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MHD2 > Block 7 (GI) - L12 to L13 > Flashcards

Block 7 (GI) - L12 to L13 Flashcards

1
Q

In general, helminths do not multiply in humans. What are the two exceptions?

A
  1. Strongyloids

2. Hymenolepsis nana

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2
Q

The severity of disease caused by helminths is related to what factor?

A

The worm burden (# of worms acquired at time of infection)

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3
Q

What is a definitive host?

A

Host in which the adult develops and reproduces sexually (often humans)

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4
Q

What is an intermediate host?

A

Any animal in which various stages of larval development occur (insect, crustacean, other vertebrae)

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5
Q

What are the three classifications of helminths?

A
  1. Nematodes (roundworms)
  2. Cestodes (segmented tapeworms)
  3. Trematodes (flatworms or flukes)
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6
Q

How are intestinal nematodes acquired (be specific)?

A

Skin: Strongyloides and Hookworm
Ingestion: Ascaris, VLM, Enterobius, Trichuris

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7
Q

How do intestinal nematodes travel through the human (be specific)?

A

Lung migration: Strongyloides, Hookworm, Ascaris

Intestine only: Ascaris, Enterobius, Trichuris

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8
Q

Which intestinal nematodes are acquired by passage through the skin?

A

Strongyloides and Hookworm

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9
Q

Where is Strongyloides stercoralis located geographically?

A

Worldwide in tropical and subtropical areas

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10
Q

Describe the life cycle of Strongyloides stercoralis.

A

Filariform larva penetrate the skin, migrate to the lungs, coughed up and swallowed, ultimately to the small bowel, where ova hatch and are passed in the stool as rhabditiform larva.

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11
Q

Which two helminths can complete their life cycles in human beings and thus cause autoinfection?

A
  1. Strongyloides stercoralis

2. Hymenolpesis nana

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12
Q

Describe the symptoms of Strongyloides with lung migration.

A

Cough, wheezing, fever

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13
Q

Describe the symptoms of Strongyloides (light infection).

A

Asymptomatic

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14
Q

Describe the symptoms of Strongyloides (moderate-heavy infection).

A

Dysentery, fever, anemia, weight loss, peritonitis

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15
Q

Describe the symptoms of Strongyloides (hyper-infection syndrome).

A

Dysentery, pneumonia, GN sepsis (tends to occur in people who are immunocompromised)

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16
Q

Describe the symptoms of Strongyloides (chronic infection).

A

Creeping eruption

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17
Q

How is Strongylodies diagnosed?

A
  1. Marked eosinophilia
  2. Rhabditiform larvae in stool
  3. Serology
  4. PCR
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18
Q

How is Strongyloides treated?

A

Ivermectin (2nd line - Albendazole); No treatment is NOT an option

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19
Q

What are the two types of hookworms and where are they found geographically?

A

Ancylostoma duodonale and Necator americanus

Worldwide (tropical and subtropical)

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20
Q

Describe the life cycle of Hookworms.

A

Ova passed in feces, hatches to rhabdidiform larva in soil, which penetrates the skin

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21
Q

What are the symptoms of infection with Hookworm?

A
  1. Ground itch (kind of papular dermatitis on lower extremities)
  2. Light - asymptomatic
  3. Moderate to heavy - GI symptoms, iron deficiency anemia (hypochromic, microcytic)
  4. Lung migration - asthma
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22
Q

How is Hookworm diagnosed?

A
  1. On differential with microcytic anemia

2. Ova in feces

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23
Q

How is Hookworm diagnosed?

A
  1. Albendazole, Mebendazole, pyrantel pamoate (kill worms)

2. Iron (repletion)

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24
Q

Which intestinal nematodes are acquired by ingestion?

A
  1. Ascaris lumbricoides
  2. VLM
  3. Enterobius
  4. Trichuris
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25
Q

Where is Ascaris found geographically?

A

Worldwide, very common due to female passing 200,000+ ova/day

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26
Q

How does Ascaris resist environmental rigors?

