T2 - Micro - Parasites 6 - Larva Migrans And Strongylodiasis And Trichinella

Front 1

what kinds of larva migrans are there? what causes them?

Back 1

these are conditions, not bugs.

cutaneous larva migrans (dog hookworm)

visceral larva migrans (dog roundworm)

ocular larva migrans (dog roundworm)

are all possible outcomes.

generally, all are caused by NEMATODE PARASITES of OTHER animals - they can invade people, but it's a dead end and they can't manage to make it to adulthood and sexually reproduce. Think dog/cat hookworms.

Front 2

what causes cutaneous larva migrans? therapy?

Back 2

dog hookworm called Ancyclostoma brazilinesis (remember that human hookworms are ancyclostoma doudenale and necator americanus.

Filaform larvae penetrate human skin. They eventually die, but it can take awhile - so as it moves, it causes PURITIC SERPINGIOUS intracutaneous lesions.

treat with oral ivermectin.

Front 3

visceral larval migrans? big symptoms and test giveaway? Who gets it?

Back 3

Roundworm from dogs this time - called Toxacara canis.

eat the eggs and they hatch AND WANDER EVERYWHERE - can get organomegaly, eosinophilic granulomas. Kids eating dirt are most at risk.

see HUGE eosinophelia - like more than 50% of the white blood cells in visceral larva migrans. Can be fatal.

need to treat the worms AND give cortiosteroids - the immune response can be fatal itself.

Front 4

Ocular larva migrans? cause? mistaken for? pathogenesis? how can you tell between this and what it's mistaken for? treatment?

Back 4

Caused by the same thing that causes visceral larva migrans (Toxacara canis).

Single larvae in the EYE. Maybe cause blindness is possible.

OFTEN MISTAKEN FOR RETINOBLASTOMA - hopefully the age of the kid gives it away. RB presents really early in life, whereas ocular larva migrans shows up between ages 3 and 13.

treat same way as visceral - also use lasers to remove the guy from the eye.

Front 5

Strongylodies - where is it found?

Back 5

all over, still in the US because it's hard to kill off completely.

Front 6

Life cycle of strongylodies - why is it hard to get rid of?

Back 6

Infected females sit in the SMALL INTESTINE.

Makes lots of eggs that DEPOSIT INTO THE EPITHELIUM.

they hatch into the L1 (rhabditiform) stage. Here, there's divertent paths:

can pass out into poop, and then either immediately develop into infectious L3 (filiraform) and get infectious within a day or two - here, behave like hookworms, break skin, end up in lungs, cough, swallow, infect another.

Or in the poop, it can develop into free-living adult males and females, live out in the environment making either L3's or more of themselves.

OR, instead of passing out in poop, they can turn into the L3 form in the gut and re-enter host.

THIS MAKES THEM AUTO-INFECTIOUS. You can be perpetually infected! Complete life cycle in one person.

Front 7

what are some typical pathologies?

Back 7

Larva currens around the anus from getting re-infected. happens a lot.

some pulmonary symptoms - this can be constant due to re-infection.

if light infection, not much - can get diarrheas and bloating and nausea, maybe malabsorption if big burden.

BUT CAN GET HYPERINFECTION/DISSEMINATION

Front 8

talk about hyperinfection/dissemination of the strongylodies - what causes it? risk factors? what's not a risk factor?

Back 8

uncontrolled autoinfection.

due to messed up host regulation and messed up parasite self-regulation.

get massive worm burden and INFECTION ALL OVER THE BODY.

seems like immunosuppression can lead to it - ESPECIALLY CORTIOSTEROID use (also post-transplant).

AIDS doesn't cause it, until very very late in infection - remember that HIV patients have diminished TH1 response from dead CD4 cells, but that EOSINOPHILS are part of the TH2 response.

Front 9

symptoms of disseminated/hyperinfection? Talk about eosinophils here.

Back 9

SUPER sick.

Bad intestinal problems.

Pulmonary bed infection = big lung problems.

CNS also infected.

Don't forget SECONDARY infections - usually gram negative bacteremia and MENINGITIS.

Remember that eosinophils keep the worm in check - but bacteremia shifts response to TH1, so you DON'T GET EOSINOPHIL response to fight off the worms. More worried about bacteria, I guess.

Front 10

what are risk factors for original infection? how can this differ from normal hookworms?

Back 10

again, it acts like a hookworm for the primary infection - so night soil and no shoes are not helpful. Recall that the bug can live as L1's out in the enviornment for years without needing to infect a host.

because it can become L3 really fast, PERSON TO PERSON contact can spread it.

Front 11

Diagnosis of strongylodies? what do you see in poop? treatment?

Back 11

remember that eggs aren't pooped out - maybe see larvae in poop.

need to do the STRING TEST probably.

if hyperinfected, pull it out of sputem or anywhere else.

ALSO SEROLOGY is pretty effective.

treat with albendazole and ivermectin.

Don't forget to evaluate possible infection BEFORE TRANSPLANTATION.

Front 12

Trichinella infection - which hosts are the intermediate and which are the definitive hosts for trichinella?

Back 12

both in the same host- can sexually reproduce in people or other animals, then become dead ended in the same animal.

Front 13

go through the life cycle of trichinella now.

Back 13

this is what you get from bad pork, so think about spores left in muscles.

males and females meet and make babies, the females MAKE LARVAE, no eggs.

Larvae penetrate/burrow out of gut, end up in blood/lymphatics, float all over body.

They burrow into muscles, go dormant for years (make "nurse cells" from muscles.) some die/calcify.

need to be eaten for cycle to continue.

released by acid of predator, begin all over again.

Front 14

talk about the pathology of trichinella infection - how do some people die?

Back 14

acute infection (first time) looks like normal food poisoning, then subsides.

next, get larval stage - as the larvae break out and go everywhere, know ORBITAL EDEMA/generalized edema.

disease from cell death (wandering larvae kill cells) and massive immune response

if lots of worms, can get myocarditis, encephalitis, pneumonitis.

massive eosinophelia.

Front 15

how do you diagnose? Treat? Control?

Back 15

need to eat undercooked meat - mostly reserved to non-store meat.

history of acute food poisoning. high eosinophelia.

Serology and muscle biopsy after 2 weeks to confirm.

Treat with steroids to stop inflammation, mebendazole, albendazole

can kill off most species of trichinella by FREEZING meet and proper cooking.
keep meat products out of animal feed and this would stop.