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

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

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

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

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…

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

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

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

Meningeal worm - Parelaphostrongylus tenuis

Meningeal worm - Parelaphostrongylus tenuis Definitive Host

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

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

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

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

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

Meningeal worm - Parelaphostrongylus tenuis Spinal nerves  spinal cord  mature 20-30 days to adults Intermediate Host

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

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

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.

Raccoon roundworm - Baylisascaris procyonis

Raccoon roundworm - Baylisascaris procyonis Definitive host

Raccoon roundworm - Baylisascaris procyonis Adults in intestines lay eggs

Raccoon roundworm - Baylisascaris procyonis Eggs are shed with feces

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

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

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

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

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

Raccoon roundworm - Baylisascaris procyonis In the eye  blindness

Raccoon roundworm - Baylisascaris procyonis 5-7% CNS disease

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

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 http://www.maniacworld.com/raccoon-encounter-with-dog-and-cat.html

Arthropds Crustacea Insecta - lice Arachnids - mites and ticks