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MicroBio - Parasitology > Intestinal Nematodes > Flashcards

Intestinal Nematodes Flashcards

1
Q

Common name: Roundworms
Environment
Varied; free living; plant parasites; animal parasites
Reproduction
Sexual reproduction only
Dioecious: Separate male and female sexes
Females: Larger
Males: Curved tails or specialized copulatory organs

A

Intenstinal Nematodes

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2
Q

Shape
Cylindrical
Tapering at both ends
Unsegmented

A

Intestinal Nematodes

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3
Q 
Cuticle
 Outer covering
 Relatively impermeable
 Protective
 Shed during molting
A

Intestinal Nematodes

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4
Q

Digestive tract: Complete
Specialized esophageal area
Intestines
Rectum
Osmoregulatory/excretory system: Ammonia waste system
Exit through anus
May have excretory pore and renette gland

A

Intestinal Nematodes

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5
Q

Nervous system

- Nerve rings : Anterior or posterior leads to receptors (sense organs): photo, mechanical and chemical
- Longitudinal nerves: Two lateral
A

Intestinal Nematodes

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6
Q

Reproductive System
Monoecious: Reproductive organs of male and female in one organism or segment
Dioecious: Separate male and female organisms
Fertilization: Internal
Cross-fertilization: Most often (when more than one adult is present)
Self-fertilization: When only one organism is present

A

Repro of Intestinal Nematodes

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7
Q

Thousands of species; most are free living
Buccal structures: Specialized for attachment
Copulatory organs
Bursa: Used for grasping the female
Spicules: Used for injection of spermatozoa

A

Intestinal Nematodes

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8
Q 
Ova: Nonoperculated
Rhabditiform larva
Filariform larva
Molts 
Several between stages
Intermediate forms observed
A

stages of development

Intestinal Nematodes

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9
Q

Common name: Giant intestinal roundworm

A

Ascaris lumbricoides

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10
Q 
Eggs are passed in feces
Mature egg ingested by man
Infective larva in intestine, hatches
Enters the venules byway of intestinal wall 
Travels through the heart to lungs
Travel into the alveoli byway of lung
    Molt
Coughed up and swallowed
Mature and mate in intestine
Female begins laying eggs
A

life cycle:

Ascaris lumbricoides

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11
Q 
Habitat: Small intestines
Intermediate host: None
 Reservoir host: Swine
 Infective form: Mature embryonated egg
 Mode of infection: Ingestion
A

Ascaris lumbricoides

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12
Q

Shape: Round and slender, male has a curved tail
Color: Creamy-white with a pinkish cast
Buccal structures: Three lips

A

Ascaris lumbricoides

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13
Q

Giant intestinal round worm.
Acquired by eating eggs from soil contamination
Worldwide dist., developing countries, poverty

A

Ascaris lumbricoides

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14
Q

Adults in small intestine
Heavy infection can cause obstruction 10k deaths/yr
Adults can perforate intestine and migrate to liver
Larvae migrate to liver and lungs causing systemic responses, eosinophilic pneumonitis (Loeffler’s)
Diagnosis: eggs or adults in feces

A

Ascaris lumbricoides

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15
Q

Common name: Pinworm or seatworm

A

Enterobius vermicularis

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16
Q 
Habitat: Large intestine, cecum
Intermediate host: None
Reservoir host: None known
 Infective form: Embryonated egg (Rhabditiform larva)
 Mode of infection: Ingestion
A

Enterobius vermicularis

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17
Q

School children age 5-14 are often victims.
Eggs infective within 6 hours and up to 20 days.
Hand-to-mouth infection. Keep hands clean.
Anal pruritis encourages scratching, secondary bacterial infections are possible.
Worms may migrate to ectopic locations

A

Enterobius vermicularis

18
Q

Specimen processing: Specimen of choice is transparent adhesive tape specimen collection (“scotch-tape prep”) or pinworm paddle

A

Enterobius vermicularis

19
Q

Known as pinworm
Worldwide dist., most prevalent in temperate
Acquired by eating eggs, autoinfection, retroinfection

A

Enterobius vermicularis

20
Q

Disease is slight, perianal itching, sleep disturbance
Spreads easily to family members
Diagnosis: D shaped eggs recovered from patient

A

Enterobius vermicularis

21
Q

Hook worms:

A

Ancylostoma duodenale

Nector americanus

22
Q

Common name: Old World hookworm

A

Ancylostoma duodenale

23
Q

Creeping eruption, pruritis, iron deficiency anemia.
Anticoagulants in bite wound maintain bleeding even after worm leaves.
Physical, cognitive, intellectual growth diminished in children.

