5_Helminthes 2 Flashcards

1
Q

Nematodes (Round worms):

characteristics

A
  • cylindrical
  • structure
    • body wall composed of outer cuticle, thin hypodermis, and musculature
    • tubular intestine w/ excretory gland
  • sexual reproduction: testes & ovaries; copulation is necessary for fertilization
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2
Q

pathogenesis of Nematodes

A
  1. diseases are caused by direct damage from worm activity and immune rxn to them
  2. large worms can physically block the intestine
  3. Infxn is related to the # adn the infective stages encountered
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3
Q

how do humans respond to infxn by Nematodes?

A
  • children are more susceptible than adults
  • waning of immune competence w/ age increases infxn
  • Immunosuppressive therapies may inc. susceptibility
  • immune defense thru production of IgE and action of mast cells and eosinophils
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4
Q

what are the common nematodes to know?

A
  • Pinworm (Enterobius cermicularis)
  • Trichinella (Trichinella spiralis)
  • Toxocariasis (Toxocara canis, Toxocara cati)
  • Whipworm (Trichuris trichura)
  • Ascariasis (Ascaris lumbricoides)
  • Hookworm (Necator ameicanus, Ancylostoma duodenale)
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5
Q

lifecycle for Enterobius vermicularis (Pinworm)

A
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6
Q

life cycle of Trichinella spiralis

A
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7
Q

name 2 worm infxns that one can contract by eating undercooked pork?

A

Taenea (tapeworm) and Trichinellosis

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8
Q

which two species cause Toxocariasis,

and which animal causes it?

A
  • Toxocara canis from dogs
  • Toxocara cati from cats (less common)
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9
Q

Life cycle of:

Toxocara species

A
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10
Q

the eyes are affected by which worm infections?

A
  • Toxocariasis - granuloma, ocular larva migrans
  • Trichinella spiralis - swelling
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11
Q

Which worm can cause splinter hemorrhages of the fingernails , or a cough?

A

Trichinella spiralis worm movement

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12
Q

life cycle and transmission:

Trichuris trichiura

A
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13
Q

life cycle of:

Ascaris lumbricoides

A
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14
Q

which of the following nematode (round worms) infect w/in the GI tract only?

  1. Pinworms
  2. Whipworms
  3. Trichinellosis
  4. Ascariasis
A

Pinworms, and Whipworms

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15
Q

Where do adult Schistosoma mansoni reside and is it in a round worm?

A

Veins that drain the intestine

S. mansoni is a type of flatworm (*NOT a roundworm)

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16
Q

Hookworm infection:

causal agents,

how frequent?

transmission?

A
  • causal agents:
    • Necator americanus - predominates in the Americas (north, central, and south america) and australia
    • Acylostoma duodenale - occurs in the middle east , southern europe, and north america
  • 2nd most common human worm infection
  • transmssion: soil-transmitted helminth (STH) - often occur in areas where human feces are used as fertilizer, or where degacation onto soil happens
17
Q

Life cycle of Hook worm

18
Q

Hookworm:

presentation

A
  • infxn is not common in adults
  • cutaneous larva migrans - red, intensely pruruitic (itchy), very painful, creeping eruption, ambiguously known as “ground itch”
    • usually heals spontaneously over wks to months
    • scratched may allow a secondary bacterial infxn to develop
19
Q

High intensity Hookworm:

affects which groups?

which symptoms?

A
  • *High intensity hookworm infxns: occur in school-age children
  • Sxs: development of anemia & protein deficiency caused by blood loss @ site of intestinal attachment
    • When continuously infected by many worms, children have loss of iron and protein, can lead to retarded growth and mental development
20
Q

Zoonotic hookworms?

key characteristics

A
  • Common in puppies/kittens, esp in areas w/ wamrer climates
  • Causal agents: Ancylostoma braziliense, A. caninum, A. tubaeforme
  • Transmitted in dog & cat feces, w/ warm, moist conditions hatch into larvae after several days
    • larvae of dog hookworms –> can infect people
    • larvae penetrate skin while people walk barefoot, or w/ exposed skin contact w/ contaminated soil/sand
    • larvae –> cutaneous larval migrans –> which don’t usually develop into adult hookworms in people –> larvae will die in the skin after several weeks w/o developing any further
      *
21
Q

Strongyloidiasis:

