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General Parasitology > Intestinal Nematodes > Flashcards

Intestinal Nematodes Flashcards

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1
Q

Adenophora class

A

T. trichura & T. spiralis

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2
Q

Truchuris trichura AKA

A

also known as the “whip worm”

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3
Q

T. trichura adults live inside

A

the large intestine and rectum

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4
Q

Embryonation of T. trichura eggs occurs in:

A

moist, warm, shady soil

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5
Q

Infection of T. trichura

A

ingesting embryonated eggs on salad vegetables, fruit, in water or in soil

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6
Q

T. trichura Larvae to adults:

A

Larvae hatch in small intestine and become adults in the cecum

Adults burrow inside mucosa, where they consume RBCs

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7
Q

2 requirements for the worm to become a serious health problem

A

poor sanitation (human feces are deposited on the soil)

physical factors that allow their survival and development (warm climate, high rainfall and humidity, moist soil and dense shade)

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8
Q

T. trichura adults pass ________

A

unembryonated eggs in feces

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9
Q

_____ may coexist with _____

A

Trichuris

Ascaris

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10
Q

It’s the 2nd most common infecting nematode in the US

A

Trichuris

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11
Q

Pathogenesis in Trichuris

A

Trauma to the mucosa can cause chronic hemorrhage that may result in anemia and bloody stools

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12
Q

Symptoms on Trichuris

A

Abdominal pain, insomnia, vomiting, prolonged diarrhea, weight loss, nausea, rectal prolapse

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13
Q

Dx of Trichuris

A

ID of a worm or egg in the stool

Eggs have 2 distinct opercular plugs

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14
Q

Treatment of Trichuris

A

Albendazole and mebendazole

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15
Q

Prevention and control of Trichuris

A

thorough washing of salad vegetables

Washing hands

Sanitary disposal of feces

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16
Q

smallest nematode parasite of humans

A

Trichinella spiralis

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17
Q

Trichinella spiralis causes a ____ infection called _____

A

Zoonotic

Trichinosis

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18
Q

Trichinella spiralis is _____ in host specificity

A

Low

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19
Q

In Trichinella spiralis uterus is filled with _______ in _______ region; _____ region contains ___________

A

developing eggs; posterior

anterior; fully developed, hatching juveniles

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20
Q

In trichinella Life cycle is unusual in that the same animal serves as:

A

both definitive and intermediate host: larvae and adults are found in different organs

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21
Q

human infection of T. spiralis is contracted from:

A

the consumption of poorly cooked pork, infected with larvae (nurse cells)

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22
Q

T. spiralis larvae to adults:

A

Larvae are swallowed, reach SI where they excapsulate, molt and then enter the intestinal mucosa

Copulation occurs, Males die after. Females give birth and then die shortly after

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23
Q

After juveniles are birthed:

T. spiralis

A

Juveniles are carried away by the hepatoportal system –> the liver –> the heart –> lungs –> arterial system, which distributes them throughout the body

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24
Q

Through out migration (T. spiralis):

