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Parasitology [LEC] > [DISCUSSION] MODULE 3 UNIT 3 > Flashcards

[DISCUSSION] MODULE 3 UNIT 3 Flashcards

1
Q

The phylum Nematoda is divided into classes based on the presence or absence of “(?)’, which are caudal chemoreceptors.

A

phasmids

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2
Q

The two (2) classes were earlier called Aphasmidia and Phasmidia, but now have been renamed as (?), respectively.

A

Adenophorea and Secernentea

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3
Q

This module unit will deal with the phasmid nematodes belonging to the class Secernentea.
 Medically important phasmids include (?)

A

Ascaris lumbricoides, Enterobius vermicularis, hookworm species, and Strongyloides stercoralis.

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4
Q

The specific name of Ascaris lumbricoides has been derived from its resemblance with earthworm ([?], meaning earthworm in Latin).

A

lumbricus

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5
Q

Two species of hookworms are human parasites:

A

(1)Ancylostoma duodenale
2) Necator americanus

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6
Q

(Greek ankylos-hooked, stoma-mouth)

A

Ancylostoma duodenale

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7
Q

(?) whose name literally means the “American murderer” (Latin necator-murderer)

A

Necator americanus

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8
Q

o identified in specimens obtained from Texas, USA, it is believed that it actually originated in Africa

A

Necator americanus

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9
Q

 Small cylidrical worms were observed in diarrheic stool of some French soldiers repatriated from Cochin-China (referring to Vietnam), thus, earliest cases were decribed as Cochin-China diarrhea.

A

These were named Strongyloides stercoralis (strongylus- round, eidosresembling, stercoralis-fecal).

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10
Q

 Common Name: Giant intestinal roundworm

A

A. Ascaris lumbricoides

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11
Q

1
(?) live in the lumen of the small intestine.The female worm produces both fertilized and unfertilized eggs which are passed out in faeces.

A

Adult worms

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12
Q

2
A female may produce approximately (?) eggs per day

A

200,000

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13
Q

3
In the (?), the fertilized egg embryonates. Larvae develop to third stage within fertile eggs after 2 to 3 weeks in moist, warm, shaded soil

A

soil

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14
Q

4
Humans become infected by ingestion of the ?

A

embryonated eggs

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15
Q

5
the (?) hatch

A

larvae

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16
Q

6
the (?) invade the intestinal mucosa, and are carried via the portal, then systemic circulation on to the heart, then into the lungs

A

larvae

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17
Q

7
The (1) break out of the capillaries into the alveoli. The (2) mature further in the lungs (10 to 14 days), after a (3), penetrate the alveolar walls, ascend the bronchial tree to the throat, and are swallowed

A
  1. larvae
  2. larvae (L4s)
  3. molt
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18
Q

 They develop into (1) in the small intestine, where they worms maintain their position due to their body muscle tone, spanning the lumen,
 and exerting pressure against the walls of the small intestine.
 Between 2 and 3 months are required from ingestion of the (2) to oviposition by the adult female.
 (3) can live 1 to 2 years.

A
  1. adult worms
  2. Infective eggs
  3. Adult worms
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19
Q

Clinical manifestations of ascariasis are caused by the pulmonary migratory phase of (?) in the small intestine and the wandering adult worms.

A

the larvae, the adult worms

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20
Q

The (?) causes allergic reaction.

A

larval migration

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21
Q

The initial exposure to (?) during the lung migration phase is usually asymptomatic, except when the larval load is heavy.

A

larvae

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22
Q

One may experience symptoms referable to respiratory system such as ?

A

asthmatic respiration, cough with bronchial rales and chest pain.

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23
Q

These symptoms may be due to the (?) and massive destruction of the lung parenchyma as the larvae break through the capillaries on their way to the alveolar sacs,

A

petechial hemorrhages

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24
Q

In massive infection, the hemorrhage may give rise to ?.

A

Ascaris pneumonitis

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25
Q

In hypersensitive individuals, even a few larvae may give rise to allergic eosinophilic infiltration of the lung called ?.

A

Loeffler’s syndrome

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26
Q

The pulmonary clinical features subside in ? after infection

A

1 or 2 weeks

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27
Q

Due to larval migration in the blood stream, the larvae may lodge in vital organs such as the ?.

