[DISCUSSION] MODULE 3 UNIT 2 AND UNIT 3

Question 1

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

Answer 1

phasmids

Question 2

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

Answer 2

Adenophorea and Secernentea

Question 3

 The origin of the name (Gr. trichos = hair + oura = the tail), is not quite correct because it is the (?) of the worm that is hair-like and not the tail.

Answer 3

anterior end

Question 4

 Whipworm

Answer 4

A. Trichuris trichiura

Question 5

Infection is caused by ingestion of embryonated eggs.

Answer 5

A. Trichuris trichiura

Question 6

 Eggs – hatch in the small intestine.

Answer 6

A. Trichuris trichiura

Question 7

 larvae (L1) – released and penetrate the intestinal villi and undergo 4 molts in 3-10 days.

Answer 7

A. Trichuris trichiura

Question 8

 young adult – passively migrate to the cecum (also in the ascending colon) and mature in about 2-3 months

Answer 8

A. Trichuris trichiura

Question 9

 usually asymptomatic, except in heavy infection

Answer 9

Trichuriasis

Question 10

 Heavily infected individuals - those with a high worm burden (greater than 200 worms, >5,000 EPG)- are most likely to
develop clinical disease.

Answer 10

Trichuriasis

Question 11

 hypochromic, microcytic type

Answer 11

Iron-deficiency anemia

Question 12

 results from chronic blood loss at the attachment site coupled with the long life span of the worms

Answer 12

Iron-deficiency anemia

Question 13

 Small amounts of blood (0.005 ml per worm) are lost each day at the ulceration in the intestinal mucosa

Answer 13

Iron-deficiency anemia

Question 14

 worm may be found even up to the rectum in heavy infection

Answer 14

Rectal prolapse

Question 15

 mucosa of the rectum protrudes through the anal opening associated with the loss of muscle tone of the anus

Answer 15

Rectal prolapse

Question 16

 Children with severe trichuriasis have:
o growth retardation
o impaired mental development
o cognitive function

Answer 16

Sever Trichuriasis

Question 17

 Pudoc worm

Answer 17

B. Capillaria philippinensis

Question 18

 In 1967, an epidemic of Capillariasis took place in
Pudoc West, Tagudin, Ilocos Sur

Answer 18

B. Capillaria philippinensis

Question 19

Infection is caused by ingestion of larvae in raw or
undercooked infected fish

Answer 19

B. Capillaria philippinensis

Question 20

 larvae - develop into adults in the small intestine
(jejenum) where they burrow into the mucosa

Answer 20

B. Capillaria philippinensis

Question 21

 Female worms - may produce two types of eggs:
o Unembryonated shelled eggs –
passed in the feces
o Embryonated eggs – hatches
within human host

Answer 21

B. Capillaria philippinensis

Question 22

 larvae - will re-invade and cause autoinfection.

Answer 22

B. Capillaria philippinensis

Question 23

 unembryonated eggs - ingested by fish when
passed into water.

Answer 23

B. Capillaria philippinensis

Question 24

 malabsorption syndrome with severe diarrhea

Answer 24

Intestinal capillariasis

Question 25

 borborygmi (gurgling stomach)

Answer 25

Intestinal capillariasis

Question 26

 abdominal pain (can become serious if not treated
because of autoinfection)

Answer 26

Intestinal capillariasis

Question 27

 Capillary liver worm

Answer 27

C. Capillaria hepatica

Question 28

 The nematode (roundworm) Capillaria hepatica (=Calodium
hepaticum) causes hepatic capillariasis in humans.

Answer 28

C. Capillaria hepatica

Question 29

 Nomenclature varies in use globally and by discipline; Capillaria
hepatica is most frequently used in medical literature.

Answer 29

C. Capillaria hepatica

Question 30

 zoonotic parasite with a low host specificity
o primarily exists in rodent and carnivore hosts
o Both true and spurious infections occur in
humans

Answer 30

C. Capillaria hepatica

Question 31

Infection is caused by ingestion of embryonated eggs in fecally-
contaminated food, water, or soil

Answer 31

C. Capillaria hepatica

Question 32

 Adult worms - are located deep within the liver parenchyma of
the host, and lay hundreds of eggs in the surrounding
parenchymal tissue.

Answer 32

C. Capillaria hepatica

Question 33

 eggs - trapped in the parenchyma; can not be passed in the feces
of the host, and remain in the liver until the animal dies, or more
likely, is eaten by a predator or scavenger

Answer 33

C. Capillaria hepatica

Question 34

o Eggs ingested by scavengers are
unembryonated (not infectious) and are passed
in through the digestive tract into and out in
feces, providing an efficient mechanism to
release eggs back into the environment

Answer 34

C. Capillaria hepatica

Question 35

o Eggs embryonate in the environment, where
they require air and damp soil to become
infective.

