helminths Flashcards
- ancylostoma duodenale and necator americanus most common type
- common in most tropical and subtropical regions
- most asymptomatic
- cutaneous larvae migrans –> cough –> GI upset
- rash –> pruritic maculopapular at site of skin penetration “ground itch”
- serpiginous tracks of intracutaneous larval migration can be seen
hookworm
hookworm transmission
- eggs shed in feces
- larval development in soil
- skin penetration
- larvae migration in the body
- continuation of the cycle
hookworm symptoms
- dry cough, wheezing, low fever with larvae migration through lungs
- 1 month later: epigastric pain, diarrhea, anorexia
- large infestations can lead to iron deficiency anemia and protein malnutrition
- impairment in growth and development in children
how to diagnose hookworm
eggs in feces –> ova and parasite test
CBC –> microcytic anemia, eosinophilia
hypoalbuminemia
occult blood in stool
hookworm treatment
albendazole
cestode infection
tapeworm
taenia saginata
beef tapeworm
taenia solium
pork tapeworm
diphyllobothrium latum
fish tapeworm
hymenolepis nana
dwarf tapeworm
taeniasis symptoms
- most asymptomatic
- N/V, anorexia, epigastric pain
- anxiety, HA, dizziness, uriticaria
diphyllobothriasis symptoms
- most asymptomatic
- fatigue, diarrhea, numbness, dizziness
- megaloblastic anemia
- competes with host for absorption of vitamin B12
classical manifestation of infection with D latus
megaloblastic anemia due to vitamin B12 deficiency
hymenolepiasis symptoms
- most common in children (fecal oral hygiene)
- most asymptomatic
- heavy infection –> crampy abd pain, diarrhea, anorexia, weight loss, fatigue
how to diagnose tapeworm
- eggs or proglottids (segment of a tapeworm) in stool (ova and parasite stool)
- multiple stool specimens (2-3)
- macrocytic anemia due to B12 deficiency
tapeworm treatment
noninvasive –> praziquantel
dwarf tapeworm treatment
increased dose of praziquantel and repeat after 1 week
- infection through direct human fecal contamination of food
- ingestion of eggs of T. Solium
- human now acts as the intermediate host
- leads to tissue infection with cysts
tapeworm cystericercosis
- can cause seizures, focal neuro deficits, altered cognition, psych disease
- intracerebral, subarachnoid, spinal cord lesion, or intraventricular cysts
neurocystericercosis
- the most common manifestation include muscle or subcutaneous tissue
- usually asymptomatic nodules 0.5 to 2.0 cm in diameter but may cause discomfort when inflamed
- acute myopathy
extraneural cystericercosis
how to diagnose tapeworm cystericercosis
- neuroimaging findings and evidence of exposure
- CT and MRI: parenchymal cysts, parenchymal calcification
- ELISA and related immunoblot assay: antigen and antibodies
- brain biopsy
tapeworm cystericercosis treatment
- can make neurologic symptoms worse due to inflammation around decaying cyst
- adjunctive steroid therapy
- cyst surgically removed
anti parasitic therapy should not be administered in the following circumstances
- untreated hydrocephalus
- high cyst burden with diffuse cerebral edema
- presence of calcified lesions only
tapeworm neurocystericecosis treatment
- treat for 10-14 days
- albendazole
- praziquantel
- adjunct corticosteroids should be administered prior to and during anti parasitic therapy
tapeworm extraneural cystericercosis treatment
- non steroidal anti inflammatory medication
- excision for symptomatic solitary lesions
- ingesting food contaminated with canine feces containing parasite eggs from tapeworms Echinococcus granulosus and E multilocularis
- forms large cystic lesions usually in liver or lung
- asymptomatic
- cysts can rupture and cause severe allergic reaction with fever and hypotension
- the fluid inside is antigenic and highly toxic and can cause a potentially fatal anaphylactic reaction in humans
tapeworm echinococcosis
tapeworm echinococcosis symptoms
- often incidental finding
- abscesses
- growing mass
- depend on specific organ affected: abdominal pain, chest pain, biliary obstruction, etc
how to diagnose tapeworm echinococcosis
imaging techniques in conjunction with serology
- ultrasound or CT
- large cyst containing daughter cysts
IgG ELISA assay
- confirmatory test
tapeworm echinococcosis treatment
long course of albendazole
enterobiasis
pinworms
- common cause of intestinal infections worldwide
- school age children
- caused ingestion of enterobius vermicularis eggs
pinworm
how does ingestion of pinworm eggs happen
- pinworms lay eggs around the anus of an infected person, usually at night. these eggs cause intense itching, leading the person to scratch the area
- eggs then transfer to the fingers and under the fingernails and my spread to surfaces, toys, bedding, clothing, and other items person touches
- if a person touches a contaminated surface and then puts their fingers in their mouth, they can ingest the eggs, leading to infection
pinworm lifecycle
- eggs hatch in duodenum and larvae move to cecum
- larva mature to adults and establish themselves in the colon
- lifespan of adult is about 2 months
- gravid females migrate nocturnally outside the anus and oviposit while crawling on the perianal area
- those eggs hatch and produce larva in 4-6 hours
pinworm symptoms
- asymptomatic
- most common: perianal pruritis*
- insomnia, restlessness, enuresis common in kids
- impetigo from scratching
- worm burden high –> abd pain, nausea, vomiting
how to diagnose pinworm
- perianal worms or eggs found in skin
- “tape test”: best done at night or first thing in morning prior to bathing
pinworm treatment
albendazole
repeat dose in 2 weeks bc common reinfection
treat close individuals
