GI Nematodes Flashcards
Nematodes also called?
Roundworms
Key soil-transmitted helminths? Spell them
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
Ascariasis lumbricoides most commonly affects? life cycle? appearance?
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
Main clinical features of ascaris ? What is lofflers syndrome? Key complications that are rare in other soil helminths?
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
Ascaris dx?
Stool microscopy for eggs
Pneumonitis is dx on clinical grounds
Ascaris Rx?
Mebendazole 100mg BD for 3 days
Or Albendazole 400mg single dose (may need repeated if heavy infection
Can use Nitazoxanide
Ascaris prevention
Hygine and sanitation
Education - Ie not using human excrement for fertilizer
Mass chemo
Hookworm appearance and life cycle
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
Why anaemia and hypoproteinaemia in hookworm
Woms consume approx 0.1ml (0.3 for necator) per day
Also get blood and plasma protein loss at site of attachment
Presentation hookworm
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
Hookworm Dx
Eosinophilia
Stool microscopy for eggs
Rx hookworm
Albendazole 3 days
Whipworm name? size? features?
Trichuris trichiura
2-5cm
Often Asx, iron deficiency anaemia
Severe infection -> dysentery and rectal prolapse
Can also cause appendicitis
Trichuris trichiura dx ? rx?
Obvious if rectal prolapse and visible worms
Stool microscopy otherwise for eggs
Mebendazole best
nitrazoxanide also works
toxocariasis 2 main species?
Usually affects?
T canis and T cati (from dogs and cats)
Usually affects children - due to consumption of soil contaminated by dog/cat faeces
2 main syndromes of toxocariasis infection? Rx?
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
Which helminths can multiply in host?
Aww SCHET they’re multiplying
Strongyloides stercolis
capillaria phillipinensis
hymenolepis nana
[enterobius vermicularis
trichuris trichiura]
Most common worm infection
Ascaris
Pin worm name? Lifecycle
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
Enterobius vermicularis DX
Peri-anal skin sticky spatula then microscopy
Pinworm (Enterobius vermicularis ) rx?
Mebendazole / albendazole
Then repeat dose after 2 weeks
Complications of Enterobius vermicularis
Female adult worm may enter vagina -> may lay eggs in cervix / fallopian tubes -> abscess
Cause granuloma
Appendicitis
Trichuris trichiura life cycle
whipworms in caecum and lay eggs which mature in soil over 2-4 weeks
Ingested
Then larvae invade intestinal mucosa crypts
Most common cause of lofflers syndrome
Ascaris
Which worm causes obstruction ? why do kids have obstruction more commonly
Ascaris - Looks like a big tangle of worms
They have smaller bowels
‘my child passed a big brown worm’
Ascaris
Which worm causing biliary obstruction? Rx?
Ascaris
ERCP
If kill it with Mebe/albendazole the worm may just die there and obstruction persists
Bar through skin how else can you be infected by hookworm
Also can penetrate oesophagal mucosa
-[ie Can be oral]
Anaemia in hookworm 2 causes
Parasites drink blood
Has to detach from area as it gets necrotic and then will bleed a little
Main issue with many worm Rx in returning traveller eg schisto
Only kills adult worm - (doesn’t affect larvae)
-> should wait 8 weeks after exposure for Rx in returning traveller
Intestinal nematodes rx generally
Mebendazole or Albendazole
Which GI nematode is most sensitive to therapy
Ascaris
Which drug for biliary obstruction caused by asaris used sometiems
Piperazine - paralyses ascaris -> helps with removal attempt surgery / ERCP
Hookworm best choice of Rx for community mass chemo
Albendazole
Trichuris trichiura best single-agent
Mebendazole
Community worm reduction measured using
reduction in prevalence
CR - cure rate
reduction in eggs/gram
ERR - egg reduction rate
When mass chemo for worms
Yearly if prevalence >20%
6m if >50%
Difference between mass chemo and individual patient rx of worms? Agent for ascaris vs hookworm vs trichuris ?
Mass - single dose
Individual - 3 days
Ascaris: Either MBZ/ABZ
* Hookworm: albendazole better
* Trichuris: Mebendazole
Who contraindicated for MBZ/ABZ/
1st trimester Pregnant [try and wait til 2nd trimester]
<1yr
1-2 years can have a reduced dose
Main worms going through skin
Hookworm
Stronglyotides
Strongyloides life cycle?
Infectious stage?
Filariaform larvae L3 [not rhabditiform]
-Rhabditiform may become filariaform and autoinfect
Eggs laid in intestine and quickly hatch into L1 larvae
L1 rhabditiform strongy
Oesophagal bulb
diagnostic stage
L3 filariform strongy - infective
Why important to differentiate filariform and rhabditiform strongy in lab ?