  1. etiologic agent, hx
  2. transmission
A
  1. causal agent: Stronglyoides stercoralis –> described in French troops stationed in Vietnam during the late 19th century
  2. Transmission: thru exposed skin, e.g. barefeet
22
Q

Strongyloidiasis:

typical manifestation

A
  • Manifestation: most infected people remain asymptomatic/undiagnosed
  • Larva currens: intensely itchy creeping raised rash, also known as ground itch
    • Allergic response to migrating filariform larvae
    • Appears recurrently along the thighs and buttocks, the site of skin penetration & intradermal migration
    • May last hours to days but in autoinfxn cycles can recur over weeks, months, & years
  • Tracheal irritation & dry cough: as larvae migrate from the lungs up thru the trachea
  • GI disturbance: abdominal pain, intermittent diarrhea/constipation, fecal occult blood, massive colonic and gastric hemorrhage
23
Q

Strongyloidiasis:

more serious manifestation

A
  • More serious manifestations: larvae invades numerous organs
  • Severe life-threatening forms of disease (fatality approaches 90%)
  • Affects pts receiving high-dose corticosteroids for the tx of asthma or COPD, and in patients getting immunosuppressive drugs bc of transplants (due to impaired host immunity à accelerated autoinfxn & # of migrating larvae)
  • Pulmonary infiltrates, acute respiratory distress syndrome (ARDS), small bowel obstruction, & multisystem organ system, & rapid clinical decline
24
Q

Which of the helminths cause pneumonia by migration to the lung is a step of the life cycle?

  1. Ascaris lumbricoides
  2. Anclyostoma duodenale
  3. Trichinellaosis (Trichinella spiralis)
  4. Toxocariasis (Toxocara canis, Toxocara cati)
  5. Strongyloidiasis (Strongyloides steroiralis)
A

1, 2, and 5

  • Ascaris lumbricoides
  • Anclyostoma duodenale
  • Strongyloidiasis (Strongyloides steroiralis)
25
Guinea worm disease: life cycle
26
**Guinea worm:** causal agent, epidemiology, sxs, complications
27
Prevention and control of ## Footnote **Guinea worm disease**
* **Safe water --\>** using water filters * Health education and community mobilization * teaching communities about the disease and how it's spread * chemically killing worms in water * identifying infected person w/in 24 hours of worm emerging * person should receive proper tx and **case management** by local health provider * w/in 7 days of worm emerging, GWEP supervisor determines that above criteria has been met
28
Which of the following worms enter orally and move outside of GI tract? 1. Ascariasis 2. Hookworm 3. Strongyloides 4. Guinea worm
* Ascariasis * Guinea worm
29
**Lymphatic Filariasis - Elephantiasis** life cycle and transmission
30
**Lymphatic Filariasis-Elephantiasis:** causal agent, epidemiology transmission
31
**Lymphatic Filariasis-Elephantiasis:** symptoms, prevention and control
Sxs: Lymphedema of limbs, hydrocoele, chyluria * Majority of pts are asymptomatic, but virtually all of them have subclinical lymphatic damage * As many as 40% have kidney damage, w/ proteinuria & hematuria * Recurrent acute attacks – extremely painful, accompanied by fever Prevention/Control: take precaution when traveling to an area w/ lymphatic filariasis * Sleep in air-conditioned room or under mosquito net; wear long-sleeves & trousers * Use mosquito repellant on exposed skin between dusk and dawn * Global campaign to eliminate lymphatic filariasis --\> annual mass tx, and controlling mosquito
32
Round worms are not transmitted by insect bites: TRUE/FALSE
False, can be via insect bites, but can also be transmitted thru soil (e.g. Filariasis-Elephantiasis)
33
# Define: Neglected parasitic infections What are the top 5?
* NPI: relatively little attention has been devoted to surveillance, prevention, and/or tx * Incl: 1. **Chagas disease** 2. **cysticercosis** 3. **toxocariasis** 4. **toxoplasmosis** 5. **trichomoniasis**
34
Which of the following worms infect by skin penetration? * Schistosoma haematobium * Dracunuculus medinensis (GWD) * Anclyostoma duodenale (Hookworms) * Anclyostoma braziliense (Dog hookworm) * Stronglyoides steroralis
* Schistosoma haematobium * Anclyostoma duodenale (Hookworms) * Anclyostoma braziliense (Dog hookworm) * Stronglyoides steroralis (All except Dracunulus medinensis (GWD), which is transmitted by infected copepods in unfiltered water)