tissue invasive nematodes Flashcards
what are filariae?
threatlike, tissue invasive roundworms transmitted by insect vectors
what did patrick manson do?
demonstrated that mosquitoes transmit filariae (first demonstration that mosquitoes can harbor infectious disease)
filarial infection local to.. 1) tropics worldwide? 2) asia? 3) africa/americas? 4) africa?
1) wuchereria bancrofti 2) brugia species 3) onchocerca volvulus (river blindness) 4) loa loa (crawls across eye)
what filarial parasite is endemic to the US?
heartworm (dirofilaria immitis) infects dogs!
general life cycle of filarial parasites
microfilarial stage L1 increase in size to infectious stage L3 enters human not through saliva like malaria but through biting parts L3 stage enters lymphatics molt to adults (thin and long) mate and make microfilaria again
lymphatic filariasis 2 causative agents? vector? location of adults? of microfilaria?
wuchereria bancrofti and brugia malayi mosquitoes (lots of species) adults in lymphatics, microfilaria in blood (increased at night)
loa loa causative agents? vector? location of adults? of microfilaria?
loa loa eye worm chrysops flies adults in SQ tissues (moving around) microfilaria in blood (daytime)
river blindness causative agent? vector? location of adults? of microfilaria?
onchocerciasis blackflies adults in SQ tissues (nodules) microfilaria in skin
treatment of 1) lymphatic filariasis 2) loa loa 3) onchocerciasis
1) DEC (diethylcarbamazine) 2) DEC (but contraindicated if the microfilaria level is super high –> inflammatory response would be too high and cause death) 3) ivermectin (DO NOT USE DEC)
adverse effect if DEC is used in loa with high microfilaremia
encephalopathy and death due to high inflammatory reaction
adverse effect if you try to treat onchocerciasis with DEC?
severe skin inflammation (microfilaria in skin) and blindness (microfilaria in cornea)
lymphatic filariasis presentation
asymptomatic or lymphangitis and lymphatic obstruction distal lymphedema (scrotal hydrocele and elephantiasis of legs) retrograte lymphangitis dermatolymphangioadenitis (bacterial/soft tissue infections)
tropical pulmonary eosinophilia
due to excessive immuine response to microfilaria in lung vasculature; complication of filariasis causes paroxysmal nocturnal asthma, pulmonary infiltrates, peripheral blood eos (>3000), elevated IgE in serum, high filarial antibody titers rapid response to anti-filarial therapy
lymphatic filariasis diagnosis
microfilaria in nighttime blood circulating antigen test in blood filaria dance sign on ultrasound positive for antibodies
microfilaria peak at midnight indicates
lymphatic filariasis
onchocerciasis caused by? vector? disease? transmission/lifecycle? symptoms?
caused by Onchocerca volvulus vector = black flies (simulium species) – mate near rivers a chronic, progressive disease called RIVER BLINDNESS high morbidity: eye, skin, lymphatic disease adult worms in SQ nodules; microfilaria in skin males are small, females are up to 80 cm! –> males travel between nodules inseminating females symptoms: nodules, dermatitis, itchy, eye disease (punctate keratitis = crawl across eye and leave scar) can cause sclerosing keratitis and blindness, hanging groin (boggy LNs)
ivermectin drug mechanism
hydrogenated form of avermectin opens gated-chloride channels that are only in susceptible helminths and arthropods.(doesnt hurt us!) This causes influx of chloride ions, hyperpolarization of cells, and paralysis. Also interact with GABA receptors use for strongyloides and onchocerca volvulus microfilaricidal BUT doesnt kill adult worms - continue treatment for 10-15 years
what can be targeted in adult onchocerca worms?
wolbachia bacteria are needed inside them add doxycycline to ivermectin
loiasis (loa loa)
Vector: Chrysops spp. (deerfly) Host: human Microfilariae: blood-borne in DAYTIME Adult worms: subcutaneous tissue symptoms: non specific (fatigue, urticaria, arthralgias, myalgias), calabar swellings (transient, hard and migratory swelling), and eyeworm worm in eye DOES NOT CAUSE BLINDNESS
loa loa treatment
DEC unless mf level is >2500
angiostrongylus cantonensis
rat lungworm; found in SE asia (thailand, malaysia) and hawaii caused by ingestion of parasites in snail or slugs (vegetables) or paratenic hosts (prawns, crabs) in humans, cause eosinophilic meningitis (go to CNS) symptoms = headache, paresthesias, neck stiffness, photophobia CSF eosinophilia and elevated protein (glucose normal or low)
trichinellosis
trichinellosis
T spiralis and T nelsoni
Eat meat containing cysts (pork, boar, horse, wild game) –> Larvae are released from cysts by gastric acid.
Adults invade sm. bowel and mature into adults over 1-2wks –> ABDOMINAL CRAMPS,
DIARRHEA IF HEAVY INFXN
Adults (who only live for about a month) make larvae –> Larvae migrate to striated mm, encyst, and live in “nurse cells”
–>MUSCLE PAIN
PERIORBITAL EDEMA
EOSINOPHILIA
OCC CNS AND HEART DAMAGE
ddx with muscle biopsy showing L1 larvae
treatment for trichinellosis
frequent natural recovery
analgesics, antipyretics, and prednisone
specific Rx with mebendazole, albendazole, or thiabendazole for intestinal and muscle stages in heavy infxns
toxocariasis
Caused by dog (Toxocara canis) and cat (Toxocara catis) ascarids –> ingestion of eggs in dog or cat feces
larvae hatch in intestine and go to liver, spleen, lungs, brain, and/or eye.
Symptoms
——Visceral Larva Migrans (VLM) = 2-5 year olds with fever, eosinophilia, hepatomegaly and also wheezing, pneumonia, splenomegaly
—— Ocular Larva Migrans (OLM) = often in 10-15 year olds with retinal lesions that appear as solid tumors, often near the macula
anisakis simplex
Acquired by ingestion of raw or undercooked seafood
In humans, parasite buries its head into gastric mucosa
— since not the right host, worm eventually dies
—-can penetrate mucosa and cause intraabdominal abscess
Symptoms
1) due to invasion of worm (pain, vomiting)
2) due to allergic rxn to worm
(mild urticaria, itchy throat, anaphylactic shock)
Treatment= endoscopic removal
blood microfilaria at night?
lymphatic filariasis
SQ nodules or skin microfilaria?
onchocerca volvulus
blood microfilaria during day?
loa loa
muscle pain + eosinophila?
trichinella
eosinophilic meningitis?
angiostrongylus
abd pain after sushi?
anisakis
eosinophilia + fever + elevated liver enzymes in child?
visceral larva migrans
