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GI First half > parasites > Flashcards

parasites Flashcards

1
Q

all helminths are

A

animals –> metozoans (complex structure, multicellular, and eukaryotic)

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2
Q

helminths 2 phyla

A

playhelminths (cestodes and trematodes) and nematodes

cestodes are tapeworms
trematodes are flukes
nematodes are roundworms

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3
Q

true or false:

  1. helminths live for years
  2. helminths multiply within host
A

1 - true

2 - do NOT multiply in host (a few exceptions); need to leave body to continue lifecycles

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4
Q

fasciolopsis buski is a …

A

trematode (fluke)

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5
Q

trematodes

A

flukes
flat, leaf shaped worms with 2 muscular suckers and a blind loop intestinal tract (regurgitates)
hermaphroditic (except scistosomes)
require intermediate host (snails/clams)

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6
Q

fasciolopsis buski

A

a trematode you acquire by eating encysted larva in aquatic vegetation (like water chestnuts)
develops in small intestine for 3 months –> eggs in stool
*can be asymptomatic OR diarrhea, fever, abd pain, ulcers, and hemorrhage
treat with praziquantel

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7
Q

what parasite encysts in water vegetation (water chestnuts/clams)?

A

fasciolopsis buski (a trematode)

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8
Q

cestodes

A

tapeworms
flat, ribbon like composed of proglottid segments which contain reproductive organs
have suckers with hooks on scolex (head) to attach to intestinal lining
has NO digestive tract – food absorbed through soft body

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9
Q

which cestode does not have hooks to attach to intestines?

A

D. latum

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10
Q

which group contains the taenia?

A

cestodes

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11
Q

taenia lifecycle

A

cystic larvae in striated muscle of animals
cooking meat destroys the cysts so transmission occurs with undercooked meat
you have to ingest the EGGS fo rinfections; tapeworm itself is not infections so ingesting an adult just results in you passing eggs in stool which THEN are infectious for next victim

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12
Q

to be infected by taenia you have to ingest

A

the eggs

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13
Q

taenia solium

A

tapeworm acquired by eating larvae in pork
ingestion of larvae –> adult in intestines
ingestion of eggs in food/water/or self (hand to mouth) –> cysticercosis
after ingestion the oncosphere penetrates intestinal wall, circulates in tissues, and develops into a cysticercus (fluid filled bladder containing the scolex of larval form –> usually head to brain, muscle, and eyes
can cause neurocysticercosis

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14
Q

neurocysticercosis

A

taenia solium eggs were ingested and cysticersi implant in brain
presents with headache, seizure, deficit, death to hydrocephalus
single lesion can resemble cancer –> tissue biopsy is only sure diagnosis
treat with albendazole or praziquantel and corticosteroids

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15
Q

treat cestodes with

A

albendazole
praziquantel
+/- corticosteroids

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16
Q

taenia saginatum

A 
a cestode (tapeworm)
acquire by eating larvae in undercooked beef; few symptoms; can grow to 10 m!!!
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17
Q

diphyllobathrium latum (d latum)

A 
a cestode (tapeworm)
acquire by eating fish larvae
causes B12 deficiency
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18
Q

e granulosus

A 
a cestode (tapeworm)
tiny tapeworm in dog bowel
larvae infect human if they ingest dog poop
worm doesnt grow in humans but can produce eggs/proglottids in stool
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19
Q

can you tell the difference between taenia eggs in feces?

A

no but you can tell difference between proglottid segments

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20
Q

nematodes

A

roundworms
nonsegmented smooth with tapered ends, nonpigmented, with flexible outer coatings (cuticle) and muscular layer underneath
has nervous, digestive, renal, and reproductive organs
under positive pressure (filled with fluid; pressure is >atm)
hydrostatic skeleton for shape and movement

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21
Q

3 ways to transmit nematode round worms

A

eating eggs in fecal contaminated food/water
direct penetration through skin
eating infected food

22
Q

type of nematode that can cause death and mortality?

