2 Parasitic Diseases of Wildlife Helminths - Multicellular eukaryotic animals w/ organ systemsPlatyhelminthes = flatworms - flattened from front to backNematodes = roundworms – tapered at both ends
3 Helminths Distinguishing characteristics of parasitic helminths May lack a digestive systemNervous system is reducedMeans of locomotion is reduced or completely lackingReproductive 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 individualsAdults may be monoecious or hermaphroditic – male and female systems in the same individual
5 Platyhelminthes = flatworms Trematodes = flukesFlat, leaf-shaped bodies, ventral and oral suckersCommon names based on tissue of the definitive host where adult lives – blood fluke, liver fluke, lung fluke…
6 Platyhelminthes = flatworms Cestodes = tapewormsHead with suckers, flat body, no digestive system
7 Nematodes = roundworms Complete digestive systemsMost species dioecious2 main categorieseggs are infectivelarva are infective
15 Meningeal worm - Parelaphostrongylus tenuis F – S with L3 are ingested abomasumIntermediate Host
16 Meningeal worm - Parelaphostrongylus tenuis Spinal nerves spinal cord mature days to adultsIntermediate Host
17 Meningeal worm - Parelaphostrongylus tenuis Adults migrate to subdural space brainIntermediate Host
18 Meningeal worm - Parelaphostrongylus tenuis From ingestion to exit of eggs in feces = prepatent periodIntermediate 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.
31 Raccoon roundworm - Baylisascaris procyonis Dead intermediate is scavenged by raccoon.
32 Raccoon roundworm - Baylisascaris procyonis Emerging zoonotic diseaseDogs 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 ArthropdsCrustaceaInsecta - liceArachnids - mites and ticks