A

Juveniles can become lodged in any tissue

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25
If T. spiralis juvenile end up in striated muscle tissue:
diaphragm, jaws, larynx, eyes, tongue they penetrate individual muscle fibers and begins to grow, eventually forming a nurse cell
26
Most susceptible are muscles to least
eye and tongue, then the jaw muscles, then diaphragm, and finally muscles of the arms and legs
27
After ~1 year: | T. spiralis
host reactions begin to calcify the cyst walls and eventually the worms themselves
28
Sylvatic trichinosis
occurs between wild carnivores and their prey. Bears, foxes and raccoons are often infected
29
Urban trichinosis
It occurs primarily as a triangle between humans, rats, and pigs
30
Trichinosis triangle
rats maintain infection via cannibalism Pigs get infected by eating rats humans get infected by eating pigs
31
Trichinosis is rare in:
jews, hindus, muslims and vegetarians
32
Pathogenesis of T. spiralis in 3 stages:
(1) mild during penetration of adult females into the mucosa (2) severe during migration of juveniles, (constituting the primary symptoms) (3) moderate during penetration and encystment in muscle cells
33
Symptoms of stage 1 in T. spiralis
intestinal inflammation and pain, nausea, vomiting, sweating and diarrhea red blotches on skin, facial edema, fever
34
Symptoms of stage 2 in T. spiralis
damaged blood vessels, pneumonia, pleurisy, encephalitis, meningitis, nephritis, deafness, and loss of vision
35
Death occurs via:
myocarditis or heart and kidney failure and respiratory complications
36
Symptoms of stage 3 in T. spiralis:
intense muscular pain difficulty breathing and swallowing, and cardiovascular, excretory, and nervous disorders
37
dx in T. spiralis:
Immunological tests | Xenodiagnosis
38
Treatment of T. spiralis:
mebendazole (against muscle larvae) & pyrantel pamoate (against adult worm)
39
Prevention and Control
Fully cook pork before eating Education on fully cooking pork before serving Laws preventing feeding of uncooked waste to pigs have greatly reduced the disease in the US
40
Hook works spp
``` Ancylostoma duodenale (old-world) Necator americanus (new-world) ```
41
Buccal capsule in A. duodenale
2 pairs of teeth on the ventral wall of its capsule
42
Buccal capsule in N. americanus
pair of dorsal and a pair of ventral cutting plates surrounding the smaller buccal capsule
43
Life cycle of hookworms (eggs - L3 stage)
eggs are passed in feces in the proper envt, they will develop and hatch into rhabditiform larvae (L2) (feeding stage) molts into filariform larvae (L3) (non-feeding stage) which moves to surface when soil is wet where they penetrate human skin
44
Migration (hookworms)
human skin --> lymphatic system --> lungs (via heart and pulmonary circulation) --> alveoli --> glottis --> coughed up and swallowed
45
Once adult hook worms are swallowed:
They arrive in SI and attach to mucosal lining where they molt into L4 stage they feed off of blood and sexually mature
46
4 factors lead to hookworm infection:
shaded sandy and loamy soil moisture in form of precipitation poor sanitation contact with contaminated soil
47
3 stages of hookworm disease:
1) Invasive 2) Pulmonary 3) Intestinal
48
Invasive: | hookworm
hemorrhage and swelling with intense itching at entry site Secondary infection possible ground itch
49
Pulmonary: | hookworm
pneumonitis, burning sensation in the chest, dry cough, and other symptoms of bronchial pneumonia
50
Intestinal: | hookworm
most important period of pathogenesis. Cause bleeding and ulceration of mucosa Anemia resulting in geophagy Intermittent abdominal pain loss of appetite
51
Heavy infection of hookworm:
malnutrition, anemia and mental dullness
52
Chronic malnutrition from hookworm infection often causes irreversible damage, resulting in:
weakness, stunned growth and below-average intelligence
53
Dx of hookworm
presence of eggs or worms in feces Smear of feces on filter paper stored in tube allows to observe hatching larvae
54
Treatment (hookworm)
Mebendazole | Iron therapy
55
Prevention (hookworm)
Wear shoes Wear protective clothing while gardening Washing salad vegetables or fruits well
56
Control (hookworm)
Control involves an increase in sanitary conditions regular chemotherapeutic campaigns proper elimination of dog feces for N. a. broad public education
57
Creeping eruptions
Caused by A. braziliense (cat) or A. caninum (dog) Penetrate human skin but are incapable of migrating to the intestine Cause trauma to the skin before they are killed by immune system
