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Tropical medicine - All clinical images copyright Gorgas course - : Instituto de Medicina Tropical Alexander von Humboldt > GI Nematodes > Flashcards

GI Nematodes Flashcards

1
Q

Nematodes also called?

A

Roundworms

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2
Q

Key soil-transmitted helminths? Spell them

A

Roundworm - As-caris lum-bri-colides
Whipworm - Trich-uris trich-iura
Hookworms - An-cylo-stoma duodenale and Necator americanus
Strongy-loides

They do NOT multiply in the host (bar strongy

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3
Q

Ascariasis lumbricoides most commonly affects? life cycle? appearance?

A

Children
Due to consumption of contaminated food. Pass through intestinal wall -> lungs [mature over 10-14 days]

Then migrate to the oesophagus and intestine where they mate and produce eggs after approx 10 weeks
200K eggs per day per worm
which become embryonated egg with larva in faeces
[Non fertilised eggs will not infect]

cream coloured worms 15-40cm (females are longer than males)
Produce 200k eggs/day which can survive in soil for years

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4
Q

Main clinical features of ascaris ? What is lofflers syndrome? Key complications that are rare in other soil helminths?

A

Pneumonitis While migrate through lungs - fever, cough, wheeze (occasionally haemoptysis)
-Lofflers is ascarisis pneumonitis + eosinophilia

Adult worms in GI
-Can cause malabsorbtion
-Intestinal obstruction +/- perf - common in kids
-Biliary obstruction - common in adults
-Pancreatic obstruction
Obstruction is due to bolus of worms in heavy infection

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5
Q

Ascaris dx?

A

Stool microscopy for eggs
Pneumonitis is dx on clinical grounds

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6
Q

Ascaris Rx?

A

Mebendazole 100mg BD for 3 days
Or Albendazole 400mg single dose (may need repeated if heavy infection

Can use Nitazoxanide

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7
Q

Ascaris prevention

A

Hygine and sanitation
Education - Ie not using human excrement for fertilizer
Mass chemo

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8
Q

Hookworm appearance and life cycle

A

1cm tubes which attach to intestinal mucosa via suction
-Fully grown after 2-3weeks
-Lay eggs which are passed in stool
-Hatch in soil and L3 form infect humans
-Goes through skin
-Migrates to lungs then get swallowed

Ancylostoma duodenale is larger than necator americanus

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9
Q

Why anaemia and hypoproteinaemia in hookworm

A

Woms consume approx 0.1ml (0.3 for necator) per day
Also get blood and plasma protein loss at site of attachment

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10
Q

Presentation hookworm

A

Iron deficiency anaemia - accounts for 40% in endemic regions
Vauge abdo sx
cutaneous lava migrans at site of entry (serpiginous rash) if not a. Duo or N. ame

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11
Q

Hookworm Dx

A

Eosinophilia
Stool microscopy for eggs

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12
Q

Rx hookworm

A

Albendazole 3 days

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13
Q

Whipworm name? size? features?

A

Trichuris trichiura
2-5cm
Often Asx, iron deficiency anaemia

Severe infection -> dysentery and rectal prolapse
Can also cause appendicitis

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14
Q

Trichuris trichiura dx ? rx?

A

Obvious if rectal prolapse and visible worms
Stool microscopy otherwise for eggs

Mebendazole best

nitrazoxanide also works

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15
Q

toxocariasis 2 main species?
Usually affects?

A

T canis and T cati (from dogs and cats)
Usually affects children - due to consumption of soil contaminated by dog/cat faeces

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16
Q

2 main syndromes of toxocariasis infection? Rx?

A

Visceral larva migrans
-Pneumonitis, fever, abdo pain, hepatosplenomegaly,… with anaemia eosinophilia and hypergamaglobulinaaemia
-Rx with Albendazole for 5 days

Ocular larva migrans
-granuloma in retina -> visual disturbance / blindness
-Rx with steroids and -azoles
-Often mistaken for retinoblastoma

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17
Q

Which helminths can multiply in host?

A

Aww SCHET they’re multiplying

Strongyloides stercolis
capillaria phillipinensis
hymenolepis nana
[enterobius vermicularis
trichuris trichiura]

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18
Q

Most common worm infection

A

Ascaris

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19
Q

Pin worm name? Lifecycle

A

Entero-bius vermicularis

Adult worms live in the distal small intestine
Male and female mate ->
At night female lays eggs on the perianal skin after 4 weeks
Eggs mature after only 6 hrs

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20
Q

Enterobius vermicularis DX

A

Peri-anal skin sticky spatula then microscopy

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21
Q

Pinworm (Enterobius vermicularis ) rx?