A

brain and spinal cord, the eyeball and the kidney

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28
Q

Cosmopolitan but is more widely distributed in tropical and subtropical countries with warm and moist soil.

A

A. Ascaris lumbricoides

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29
Q

Over a billion of people are infected globally.

A

A. Ascaris lumbricoides

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30
Q

Infection rates are highest in children.

A

A. Ascaris lumbricoides

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31
Q

 It co-exists with Trichuris trichiura.

A

A. Ascaris lumbricoides

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32
Q

In many countries, the Philippines included, the prevalence may reach 80-90% in certain high risk groups like public elementary school children.

A

A. Ascaris lumbricoides

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33
Q

Fecal-oral route.

A

A. Ascaris lumbricoides

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34
Q

Infection occurs in humans when the embryonated eggs containing the infective third-stage larvae are swallowed in soil-contaminated food.

A

A. Ascaris lumbricoides

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35
Q

The population most at risk of contracting Ascaris lumbricoides infection is children who place their contaminated hands into their mouths.

A

A. Ascaris lumbricoides

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36
Q

Sources of contamination range from children’s toys to the soil itself.

A

A. Ascaris lumbricoides

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37
Q

This often occurs in areas where poor sanitation practices are common, such as open defecation or using night soil as fertilizer for vegetables.

A

A. Ascaris lumbricoides

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38
Q

House flies and cockroaches can serve as mechanical vectors.

A

A. Ascaris lumbricoides

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39
Q

The embryonated eggs can survive in moist shaded soil for a few months to about 2 years in tropical and subtropical areas, but for much longer in temperate regions.

A

A. Ascaris lumbricoides

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40
Q

Resistance of Ascaris eggs to chemicals is almost legendary.

A

A. Ascaris lumbricoides

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41
Q

They can embryonate successfully in 2% formalin, in potassium dichromate, and in 50% solutions of hydrochloric, nitric, acetic, and sulfuric acid, among other similar inhospitable substances.

A

A. Ascaris lumbricoides

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42
Q

(?) is the primary species involved in human infections globally, but Ascaris derived from pigs (often referred to as A. suum) may also infect humans.

A

Ascaris lumbricoides

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43
Q

 Formerly called Oxyuris vermicularis.

A

B. Enterobius vermicularis

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44
Q

Common Names: Pinworm, seatworm.

A

B. Enterobius vermicularis

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45
Q

In United Kingdom and Australia, threadworm is used, which is also used to refer to ?

A

Strongyloides stercoralis.

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46
Q

1
(?) Enterobius vermicularis deposits eggs on perianal folds

A

Gravid adult female

47
Q

2
Man acquires infection by ingesting (?) containing third-stage larva

A

embryonated eggs

48
Q

It takes about 1 month for the female to mature and begin egg production.

A

B. Enterobius vermicularis

49
Q

The adult life span is about two months.

A

B. Enterobius vermicularis

50
Q

After fertilization of the female worms, the males usually die.

A

B. Enterobius vermicularis

51
Q

Gravid female worms migrate out of the anus at night (nocturnal migration) when the anal sphincter is relaxed and the oxygen tension is decreased.

A

B. Enterobius vermicularis

52
Q

They lay eggs that adhere to the perianal skin

A

B. Enterobius vermicularis

53
Q

A single female lays up to 17,000 (average of 11,000) eggs per day.

A

B. Enterobius vermicularis

54
Q

When all the eggs are laid, the female worm dies.

A

B. Enterobius vermicularis

55
Q

When laid, each egg contains a partially developed larva, which can develop to infectivity in 4 to 6 hours under optimal conditions

A

B. Enterobius vermicularis

56
Q

Infected individuals may reinfect themselves, known as an autoinfection, if infective eggs are ingested via hand-to-mouth contamination due to scratching of perianal area with fingers leading to deposition of eggs under the nails.

A

B. Enterobius vermicularis

57
Q

This mode of infection is mostly common in children.

A

B. Enterobius vermicularis

58
Q

In retroinfection, the eggs laid on the perianal skin immediately hatch into the infective stage larva and migrate through the anus to develop into worms in the cecum.

A

B. Enterobius vermicularis

59
Q

Rarely, eggs may become airborne and be inhaled and swallowed.

A

B. Enterobius vermicularis

60
Q

About one-third of enterobiasis or oxyuriasis are asymptomatic.