Filiariaform means autoinfection is taking place
Risks for strongy hyperinfection ? which cytokines important?
corticosteroids, cancer, HTLV-1
TH-2 and IL-5 key
Strongy with this means?
Larva currens
Autoinfection likely
Stongy with cough and wheeze syndrome
Löffler syndrome
cough
shortness of breath
wheezing
pulmonary interstitial infiltrates
eosinophilia
Strongy hyperinfection key issues
GI - Obstruction, ulceration, enteritis, protein-loosing enteropathy, GI bleed.
Lung involment more porminent
CNS: sepsis + meningitis
Mechanism of corticosteroid therapy causing strongy
reduced eosinophil numbers (Th2 cell apoptosis, decreased IL-5)
[early lymphocyte death (decreased IL-2)
poor mast cell responses in small bowel]
Better method for strongy diagnosis than stool microscopy
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
Stongy serology issue for diagnosis
does not distinguish between current or previous infection
Strongy Rx
Ivermectin for 2 days, then repeat dose after 2 weeks
What infection is strongyloidiasis hyperinfection strongly assoc with?
HTLV-1
Papa new guinea - children with swollen belly have which particular sub group of strongyloidiasis
strongyloidiasis fulleborni
[Fulle Belly in a recently Borni]
strongyloidiasis life cycle and appearance
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
Only soil-transmitted helminth that can multiply while living in soil?
strongyloidiasis
How can strongyloidiasis persist for decades?
Auto reinfection.
Occationally the larvae turn into infective ones and penetrate mucosa / perianal skin to start cycle again.
Acute strongyloidiasis symptoms ?
-May have itchy site where enters skin
-occational cough and wheeze
-vauge abdo pain and diarrhoea
Why are eosinophils often normal in chronic strongyloidiasis
Become immune tolerant
Also strongy inhibits IL5
(virtually) pathognomic feature of strongyloidiasis? explain it
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
What happens if you have strongyloidiasis and then become immunocompromised? Eg post transplant.
Sx?
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
strongyloidiasis control
footwear
Screen those who may require immunosuppressive therapy
Enterobius vermicularis eggs
L-1 (rhabditoid) Strongy
L-1 (rhabditoid) Strongy
L-3 (filariform)) Strongy
Itchy bum at night what is a complication? Key Ix? Rx?
Vulvovaginitis. Paddle or tape test (AM)
Treat all household members (-bendazoles)
rx?
Trichuris trichiura
-Note key DDx of egg
Mebendazole > Albendazole
Ascaris lumbricoides
(unfertilised)
Ancylostoma duodenale / Necator americanus
Who am I
Ascaris
Ancyclostoma duodenale (sharp teeth)
Necator americanis (cutting plate)
Surface of nematodes called
Cuticle
Whats the red arrow pointing to?
Spicule (strongy)
Whats this showing?
Spicule - Trichuris Trichiura
Develops cough and wheeze. Blood film shows this - whats most likely?
Loeffler Syndrome - Eosinophilia
Ascaris > hookworms > Strongyloides
Develops cough and wheeze. Blood film shows this - whats most likely?
Loeffler Syndrome - Eosinophilia
Ascaris > hookworms > Strongyloides
NASA mneumonic
Necator, Ancylostoma, S rongyloides, Ascaris
Trichuris trichiura: barrel shaped , thick, shell, mucus plug at both poles. Bile stained
Trichuris trichiura
Ascaris lumbricoides
Unfertilized egg
Ascaris lumbricoides
Fertilized egg
Mamillated
Ascaris lumbricoides
Fertilized egg
Decorticated
Enterobius vermicularis
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.
Hookworm egg
Ancylostoma duodenale
Necator americanus
Feal oral egg transmission helminths
EATT
Enterobius vermicularis
Ascaris lumbricoides
Trichuris trichiura
Toxocara canis/catis
Name 2 medications causing eosinophilia
antibiotics (e.g. beta l actams , quinolones , sulfas)
NSAIDS,
anti epileptic drugs
H2 blockers
Name 3 infections other than helminths causing eosinophilia
Bronchopulmonary aspergillosis
Coccidioidomycosis
Scabies,
Myiasis
Cystoisospora
Congenital toxoplasmosis
HIV (allergies, eosinophilic folliculitis
Name 2 non infectious causes of eosinophilia
Contact dermatitis / psoriasis
IBD
Asthma
Hypereosinophilic syndrome
Malignancy
Drug reaction
65F immigrant from Cambodia 20 y prior
Notes mild abdominal pain
Raised eosinophils. Stool O&P negative
Strongyloides stercoralis
Larva currens (Strongyloidies stercoralis)