A

Mamillated coating of ova

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27
Q

Discuss the life cycle of Ascaris.

A

Ova passed in feces are ingested, can migrate to lungs

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28
Q

What are the clinical manifestations of Ascaris?

A
  1. Asthma (lung migration)
  2. Light - asymptomatic, may pass worm
  3. Moderate/heavy - intestinal or biliary obstruction, aberrant migration to nose or skin
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29
Q

How is Ascaris diagnosed?

A
  1. Ova (easy to find, characteristic morphology)

2. X-ray/Barium study

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30
Q

How is Ascaris treated?

A

Albendazole, Mebendazole, Ivermectin, Nitazoxanide

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31
Q

What is the characteristic morphology of Ascaris ova?

A

Thick, mammillated, tree bark appearance

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32
Q

What are the larva migrans and where are they found?

A
  1. Toxocara canis - Ascarid worm of dog
  2. Toxocara catis - Ascarid worm of cat
  3. Baylisascaris procyonis - Ascarid of raccoon

Humans are an accidental host

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33
Q

What is the life cycle of VLM?

A

Children ingest embryonated ova from the stool of an animal;; larva wander in viscera

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34
Q

Where do larva wander to in Toxicariasis?

A

Liver, heart, kidney, eye

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35
Q

Where do larva wander to in Baylisascaris (in particular)?

A

Brain, spinal cord

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36
Q

What is the pathogenesis of larva migrans?

A

Wandering larvae produce hemorrhage and inflammation, leading to eosinophilic infiltration and granulomas

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37
Q

What are the manifestations of visceral larva migrans?

A

Fever, hepatomegaly, pulmonary infiltrates and bronchospasm, myalgia and arthralgia, eosinophilia

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38
Q

What are the manifestations of ocular larva migrans?

A

Eye pain, visual disturbance

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39
Q

What are the manifestations of neural larva migrans?

A

Fever, lethargy, ataxia, leading to sezures, coma, and death

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40
Q

How is VLM diagnosed?

A
  1. Eosinophilia
  2. Larva in tissue
  3. Serology
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41
Q

How is VLM treated?

A

Self-limited, but can give anti-helminths (unclear if effective)

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42
Q

Where is Enterobius (pinworm) found geographically?

A

Worldwide (cosmopolitan)

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43
Q

What is the life cycle of Enterobius?

A

Ova ingested, develop in intestine, female migrates to perianal region to deposit eggs, transmitted (anus or fomites, inhalation of dust, retroinfection)

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44
Q

What are the symptoms of Enterobius?

A
  1. Perianal and perineal itching
  2. GI and GU granuloma
  3. Appendix
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45
Q

How is Enterobius diagnosed?

A
  1. Visualization of ova
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46
Q

How is Enterobius treated?

A

Albendazole, mebendazole, pyrantel pamoate

Other family members should be tested

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47
Q

Where is Trichuris trichiura located?

A

Worldwide, common in tropics

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48
Q

What is the life cycle of Trichuris trichiura?

A

Ingest ova, develop in intestines only (embed in colonic surface)

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49
Q

What are the symptoms of Trichuris trichiura?

A
  1. Light - asymptomatic

2. Heavy - diarrhea, abdominal pain, rectal prolapse, anemia

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50
Q

How is Trichuris trichiura diagnosed?

A
  1. Ova in feces

2. Characteristic morhpology

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51
Q

How is Trichuris trichuria treated?

A

Mebendazole

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52
Q

Describe the characteristic morphology of Trichuris trichiura ova.

A

Polar plugs

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53
Q

What does Trichinella spiralis infect?

A

Carnivorous animals (rat, swine, bear)

54
Q

Where is Trichinella spiralis found geographically?

A

Worldwide (cosmopolitan)

55
Q

What is the life cycle of Trichinella spiralis?

