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
May lack a digestive system
Nervous system is reduced
Means of locomotion is reduced or completely lacking
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. Meningeal worm - Parelaphostrongylus tenuis
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
Spinal nerves  spinal cord  mature days to adults
Intermediate Host

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

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

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. Raccoon roundworm - Baylisascaris procyonis
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. Raccoon roundworm - Baylisascaris procyonis
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

33. Arthropds
Crustacea
Insecta - lice
Arachnids - mites and ticks