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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
Where is Ascaris found geographically?
Worldwide, very common due to female passing 200,000+ ova/day
26
How does Ascaris resist environmental rigors?
Mamillated coating of ova
27
Discuss the life cycle of Ascaris.
Ova passed in feces are ingested, can migrate to lungs
28
What are the clinical manifestations of Ascaris?
1. Asthma (lung migration) 2. Light - asymptomatic, may pass worm 3. Moderate/heavy - intestinal or biliary obstruction, aberrant migration to nose or skin
29
How is Ascaris diagnosed?
1. Ova (easy to find, characteristic morphology) | 2. X-ray/Barium study
30
How is Ascaris treated?
Albendazole, Mebendazole, Ivermectin, Nitazoxanide
31
What is the characteristic morphology of Ascaris ova?
Thick, mammillated, tree bark appearance
32
What are the larva migrans and where are they found?
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
33
What is the life cycle of VLM?
Children ingest embryonated ova from the stool of an animal;; larva wander in viscera
34
Where do larva wander to in Toxicariasis?
Liver, heart, kidney, eye
35
Where do larva wander to in Baylisascaris (in particular)?
Brain, spinal cord
36
What is the pathogenesis of larva migrans?
Wandering larvae produce hemorrhage and inflammation, leading to eosinophilic infiltration and granulomas
37
What are the manifestations of visceral larva migrans?
Fever, hepatomegaly, pulmonary infiltrates and bronchospasm, myalgia and arthralgia, eosinophilia
38
What are the manifestations of ocular larva migrans?
Eye pain, visual disturbance
39
What are the manifestations of neural larva migrans?
Fever, lethargy, ataxia, leading to sezures, coma, and death
40
How is VLM diagnosed?
1. Eosinophilia 2. Larva in tissue 3. Serology
41
How is VLM treated?
Self-limited, but can give anti-helminths (unclear if effective)
42
Where is Enterobius (pinworm) found geographically?
Worldwide (cosmopolitan)
43
What is the life cycle of Enterobius?
Ova ingested, develop in intestine, female migrates to perianal region to deposit eggs, transmitted (anus or fomites, inhalation of dust, retroinfection)
44
What are the symptoms of Enterobius?
1. Perianal and perineal itching 2. GI and GU granuloma 3. Appendix
45
How is Enterobius diagnosed?
1. Visualization of ova
46
How is Enterobius treated?
Albendazole, mebendazole, pyrantel pamoate Other family members should be tested
47
Where is Trichuris trichiura located?
Worldwide, common in tropics
48
What is the life cycle of Trichuris trichiura?
Ingest ova, develop in intestines only (embed in colonic surface)
49
What are the symptoms of Trichuris trichiura?
1. Light - asymptomatic | 2. Heavy - diarrhea, abdominal pain, rectal prolapse, anemia
50
How is Trichuris trichiura diagnosed?
1. Ova in feces | 2. Characteristic morhpology
51
How is Trichuris trichuria treated?
Mebendazole
52
Describe the characteristic morphology of Trichuris trichiura ova.
Polar plugs
53
What does Trichinella spiralis infect?
Carnivorous animals (rat, swine, bear)
54
Where is Trichinella spiralis found geographically?
Worldwide (cosmopolitan)
55
What is the life cycle of Trichinella spiralis?
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
What are the three phases of trichinosis?
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
Phase II of trichinosis is ___-dependent.
Inoculum
58
How is trichinosis diagnosed?
1. Symptom triad - fever, eosinophilia, muscle pain (measure muscle enzymes) 2. Serology 3. Biopsy of muscle (calcified cysts)
59
How is trichinosis treated?
Mebendazole or albendazole (add steroids if severe)
60
Describe the life cycle of Angiostrongylus cantonensis.
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
What does Angiostrongylus cantonensis cause?
Eosinophilic meningitis
62
What are the symptoms of eosinophilic meningitis?
2-4 weeks after ingestion - headache, fatigue, meningeal signs, hyperesthesia or paraesthesia, vomiting, diarrhea, fever
63
How is eosinophilic meningitis diagnosed?
Eosinophils and larvae in CSF, Ab in CSF or serum
64
How is eosinophilic meningitis treated?
No specific treatment - albendazole/mebendazole possibly effective + corticosteroids
65
What causes filarial infections?
Arthropod-transmitted nematodes
66
What two helminths cause lymphatic filariasis? What is the life cycle?
1. Wuchereria bancrofti 2. Brugia malayi Larvae transmitted by several mosquito types Adults in lymphatics produce larvae which circulate in blood
67
Discuss the clinical symptoms of lymphatic filariasis.
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
How is lymphatic filariasis diagnosed?
1. Eosinophilia 2. Blood smears 3. Serology 4. Ag detection
69
How is lymphatic filarisis treated?
1. Diethylcarbamazine (kills microfilaria) 2. Doxycycline (sterilizes adult female, leading to decreased microfilariae) 3. Not effective in chronic obstructive disease
70
What is the life cycle of Onchocerca volvulus?
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
What is the vector of Onchocerca volvulus?
Black fly simulium
72
What causes the signs and symptoms of onchocerciasis?
Dead or dying microfilariae
73
Describe the clinical manifestation of onchocerciasis.
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
How is onchocerciasis diagnosed?
1. Biopsy (skin snips) 2. PCR 3. Serology 4. Test strips 5. Eosinophila
75
How is onchocerciasis treated?
Ivermectin every 6-12 months
76
What is the vector of loa loa?
Tabinid fly Chrysops
77
Describe the life cycle of loa loa.
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
What are the symptoms of loa loa?
