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
