export_gi roundworms parasites ii Flashcards
Enterobius vermicularis
Pinworm
Most common helminthic infection in the U.S.
Geohelminths, two groups
Nematode infection acquired via infected soil
Ingestion of infectious eggs OR penetration of skin by infectious larvae
Which geohelminth infections are the result of ingesting infectious eggs?
Ascaris
Trichuris
Which geohelminth infections are the result of penetration of the skin by larvae?
Strongyloides
Hookworms
Enterobius vermicularis life cycle
Eggs on perianal folds, fecal-oral transmission, embryonated infective egg stage, eggs hatch in small intestine and larvae migrate to large intestine, penetrate into mucosa and mature into adults, females lay eggs in perianal region
Pinworm infection transmission from other reservoirs (pigs, etc.)
Does NOT occur; pinworms from animals cannot infect humans
Symptoms and diagnosis of enterobius vermicularis infection
Perianal itching
Secondary bacterial infection
Identification of eggs
Enterobius vermicularis treatment
Anti-helminthic compounds, two treatments (second one ~2 weeks later)
Treat ALL household members
Trichuris trichiura disease
Whipworm
Trichuris trichiura life cycle
Excretion of one-cell eggs, cleavage in external environment (3 weeks), ingestion of infective stage egg, eggs hatch in small intestine, migrate to large intestine and penetrate mucosa, adults in cecum, female starts laying eggs after ~3 months
Symptoms of Trichuris trichiura
Heavy worm burden (>200 worms)
Dysentery
Rectal prolapse in children
Trichuris trichiura diagnosis
Identification of eggs in stool
Ascaris lumbricoides disease
Ascariasis
Ascaris lumbricoides life cycle
Excretion of fertilized one-cell egg, cleavage in external environment (10-14 days), ingestion of infective stage eggs, into circulation (lungs), adults in small intestine, egg production in 60-75 days
Ascariasis symptoms
Range from abdominal discomfort to death (rare)
Indigestion, loss of appetite, vomiting, diarrhea, heavy infections can result in physical obstruction
Ascariasis pulmonary disease
Pneumonitis, asthmatic attack, eosinophilia
Ascaris lumbricoides diagnosis
Eggs in stool, larvae in sputum
Necator americanus disease
Hookworm
Ancylostoma duodenale disease
Hookworm
Hookworm life cycle
Excretion of egg, hatches in soil, penetrates skin, travels via circulation to lungs and is swallowed as it travels up to pharynx, adults attach to small intestine, lay eggs
Hookworm symptoms
Iron-deficiency anemia
Protein malnourished
Moderate dermatitis from penetration of the skin
Pneumonia and eosinophilia in the lungs
Hookworm diagnosis
Examine eggs in stool
Examination of adult worms or larvae necessary to distinguish between Necator and Ancylostoma
Strongyloides stercoralis disease
Strongyloidiasis
Unique feature of Strongyloides stercoralis
Free-living
Can multiply in the host and in the environment
Strongyloides stercoralis transmission
Penetration of skin by infectious larvae
Auto-infection can occur, as infectious larvae can penetrate the intestine, enter the bloodstream, and re-initiate infection
Symptoms of strongyloidiasis
Epigastric pain, tenderness, bloating, heartburn
Pulmonary inflammation
Hyperinfection if immune system fails to get rid of it, worsens symptoms, can become disseminated (most common in immunosuppressed)
Diagnose Strongyloides stercoralis
Detection of LARVAE in stool
Enterobius vermicularis eggs
Flat on one side
Trichuris trichiura eggs
Lemon/barrel
Ascaris lumbricoides eggs
Lumpy, bumpy
Hookworm eggs
Boring/plain
