helminths Flashcards
What are the filarial nematodes (these are round worms belonging to superfamily Filarioidea, filarial means threadlike)
- most times they dont X in humans or produce dz, inflm actions are to blame (ex. schistosome eggs –> granulomatous response)
- lymphatic filariasis / “elephantiasis”/ Wuchereria bancrofti
- Onchocerciasis / “river blindness” / Onchocerca volvulus
- Loiasis / loa loa, african eyeworm
what are roundworms, flatworms, tapeworms in fancy name?
EOSINOPHILS
roundworms = nematodes
flatworms = trematodes
tapeworms = cestodes (no GI tract, diffusion)
- lymphatic filariasis / elephantiasis / wuchereria bancrofti
- common by worm Wuchereria bancrofti, less common by worm Brugia malayi. endemic areas have ab’s.
- humans get it from mosq bites (cutex, aedes, anopheles, mansoria)
- invades LYMPHATICS –> lymphangitis and lymph obst –> edema –> chronic inf –> scarring –> elephantiasis
- most freq: inguinal, testis, epididymis, epitrochlear and axillary LNs.
occult filariasis (indirect evidence of filarial inf (ab’s) –> tropical pul eosinophilia. range from fatal pna–> mild asthma)
- Onchocerciasis / “river blindness”
- caused by onchocerca volvulus
- adult worms like deep fasciae and subcut–> release babies that travel to eyes, skin, lymphatics.
- eyes –> sclerosing keratitis, iridocyclitis, optic atrophy, chorioretinitis.
- skin –> onchocercal nodules (adult worms encapped by fibrous scar)
- when the worms die –> inflm responses –> destruction of structures
Sx: SKIN PRURITIS (traveling), ELEPHANTIASIS, BLINDNESS/VISION LOSS
TX: ANTIHELM THERAPY
- Loiasis
- caused by loa loa, african eyeworm
- inf transmitted by mangoflies
- adult worms migrate in skin and occasionally crosses eye beneath conjunctiva, gravid (preggo) worm releases microfilariae (babies), babies like blood in AM, skin lungs organs in PM
SX: mostly Asx, but can persist for yrs.
- some have “Calabar” swellings (red, pruritic subcut)
- eyelid swelling, itching, pain
- dead worms near nerves –> paralysis/paresthesia
TX: microfilariacides –> massive death of worms –> fever, meningoencephalitis –> death
what are the intestinal nematodes?
Sx occurs when inc #worms, or in IC,
-endemic in tropics, dec hygiene areas
-eggs/larvae passed in stools
- ascariasis
- trichuriasis/whipworm
- hookworms
- strongyloidiasis/threadworm
- pinworm infections
- ascariasis (ascaris lumbricoides)
- most common worm infection (1mil pp), usually Asx.
-ingest egg and hatch in SI –> penetrate bowel wall and go to lungs (may cause Ascaria pna if high ## of larvae) –> venous circ –> alv -> trachea -> swallowed and goes to SI to mature and live for 1-2yrs.
-If inc # –> intestinal obst –> VOMITING, MALNUTRITION, PANCREATITIS, CHOLANGITIS, LIVER ABSCESS .
TX: ASCARICIDAL DRUGS
- TRICHURIASIS / whipworm
- caused by whipworm Trichuris trichiura
- superficial invasive infection of LI
- susceptible: CHILDREN, (fecal-oral)
- ingest egg-> larvae hatch in SI and migrate to cecum and colon –> BURROWS into superficial mucosa
SX: weight loss, cramping abd pain, BLOODY diarrhea, anemia
TX: MEBENDAZOLE
- hookworms
- caused by necator americanus, ancylostoma duodenale
- larvae penetrates SKIN (pruritic eruption - ‘Ground itch”) –> venous cir–> lungs –> alv –> trachea –> swallowed –> hooks onto duodenum and molts.
