Angiostrongylosis in Wildlife, Dogs & People

Transcription

1 Angiostrongylosis in Wildlife, Dogs & People Gemma Ma, Michelle Dennis, Richard Malik, Karrie Rose, Derek Spielman, Dave Spratt, Alexandra Walker, Michael Ward

2 Aetiological Agent Angiostrongylus cantonensis

3 Angiostrongylus cantonensis Definitive hosts: Life History Rattus norvegicus & Rattus rattus Intermediate hosts: slugs species vary greatly in their susceptibility; e.g., Agrilimax laevis (a small dark slug) hosts > 200 infective larvae; Limax arborum (a medium yellow slug) hosts 1-5

4 A. cantonensis Life History - Rats Ova: ova circulating pulmonary blood lodge as emboli in smaller vessels develop to first-stage larvae (L1) L1 break into the respiratory tract pass up the trachea swallowed

5 A. cantonensis Life History L1: pass out in faeces very active, penetrate foot of slug in slug moult at 10 days L2 and again at 15 days infective third stage larvae (L3)

6 A. cantonensis Life History - Rats L3 ingested by rats: liberated from ingested slug in stomach small intestine penetrate ileal wall mesentery & mesenteric veins right ventricle by 4 h post-ingestion

7 A. cantonensis Life History - Rats L3 by 17 h: many in lungs & kidneys, a few in spinal cord & spinal CSF, some in cerebral hemispheres & cerebellum invade brain & spinal cord by 24 h

8 A. cantonensis Life History - Rats L3 in brain: move in grey matter without obvious haemorrhage or reaction moult L4 by day 7 final moult by day L5

9 A. cantonensis Life History - Rats Sub-adult in brain: migrate to surface of cerebrum thickened meninges, dilated vessels moderately infested rats show no signs of cerebral derangement

10 A. cantonensis Life History - Rats Young adult lungworms: enter turgid congested meningeal veins mature to adults in pulmonary arteries in 7-10 days

11 Neuro-angiostrongyliasis In mice given large infective doses: adult worms in cerebrum & cerebellum worms die surrounded by phagocytes cerebral irritation

12 Neuro-angiostrongyliasis In mice this cerebral irritation manifests as: incoordination, disinclined to move twitching, tight circling death

13 Angiostrongyliasis In guinea pigs given large infective doses: a few L2 or L3 worms in cerebrum worms die surrounded by phagocytes no signs of cerebral irritation or any other abnormality

14 A. cantonensis Life History

15 Neuro-angiostrongyliasis in Humans In humans: eosinophilic meningitis, meningoencephalitis first confirmed human infection Taiwan 1945 first confirmed human death Hawaii 1962

16 Neuro-angiostrongyliasis in Humans Humans affected following ingestion of an intermediate or paratenic host infected with L3 Larvae move quickly from the GIT to the CNS but are unable to mature and die in the brain, damaging CNS tissue Incubation 1 36 days

17 Neuro-angiostrongyliasis in Humans The number of L3 that reach the CNS determine disease severity Most cases are self limiting with complete recovery However, much more severe disease in children they tend to ingest live molluscs which can contain numerous larval parasites Deaths are due to massive infections

18 Epidemiology Humans rarely suffer angiostrongyliasis in welldeveloped areas despite high prevalence in rats and molluscs (e.g. Hawaii) Occasional infections occur when people eat infected intermediate and paratenic hosts such as snails and prawns In less-developed enzootic regions transmission is facilitated by poverty, poor hygiene and ignorance Here human infants and juveniles, pets and livestock are likely to be fatally infected

19 Epidemiology The expansion of prawn aquaculture into tropical countries where A. cantonensis is enzootic risks intensifying local transmission and of introducing it into distant human populations which import the prawns

20 Neuro-angiostrongyliasis in Australia Most infections in Australia are attributed to salad vegetables contaminated with small snails or slugs or infective larvae in slug or snail mucus but release of A. cantonensis larvae in snail secretions is questionable In south-eastern Queensland fatal infections have been reported increasingly from domestic dogs, horses, captive wallabies and bettongs, captive tamarins, wild flying foxes and captive and wild cockatoos

21 Neuro-angiostrongyliasis in Australia A. cantonensis is now considered well established in the Sydney region where it is increasingly reported as causing neurological disease in domestic dogs, people, wild tawny frogmouths, brushtail possums and grey-headed flying foxes The first reported human A. cantonensis infection in Australia was in Brisbane in 1971

22 Tawny Frogmouths SN 407/07: TF with severe posterior paresis

23 Tawny Frogmouths SN 407/07: TF with severe posterior paresis

24 Tawny Frogmouths

25 Tawny Frogmouths

26 Tawny Frogmouths

27 Tawny Frogmouths

28 Tawny Frogmouths

29 Tawny Frogmouths strong seasonality Ma et al Angiostrongylosis Confirmed A. cantonensis

30 Brushtail Possum Case Studies Case 1: hand reared sub-adult BTP ready for release food uneaten over Easter food handed to possum in box eaten ravenously BTP taken out of box: unable to use hind legs very thin hind limb & tail paralysis

31 Brushtail Possum Case 1

32 TF Histopathology

33 TF Histopathology

34 BTP Histopathology

35 BTP Histopathology

36 BTP Histopathology

37 Canine angiostrongylosis strong seasonality Number of CNA cases Spring Summer Autumn Winter Season of presentation

38 Human Neuro-angiostrongyliasis in Sydney First Sydney case in 2001: young man admitted with 3-day history of gradualonset headache, nausea, vomiting, neck stiffness & photophobia 3 weeks earlier he had GIT illness (nausea, abdominal cramps, diarrhoea, myalgia & fever) that persisted for 1 week cerebral computed tomography scan: no abnormality

39 Human Neuro-angiostrongyliasis in Sydney First case 2001: serological tests for Strongyloides & Angiostrongylus were negative CSF & blood cultures: no growth 12 days later discharged 5 days later increasing headache & drowsiness admitted to another hospital afebrile, drowsy, irritable, gross bilateral papilloedema, mild paraesthesiae in both hands

40 Human Neuro-angiostrongyliasis in Sydney First case 2001: peripheral blood eosinophilia MRI: multiple focal lesions in both cerebral hemispheres and the corpus callosum repeated questioning: for a dare 5 weeks earlier the patient had ingested two slugs repeat Angiostrongylus IgG ELISA tested in parallel with the first specimen confirmed seroconversion 5 months later he successfully returned to full-time studies and competitive sport

41 Human case Sydney year old male lapsed into a 446 day coma, released from intensive care in Feb 2013, currently undergoing rehabilitation

42 Human case Sydney month old girl died in March 2011 after becoming infected, possibly from crawling over slug or snail slime trails

43 Current Research A. cantonensis Ecology & Epidemiology: developing a PCR specific for A. cantonensis to distinguish from A. mackerrasae test slugs, snails and rats in Sydney and coastal NSW developing effective treatment for neuroangiostrongyliasis in dogs