A

intestinal nematodes

23
Q

intestinal nematodes cause

A

stunted growth, reduced, physical activity, lower cognitive performance and low school attendance in children

24
Q

determinant of nematode symptoms is

A

the number of nematodes

25
Q

three characteristics of pathogenic nematodes

A

Smooth borders, Even shapes with tapered ends, Not pigmented

26
Q

nematode symptoms

A

 GI - Abdominal discomfort, Bloating, diarrhea, perianal itching, Malabsorption
 Pulmonary – Pneumonitis, Transient infiltrates – migrate through the lungs, wheeze
 Skin
• Cutaneous larva migrans  Worms get lost and can’t penetrate the subcutaneous tissue so they just move around until they die or you treat it
• Hives (both hookworm and Strongyloides)IgE reaction to the worm causes generalize allergic reaction when invading into mucosa
 Nutrition/Hematologic - Fatigue due to iron deficiency (hookworm), Vitamin A/Zinc deficiency, & Protein losses

27
Q

cutaneous larva migrans

A

nematode Worms get lost and can’t penetrate the subcutaneous tissue so they just move around until they die or you treat it

28
Q

helminths and poverty

A

a vicious cycle
 Anemia (esp. hookworm)  Reduced work output, Impaired cognitive ability, and Decreased school attendance
 This leads to… poverty – contributes to poor levels of sanitation/education and more helminth infections

29
Q

 Strongyloides and Hookworm lifecycle?

A

SKIN –> LUNGS –> GUT

30
Q

ascaris lifecycle?

A

gut –> liver –> lungs –> gut

31
Q

when ascaris is in lungs it causes

A

igE

pulmonary eosinophilia

32
Q

ascaris

A

most common helminth; largest nematode (up to 40 cm) One female can lay up to 200,000 eggs/day
 Worms will crawl out if the host is anaesthetized or has a fever
 Life Cycle
• Eggs in soil (remain infective for years)  embryonated eggs ingested  larvae hatch and molt in bowel  migrate in the blood to the lungs (PULMONARY EOSINOPHILS – loefflers syndrome) ascend airways to glottis and are swallowed  become adults in GI tract and cause obstruction, malnutrition, infection, can also obstruct biliary/pancreatic ducts  lays up to 200,000 eggs which are pooped out and continue cycle
 Clinical Manifestations
• Most patients: asymptomatic
• GI: abdominal discomfort, Intestinal obstruction, Biliary/pancreatic obstruction (aberrant migration)
• Pulmonary: Löeffler’s syndrome (transient pulmonary infiltrates, dyspnea, dry cough, occasional fever, and eosinophilia)
 Diagnosis
• Will not find eggs until 2-3 months after pulmonary symptoms occur – sputum may have Charcot-Leyden crystals
• After 2-3 months, easy to find eggs since females make 200,000/day
 Treatment
• Pulmonary disease: self-limited
• GI disease: single dose therapy of Mebendazole or Albendazole

33
Q

loeffler syndrome

A

caused by ascaris nematode

transient pulmonary infiltrates, dyspnea, dry cough, occasional fever, and eosinophilia

34
Q

hookworm

A

Sucks blood  A major cause of anemia worldwide (most prevalent in warm/humid areas)
 Infection by one of 2 species: Ancylostoma duodenale and Necator americanus
 Most risk: Children, pregnant/lactating women, women who menstruate heavily
 Life Cycle
• Eggs pooped out and larvae develop in soil  sit on grass  penetrate skin and enter bloodstream  larvae go to heart, lung capillaries, and alveolar spaces  get coughed up and swallowed  mature in the small intestine and can live up to 9 yrs-> eggs pooped and cycle continues

35
Q

Necator americanus

A

Cutting plates
• 0.2-0.4 inches long
• 5-10,000 eggs/day
• Drinks .03 mL/worm/day  Need 25 worms to lose 1 ml blood/day

36
Q

A

Teeth
• 0.3-0.5 inches long
• 10-30,000 eggs/day
• Drinks 0.15 ml/worm/d  5 worms cause 1 ml blood/day loss
• Secrete anticoagulants so more blood is lost

37
Q

which helminth secretes anticoagulant?

A

Ancylostoma duodenale - a hookworm

38
Q

hookworm symptoms

A
  • Abd pain, wheezing, dsypnea, dry cough (usually a few days to weeks after infection)
  • Urticarial rash
  • Fatigue due to iron deficiency anemia (chronic)
  • If sensitized à papulovesicular dermatitis at entry site “ground itch”
  • If worms migrate laterally à cutaneous larvae migrans (especially dog and cat hookworms, as late as 2-8 wks after exposure to A. braziliense)
39
Q

hookworms and pregnancy

A
  • Hookworm anemia in pregnancy causes: IUGR, Low birth weight/Stunting
  • Antenatal antihelminthics increase maternal hemoglobin and Infant birth weight/survival
40
Q

hookworm treatment

A

• Mebendazole x3 or Albendazole once

41
Q

trichuriasis

A

whip worm
 4cm long nematode; both intracellular and extracellular
 Hair-like part contains the head(goes into epithelium); Wider posterior section has reproductive organs(protrudes into GI lumen)
 Eggs take 2-4 weeks in soil to become infective;2-3 months to mature in humans
 Make 0-20,000 eggs/day – Eggs have bipolar plugs.
 Fecal oral lifecycle
• Eggs are ingested, larvae hatch and migrate to caecum where they mature
• Large # worms can cause colitis mimicking IBD– abdominal pain and diarrhea
 Symptoms à
• Usually asymptomatic
• In heavy infections (because adults live primarily in cecum):
o Loose and frequent stools with mucus, Tenesmus (the feeling one has to constantly defecate), blood
o In heavily infected children: rectal prolapse
 Treatment: ivermectin, mebendazole, or albendazole (1-3 days depending on severity)