A

Mebendazole / albendazole
Then repeat dose after 2 weeks

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22
Q

Complications of Enterobius vermicularis

A

Female adult worm may enter vagina -> may lay eggs in cervix / fallopian tubes -> abscess

Cause granuloma

Appendicitis

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23
Q

Trichuris trichiura life cycle

A

whipworms in caecum and lay eggs which mature in soil over 2-4 weeks
Ingested
Then larvae invade intestinal mucosa crypts

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24
Q

Most common cause of lofflers syndrome

A

Ascaris

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25
Q

Which worm causes obstruction ? why do kids have obstruction more commonly

A

Ascaris - Looks like a big tangle of worms
They have smaller bowels

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26
Q

‘my child passed a big brown worm’

A

Ascaris

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27
Q

Which worm causing biliary obstruction? Rx?

A

Ascaris
ERCP
If kill it with Mebe/albendazole the worm may just die there and obstruction persists

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28
Q

Bar through skin how else can you be infected by hookworm

A

Also can penetrate oesophagal mucosa
-[ie Can be oral]

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29
Q

Anaemia in hookworm 2 causes

A

Parasites drink blood
Has to detach from area as it gets necrotic and then will bleed a little

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30
Q

Main issue with many worm Rx in returning traveller eg schisto

A

Only kills adult worm - (doesn’t affect larvae)
-> should wait 8 weeks after exposure for Rx in returning traveller

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31
Q

Intestinal nematodes rx generally

A

Mebendazole or Albendazole

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32
Q

Which GI nematode is most sensitive to therapy

A

Ascaris

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33
Q

Which drug for biliary obstruction caused by asaris used sometiems

A

Piperazine - paralyses ascaris -> helps with removal attempt surgery / ERCP

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34
Q

Hookworm best choice of Rx for community mass chemo

A

Albendazole

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35
Q

Trichuris trichiura best single-agent

A

Mebendazole

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36
Q

Community worm reduction measured using

A

reduction in prevalence
CR - cure rate

reduction in eggs/gram
ERR - egg reduction rate

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37
Q

When mass chemo for worms

A

Yearly if prevalence >20%
6m if >50%

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38
Q

Difference between mass chemo and individual patient rx of worms? Agent for ascaris vs hookworm vs trichuris ?

A

Mass - single dose
Individual - 3 days

Ascaris: Either MBZ/ABZ
* Hookworm: albendazole better
* Trichuris: Mebendazole

39
Q

Who contraindicated for MBZ/ABZ/

A

1st trimester Pregnant [try and wait til 2nd trimester]
<1yr

1-2 years can have a reduced dose

40
Q

Main worms going through skin

A

Hookworm
Stronglyotides

41
Q

Strongyloides life cycle?
Infectious stage?

A

Filariaform larvae L3 [not rhabditiform]
-Rhabditiform may become filariaform and autoinfect

Eggs laid in intestine and quickly hatch into L1 larvae

42
Q
A

L1 rhabditiform strongy
Oesophagal bulb
diagnostic stage

43
Q
A

L3 filariform strongy - infective

44
Q

Why important to differentiate filariform and rhabditiform strongy in lab ?

A

Filiariaform means autoinfection is taking place

45
Q

Risks for strongy hyperinfection ? which cytokines important?

A

corticosteroids, cancer, HTLV-1

TH-2 and IL-5 key

46
Q

Strongy with this means?

A

Larva currens
Autoinfection likely

47
Q

Stongy with cough and wheeze syndrome

A

Löffler syndrome

cough
shortness of breath
wheezing
pulmonary interstitial infiltrates
eosinophilia

48
Q

Strongy hyperinfection key issues

A

GI - Obstruction, ulceration, enteritis, protein-loosing enteropathy, GI bleed.

Lung involment more porminent

CNS: sepsis + meningitis

49
Q

Mechanism of corticosteroid therapy causing strongy

A

reduced eosinophil numbers (Th2 cell apoptosis, decreased IL-5)

[early lymphocyte death (decreased IL-2)
poor mast cell responses in small bowel]

50
Q

Better method for strongy diagnosis than stool microscopy

A

Baermann method
-Cheap and quick
- Faeces are suspended in water. The larvae move into the water. They sink to the bottom and can be collected for identification.

Agar plate culture
-culture stools for 5-7 d
-presence of larvae bacteria grows
along larvae moving tracks
-more sensitive (96%) than Baermann

51
Q

Stongy serology issue for diagnosis

A

does not distinguish between current or previous infection

52
Q

Strongy Rx

A

Ivermectin for 2 days, then repeat dose after 2 weeks

53
Q

What infection is strongyloidiasis hyperinfection strongly assoc with?

A

HTLV-1

54
Q

Papa new guinea - children with swollen belly have which particular sub group of strongyloidiasis

A

strongyloidiasis fulleborni

[Fulle Belly in a recently Borni]

55
Q

strongyloidiasis life cycle and appearance

A

2mm worms live in small intestine (females in mucosa)
-Eggs hatch and release non-infective larvae which are released in faeces.
- Develop into worms in soil which then produce a second round of larvae
[This stage may be repeated many times]
-Humans infected through penetration of skin of this second generation
-Skin-> lungs where they are swallowed

56
Q

Only soil-transmitted helminth that can multiply while living in soil?