A

B. Enterobius vermicularis

61
Q

The worm produces intense itching of the perianal area (pruritus ani) and also the perineal area, when it crawls out of the anus to lay eggs.

A

B. Enterobius vermicularis

62
Q

This leads to scratching and irritation of the skin around the anus. and may give rise to secondary bacterial infection.

A

B. Enterobius vermicularis

63
Q

Children infected with this parasite may suffer from insomnia due to the pruritus.

A

B. Enterobius vermicularis

64
Q

Other signs of infection are poor appetite, weight loss, irritability, nocturnal enuresis (involuntary urination), grinding of teeth, and abdominal pain.

A

B. Enterobius vermicularis

65
Q

Unlike the other intestinal nematodes, Enterobiasis is not associated with eosinophilia or with elevated immunoglobulin E (lgE).

A

B. Enterobius vermicularis

66
Q

In female patients, the worms may cause ectopic migration when they crawl into the vulva and vagina causing irritation.

A

B. Enterobius vermicularis

67
Q

It may migrate up to the uterus and fallopian tubes.

A

B. Enterobius vermicularis

68
Q

This may cause symptoms of cervicitis, chronic salpingitis, peritonitis, and recurrent urinary tract infections.

A

B. Enterobius vermicularis

69
Q

The worm is sometimes found in surgically removed appendix and has been claimed to be responsible for appendicitis.

A

B. Enterobius vermicularis

70
Q

Cosmopolitan, in both temperate and tropical areas.

A

B. Enterobius vermicularis

71
Q

Prevalence rates for Enterobius vermicularis are highest in temperate regions and also in urban areas.

A

B. Enterobius vermicularis

72
Q

Enterobiasis is considered to be the most common helminth infection in the United States.

A

B. Enterobius vermicularis

73
Q

In the Philippines, prevalence levels have been found to be 29% among schoolchildren from exclusive private schools, and 56% among those from public schools.

A

B. Enterobius vermicularis

74
Q

Locally, prevalence is consistently higher in females (16%) compared to males (9%).

A

B. Enterobius vermicularis

75
Q

The most common means of transmission is by anus-to-mouth through contaminated fingers or other objects in the mouth, or by inhalation of dust containing Enterobius eggs.

A

B. Enterobius vermicularis

76
Q

Under cool moist conditions, the egg remains viable for about 2 weeks, but under warm, dry conditions, they begin to lose their infectivity within 2 days.

A

B. Enterobius vermicularis

77
Q

Transmission is facilitated by factors including overcrowding, wearing soiled clothing, lack of adequate bathing and poor personal hygiene, especially among young school-aged children.

A

B. Enterobius vermicularis

78
Q

Finger sucking and nail biting may be sources of recurrent infection in children.

A

B. Enterobius vermicularis

79
Q

It may be transmitted through sexual activity, especially via oral and anal sex

A

B. Enterobius vermicularis

80
Q

Enterobiasis is extremely contagious and can easily spread among members of a family or in institutions.

A

B. Enterobius vermicularis

81
Q

Hence, it has been described as a familial or a group disease.

A

B. Enterobius vermicularis

82
Q

Humans are the only natural host for Enterobius vermicularis

A

B. Enterobius vermicularis

83
Q

Two (2) species of hookworms are human parasites:

A
  • Necator americanus - Ancylostoma duodenale
84
Q

Common Names:
o (1): New world hookworm
o (2): Old world hookworm

A
  1. Necator americanus
  2. Ancylostoma duodenale
85
Q

1
? are passed in the stool

A

Eggs

86
Q

2
under favorable conditions (moisture, warmth, shade), (?) hatch in 1 to 2 days and become freeliving in contaminated soil

A

larvae

87
Q

3
These released (1) larvae grow in the feces and/or the soil , and after 5 to 10 days (and two molts) they become (2) larvae that are infective

A
  1. rhabditiform (first-stage)
  2. filariform (third-stage)
88
Q

4
 These (1) can survive 3 to 4 weeks in favorable environmental conditions  On contact with the human host, typically bare feet, the (2) penetrate the skin and are carried through the blood vessels to the heart and then to the lungs.
 They penetrate into the pulmonary alveoli, ascend the bronchial tree to the pharynx, and are swallowed

A
  1. infective larvae
  2. larvae
89
Q

5
The (1) reach the jejunum of the small intestine, where they reside and mature into adults.
(2) live in the lumen of the small intestine, typically the distal jejunum, where they attach to the intestinal wall by means of well-developed mouth parts (cutting plates in N. americanus and teeth in A. duodenale)

A
  1. larvae
  2. Adult worms
90
Q

Most adult worms are eliminated in 1 to 2 years, but the longevity may reach several years ((1) - 4 to 20 years; (?): 2-7 years).

