General

Question 1

Where do adult enterobius vermicularis live?

Answer 1

In the cecum (7-13 weeks) emerging nocturnally (eggs need O2 4-6 h to mature)

Question 2

Where do trichuris trichiura adults live?

What is the life cycle

Answer 2

eggs mature in soil after being pooped out (over 2-4 weeks) then ingest eggs and larva invade crypts of intestinal mucosa, mature over 3 months
adults live in cecum, colon.

Question 3

Symptoms of Trichuris Trichura

Tx?

Answer 3

growth retardation, diarrhea, anemia, rectal prolapse, appendicitis
Tx: mebendazole better than others, but hard to treat/not great at treating but not better with anything else

Question 4

Life cycle of Ascaris Lumbricoides?

Answer 4

Eggs mature and fertilize in soil over 2 weeks, we ingest embryonated eggs, eggs hatch in bowel, larva migrate via blood to lungs then ascend airways and are swallowed where they mature into adults (living 1-2 years)

Stool exam may be negative in early stages

Question 5

Symptoms of ascaris lumbricoides?

Answer 5

Loefflers syndrome - pulm eosinophilia
occasional intestinal obstruction, malnutrition with heavy infection or single worms may migrate to obstruct biliary or pancreatic ducts (** Cause of biliary obstruction)

Question 6

Ancyclostoma duodenale, Necator americanus Lifecycle?

Answer 6

Eggs from stool into SOIL develop into rhabditiform larvae 7-10 days then into filariform larva which PENETRATE SKIN (ancyclostoma gut). Filariaform larva migrate via blood to lungs ascend airways and are swallowed. adults live 1-9 years in bowel taking blood

Question 7

Symptoms of hookworm?

Treatment?

Answer 7

Eosinophilia, Abdominal pain in acute stage, anemia in chronic stage (adults also secrete a/c)
single dose mebendazole (is available as powder/dissolvable for kids; doesn’t work super well), multi day ABZ is most effective
all drugs don’t get immature larva (of all intestinal helminths). So have to wait until all the immature larva become adults –> wait 6 weeks then treat.

Question 8

Piperazine used to?

Answer 8

Paralyze ASCARIS with biliary obstruction, works well and very cheap (not in US/Europe)

Question 9

What is visceral larva migrans

Answer 9

toxocara canis

Question 10

Life cycle Toxocara canis or cati?

Visceral larva migrans

Answer 10

puppies/dogs poop eggs, cleave in SOIL -> dog eats or we eat, larva hatch in bowel and migrate through blood to liver/spleen/lungs (eosinophilia, hepatosplenomegaly and fever with heavy infxn) or eye (retinal granuloma)

Question 11

Symptoms of toxocara canis/cati (visceral larva migrans)

Tx?

Answer 11

MC asx with eosinophilia. (worldwide temperate/tropical), kids with puppy/soil contact
migration can cause abd pain, resp sx, hepatomegaly, fever, ocular presentation would cause uveitis, retinitis
Tx? DEC (not available in developing) or ABZ (no evidence but only option)
ocular - steroids

Question 12

Trichinella Spiralis (not in south america)

Answer 12

eat undercooked pork, boar, bear, horse with cysts -> release larva in SI (causing mild cramping/diarrhea 1-2 weeks– need to tx now) then larva migrate to striated muscle and reside in “nurse cells” and encyst –> muscle pain, fever, periorbital edema, eosinophilia, occasional CNS/cardiac damage.

Question 13

Trichinella spiralis dx and tx?

Answer 13

ab can be detected only 3 weeks after infection. PCR. may see high ESR, CK, LDH
Tx with ABZ/MBZ/TBZ only work against gut larva NOT tissue larva so only useful early in disease

Question 14

Strongyloides presentation

Answer 14

In immunocompetent - asx or min sx
Acute - larva currens associated w/ autoinfection, allergic rxn to filariaform larvae (several days/recurrent)
loeffler syndrome in acute

Chronic - indigestion/abd pain/diarrhea w/ malabsorption, weight loss, ulcerations, duodenal edema, eosinophilia, increased IgE

Beware of hyperinfection (steroids/HTLV1) - worse sx - abd pain/d/c, obstruction, protein loosing eneteropathy, gi bleed, hemorrhagic pneumonitis, larva may transport gut bacteria into blood -> sepsis+/- meningitis

Question 15

Strongy dx

Answer 15

NO gold standard
with chronic infections, low egg excretion, need mult stool testing
direct exam - very poor Ss (30-50%)
by request - Baermann method on 3+ stools exams to increase Ss (operator dependent)
**culture is most Ss (5-7 days, laborious and $$) - in the presence of larva, bacteria grows on the larva tracts
** Serology for ab - doesn’t distinguish btw past/current infxn, cross reacts w/ other helminths. Ss 80-90%, Sp 95-98%
** PCR of stool - very Ss but takes long time and is very $$ (not used in endemic areas)

Question 16

Strongyloides Stercoralis Treatment?

Answer 16

ivermectin 200ug/kg PO, repeat dose 2 weeks apart (if IC needs second course)
ALT: tiabendazole 25mg/kg BID x 3 days, or ABZ 10mg/kg/d PO x 3 days (lower efficacy)