Answer 35

C. Capillaria hepatica

Question 36

 Under natural conditions, embryonation is slow and may take
between 6 weeks and 5 months.

Answer 36

C. Capillaria hepatica

Question 37

 The cycle continues when embryonated eggs are eaten by a
suitable mammalian host.

Answer 37

C. Capillaria hepatica

Question 38

 Infective eggs hatch in the intestine, releasing first stage larvae.

Answer 38

C. Capillaria hepatica

Question 39

 The larvae penetrate the intestinal wall and migrate via the portal
vein to the liver parenchyma within 3-4 days.

Answer 39

C. Capillaria hepatica

Question 40

 Larvae take about 3-4 weeks to mature into adults and mate.

Answer 40

C. Capillaria hepatica

Question 41

 rare in humans

Answer 41

Hepatic capillariasis

Question 42

 typically manifests as an acute or subacute hepatitis with:
o peripheral leukocytosis and eosinophili
o hepatomegaly
o persistent fever (which may be as high as 40°C)

Answer 42

Hepatic capillariasis

Question 43

 Trichina worm

Answer 43

D. Trichinella spiralis

Question 44

 The name Trichinella is derived from the minute size of the adult (Gr. trichos =hair, ella suffix for diminutive) and spiralis refers to the spirally coiled
appearance of larvae in muscles.

Answer 44

D. Trichinella spiralis

Question 45

Infection is caused by ingestion of raw/rare or undercooked meat containing encysted larvae

Answer 45

D. Trichinella spiralis

Question 46

 Adult worms and encysted larvae develop within:
o 1 vertebrate host
o definitive host and potential intermediate host : infected animal
o A second host is required to perpetuate the life cycle of Trichinella.

Answer 46

D. Trichinella spiralis

Question 47

 domestic cycle
o pigs
o anthropophilic rodents
o other domestic animals
 horses

Answer 47

D. Trichinella spiralis

Question 48

 sylvatic cycle
o bear
o moose
o wild boar

Answer 48

D. Trichinella spiralis

Question 49

 After exposure to gastric acid and pepsin, the larvae are released from the cysts (excystation) invade the small bowel mucosa, molt four times and
rapidly develop into adults, either male or female, by the 2nd day of infection.

Answer 49

D. Trichinella spiralis

Question 50

 Within 5 days, they become sexually mature

Answer 50

D. Trichinella spiralis

Question 51

 The male dies after fertilizing the female.

Answer 51

D. Trichinella spiralis

Question 52

 After 1 week of infection, the fertilized females release larvae.

Answer 52

D. Trichinella spiralis

Question 53

 Larvae continue to be discharged during the remaining part of the lifespan of the female worm, which ranges from 4 weeks to 4 months.

Answer 53

D. Trichinella spiralis

Question 54

 These larvae enter the intestinal lymphatics or mesenteric venules and are transported in circulation to different parts of the body.
o They get deposited in the muscles, central nervous system and other sites.

Answer 54

D. Trichinella spiralis

Question 55

 The larvae die in most other situations, except in the skeletal muscles, where they grow.

Answer 55

D. Trichinella spiralis

Question 56

 Within 20 days after entering the muscle cells, the larvae encyst within nurse cells.

Answer 56

D. Trichinella spiralis

Question 57

 Encysted larvae lie parallel to the muscles of host and can survive for months to years and eventually calcify and die.

Answer 57

D. Trichinella spiralis

Question 58

 In man, the life cycle ends here.
o Man is a dead-end host of the parasite, as the cysts in human muscles are unlikely to be eaten by another host.

Answer 58

D. Trichinella spiralis

Question 59

 Trichinella spiralis has an unusual life cycle in that the same individual animal serves as both definitive and intermediate host, adults and larvae
located in different organs.

Answer 59

D. Trichinella spiralis

Question 60

 autoheteroxenous parasite

Answer 60

D. Trichinella spiralis

Question 61

Cysts develop preferentially in muscles relatively poor in glycogen and in hypoxic environment.
o Therefore, the biceps, deltoid, gastrocnemius, pectoralis, masseter, extraocular muscles, intercostal muscles and diaphragm, which
are constantly active, are the ones mostly affected.

Answer 61

D. Trichinella spiralis

Question 62

• gastrointestinal symptoms
   diarrhea
   abdominal pain
   vomiting

Answer 62

Intestinal phase

Question 63

 high fever
 periorbital and facial edema
 conjunctivitis
 blurred vision
 myalgias
 splinter hemorrhages
 rashes
 peripheral eosinophilia lasting 1 month in heavy infection
Occasional life-threatening manifestations:
 myocarditis
 central nervous system involvement
 pneumonitis

Answer 63

Migration phase

Question 64

 myalgia and weakness o followed by subsidence of symptoms

Answer 64

Larval encystment

Question 65

 abdominal tenderness and pain
 weight loss
 weakness
 mucoid or bloody stool

Answer 65

A. Trichuris trichiura

Question 66

 Cosmopolitan
 Tropical and subtropical countries with warm and moist soil.