A
  1. N. americanus
  2. A. duodenale
91
Q

A (?) lays about 25,000-30,000 eggs in a day and some 18- 54 million during its life time.

A

single female worm

92
Q

Some (?), following penetration of the host skin, can become dormant (hypobiosis in the intestine or muscle).

A

A. duodenale larvae

93
Q

These (?) are capable of re-activating and establishing patent, intestinal infections.

A

larvae

94
Q

In addition, infection by A. duodenale may probably also occur by the oral route, when (1) of A. duodenale are swallowed and develop into (2) in the intestine without migrating through the lungs, and the transmammary route.

A
  1. mature filariform larvae
  2. mature worms
95
Q

Hookworm disease (necatoriasis or ancylostomiasis) manifests three main phases of pathogenesis:

A

o the invasion or cutaneous period
o the migration or pulmonary phase
o the intestinal phase.

96
Q

This begins when filariform larvae penetrate skin.

A

Invasion or cutaneous phase C. Hookworm species

97
Q

They do little damage to superficial layers, since they seem to slip unbroken skin through hair follicles, or pores.

A

Invasion or cutaneous phase C. Hookworm species

98
Q

The usual sites of infection are the dorsum of the feet or between the toes; also on the hands, especially interdigital spaces.

A

Invasion or cutaneous phase C. Hookworm species

99
Q

Once in the dermis, however, their attack on blood vessels initiates a tissue reaction.

A

Invasion or cutaneous phase C. Hookworm species

100
Q

If, as it usually happens, pyogenic bacteria are introduced into skin with the invading larva, a severe local itching known as ground itch, dew itch, or coolie itch will result.

A

Invasion or cutaneous phase C. Hookworm species

101
Q

Erythematous papular rash develops when a large number of larvae penetrate the skin.

A

Invasion or cutaneous phase C. Hookworm species

102
Q

This is a self-limiting condition, lasting for 2 to 4 weeks.

A

Invasion or cutaneous phase C. Hookworm species

103
Q

This occurs when larvae break out of the lung capillary bed into alveoli and progress up bronchi to the throat.

A

Migration or pulmonary phase C. Hookworm species

104
Q

Each site hemorrhages slightly, with serious consequences in massive infections; however, very large numbers of larvae migrating through the lungs simultaneously are rare.

A

Migration or pulmonary phase C. Hookworm species

105
Q

The phase is usually asymptomatic, although there may be some dry coughing and sore throat.

A

Migration or pulmonary phase C. Hookworm species

106
Q

A pneumonitis and Loeffler’s syndrome may occur in heavy larvae infection.

A

Migration or pulmonary phase C. Hookworm species

107
Q

Intestinal hookworm infections are commonly asymptomatic.

A
108
Q

Attachment of the worms to the mucosa with their strong buccal capsule and teeth or cutting plates may stimulate abdominal pain, nausea, and anorexia.

A

Intestinal Phase C. Hookworm species

109
Q

Adult worms suck blood aided by the anticoagulant that they secrete.

A

Intestinal Phase C. Hookworm species

110
Q

The worms change feeding sites and the old biting sites will continue to bleed.

A

Intestinal Phase C. Hookworm species

111
Q

Blood loss per worm is about 0.03 ml per day for N. americanus and about 0.15-0.25 ml per day for A. duodenale.

A

Intestinal Phase C. Hookworm species

112
Q

Thus, in heavy infection, a substantial amount of blood can be lost, and a severe irondeficiency (microcytic, hypochromic) anemia may develop in a short time.

A

Intestinal Phase C. Hookworm species

113
Q

Nevertheless, a moderate hookworm infection will gradually produce an iron-deficiency anemia as body reserves of iron are used up.

A

Intestinal Phase C. Hookworm species

114
Q

Patients have reported vague gastrointestinal disturbances and eosinophilia (sometimes referred to as Wakana syndrome) following peroral infection.

A

Intestinal Phase C. Hookworm species

Parasitology [LEC] (23 decks)

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