-causes blood loss –> anemia
no Sx usually, but the MOST COMMON CAUSE of CHRONIC ANEMIA worldwide (also iron-def anemia too)
- Strongyloidiasis
-caused by threadworm called Strongyloides stercoralis in warm and poor sanitation areas (mental hospitals)
- mostly Asx with moderate eosinophilia, can cause disseminated dz/hyperinfection Sd (esp in ppl with steroid therapy)
- disseminated: gut ulceration, edema, severe inflm, sepsis (IO w. gram -), FATAL UNTX, 30% survive w. thiabendzole or ivermectin
- female lives in SI mucosa, lays eggs and hatch –> release rhabditiform larvae –> feces –> becomes filariform in soil (infectious)
- -> penetrates skin –> blood to lungs –> small bowl (similar to hookworms) –> mature and unlike other intestinal nematodes, it can reproduce via AUTOINFECTION (when larvae becomes filariform within intestine and repenetrate intestinal wall or perianal skin (therefore new cycle within 1 host)
- pinworm
- caused by enterobius vermicularis
- SX: PERIANAL PRURITIS (mig worms depositing eggs)
- most in temperate zones and common in young kilds
- adult female worm lives in cecum and appendix -migrate-> perianal and perineal skin to deposit eggs ITCHY
- eggs stick to fingers, linens, towels, clothing. if ingested, hatch in SI and mature
what are the tissue nematodes?
- trichinosis (trichinella spiralis)
- visceral larva migrans / toxocariasis (toxocara canis and t. catis)
- cutaneous larva migrans (“creeping eruption”)
- Dracunculiasis / guinea worm (Dracunculus medinensis)
- trichinosis
-caused by trichinella spiralis
-when animals eat infected meat and then we eat uncooked/infected PORK
SX: MYOSITIS (diaphragm, heart (myocarditis), extraocular mm, tongue: in IC: mm, CNS –> MENINGOENCEPHALITIS
usually Asx, some extremes: 50% eosinophilia, periorbital edema, if brain/heart –> fatal. TX corticosteroids and antihelm
worm (f+m) burrows into intestinal mucosa–> female releases larvae that travels to skeletal mm.(inflm, eosinophils and macrophages) may encyst and survive and form capsule. years later, die and calcify.
- visceral larva migrans / toxocariasis
- caused by toxocara canis and T. catis sporadically, usually with young kids in overcrowded areas and living with dogs and cats
- mostly Asx, but in Sx: hypereosinophilia, pneumonitis, hypergammaglobinemia,, toxocaral endophthalmitis (mistaken for RB). (all the ‘itis’ –> granulomas–>scarring) self limiting, lasts for 1year. TX: diethylcarbamazine, thiabendazole
- ingestion of embryonated ova–> human SI –> hatch and larvae invade intestine wall –> liver –> sys circulation (some)–> body
- cutaneous larva migrans = creeping eruption
aka sandworm, plumber’s itch, dunk hunter’s itch, epidermis linearis migrins (common in plumbers, animal caretakers
-SX: pruritic eruption, when larval nematodes migrate through skin –> provokes inflm that appears as serpiginous urticarial trials
TX: thiabendazole
-cause: strong. stercoralis, ancylostoma braziliensis, necator americanus: MAJOR SOURCE: CATS AND DOGS INFECTED WITH HOOKWORM
- Dracunculiasis/guinea worm
- caused by dracunculus medinensis (twists into stick)
- common in areas of Af, middle E, india, pakistan
- transmitted in drinking water contaminated w. crustacean of genus cyclops, live in sc tissue and CT and release larvae thru ulcerated blister. when blister gets in contact with water again, it releases larvea thats eaten by cyclops.
Sx: 1 year after ingestion –> systemic allergic sx: PRURITIC URTICARIAL RASH, reddish papule develops and vesiculates –> water–> release larvae and female worm partially emerges
- if secondary inf of blister –> spreading cellulitis
- if worm dies –> intense inflm response.