1. Painful calabar swellings 2. Allergic symptoms (pruritis, asthma, hypereosinophilia) 3. Worm in conjunctivae
79
How is loa loa diagnosed?
1. Microfilariae in blood smear 2. Adult in subcutaneous nodule or eye 3. Serology 4. PCR
80
How is loa loa treated?
1. Diethylcarbamazine (side effects with large worm burden) | 2. Surgery
81
What is Dracunculus medinensis?
Guinea worm (not a filarial worm)
82
Describe the life cycle of Dracunculus mediensis.
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
What are the symptoms of Dracunculus medinensis?
Blister, leading to a chronic, painful sore (can become infected secondarily)
84
How is Dracunculus diagnosed?
1. See worm in skin | 2. X-ray
85
How is Dracunuclus treated?
1. Surgical removal of the worm | 2. Metronidazole or mebendazole
86
How is Dracunulus prevented?
1. Replace step in wells with pump
87
List the cestodes (tapeworms).
1. Taenia saginata 2. Taenia solium 3. Diphyllobothrium latum 4. Hymenolpesis nana 5. Echinococcus granulosis
88
What is the larval form of pork tapeworm?
Cysticercosis
89
Describe the life cycle of taenia saginata.
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
What are signs and symptoms of infection with tapeworms, generally?
Asymptomatic
91
What specific clinical manifestation is seen with T. saginata?
Anal discomfort
92
What specific clinical manifestation is seen with H. nana?
Enteritis
93
What specific clinical manifestation is seen with D. latum?
B12 deficiency anemia
94
What is cysticercosis?
Infection with larval form of T. solium after ingestion of ova from human feces. Larvae form cysts, especially in CNS and subcutaneous tissue
95
What are the symptoms of cerebral cysticercosis?
Meningoencephalitis and hydrocephalus, seizures
96
How are cestodes diagnosed?
1. Ova or proglottids in feces 2. PCR 3. MRI/CT/X-ray/Biopsy/Serology for cysticercosis
97
How are cestodes treated?
Praziquantel (Niclosamide is 2nd line)
98
How is Cysticercosis treated?
Albendazole and Praziquantel
99
How is D. latum acquired?
Ingestion of encysted fish
100
How is H. nana acquired?
Ingestion of ova or flea
101
What are the definitive hosts of E. granulosis?
Dogs, cats, foxes
102
What are the intermediate hosts of E. granulosis?
Sheep, cattle, pigs, camels, goats
103
How are humans infected with E. granulosis?
Ingestion of ova from canine feces
104
What is the life cycle of E. granulosus?
1. Eggs are ingested. | 2. Larvae hatch in small intestine, where they penetrate and develop cysts in liver/other organs.
105
What are the definitive hosts of E. multilocularis?
Sylvatic canines (fox)
106
What is the intermediate host of E. multilocularis?
Rodents
107
Echincoccal disease is associated with areas where ___ is common.
Sheep husbandry
108
How does E. granulosis present?
Slowly enlarging, space-occupying cysts in the liver, lung, bone, and kidney
109
How does E. multilocularis present?
Poorly formed cyst, spreads like malignancy
110
How is Echinococcus diagnosed?
1. Imaging (ultrasound, CT, MRI) 2. Serology 3. Ag in cyst fluid
111
How is Echinococcus treated?
Staged approach based on imaging (surgical removal of cyst, percutaneous drainage of cyst, treatment with albendazole)
112
How is Schistosoma mansoni transmitted?
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
How is Schistosoma haematobium transmitted?
2. Schistosmula migrate to lungs, then to liver 3. Adults mate in the liver and migrate to the bladder 4. Eggs pass into urine, end up in water 5. Eggs hatch in water; miracidia penetrate snail (repeat)
114
Discuss the pathobiology of Schistosomiasis.
Adults absorb host protein and avoid immune elimination Ova cause intense fibrosis with granuloma formation
115
Broadly, what is caused by Schistosomiasis?
Katayama fever - acute fever, cough, lymphadenopathy, hepatosplenomagly
116
What is caused by S. mansoni and S. japonicum?
Periportal fibrosis and portal HTN (ascites, variceal bleeding); hepatic synthetic function is preserved
117
What is caused by S. haematobium?
Urinary fibrosis (voiding symptoms due to non-distensible bladder and inflammation, obstructive uropathy, late association with bladder cancer)
118
Schistosomiasis can migrate to the ___.
CNS (encephalopathy, myelopathy)
119
How is Schistosomiasis diagnosed?
1. Characteristic ova in feces or urine 2. Rectal biopsy crush preparation 3. PCR 4. Serology
120
How is Schistosomiasis treated?
Praziquantel
121
What is cercarial dermatitis?
Accidental infection of human swimmers with avian schistosome; cercaria penetrate skin but cannot develop an further Causes papular dermatitis with intense itching
122
What is Chlonorchis?
Liver fluke
123
What is the life cycle of Chlonorchis?
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
How does Clornorchis sinensis present?
Usually asymptomatic Can present with obstructive biliary tract disease and is associated with cholangiocarcinoma
125
How is Clonorchis diagnosed?
Ova in feces and seroogy
126
How is Clornorchis treated?
Praziquantel
127
What is Paragonimu?
Lung fluke
128
What is the life cycle of Paragonimus westermani?
Same as Clornorchis, but cercariae are transmitted to a crab rather than a fish
129
Describe the clinical presentation of Paragonimus westermani.
Cough, hemoptysis, chronic pneumonia, lung abscess, pleural empyema, progressive bronchitis, bronchietctasis, pulmonary fibrosis
130
How is Paragonimus diagnosed?
Ova in sputum or feces, serology
131
How is Paragonimus treated?
Praziquantel or Triclabendazole

MHD2 (34 decks)

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