A
  1. Acquired by ingestion of larvae encysted in undercooked pork (bear, wild game)
  2. Adult female in intestine bears larvae close to blood or lymphatic vessels
  3. Larvae enter cells throughout the body
56
Q

What are the three phases of trichinosis?

A
  1. Intestinal: 24-72 hours, diarrhea, nausea, vomiting, abdominal pain
  2. Migration and Encystment: 7-42+ days (usually 2-3 weeks), fever, muscle pain, tenderness, headache, periorbital edema, cough, dyspnea, death
  3. Recovery
57
Q

Phase II of trichinosis is ___-dependent.

A

Inoculum

58
Q

How is trichinosis diagnosed?

A
  1. Symptom triad - fever, eosinophilia, muscle pain (measure muscle enzymes)
  2. Serology
  3. Biopsy of muscle (calcified cysts)
59
Q

How is trichinosis treated?

A

Mebendazole or albendazole (add steroids if severe)

60
Q

Describe the life cycle of Angiostrongylus cantonensis.

A
  1. Matures in the lung of the rat, eggs hatch and larvae are passed in feces
  2. Transmitted to snails (intermediate hosts)
  3. Humans ingest larvae
61
Q

What does Angiostrongylus cantonensis cause?

A

Eosinophilic meningitis

62
Q

What are the symptoms of eosinophilic meningitis?

A

2-4 weeks after ingestion - headache, fatigue, meningeal signs, hyperesthesia or paraesthesia, vomiting, diarrhea, fever

63
Q

How is eosinophilic meningitis diagnosed?

A

Eosinophils and larvae in CSF, Ab in CSF or serum

64
Q

How is eosinophilic meningitis treated?

A

No specific treatment - albendazole/mebendazole possibly effective + corticosteroids

65
Q

What causes filarial infections?

A

Arthropod-transmitted nematodes

66
Q

What two helminths cause lymphatic filariasis? What is the life cycle?

A
  1. Wuchereria bancrofti
  2. Brugia malayi

Larvae transmitted by several mosquito types

Adults in lymphatics produce larvae which circulate in blood

67
Q

Discuss the clinical symptoms of lymphatic filariasis.

A
  1. Majority are asymptomatic (immune system does not respond)
  2. Acute - lymphangitis and lymphadenitis (self-limited but may recur)
  3. Chronic - lymphatic destruction (obstruction and chronic lymphedema)
  4. Tropical pulmonary eosinophilia (nocturnal cough and wheezing)
68
Q

How is lymphatic filariasis diagnosed?

A
  1. Eosinophilia
  2. Blood smears
  3. Serology
  4. Ag detection
69
Q

How is lymphatic filarisis treated?

A
  1. Diethylcarbamazine (kills microfilaria)
  2. Doxycycline (sterilizes adult female, leading to decreased microfilariae)
  3. Not effective in chronic obstructive disease
70
Q

What is the life cycle of Onchocerca volvulus?

A
  1. Adults form nodules in subcutaneous tissues
  2. Microfilariae migrate in subcutaneous tissues
  3. Blackfly takes blood meal, ingests larvae, which develop
  4. Blackfly takes a second blood meal (repeat)
71
Q

What is the vector of Onchocerca volvulus?

A

Black fly simulium

72
Q

What causes the signs and symptoms of onchocerciasis?

A

Dead or dying microfilariae

73
Q

Describe the clinical manifestation of onchocerciasis.

A
  1. Subcutaneous nodules (painless)
  2. Dermatitis (reaction to Ag on circulating microfilariae, destroys supporting structures, leads to sagging, aged skin)
  3. Eye (keratitis with fibrosis leads to blindness)
74
Q

How is onchocerciasis diagnosed?

A
  1. Biopsy (skin snips)
  2. PCR
  3. Serology
  4. Test strips
  5. Eosinophila
75
Q

How is onchocerciasis treated?

A

Ivermectin every 6-12 months

76
Q

What is the vector of loa loa?

A

Tabinid fly Chrysops

77
Q

Describe the life cycle of loa loa.