Answer 66

A. Trichuris trichiura

Question 67

Global
 604 to 795 million
o Children

Answer 67

A. Trichuris trichiura

Question 68

Phlippines
 4.5 to 55.1%
o preschool children
 8.1 to 57.9%
o school-age children

Answer 68

A. Trichuris trichiura

Question 69

 Natural host: Humans

Answer 69

A. Trichuris trichiura

Question 70

 morphologically similar worms are found to infect:
o pigs
o dogs
o some monkeys

Answer 70

A. Trichuris trichiura

Question 71

 At risk: ↑ children

Answer 71

A. Trichuris trichiura

Question 72

 Area: poor sanitation practices are common
o open defecation
o night soil as fertilizer

Answer 72

A. Trichuris trichiura

Question 73

 Mechanical vectors:
o House flies
o Cockroaches

Answer 73

A. Trichuris trichiura

Question 74

Symptoms
 severe protein-losing enteropathy and hypoalbuminemia
 malabsorption of fats and sugars
 decreased excretion of xylose
 low serum potassium, sodium and calcium
 high levels of IgE
 Serious cases may be fatal in 2 weeks to 2 months.

Answer 74

B. Capillaria philippinensis

Question 75

 Endemic
o Ilocos Norte, Ilocos Sur, Cagayan, La Union, Pangasinan, Zambales, Agusan del Norte, Leyte
o More:  Zamboanga del Norte
o Few:
 Zamboanga del Sur
 Agusan del Sur
 Misamis Occidental.

Answer 75

B. Capillaria philippinensis

Question 76

 Twice as many males as females become infected.

Answer 76

B. Capillaria philippinensis

Question 77

 Males are mostly fishermen who partake of the days catch.

Answer 77

B. Capillaria philippinensis

Question 78

 Definitive host/Reservoir: Fish-eating birds
 Intermediate host
o fresh or brackish water fish

Answer 78

B. Capillaria philippinensis

Question 79

 Migratory birds
o parasite is widely distributed throughout Asia and elsewhere

Answer 79

B. Capillaria philippinensis

Question 80

 deposition of eggs in the liver parenchyma causes:
o granuloma formation and liver necrosis, which in heavy infections can lead to potentially fatal liver dysfunction

Answer 80

C. Capillaria hepatica

Question 81

 Cosmopolitan in wildlife
o Human cases have originated from all inhabited continents except for Australia, although it exists in wildlife

Answer 81

C. Capillaria hepatica

Question 82

 The prevalence in humans may be underestimated due to the nonspecific clinical presentation and difficulty of diagnosis

Answer 82

C. Capillaria hepatica

Question 83

 Typical host: rodents such as rats
o has a low host specificity

Answer 83

C. Capillaria hepatica

Question 84

 Infections have also been identified in:
o wild and domestic carnivores o humans

Answer 84

C. Capillaria hepatica

Question 85

 contaminated food is ingested
 human feces are not the source of contamination
 feces of carnivores or flesh-eating rodents are involved

Answer 85

C. Capillaria hepatica

Question 86

 Other symptoms vary depending on the location and number of larvae present

Answer 86

D. Trichinella spiralis

Question 87

 Cosmopolitan
o most common in Europe and America
o rarely reported in the tropics

Answer 87

D. Trichinella spiralis

Question 88

 It occurs particularly in members of the meat-eating population but the prevalence is low

Answer 88

D. Trichinella spiralis

Question 89

 pig
 deer
 bear
 walrus
 rat

Answer 89

D. Trichinella spiralis

Question 90

 ingestion of contaminated pork scraps by pigs

Answer 90

D. Trichinella spiralis

Question 91

 ingestion of contaminated infected rats by pigs – ubiquitous in pig farms

Answer 91

D. Trichinella spiralis

Question 92

 ingestion of contaminated meat by other animals

Answer 92

D. Trichinella spiralis

Question 93

 ingestion of contaminated pork meat by humans
o Cooking meat to 60ºC or freezing (20 days in a normal freezer or at - 20°C for 3 days) will kill larvae.
o Smoking, salting or drying the meat does not destroy the infective larvae.

Answer 93

D. Trichinella spiralis

Question 94

The Trichinella cycle that is maintained in nature occurs among cannibalistic and carrion-feeding carnivores

Answer 94

D. Trichinella spiralis

Question 95

 Giant intestinal worm

Answer 95

A. Ascaris lumbricoides

Question 96

Infection is caused by ingestion of embryonated eggs.