A

strongyloidiasis

57
Q

How can strongyloidiasis persist for decades?

A

Auto reinfection.
Occationally the larvae turn into infective ones and penetrate mucosa / perianal skin to start cycle again.

58
Q

Acute strongyloidiasis symptoms ?

A

-May have itchy site where enters skin
-occational cough and wheeze
-vauge abdo pain and diarrhoea

59
Q

Why are eosinophils often normal in chronic strongyloidiasis

A

Become immune tolerant
Also strongy inhibits IL5

60
Q

(virtually) pathognomic feature of strongyloidiasis? explain it

A

larva currens - due to autoreinfection
- raised line (serpiginous wheal) surrounded by a erythema (flare)
-Moves quickly and comes and goes within hours
-Very itchy and confined to trunk usually

61
Q

What happens if you have strongyloidiasis and then become immunocompromised? Eg post transplant.
Sx?

A

Get hyperinfection syndrome - due to rapid increase in worms which invade many other tissues

-Bloody diarrhoea - abdo inflammation and micro perfs
-peritonitis
-Pulm eg haemoptysis
-Meningioencepahlitis

62
Q

strongyloidiasis control

A

footwear

Screen those who may require immunosuppressive therapy

63
Q
A

Enterobius vermicularis eggs

64
Q
A

L-1 (rhabditoid) Strongy

64
Q
A

L-1 (rhabditoid) Strongy

65
Q
A

L-3 (filariform)) Strongy

66
Q

Itchy bum at night what is a complication? Key Ix? Rx?

A

Vulvovaginitis. Paddle or tape test (AM)
Treat all household members (-bendazoles)

67
Q

rx?

A

Trichuris trichiura
-Note key DDx of egg

Mebendazole > Albendazole

68
Q
A

Ascaris lumbricoides
(unfertilised)

69
Q
A

Ancylostoma duodenale / Necator americanus

70
Q

Who am I

A

Ascaris

71
Q
A

Ancyclostoma duodenale (sharp teeth)

72
Q
A

Necator americanis (cutting plate)

73
Q

Surface of nematodes called

A

Cuticle

74
Q

Whats the red arrow pointing to?

A

Spicule (strongy)

75
Q

Whats this showing?

A

Spicule - Trichuris Trichiura

76
Q

Develops cough and wheeze. Blood film shows this - whats most likely?

A

Loeffler Syndrome - Eosinophilia
Ascaris > hookworms > Strongyloides

77
Q

Develops cough and wheeze. Blood film shows this - whats most likely?

A

Loeffler Syndrome - Eosinophilia
Ascaris > hookworms > Strongyloides

NASA mneumonic
Necator, Ancylostoma, S rongyloides, Ascaris

78
Q
A

Trichuris trichiura: barrel shaped , thick, shell, mucus plug at both poles. Bile stained

79
Q
A

Trichuris trichiura

80
Q
A

Ascaris lumbricoides
Unfertilized egg

81
Q
A

Ascaris lumbricoides
Fertilized egg
Mamillated

82
Q
A

Ascaris lumbricoides
Fertilized egg
Decorticated

83
Q
A

Enterobius vermicularis

84
Q
A

Ancylostoma duodenale / Necator americanus
Egg - : transparent thin shell , multicellular embryo (4 8/16 cells), blunt rounded ends.
There is a clear space between the segmented ovum and the shell.

85
Q
A

Hookworm egg

86
Q
A

Ancylostoma duodenale

87
Q
A

Necator americanus

88
Q

Feal oral egg transmission helminths

A

EATT

Enterobius vermicularis
Ascaris lumbricoides
Trichuris trichiura
Toxocara canis/catis

89
Q

Name 2 medications causing eosinophilia

A

antibiotics (e.g. beta l actams , quinolones , sulfas)
NSAIDS,
anti epileptic drugs
H2 blockers

90
Q

Name 3 infections other than helminths causing eosinophilia

A

Bronchopulmonary aspergillosis
Coccidioidomycosis
Scabies,
Myiasis
Cystoisospora
Congenital toxoplasmosis
HIV (allergies, eosinophilic folliculitis

91
Q

Name 2 non infectious causes of eosinophilia

A

Contact dermatitis / psoriasis
IBD
Asthma
Hypereosinophilic syndrome
Malignancy
Drug reaction

92
Q

65F immigrant from Cambodia 20 y prior
Notes mild abdominal pain
Raised eosinophils. Stool O&P negative

A

Strongyloides stercoralis

93
Q
A

Larva currens (Strongyloidies stercoralis)

Tropical medicine - All clinical images copyright Gorgas course - : Instituto de Medicina Tropical Alexander von Humboldt (26 decks)

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