A
  1. Larvae develop in subcutaneous tissue
  2. Microfilariae migrate to blood
  3. Fly takes blood meal, ingests larvae
  4. Fly takes second blood meal (repeat)
78
Q

What are the symptoms of loa loa?

A
  1. Painful calabar swellings
  2. Allergic symptoms (pruritis, asthma, hypereosinophilia)
  3. Worm in conjunctivae
79
Q

How is loa loa diagnosed?

A
  1. Microfilariae in blood smear
  2. Adult in subcutaneous nodule or eye
  3. Serology
  4. PCR
80
Q

How is loa loa treated?

A
  1. Diethylcarbamazine (side effects with large worm burden)

2. Surgery

81
Q

What is Dracunculus medinensis?

A

Guinea worm (not a filarial worm)

82
Q

Describe the life cycle of Dracunculus mediensis.

A
  1. Copepods ingest larvae
  2. Larvae are swallowed with infected copepods
  3. Larvae are found in SI, where they enter the abdominal wall and subcutaneous tissue and migrate
  4. Larvae pass into water, released from blisters
83
Q

What are the symptoms of Dracunculus medinensis?

A

Blister, leading to a chronic, painful sore (can become infected secondarily)

84
Q

How is Dracunculus diagnosed?

A
  1. See worm in skin

2. X-ray

85
Q

How is Dracunuclus treated?

A
  1. Surgical removal of the worm

2. Metronidazole or mebendazole

86
Q

How is Dracunulus prevented?

A
  1. Replace step in wells with pump
87
Q

List the cestodes (tapeworms).

A
  1. Taenia saginata
  2. Taenia solium
  3. Diphyllobothrium latum
  4. Hymenolpesis nana
  5. Echinococcus granulosis
88
Q

What is the larval form of pork tapeworm?

A

Cysticercosis

89
Q

Describe the life cycle of taenia saginata.

A
  1. Cysticerci are ingested with raw or undercooked beef.
  2. Cysticerci are released from muscle in the stomach
  3. Worms mature in the small intestine
  4. Adults live in the small intestine, where they grow
  5. Proglottids pass in feces
  6. Embronated eggs are ingested, larvae migrate to tissues and become cysticerci (found in muscle)

Same for Taenia solium, which are found in pigs

90
Q

What are signs and symptoms of infection with tapeworms, generally?

A

Asymptomatic

91
Q

What specific clinical manifestation is seen with T. saginata?

A

Anal discomfort

92
Q

What specific clinical manifestation is seen with H. nana?

A

Enteritis

93
Q

What specific clinical manifestation is seen with D. latum?

A

B12 deficiency anemia

94
Q

What is cysticercosis?

A

Infection with larval form of T. solium after ingestion of ova from human feces. Larvae form cysts, especially in CNS and subcutaneous tissue

95
Q

What are the symptoms of cerebral cysticercosis?

A

Meningoencephalitis and hydrocephalus, seizures

96
Q

How are cestodes diagnosed?

A
  1. Ova or proglottids in feces
  2. PCR
  3. MRI/CT/X-ray/Biopsy/Serology for cysticercosis
97
Q

How are cestodes treated?

A

Praziquantel (Niclosamide is 2nd line)

98
Q

How is Cysticercosis treated?

A

Albendazole and Praziquantel

99
Q

How is D. latum acquired?

A

Ingestion of encysted fish

100
Q

How is H. nana acquired?

A

Ingestion of ova or flea

101
Q

What are the definitive hosts of E. granulosis?

A

Dogs, cats, foxes

102
Q

What are the intermediate hosts of E. granulosis?

A

Sheep, cattle, pigs, camels, goats

103
Q

How are humans infected with E. granulosis?

A

Ingestion of ova from canine feces

104
Q

What is the life cycle of E. granulosus?

A
  1. Eggs are ingested.

2. Larvae hatch in small intestine, where they penetrate and develop cysts in liver/other organs.

105
Q

What are the definitive hosts of E. multilocularis?