Answer 96

A. Ascaris lumbricoides

Question 97

 Larvae invade the intestinal mucosa, and are carried via the portal, then systemic circulation on to the heart, then into the lungs

Answer 97

A. Ascaris lumbricoides

Question 98

 The larvae break out of the capillaries into the alveoli.

Answer 98

A. Ascaris lumbricoides

Question 99

 The larvae (L4s) mature further in the lungs (10-14 days), after a molt, penetrate the alveolar walls, ascend the bronchial tree to the throat, and are swallowed.

Answer 99

A. Ascaris lumbricoides

Question 100

 Upon reaching the small intestine, they develop into adult worms.

Answer 100

A. Ascaris lumbricoides

Question 101

 Between 2 and 3 months are required from ingestion of the infective eggs to oviposition by the adult female.

Answer 101

A. Ascaris lumbricoides

Question 102

 Adult worms can live 1 to 2 years.

Answer 102

A. Ascaris lumbricoides

Question 103

 Unfertilized eggs may be ingested but are not infective.

Answer 103

A. Ascaris lumbricoides

Question 104

 Larvae develop to infectivity within fertile eggs after 18 days to several weeks, depending on the environmental conditions (optimum: moist, warm, shaded soil).

Answer 104

A. Ascaris lumbricoides

Question 105

Clinical manifestations of ascariasis are caused by the (?) of the:
o Larvae
o adult worms in the small intestine
o wandering adult worms

Answer 105

pulmonary migratory phase

Question 106

The (?) causes allergic reaction.

Answer 106

larval migration

Question 107

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

Answer 107

lung migration phase

Question 108

 asthmatic respiration
 cough with bronchial rales
 chest pain

Answer 108

A. Ascaris lumbricoides

Question 109

These symptoms may be due to the petechial hemorrhages and massive destruction of the lung parenchyma as the larvae break through the capillaries on their way to the alveolar sacs, in massive infection, the hemorrhage may give rise to Ascaris pneumonitis.

Answer 109

A. Ascaris lumbricoides

Question 110

The pulmonary clinical features subside in 1 or 2 weeks after infection. Due to (?) in the blood stream, the larvae may lodge in vital organs such as the brain and spinal cord, the eyeball and the kidney.

Answer 110

larval migration

Question 111

Clinical manifestations due to adult worm vary from asymptomatic infection to severe and even fatal consequences.

Answer 111

A. Ascaris lumbricoides

Question 112

The (?), when present, are caused by spoliative action, toxic action, mechanical effects and wandering effects

Answer 112

pathological effects

Question 113

 The adult worms in the lumen of the small intestine feed on the liquid nutrient in the intestinal fluids.

Answer 113

A. Ascaris lumbricoides

Question 114

 The nutritional effects are usually seen when there is heavy worm burden.

Answer 114

A. Ascaris lumbricoides

Question 115

 The worms interfere with proper digestion and absorption of food.

Answer 115

A. Ascaris lumbricoides

Question 116

 Ascariasis may contribute to protein-energy malnutrition and vitamin A deficiency.

Answer 116

A. Ascaris lumbricoides

Question 117

The (?) are due to hypersensitivity to the worm antigens and may be manifested as fever, urticaria and edema.

Answer 117

toxic effects

Question 118

Ascariasis may cause complications due to (?). Masses of worms (Ascaris bolus) may cause intestinal obstruction.

Answer 118

mechanical effect

Question 119

(?) is a complication of ascariasis due to a few factors, e.g. fever, use of anesthesia during surgery, and worms seeking mates.

Answer 119

Ectopic migration

Question 120

 The worm may migrate up or down along the intestine.
o It may block the biliary or pancreatic ducts causing acute biliary obstruction or pancreatitis.

Answer 120

A. Ascaris lumbricoides

Question 121

 It may enter the liver parenchyma causing liver abscesses.

Answer 121

A. Ascaris lumbricoides

Question 122

 The worm may go up the esophagus and come out through the mouth, nose, or ears.
o It may obstruct the appendix causing appendicitis. It may lead to peritonitis when it perforates the intestine.

Answer 122

A. Ascaris lumbricoides

Question 123

 This tendency makes preoperative deworming necessary before gastrointestinal surgery in endemic areas. The wandering worm may also reach kidneys.

Answer 123

A. Ascaris lumbricoides

Question 124

 most common human helminthic infection

Answer 124

A. Ascaris lumbricoides

Question 125

 ↑ tropical and subtropical regions o 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

Answer 125

A. Ascaris lumbricoides

Question 126

 inadequate sanitation

Answer 126

A. Ascaris lumbricoides

Question 127

 rare to absent in developed countries

Answer 127

A. Ascaris lumbricoides

Question 128

 sporadic cases may occur in rural, impoverished regions of those countries

Answer 128

A. Ascaris lumbricoides

Question 129

 Some cases in these areas where human transmission is negligible have direct epidemiologic associations to pig farms.

