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Parasitic Diseases of Wildlife Helminths = worms Arthropods (lice, mites, ticks)

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Presentation on theme: "Parasitic Diseases of Wildlife Helminths = worms Arthropods (lice, mites, ticks)"— Presentation transcript:

1 Parasitic Diseases of Wildlife Helminths = worms Arthropods (lice, mites, ticks)

2 Parasitic Diseases of Wildlife Helminths - Multicellular eukaryotic animals w/ organ systems Platyhelminthes = flatworms - flattened from front to back Nematodes = roundworms – tapered at both ends

3 Helminths Distinguishing characteristics of parasitic helminths 1.May lack a digestive system 2.Nervous system is reduced 3.Means of locomotion is reduced or completely lacking 4.Reproductive system is complex, produce large numbers of fertilized eggs

4 Helminths Generalized Life Cycle Can be very complex, succession of intermediate hosts for completion of each larval (developmental) stage of the parasite and a definitive host for the adult parasite. Adults may be dioecious – male and female reproductive systems in separate individuals Adults may be monoecious or hermaphroditic – male and female systems in the same individual

5 Platyhelminthes = flatworms Trematodes = flukes Flat, leaf-shaped bodies, ventral and oral suckers Common names based on tissue of the definitive host where adult lives – blood fluke, liver fluke, lung fluke…

6 Platyhelminthes = flatworms Cestodes = tapeworms Head with suckers, flat body, no digestive system

7 Nematodes = roundworms Complete digestive systems Most species dioecious 2 main categories eggs are infective larva are infective

8 Nematodes = roundworms Meningeal (brain) worm - Parelaphostrongylus tenuis Raccoon roundworm - Baylisascaris procyonis

9 Meningeal worm - Parelaphostrongylus tenuis

10 Definitive Host

11 Meningeal worm - Parelaphostrongylus tenuis A – Adult worms in meninges lay eggs

12 Meningeal worm - Parelaphostrongylus tenuis B - Eggs go into circulation, reach lungs (C), hatch into larvae L1.

13 Meningeal worm - Parelaphostrongylus tenuis The L1 migrate up bronchial tree (D) to pharynx, coughed, swallowed  feces (E)

14 Meningeal worm - Parelaphostrongylus tenuis L1 infects snails or slugs thru foot  L3, takes ~3 wks. Intermediate Host

15 Meningeal worm - Parelaphostrongylus tenuis F – S with L3 are ingested  abomasum Intermediate Host

16 Meningeal worm - Parelaphostrongylus tenuis Intermediate Host Spinal nerves  spinal cord  mature days to adults

17 Meningeal worm - Parelaphostrongylus tenuis Intermediate Host Adults migrate to subdural space  brain

18 Meningeal worm - Parelaphostrongylus tenuis Intermediate Host From ingestion to exit of eggs in feces = prepatent period

19 Meningeal worm - Parelaphostrongylus tenuis If infected snails or slugs are ingested by susceptible incidental hosts, the L3 are released in the digestive tract. L3 migrate to the spinal cord and continue to migrate aimlessly within the CNS causing neurologic disease. Do not develop into adults.

20 Raccoon roundworm - Baylisascaris procyonis

21 Definitive host

22 Raccoon roundworm - Baylisascaris procyonis Adults in intestines lay eggs

23 Raccoon roundworm - Baylisascaris procyonis Eggs are shed with feces

24 Raccoon roundworm - Baylisascaris procyonis Over 2-4 weeks the eggs develop larvae

25 Raccoon roundworm - Baylisascaris procyonis Embryonated egg with larvae is ingested by raccoon

26 Raccoon roundworm - Baylisascaris procyonis Larvae in intestines develop into egg-laying adults Infection rates in raccoons are high – as high as 70% of adults and over 90% of juveniles

27 Raccoon roundworm - Baylisascaris procyonis Embryonated egg with larvae are ingested by intermediate hosts

28 Raccoon roundworm - Baylisascaris procyonis Eggs hatch and release larvae into intestines  gut wall  migrate thru the various tissue causing considerable damage and then encyst

29 Raccoon roundworm - Baylisascaris procyonis In the eye  blindness

30 Raccoon roundworm - Baylisascaris procyonis 5-7% CNS disease

31 Raccoon roundworm - Baylisascaris procyonis Dead intermediate is scavenged by raccoon.

32 Emerging zoonotic disease Dogs may be reservoir hosts, can shed eggs. Infective eggs found in aging feces. Can remain in the environment for years. Resistant to all common disinfectants Raccoon roundworm - Baylisascaris procyonis

33 Arthropds Crustacea Insecta - lice Arachnids - mites and ticks


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