Larvae then penetrate the skin. Mature to adults in the small intestine.
What are the risk factors for Necateur americanus?
Not wearing shoes
Symptoms of Necateur americanus
"Ground Itch", usually in the soles of the feet Most cases are asymptomatic. Blood loss (causing anemia), gastric pain, pulmonary manifestations (not as severe as Ascaris)
Where is Strongyloides stercoralis found?
Southern U.S.
What kind of life cycle does Strongyloides stercoralis have?
It has a Direct Cycle and an Autoinfective Cycle
Symptoms of Strongyloides stercoralis
Pulmonary & GI symptoms
Hallmark feature is peptic-ulcer like pain with peripheral eosinophilia
Diagnosis of Strongyloides stercoralis
“Larva currens”…raised “creeping” red lesion over the buttocks or lower back
Shows “trails” of bacteria on a blood agar plate
Treatment for Strongyloides stercoralis
Ivermectin
Where is Ancyclostoma duodenale distributed?
Americas, Middle East, Africa
What is the life cycle of Ancyclostoma duodenale?
Eggs hatch to larvae outside the body. Larvae penetrate the skin.
Diagnosis for Necateur/Ancyclostoma
Examine stool for worm eggs
Necateur and Ancyclstoma eggs are indistinguishable
Treatment for Ancyclostoma/Necateur
Pyrantel pamoate
What is the distribution of Ancyclostoma braziliense?
Tropical & subtropical regions
What is the life cycle of Ancyclostoma braziliense?
Larvae hatch from eggs in dog/cat feces
What are the risk factors for Ancyclostoma braziliense?
Larvae contaminated sand (Beachgoers or sandbox)
Close contact with dogs/cats
Symptoms of Ancyclostoma braziliense
Cutaneous larval migrans. Scratching it can lead to secondary infection.
50% of individuals develop Loffler’s Syndrome (Migratory pulmonary infiltrates associated with peripheral eosinophilia)
Diagnosis of Ancyclostoma braziliense
“Creeping eruption”
Long red raised pruritic lesion
Pulmonary manifestations
Treatment of Ancyclostoma brazilense
Albendazole Ivermectin Topical Thiabendazole Anti-histamines Antibiotics
What is the life cycle of Toxocara canis?
Eggs eaten by dogs
Who is at risk to get Toxocara canis?
Young children and dog owners
What are the symptoms of Toxocara canis?
Visceral Larva Migrans
Ocular Larva Migrans
Unilateral strabismus. Decreased vision
Will see Granulomatous endophthalmitis on eye exam (white spots in the retina)
Diagnosis of Toxocara canis
Larvae in liver biopsy
Eosinophilic leukocytes
Treatment
Anti-helminthes
Corticosteroids
What is the distribution of Baylisacaris procyonis?
U.S., Europe, Japan
What animal is Baylisacaris procyonis associated with?
Racoons
What are the risk factors for Baylisacaris procyonis?
Anyone around racoons
Symptoms of Baylisacaris procyonis
Similar to Toxocara canis, but more severe
Loss of coordination, muscle control, blindness, coma
Diagnosis of Baylisacaris procyonis
Sensitivity to light on eye exam, inflammation of the eye
Eosinophilic pleocytosis, peripheral eosinophilia
Treatment of Baylisacaris procyonis
None are considered truly effective
Albendazole
What animal is Taenia solium associated with?
Pigs
Symptoms of Taenia solium
Cysterci develop in eyes, muscles, and brain
Diagnosis of Taenia solium
Eggs/proglottids in stool
CT the brain for neurocysticerosis
Treatment for Taenia solium
Albendazole
Praziquantel
What animal is Trichinella spiralis associated with?
Wild game (bear, cougar, boar)
Symptoms of Trichinella spiralis
Eyelid swelling, small hemorrhages beneath the fingernails
Hemoptysis
EKG anomalies
Diagnosis of Trichinella spiralis
Swirls on H&E stain (eosinophilic)
Treatment of Trichinella spiralis
Mebendazole
Albendazole