Answer 129

A. Ascaris lumbricoides

Question 130

Global
 billion
 ↑ children
 co-exists with Trichuris trichiura

Answer 130

A. Ascaris lumbricoides

Question 131

Phlippines
 80-90%
 Risk group: public elementary school children

Answer 131

A. Ascaris lumbricoides

Question 132

 Ascaris lumbricoides – humans

Answer 132

A. Ascaris lumbricoides

Question 133

 Ascaris suum – humans and pigs

Answer 133

A. Ascaris lumbricoides

Question 134

 Fecal-oral route
 ↑ children
 Night-soil
 House-flies and cockroaches

Answer 134

A. Ascaris lumbricoides

Question 135

 Resistance of Ascaris eggs to chemicals – lipid layer of their eggshell
o 2%
 Formalin
 potassium dichromate
o 50%
 Hydrochloric
 Nitric
 Acetic
 Sulfuric acid

Answer 135

A. Ascaris lumbricoides

Question 136

 Pinworm, seatworm
 Former name: Oxyuris vermicularis

Answer 136

B. Enterobius vermicularis

Question 137

Infection occurs from ingestion of infective eggs

Answer 137

B. Enterobius vermicularis

Question 138

 These eggs hatch in the small intestine, and the adults establish themselves in the colon, usually in the cecum

Answer 138

B. Enterobius vermicularis

Question 139

 The time interval from ingestion of infective eggs to oviposition by the adult females is about one month.

Answer 139

B. Enterobius vermicularis

Question 140

 At full maturity adult females measure 8-13 mm, and adult males 2-5 mm; the adult life span is about two months.

Answer 140

B. Enterobius vermicularis

Question 141

 Gravid females migrate nocturnally outside the anus and oviposit while crawling on the skin of the perianal area.

Answer 141

B. Enterobius vermicularis

Question 142

 The larvae contained inside the eggs develop (the eggs become infective) in 4 to 6 hours under optimal conditions

Answer 142

B. Enterobius vermicularis

Question 143

? – infected individuals may reinfect themselves
 infective eggs are ingested via hand-to-mouth contamination due to scratching of perianal area with fingers → deposition of eggs under the nails.
o ↑ children

Answer 143

Autoinfection

Question 144

 eggs laid on the perianal skin immediately hatch into the infective stage larva and migrate through the anus → develop into worms in the cecum

Answer 144

Retroinfection

Question 145

 one-third are asymptomatic

Answer 145

Enterobiasis or oxyuriasis

Question 146

 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
o scratching and irritation of the skin around the anus
o may give rise to secondary bacterial infection
o Children infected – insomnia due to the pruritus

Answer 146

Enterobiasis or oxyuriasis

Question 147

 poor appetite
 weight loss
 irritability
 nocturnal enuresis (involuntary urination)
 grinding of teeth
 abdominal pain

Answer 147

B. Enterobius vermicularis

Question 148

not associated with eosinophilia or with elevate lgE

Answer 148

B. Enterobius vermicularis

Question 149

In female patients
 worms may cause (?) when they crawl into the vulva and vagina causing irritation

Answer 149

ectopic migration

Question 150

 It may migrate up to the uterus and fallopian tubes

Answer 150

B. Enterobius vermicularis

Question 151

 This may cause symptoms of:
o Cervicitis o chronic salpingitis o peritonitis o recurrent urinary tract infections

Answer 151

B. Enterobius vermicularis

Question 152

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

Answer 152

B. Enterobius vermicularis

Question 153

 Cosmopolitan
o both temperate and tropical areas

Answer 153

B. Enterobius vermicularis

Question 154

Global
 ↑ temperate regions and urban areas
 Enterobiasis – most common helminth infection in the United States

Answer 154

B. Enterobius vermicularis

Question 155

Phlippines
 29% - schoolchildren from exclusive private schools
 56% - public schools
 16% - females
 9% - males

Answer 155

B. Enterobius vermicularis

Question 156

 Natural host: Humans

Answer 156

B. Enterobius vermicularis

Question 157

 Rare: airborne – inhaled and swallowed

Answer 157

B. Enterobius vermicularis

Question 158

 anus-to-mouth
o contaminated fingers or other objects in the mouth
o inhalation of dust containing Enterobius eggs

Answer 158

B. Enterobius vermicularis

Question 159

 cool moist conditions – eggs remains viable for about 2 weeks

Answer 159

B. Enterobius vermicularis

Question 160

 warm, dry conditions – eggs begin to lose their infectivity within 2 days

Answer 160

B. Enterobius vermicularis

Question 161

Factors:
 Overcrowding
 wearing soiled clothing
 lack of adequate bathing and poor personal hygiene
o especially among young school-aged children
 Finger sucking and nail biting
o may be sources of recurrent infection in children
 sexual activity o oral and anal sex
 extremely contagious and can easily spread among members of a family or in institutions o familial or a group disease