58
Largest nematodes
Ascaris lumbricoides
59
Ascaris lumbricoides eggs in uterus
Uteri may contain > 27 million eggs at a time, with 200,000 being laid per day
60
Ascairs eggs have a ______ outer layer which allows them to be _______
Mammilated | Resilient
61
Ascaris lifecycle
Unembryonated eggs passed in feces, in soil they develop if optimal conditions are present
62
Although the eggs are resistant to ____ temperature, ________, and strong _____, _________ is retarded by such factors
low desiccation chemicals embryonation
63
Infection with Ascaris occurs when
embryonated eggs are swallowed with contaminated food and water
64
Once Ascaris eggs are ingested
Eggs containing 2nd stage larva hatch in the small intestine, penetrate mucosa/submucosa, enter lymph/circulatory system and migrate from liver --> right heart --> lungs
65
During ascaris migration:
many worms get lost and accumulate in every possible organs of the body, causing acute tissue reactions
66
Ascaris in lungs:
juveniles molt twice and emerge from pulmonary capillaries --> alveoli --> trachea --> glottis --> SI via coughing and swallowing
67
Ascaris in SI:
4th stage larvae mature and sexually reproduce
68
Proposed reasons why ascaris travels back to intestine where they originated
(1) migration simulates an intermediate host | (2) ancestor was a skin penetrator for which the migration (L2 -> L3 -> L4) was a developmental necessity
69
Prevention/control for Ascaris
Organism is difficult to control because eggs are so resistant and eggs can be carried by wind-borne dust Avoid/wash raw vegetables Proper disposal of feces Regular chemotherapy to carriers
70
Pathogenesis in Ascaris (lungs)
When juveniles emerge from capillaries they cause hemorrhage
71
Ascaris causes what type of pneumonia
Loeffler’s pneumonia - small pools of blood clog air spaces, accumulation of WBCs and dead epithelium add to respiratory congestion
72
In heavy intestinal Ascaris infections:
In children, protein malnutrition is common. Intestinal obstruction results in severe abdominal pain, loss of appetite, nausea and vomiting
73
Dx for Ascaris
ID of eggs in feces as well as egg counts Xray of abdomen
74
Treatment for Ascaris
``` None for juveniles piperazine citrate for adults Albendazole and mebendazole Surgery IV fluids ```
75
Enterobius vermicularis AKA
Pin worm or Seat worm
76
Does Enterobius vermicularis have an intermediate host?
NO
77
Adult Enterobius vermicularis live in:
ileocecal region of intestine
78
Enterobius vermicularis adults commonly travel throughout:
GI tract (stomach to anus)
79
Infection of E. vermicularis usually occurs via:
ingestion of eggs containing 3rd stage juvenile
80
Adult E. vermicularis feed off of :
Bacteria and epithelial cells
81
Life cycle (E. vermicularis):
Gravid female migrates out of the anus and lays sticky eggs at night
82
Female and male survival (E. vermicularis)
Males die after copulation females die shortly after they lay eggs or sometimes burst open while laying eggs
83
Eggs deposited on the anal skin in E. vermicularis:
Causes pruritus - intense itching and swelling
84
Eggs can be ______
Inhaled When inhaled, eggs may remain in the nose until they hatch
85
retroinfection
If the perianal or vaginal folds are unclean for long periods, the attached eggs may hatch and juveniles wander into the anus and back into the intestine
86
If E. vermicularis is ingested:
the larvae slowly move down the small intestine, molting twice to become adults by the time they arrive at the SI-LI junction
87
Heavy infections of E. vermicularis in children result in:
sleeplessness, weight loss, hyperactivity, grinding of teeth, abdominal pain, and vomiting
88
e most common nematode parasitizing humans in the U.S.
E. vermicularis
89
Dx of E. vermicularis
finding eggs and worms Examining under flash light either early or at night
90
Treatment of E. vermicularis
Albendazole and mebendazole
91
How to confirm treatment in E. vermicularis:
cellophane tape is pressed against the perianal skin, then removed and pressed against a glass slide for exam. Negative results for 7 consecutive days means the patient is cured
92
Prevention and control in E. vermicularis:
Frequent washing of hands, bed sheets and clothes in hot water are strongly recommended. Since eggs can survive for days in moist, cool home, everyone in the infected household should be properly treated

General Parasitology (19 decks)

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