A

Ancylostoma duodenale

24
Q 
Color: Grayish-white
 Buccal structures: Two fused, sharp "teeth" on each side of ventral surface
 Copulatory bursa: Male
 Paired copulatory spicules: Separated
 Small paired dorsal rays: Tripartite
A

Ancylostoma duodenale

25
Q

Common name: New World hookworm (archaic)

A

Necator americanus

26
Q

Found worldwide, with focal locations for species.

Life cycle and symptoms similar with both species.

A

Hookworms

27
Q

Symptoms vary with worm migrations, number of infections (repeats and burden), eosinophilia, pneumonia, abdominal discomfort.
Cause blood loss, anemia
Diagnosis: clinical signs, eggs in feces

A

Hookworms

28
Q

Common name: Threadworm

A

Strongyloides stercoralis

29
Q

Develop into infective filariform larvae that penetrate the skin and follow a lung migration (blood-lung-intestinal route), or
May develop into adults and exist for some time (two or more generations) as free-living nematodes, producing the filariform later

A

Life cycle:

Strongyloides stercoralis

30
Q 
Intestinal infection
 Desquamation
 Severe diarrhea and gastroenteritis
 Anemia
 Weight loss

**Hyperinfection may be fatal in immunosuppressed patients

A

Strongyloides stercoralis

31
Q

Autoinfective**, can build large numbers in victim.
Some infections documented to last over 60 years.
Person to person transmission possible.
Epigastric pain, fluctuating eosinophilia, recurrent maculopapular rash of buttocks, perineum and thighs.

A

Strongyloides stercoralis

32
Q

Discovery and ID of rhabditiform LARVAE IN STOOL examination.

May need a large volume and concentrate.
Serology available from CDC, maybe some commercial sources.
Some cross-reactivity with other helminths occurs

A

Strongyloides stercoralis

33
Q

Resembles that of Hookworm
Males are either eliminated early in the parasitic cycle or the gravid females enter the mucosa and deposit their eggs through PARTHENOGENESIS.

Eggs hatch in the mucosa liberating the rhabditiform larvae
burrows back into the lumen of the intestine to pass out with the feces

A

Strongyloides stercoralis

34
Q

Found worldwide, endemic in Appalachia in US.

Life cycle similar to hookworm, but also capable of free living.

Causes intestinal and organ damage.

A

Strongyloides stercoralis

35
Q

Uses parthenogenesis while in parasitic mode.

Autoinfective an hyperinfective in immunocompromised.

Diagnosis: Larvae in stool, sometimes eggs in stool, possibly ELISA available.

A

Strongyloides stercoralis

36
Q

Common name: Whipworm

A

Trichuris trichiura

37
Q

Known as the Whipworm because of shape.

Found worldwide especially poor or developing countries.

A

Trichuris trichiura

38
Q

Acquired by eating food contaminated by eggs found in soil.

Causes disease with heavy infections, adults in cecum and large intestine. Destruction and inflammation of intestine..leads to malnutrition, iron deficiency, and RECTAL PROLAPSE.

Diagnosis: Characteristic eggs in feces, colonoscopy.

A

Trichuris trichiura

39
Q

Which of these parasites are best known for the ability to autoinfect an individual?

A. Trichuris trichiura
B. Ancylostoma duodenale
C. Ascaris lumbricoides
D. Strongyloides stercoralis

A

D. Strongyloides stercoralis

40
Q 
This worm is frequently called the “pinworm” and is usually associated with young children?

A. Ascaris lumbricoides
B. Enterobius vermicularis
C. Strongyloides stercoralis
D. Trichuris trichiura
A

B. Enterobius vermicularis

MicroBio - Parasitology (14 decks)

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