Answer 161

B. Enterobius vermicularis

Question 162

Two (2) species of hookworms are human parasites:
 Necator americanus - New world hookworm
 Ancylostoma duodenale - Old world hookworm

Answer 162

C. Hookworms

Question 163

Infection occurs from penetration of filariform larvae (L3) larvae

Answer 163

C. Hookworms

Question 164

 Infective stage are filariform larvae (L3) that penetrate the skin and are carried through the blood vessels to the heart and then to the lungs.
o penetrate into the pulmonary alveoli
o ascend the bronchial tree to the pharynx
o are swallowed o reach the jejunum of the small intestine
 reside and mature into adults

Answer 164

C. Hookworms

Question 165

 Adult worms 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)

Answer 165

C. Hookworms

Question 166

 Eggs are passed in the stool, and under favorable conditions

Answer 166

C. Hookworms

Question 167

 Larvae hatch in 1 to 2 days and become free-living in contaminated soil.
o These released rhabditiform (L1) larvae grow in the feces and/or the soil, and after 5 to 10 days (and two molts) they become filariform (third-stage) larvae that are infective

Answer 167

C. Hookworms

Question 168

Hookworm disease (?) manifests three main phases of pathogenesis

Answer 168

necatoriasis or ancylostomiasis

Question 169

 filariform larvae penetrate skin

Answer 169

the invasion or cutaneous period

Question 170

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

Answer 170

the invasion or cutaneous period

Question 171

 usual sites of infection:
o the dorsum of the feet or between the toe
o the hands, especially interdigital spaces

Answer 171

the invasion or cutaneous period

Question 172

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

Answer 172

the invasion or cutaneous period

Question 173

 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

Answer 173

the invasion or cutaneous period

Question 174

 Erythematous papular rash develops when a large number of larvae penetrate the skin.
o This is a self-limiting condition, lasting for 2 to 4 weeks

Answer 174

the invasion or cutaneous period

Question 175

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

Answer 175

the migration or pulmonary phase

Question 176

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

Answer 176

the migration or pulmonary phase

Question 177

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

Answer 177

the migration or pulmonary phase

Question 178

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

Answer 178

the migration or pulmonary phase

Question 179

 Asymptomatic

Answer 179

the intestinal phase

Question 180

 Attachment of the worms to the mucosa with their strong buccal capsule and teeth or cutting plates may stimulate:
o Abdominal pain
o Nausea
o Anorexia

Answer 180

the intestinal phase

Question 181

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

Answer 181

the intestinal phase

Question 182

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

Answer 182

the intestinal phase

Question 183

 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.

Answer 183

the intestinal phase

Question 184

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

Answer 184

the intestinal phase

Question 185

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

Answer 185

the intestinal phase

Question 186

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

Answer 186

the intestinal phase

Question 187

 Cosmopolitan

Answer 187

C. Hookworms

Question 188

 N. americanus – tropical Africa and the Americas

Answer 188

C. Hookworms

Question 189

 A. duodenale – Europe and Southwestern Asia

Answer 189

C. Hookworms

Question 190

 But now, both species have become widely distributed throughout the tropics and subtropics, and rigid demarcations are no longer present

Answer 190

C. Hookworms

Question 191

Global
 25%

Answer 191

C. Hookworms

Question 192

Phlippines
 5-45%

Answer 192

C. Hookworms

Question 193

 N. americanus – 97%
 A. duodenale – 1%
 mixed infections – 2%

Answer 193

C. Hookworms

Question 194

 Principal host: Humans

Answer 194

C. Hookworms

Question 195

 percutaneous transmission of filariform larvae from the soil

Answer 195

necatoriasis and ancylostomiasis

Question 196

 oral route
o eating raw vegetables contaminated with infective filariform larvae
o A. duodenale may remain dormant in the intestines or in the muscles, resulting in a prolonged incubation period and creating problems in treatment.
 Transmammary
o larvae are able to pass into the mammary glands of the mother, so that the newborn baby can receive a large dose of infective larvae through its mother’s milk
o cases of heavy and sometimes fatal hookworm infections in children a month or so of age

Answer 196

ancylostomiasis

Question 197

 Ancylostoma caninum (dog hookworm)
 Ancylostoma braziliense (cat hookworm)

Answer 197

D. Zoonotic hookworms

Question 198

 The larvae produce itching papules, which develop into serpigenous tracks in the epidermis called (?) or creeping eruption.
o These tracts can elongate by several centimeters a day; larvae can migrate for upto one year until they die, but the lesions usually heal spontaneously within weeks to months.
o Secondary pyogenic infection may occur at these sites.

