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LSHTM > Zoonotic nematodes > Flashcards

Zoonotic nematodes Flashcards

1
Q

Trichinella spp - species names

A

7 species:
T spiralis
T britovi
T nativa
T nelson
T murrelli
T pseudospiralis
T papuae

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2
Q

Trichinella spp - distribution

A

Worldwide

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3
Q

Trichinella spp - lifecycle

A

Parasite of meat eaters
Infective larvae [L1] in muscle tissue of infected carnivorous and omnivorous animals
When ingested - larvae emerge in duodenum
Females = 2-4mm // Males = 1-2mm
Adults bury into intestinal mucosa
Females produce L1 larvae - intestinal wall - lymphatics and blood - skeletal muscles = penetrate striated muscle cell - transform into a nurse cell containing coiled L1 larvae [cysts] - intracellular larvae
Cysts calcify but larvae remain dormant

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4
Q

Trichinella spp - source of infection

A

Domestic pigs and rats [humans dead-end host]

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5
Q

Trichinella spp - acute phase clinical features

A

Acute phase:

2-7 days = GI symptoms - diarrhea, N+V

7-21 days = acute inflammatory response to larval migration in striated muscle
-Fever, myalgia, oedema - typically of tongue and eyelids

May also present:
-Myocarditis 5-20%
-Pneumonitis
-Larvae in CNS
-Vasculitis

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6
Q

Trichinella spp - chronic phase clinical features

A

Chronic inflammatory cysts
Calcification - persistent impaired muscle strength

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7
Q

Trichinella spp - diagnosis

A

Clinical:
-Fever, muscle pain, swollen eyelids

Lab:
-Eosinophilia
-Serum creatinine kinase and LDH
-Serology = ELISA, western blot

Parasitological:
-Muscle biopsy squash from 4 weeks

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8
Q

Trichinella spp - treatment

A

Once encapsulated = very resistant to antihelminthics

Post-exposure prophylaxis = albendazole or mebendazole given within 6 days

Chronic stage = high daily doses of benzimidazoles for extended periods

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9
Q

Capillaria philipinensis - distribution

A

Most cases - Philippines, Thailand, Taiwan, Japan

mostly middle-aged men

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10
Q

Capillaria philipinensis - lifecycle

A

Normal definitive host = marine birds

Embryonated eggs eaten by fish
Infective larvae develop in fish
Ingestion of undercooked fish
Can cause internal autoinfection

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11
Q

Capillaria philipinensis - clinical

A

Symptoms - related to worm burden:
-Diarrhea, abdominal pain, weight loss, protein and electrolyte loss

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12
Q

Capillaria philipinensis - treatment

A

Mebendazole or albendazole

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13
Q

Toxocara spp - diseases

A

Toxocariasis
Visceral larva migrans
Ocular larva migrans

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14
Q

Toxocara spp - species

A

T canis
T cati

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15
Q

Toxocara spp - distribution

A

Worldwide

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16
Q

Toxocara spp - transmission

A

Ingestion of infective stages

17
Q

Toxocara spp - lifecycle

A

Adult wormsn in intestine of puppies and young dogs
Immature eggs passed
Infective in 2-4 weeks [L2 stage]
In puppies <5 weeks = heart-lung cycle followed by GI

In adult dogs = arrest at L2 stage but can infect puppies in utero

In humans = L2 migrate in body and eventually die

18
Q

Toxocara spp - clinical

A

Toxocariasis
Mild subclinical febrile illness

Visceral larva migrans:
-Migration of larvae through internal organs
-Mainly children <5 years
-Death of larvae provoke strong inflammatory response
-Non-specific symptoms

Ocular larva migrans:
-Older children and young adults
-Granuloma formation leading to unilateral visual loss, retinal fibrosis, retinal detachment

19
Q

Toxocara spp - diagnosis

A

Clinical
Tissue biopsy
ELISA

20
Q

Toxocara spp - treatment

A

Albendazole +/- steroids

21
Q

Angiostrongylus cantonensis [rat lung worm] - disease

A

Eosinophilic meningitis

22
Q

Angiostrongylus cantonensis [rat lung worm] - distribution

A

South Asia, China, Pacific, Australia

23
Q

Angiostrongylus cantonensis [rat lung worm] - transmission

A

Undercook snails and slugs
Infected paratenic hosts - shrimps, prawns, mussels
Salads and other leafy vegetables containing small snail

24
Q

Angiostrongylus cantonensis [rat lung worm] - lifecycle

A

Humans:
Larvae 2mm migrate to brain, lungs or eye - where they ultimately die

Rat [natural host]:
-Adult worms 2cm in pulmonary arteries of rats - produce eggs - develop into L1 larvae
-Migrate to pharynx - swallowed and passed faeces
-Penetrate or ingested by intermediate hosts [snail or slug]
-Eaten by rats = L3 migrate to subarachnoid space in brain
-Develop and return to venous system - pulmonary arteries

25
Q

Angiostrongylus cantonensis [rat lung worm] - clinical

A

Can be benign and self-limiting - also fatal

Most common cause of eosinophilic meningitis:
-Severe HA, neck stiffness, clouded consciousness

26
Q

Angiostrongylus cantonensis [rat lung worm] - diagnosis

A

Eosinophilia
Raised cell count CSF >25% eosinophilis

27
Q

Angiostrongylus cantonensis [rat lung worm] - treatment

A

Antihelminthic = not recommended

28
Q

Anasakidae - organisms

A

Anisakis simplex
Pseudoterranova decipiens

29
Q

Anasakidae - transmission

A

Ingestion of infected raw fish or squid by humans - L3 persist

30
Q

Anasakidae - clinical

A

Can penetrate bowel wall - leading to extra-inetstinal eosinophilic inflammatory mass

Severe epigastric or abdominal pain
N+V - often within hours of eating infected fish

Generally self-limiting

Can cause anaphylatic reactions in previously sensitised people

31
Q

Anasakidae - diagnosis

A

Clinical - may be mistaken for PUD or appendicitis
Eosinophilia

32
Q

Anasakidae - diagnosis

A

Unclear
Albendazole - some successful reports

33
Q

Anasakidae - lifecycle

A

Adults in gut of marine mammals - seals, whales, dolphis
L2 ingested by crustaceans and mature
Infected crustaceans are eaten by fish and squid [paratenic hosts]

34
Q

Gnathostoma spingerum [spiny headed worm] - Distribution

A

SE asia
Central and South America

35
Q

Gnathostoma spingerum [spiny headed worm] - Lifecycle

A

Adults worms in stomach of carnivores
Eggs, hatch in water, L1 infects copepod [cyclops]
Eaten by fish or frog - develop to L3
If eaten by humans - migrate around body

36
Q

Gnathostoma spingerum [spiny headed worm] - clinical

A

Non-specific symptoms lasting 2-3 weeks
Penetrates gut wall - epigastric pain
Marked eosinophilia
Larvae wanders through tissues [long lived, >10 years]

37
Q

Gnathostoma spingerum [spiny headed worm] - disease forms

A

Visceral larva migrans
Cutaneous forms [most common] = painless migrating oedema
Eosinophilic meningitis

38
Q

Gnathostoma spingerum [spiny headed worm] - diagnosis

A

Clinical = history of migrating subcutaneous swelling, eosinophilia

Serology = ELISA, western blot

39
Q

Gnathostoma spingerum [spiny headed worm] - treatment

A

Prolonged albendazole or ivermectin

LSHTM (47 decks)

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