A

Sylvatic canines (fox)

106
Q

What is the intermediate host of E. multilocularis?

A

Rodents

107
Q

Echincoccal disease is associated with areas where ___ is common.

A

Sheep husbandry

108
Q

How does E. granulosis present?

A

Slowly enlarging, space-occupying cysts in the liver, lung, bone, and kidney

109
Q

How does E. multilocularis present?

A

Poorly formed cyst, spreads like malignancy

110
Q

How is Echinococcus diagnosed?

A
  1. Imaging (ultrasound, CT, MRI)
  2. Serology
  3. Ag in cyst fluid
111
Q

How is Echinococcus treated?

A

Staged approach based on imaging (surgical removal of cyst, percutaneous drainage of cyst, treatment with albendazole)

112
Q

How is Schistosoma mansoni transmitted?

A
  1. Cecariae enter skin
  2. Schistosmula migrate to lungs, then to liver
  3. Adults mate in the liver and migrate to the mesenterics
  4. Eggs are passed into the small intestine and the feces (end up in water)
  5. Eggs hatch in water; miracidia penetrate snail (repeat)
113
Q

How is Schistosoma haematobium transmitted?

A
  1. Schistosmula migrate to lungs, then to liver
  2. Adults mate in the liver and migrate to the bladder
  3. Eggs pass into urine, end up in water
  4. Eggs hatch in water; miracidia penetrate snail (repeat)
114
Q

Discuss the pathobiology of Schistosomiasis.

A

Adults absorb host protein and avoid immune elimination

Ova cause intense fibrosis with granuloma formation

115
Q

Broadly, what is caused by Schistosomiasis?

A

Katayama fever - acute fever, cough, lymphadenopathy, hepatosplenomagly

116
Q

What is caused by S. mansoni and S. japonicum?

A

Periportal fibrosis and portal HTN (ascites, variceal bleeding); hepatic synthetic function is preserved

117
Q

What is caused by S. haematobium?

A

Urinary fibrosis (voiding symptoms due to non-distensible bladder and inflammation, obstructive uropathy, late association with bladder cancer)

118
Q

Schistosomiasis can migrate to the ___.

A

CNS (encephalopathy, myelopathy)

119
Q

How is Schistosomiasis diagnosed?

A
  1. Characteristic ova in feces or urine
  2. Rectal biopsy crush preparation
  3. PCR
  4. Serology
120
Q

How is Schistosomiasis treated?

A

Praziquantel

121
Q

What is cercarial dermatitis?

A

Accidental infection of human swimmers with avian schistosome; cercaria penetrate skin but cannot develop an further

Causes papular dermatitis with intense itching

122
Q

What is Chlonorchis?

A

Liver fluke

123
Q

What is the life cycle of Chlonorchis?

A
  1. Ingest metacercariae with raw or undercooked infected fish
  2. Larva hatch in small intestine and migrate to bile duct, where they mature.
  3. Eggs are passed in feces and eaten by snails
  4. Cercaria leaves the snail and encysts on fish (repeat)
124
Q

How does Clornorchis sinensis present?

A

Usually asymptomatic

Can present with obstructive biliary tract disease and is associated with cholangiocarcinoma

125
Q

How is Clonorchis diagnosed?

A

Ova in feces and seroogy

126
Q

How is Clornorchis treated?

A

Praziquantel

127
Q

What is Paragonimu?

A

Lung fluke

128
Q

What is the life cycle of Paragonimus westermani?

A

Same as Clornorchis, but cercariae are transmitted to a crab rather than a fish

129
Q

Describe the clinical presentation of Paragonimus westermani.

A

Cough, hemoptysis, chronic pneumonia, lung abscess, pleural empyema, progressive bronchitis, bronchietctasis, pulmonary fibrosis

130
Q

How is Paragonimus diagnosed?

A

Ova in sputum or feces, serology

131
Q

How is Paragonimus treated?

A

Praziquantel or Triclabendazole

MHD2 (34 decks)

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