Answer 198

cutaneous larva migrans (CLM)

Question 199

 Definitive host: dogs and cats

Answer 199

D. Zoonotic hookworms

Question 200

 Threadworm
o UK and Australia – pinworm or seatworm (Enterobius vermicularis)

Answer 200

E. Strongyloides stercoralis

Question 201

 Free-living cycle - Heterogonic cycle
 Parasitic cycle - Homogonic

Answer 201

E. Strongyloides stercoralis

Question 202

 Rhabditiform larvae in the gut become infective filariform larvae that can penetrate either the intestinal mucosa (internal autoinfection) or the skin of the perianal and perineal area (external autoinfection).

Answer 202

Autoinfection

Question 203

 They ultimately enter the lymphatics or venules and are carried to the right heart and the lungs to complete the life cycle as earlier, or disseminate throughout the body

Answer 203

Autoinfection

Question 204

 benign and asymptomatic

Answer 204

Strongyloidiasis

Question 205

 only indications of infection
o Eosinophilia and larvae in stool

Answer 205

Strongyloidiasis

Question 206

 In immunocompromised individuals, it may cause clinical manifestations which may be severe and even fatal

Answer 206

Strongyloidiasis

Question 207

 filariform larvae may enter blood circulation and lodge in various organs, e.g. heart, lungs, brain, kidneys, pancreas, liver and lymph nodes

Answer 207

Disseminated strongyloidiasis

Question 208

• dermatitis, with erythema and itching at the site of penetration of the filariform larva, particularly when large numbers of larvae enter the skin

Answer 208

Cutaneous manifestations

Question 209

• larva currens (meaning racing larvae) has been applied to the rapidly progressing linear or serpiginous urticarial tracks caused by migrating filariform larvae

Answer 209

Cutaneous manifestations

Question 210

• often follow autoinfection and start perianally

Answer 210

Cutaneous manifestations

Question 211

• This rash usually advances very rapidly (up to 10 cm/hr)

Answer 211

Cutaneous manifestations

Question 212

• When the larva escape from the pulmonary capillaries into the alveoli, small hemorrhages may occur in the alveoli and bronchioles.
  Pneumonia and Loeffler’s syndrome may be present in some patients.

Answer 212

Pulmonary manifestations

Question 213

• This may present as malabsorption syndrome.
  Diarrhea is often present.

Answer 213

Intestinal manifestations

Question 214

• In heavy infection, there may be extensive sloughing of the intestinal mucosa.

Answer 214

Intestinal manifestations

Question 215

 internal autoinfection in immunocompromised

Answer 215

Hyperinfection

Question 216

 large number of worms in the intestine and lungs

Answer 216

individuals

Question 217

 Other manifestations include:
o protein losing enteropathy
o paralytic ileus

Answer 217

E. Strongyloides stercoralis

Question 218

 Clinical manifestations depend on the sites affected:
o Brain abscess
o meningitis and peritonitis

Answer 218

E. Strongyloides stercoralis

Question 219

 Cosmopolitan
o tropics and subtropics
o Europe and the USA
o follows a distribution pattern similar to hookworm

Answer 219

E. Strongyloides stercoralis

Question 220

Global
 Unknown
 Estimate: 30–100 million

Answer 220

E. Strongyloides stercoralis

Question 221

Phlippines
 relatively rare

Answer 221

E. Strongyloides stercoralis

Question 222

Host
 Humans

Answer 222

E. Strongyloides stercoralis

Question 223

 Rarer human-infecting species of Strongyloides zoonotics:
o S. fuelleborni (fülleborni) subsp. fuelleborni
o S. fuelleborni subsp. kellyi

Answer 223

E. Strongyloides stercoralis

Question 224

 direct contact with soil contaminated by Strongyloides larvae

Answer 224

E. Strongyloides stercoralis

Question 225

 area: poor sanitation
o feces are disposed in the warm moist soil
o provide an optimal atmosphere for the organism to exist

Answer 225

E. Strongyloides stercoralis

Question 226

 allows for maintenance of the parasite within the host for years following the initial exposure

Answer 226

Autoinfection

Question 227

 Toxocara canis - dog ascarid
 Toxocara cati - cat ascarid

Answer 227

F. Toxocara spp.

Question 228

Ingesting infective eggs or undercooked meat/viscera of infected paratenic hosts

Answer 228

F. Toxocara spp.

Question 229

 Humans are accidental hosts

Answer 229

F. Toxocara spp.

Question 230

 eggs hatch

Answer 230

F. Toxocara spp.

Question 231

 larvae penetrate the intestinal wall and are carried by the circulation to a variety of tissues (liver, heart, lungs, brain, muscle, eyes)

Answer 231

F. Toxocara spp.

Question 232

Toxocara spp. can follow a [?] (one host) or [?] (multiple host) life cycle.