42
Q

o Strongyloides stercoralis

A

 Has both free living and parasitic forms
 Causes autoinfection/problems in immunosuppressed
 Infection can last decades
 Symptomatic: Diarrhea, abdominal pain, nausea, vomiting
 LARVAE are shed in stool (not eggs)
• RABDITIFORM LARVAE ARE EXCRETED IN STOOL  can either become free living adults, auto infect or become filariform larvae
• Free living produce eggs, rabditiform hatch and become infective filarform larvae  penetrate skin
• Autoinfection: rabditiform larvae in large intestine become filariform larve, penetrate intestinal mucosa or perianal skin and follow infective cycle
• Cycle  filariform larvae enter circulatory system, go to lungs/alveolar spaces  coughed and swallowed into small intestine to become adults  adult female deposits eggs in intestinal mucosa  hatch and migrate to lumen as rabditiform larvae  excreted or autoinfection

43
Q

 Strongyloides Hyperinfection syndrome

A

• Immunocompromised state
• Large burden of parasites
• GI: Nausea, vomiting, abd. pain, diarrhea, many erosions due to millions of larvae in intestinal mucosa
• Pulmonary: diffuse infiltrates, wheezing, dyspnea, cough with hemorrhage, pneumonitis, and edema
• Neurologic: gram negative polymicrobial meningitis
• Systemic: fever, hypotension àgram negative sepsis
 Clinical clues – abdominal discomfort, wheezing, eosinophilia
 Diagnosis
• Stool o/p isn’t good due to : low worm burden, low/irregular egg production, and uneven distribution
• So…multiple stools on multiple days (time from infection to shedding of larvae is 3-5 weeks)
• Examination for larvae on duodenal aspirate via endoscopy
 Treatment  Ivermectin, Albendazole, or Thiabendazole

44
Q

nematode from eating raw freshwater fish in se asia

A

o Paracapillaries (Capillaria) philippinens –

45
Q

o Paracapillaries (Capillaria) philippinens –

A

 Like Strongyloides, can autoinfect
 Symptoms:
• Often initially asymptomatic  watery diarrhea, abdominal pain, and often death
• Over time develop: Borborygmus, Abdominal pain, Watery diarrhea
 If not treated over weeks to months get large electrolyte losses and dehydration which can lead to death
 Pathogenesis:
• Eat infected raw fish
• Larvae released into intestine  Grow to adults which burrow in mucosa
• Female worms lay eggs (oviparous); Some female worms are larviparous  into stool
• Some larvae burrow into the intestinal lining and develop into adults
• Over time the worm burden increases (from a few to thousands) and symptoms progress
 Diagnosis: stool o/p (eggs similar to Trichuris)
 Treatment: 10 d course albendazole + supportive Rx (IVF, replete electrolytes, etc.)

46
Q

helminth prevalent most in temperate areas

A

o Pinworm (Enterobius vermicularis)

47
Q

o Pinworm (Enterobius vermicularis)

A

common in TEMPERATE areas
 Kids>adults; causes peri-anal ITCHING
 Humans are the only host –> fecal/oral transmission
 Diagnosis  early am, before showering or defecating, ”Scotch tape test” tape side down on slide
• Stool O/Ps not very helpful
 Treatment = Mebendazole, pyrantel pamoate, or ivermectin
• Treat all members of households and repeat in two weeks to prevent reinfection
• Careful trimming of fingernails, handwashing, washing of bedclothes to rid house of eggs

48
Q

• Polyparasitism

A

o In areas where helminth infections are common, usually people are infected with MULTIPLE helminth species

49
Q

signs indicating you to consider intestinal nematodes

A

o Consider in cases of unexplained abdominal pain, nutritional deficiencies, rash, or eosinophilia in immigrant or traveler.

50
Q

diagnostic plan for nematodes

A

stool O&P (OVA & PARASITE) x 3 , plus Strongyloides serology
o Would empirically treat immigrants (and long-term travelers) with ivermectin prior to immunosuppression to prevent possibility of Strongyloides hyperinfetion.

51
Q

nonsegmented roundworms?

A

nematodes

GI First half (8 decks)

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