1. Pathogenic Human Helminthes
Parasitic Worms
Pathogenic Human Helminthes

2. Characteristics Multicellular Well developed organ systems
Reproductive
Dioecious
Hermaphrodite
Worldwide
Tropical, subtropical
Survival of eggs
Survival of larval stages
Less developed
Sanitation
Intermediate host survival

3. Life Cycle
Host
Definitive: a vertebrate in which the parasite reproduces sexually and causes infection
Intermediate: an invertebrate (eg mollusc) in which parasite develops or reproduces asexually
Cycle
Egg  ingestion
Larvae ingestion, penetration, migration
Infectious stage  intermediate host
Adultreproduces

4. Overview of Generic Life Cycle

5. Helminth Types Platyhelminths Nematoda Flatworms Roundworms Flukes
Trematodes
Flat, leaf shaped
Suckers
Named for location
Tapeworms
Cestodes
Long body
Scolex
Proglottid
Nematoda
Roundworms
Cylindrical body
Cuticle
Dioecious
Hookworms
Pinworms
Whipworms
Strongyles
Filaria

6. PLATYHELMINTHS
Flat body
Hermaphrodites
Parasitic
Trematodes
Cestodes

7. FLUKES (Trematodes) Schistostomiasis Fascioliasis Intestinal Fluke
Chinese Liver Fluke
Lung Fluke
Life Cycle
Eggs
Miracidia (ciliated larva)
Intermediate host
Cercariae
Second intermediate host
Metacercariae (juvenile)
Definitive host
Adult fluke

8. Fluke Anatomy and Life Cycle
Miracidia
Adult Fluke

9. Liver Flukes Fasciola hepatica Chinese Liver Fluke Typical life cycle
Snail intermediate host
Humans exposed to metacercaria by eating watercress
Intestine  Liver  Bile Ducts  eggs in feces
Chinese Liver Fluke
Typical life cycle
Snail intermediate host
Humans exposed to metacercaria by eating undercooked fish
Intestine  Liver  Bile ducts eggs in feces

10. Flukes: Fasciola sp.

11. Flukes of other Organs : Lungs
Paragonimus westermani
Eggs coughed and swallowed, passed in feces that contaminate water
Cercaria in snails
Metacercaria in crabs
Humans eat crabmeat
Adult flukes migrate from GI Blood  Lungs
Signs: Coughing
Egg
Adult Fluke

12. Flukes of other Organs: Urine
Schistostoma (blood flukes)
Eggs in urine, feces
Miracidia in snails
Cercaria in snails
Penetrate skin
Schistosomulae in liver
Adults migrate to urinary system
Signs: damage to liver, and urinary bladder

13. Schistostoma Life Cycle

14. Flukes DX TX Prevention Eggs in feces Antihelmenics
Thoroughly cook meats
Cook vegetables
Proper Sanitation

15. TAPEWORMS: (Cestodes)

16. Life Cycle of Tapeworms
Eggs in proglottids passed in stool
Larval phase in Intermediate host
Intestine  blood  Skeletal muscle and other tissue  cysts
Acquire by eating raw meat with cysts
Cysts  adult worms in intestines

17. Tapeworm Life Cycle

18. Tapeworm Anatomy
Scolex with hooks
Adult Tape worm
Proglottids

19. Taenia tapeworms Taenia saginata (beef) Taenia solium (pork) Symptoms
Abdominal discomfort
Diagnosis
Worm segments
Eggs in stool
Treatment
Antihelminics
Prevention
Cook meat
Good Hygiene

20. Taenia species

21. Tapeworms
Taenia eggs
Ecchinococcus
Diplidium canium

22. Tapeworm

23. Sheep Fluke

24. NEMATODES
“Roundworms”
Cyclindrical body
Dioecious
Cuticle

25. Filaria Worms

26. FILARIASIS Elephantitis Loaisis Wuchereia bancrofti Mosquito
Lymphatics
Microfilaria in blood
Adults in LN
Blockage
Swelling
Loaisis
Onchocerca volvulus
Biting flies CT
Microfilaria in blood
Adults in conjunctiva
Inflammation
swelling

27. Fliaria Summary DX TX Prevention Id microfilaria in blood
Diethylcarbamazine
Prevention
Control of intermediate hosts
Wuchereia bancrofti

28. Elephantitis

29. Loaisis

30. Roundworms Ascaris lumbriocoides Fecal contaminated food Eggs ingested
Larvae released and migrate
GI  lymph/blood  lung alveoli  coughed  swallowed
Adults mature in upper GI (stomach and SI)

31. ASCARIASIS

32. Roundworms (Ascarids)
Symptoms
Asymptomatic
Respiratory GI DX
Eggs in stool
Adults in vomitus TX
Prevention
Sanitation
Cook food

33. Toxocariasis Toxacaris canis, T. cati Eggs in environment Fecal  oral
Larvae hatch in GI  Blood  Liver  Lung  any tissue
aka Visceral Larval Migrans
Zoonosis

34. Toxocariasis Symptoms Resp: cough, fever, wheezing Organomegaly
Skin: rash
Eye: inflammation DX
Blood work
Biopsy
Eggs in stool TX
Prevention
Hygiene
Deworm animals

35. Hookworms Ancylostoma, Necator Eggs in feces hatch
Larvae mature in soil and penetrate skin
Skin  Lymphatic Blood  Lungs coughed & swallowed
Adults develop in SI by attaching mouth parts to lining  blood meals

36. Hookworm

37. Hookworm Life Cycle

38. Hookworms Symptoms DX TX Prevention Skin rash, pruritic Resp GI: pain
Anemia DX
Eggs / larvae in stool TX
Prevention
Limit soil exposure

39. Trichuriasis

40. Whipworms Trichuris trichura
Eggs in soil, ingestion of contaminated food
Larve hatch in SI, migrate to cecum
Larvae mature to adult stage

41. Whipworm Symptoms DX TX : Antihelminthics Prevention
GI: pain, diarrhea, bleeding, anemia, rectal prolapse DX
Eggs in stool
Colonoscopy to view adults
TX : Antihelminthics
Prevention
Sanitation
Wash vegetables

42. Pinworms Enterobiasis vermicularis Eggs @ perineum Fecal-oral
Eggs hatch  Lower GI to mature
Female moves to perineal region to deposit eggs in sticky substance
HUMANS ONLY !!
DX:
GI itching, eggs
Worms in colon
TX: Anthelminthics
Prevetion:
Hygiene
Wash clothing

43. Trichinosis

44. Trichinosis Trichinella spiralis Larvae in skeletal m.
Exposure by eating uncooked meat
Cyst  larvaeadult in intestine mature and release larvae
Larvae –> migrate using blood/lymph  penetrate muscles to form cysts

45. Trichinosis Symptoms Asymptomatic GI: cramps, diarrhea
Muscle: stiffness, pain, soreness
Skin: rash
Eyelid: swelling, pain, injected sclera
DX: symptomatic TX
Prevention
Cook
Freeze

46. Strongyloidiasis Eggs hatch in SI mucosal glands Larva
Strongyloides stercoralis
Eggs hatch in SI mucosal glands
Larvae passed in stool
Exposure: larvae migrate through skin
Skin  Lungs  coughed and swallowed  Intestines
Larvae mature to adult stage
Larva
Adult

47. Guinea Worm Disease Drancunculus Larvae in water Crustacean (IH)
Humans ingest uncooked meat
Larvae released  skin  Adult in blister like lesion
Larvae produced and released with water

48. Drancunculus removal