Answer 232

direct
indirect

Question 233

 Unembryonated eggs are shed in the feces of the definitive host.

Answer 233

F. Toxocara spp.

Question 234

 Eggs embryonate over a period of 1 to 4 weeks in the environment and become infective, containing thirdstage (L3) larvae.

Answer 234

F. Toxocara spp.

Question 235

 Following ingestion by a definitive host, the infective eggs hatch and larvae penetrate the gut wall

Answer 235

F. Toxocara spp.

Question 236

In younger dogs (T. canis) and in cats (T. cati):
 the larvae migrate through the lungs, bronchial tree, and esophagus, where they are coughed up swallowed into the gastrointestinal tract
 adult worms develop and oviposit in the small intestine

Answer 236

direct (one host)

Question 237

In older dogs, patent (egg-producing) infections can also occur
 larvae more commonly become arrested in tissues
 Arrested larvae are reactivated in female dogs during late gestation and may infect pups by the transplacental (major) and transmammary (minor) routes in whose small intestine adult worms become established

Answer 237

direct (one host)

Question 238

In cats, T. cati:
 larvae can be transmitted via the transmammary route to kittens if the dam is infected during gestation
 somatic larval arrest and reactivation does not appear to be important as in T. canis

Answer 238

direct (one host)

Question 239

 ingestion of paratenic hosts

Answer 239

indirect (multiple host)

Question 240

 Eggs ingested by suitable paratenic hosts hatch and larvae penetrate the gut wall and migrate into various tissues where they encyst

Answer 240

indirect (multiple host)

Question 241

 The life cycle is completed when definitive hosts consume larvae within paratenic host tissue, and the larvae develop into adult worms in the small intestine

Answer 241

indirect (multiple host)

Question 242

 preschool children

Answer 242

visceral larva migrans (VLM)

Question 243

 larvae invade multiple tissues
o commonly liver
o lung
o skeletal muscle
o occasionally heart

Answer 243

visceral larva migrans (VLM)

Question 244

 cause various nonspecific symptoms
o fever
o myalgia
o weight los
o cough
o rashes
o hepatosplenomegaly
 usually accompanied by hypereosinophilia

Answer 244

visceral larva migrans (VLM)

Question 245

 Migration to the central nervous system

Answer 245

neurotoxocariasis or neural larva migrans

Question 246

 Uncommon

Answer 246

neurotoxocariasis or neural larva migrans

Question 247

 eosinophilic meningoencephalitis

Answer 247

neurotoxocariasis or neural larva migrans

Question 248

 Death
o severe cardiac
o pulmonary
o neurologic involvement

Answer 248

neurotoxocariasis or neural larva migrans

Question 249

 larvae produce various ophthalmologic lesions

Answer 249

(OLM)

Question 250

 may cause diffuse unilateral subacute neuroretinitis (DUSN)
o unilateral (affecting one eye) involvement

Answer 250

(OLM)

Question 251

associated visual impairment usually presents with
 uveitis, retinitis, or endophthalmitis
 permanent visual damage or blindness

Answer 251

F. Toxocara spp.

Question 252

associated larval granulomas
 misdiagnosed as retinoblastoma

Answer 252

F. Toxocara spp.

Question 253

 Cosmopolitan
o among domestic dogs and cats

Answer 253

F. Toxocara spp.

Question 254

 both animals and people
o ↑ developing countries

Answer 254

F. Toxocara spp.

Question 255

 people of lower socioeconomic strata
o ↑ developed countries

Answer 255

F. Toxocara spp.

Question 256

 Public places: 10-30%

Answer 256

F. Toxocara spp.

Question 257

 western countries: 25% to 30 to 60% (dogs)

Answer 257

F. Toxocara spp.

Question 258

 Accidental hosts: Humans

Answer 258

F. Toxocara spp.

Question 259

 all wild and domestic canids
 puppies
o patent infections

Answer 259

Toxocara canis

Question 260

 wild and domestic felids of all ages
 kittens
o patent infections

Answer 260

Toxocara cati

Question 261

Paratenic hosts: mammals and birds; livestock
Paratenic or transport hosts: Cockroaches and earthworms

Answer 261

F. Toxocara spp.

Question 262

 soil-transmitted zoonosis

Answer 262

Human toxocariasis

Question 263

 ↑ children living in homes and in neighborhoods where dogs and puppies are not dewormed o tendency to play in soil o geophagia or soil eating

Answer 263

Human toxocariasis

Question 264

 Poor personal hygiene

Answer 264

Human toxocariasis

Question 265

 consumption of inadequately washed vegetables chronic low-dose infections

Answer 265

Human toxocariasis

Question 266

 consumption of undercooked beef, lamb, chicken, and duck meat (particularly liver)

Answer 266

Human toxocariasis