1. Classification of Parasites
helminths
Protozoa
Mulicellular
Specialized cells
Unicellular
Single cell for all function
Round worms
(Nematodes) cylindrical,
unsegmented
Flat worms
1-Trematodes:
leaf-like, unsegmented.
2-Cestodes:
tape-like, segmented
Amoebae:
move by psudobodia.
Flagellates:
move by flagella.
Ciliates :
move by cilia
Apicomplexa
(sporozoa) Tissue
parasites

2. Nematodes General features:
Elongated worm, cylindrical, unsegmented and tapering at both ends.
Variable in size, measure <1 cm to about 100cm.
Sex separate and male is smaller than female

3. Location of Nematodes: Tissue nematodes
Intestinal nematodes
Tissue nematodes

4. Intestinal Nematodes

5. Common intestinal nematode infections:
Enterobius (Oxyuris) vermicularis (Pinworm,seatworm,threadworm)
Trichuris trichiura (whipworm)
Ascaris lumbricoides (roundworm)
Ancylostoma duodenale & Necator americanus (hookworms)
Strongyloides stercoralis :

6. Enterobius vermicularis (Oxyuris)
(Pin worm, seat worm, thread worm(
Found all over the world.
adult in lumen of cecum and appendix from which adult female migrate to rectum.
It can be seen by naked eye as white thread ± 1cm.
Male is smaller than female ± 0.5cm, with coiled end.

7. Enterobius vermicularis (Oxyuris)
LIFE CYCLE

8. Pathology Enterobius vermicularis (Oxyuris)
Majority of infectiona are asymptomatic.
Main clinical presentation pruritus ani
perianal excoriation
Ectopic enterobiasis occurs in female when invade valva and vagina result in valvovagintis
Usually accompanied by insomnia, anorexia, loss of weight and concentration (Side effect)

9. Enterobius vermicularis (Oxyuris)

10. Enterobius vermicularis (Oxyuris)

11. Treatment ِِAlbandazole , Mebendazole for whole family
Enterobius vermicularis (Oxyuris)
Treatment
ِِAlbandazole , Mebendazole
for whole family

12. Ascaris lumbricoides (roundworm)

13. Ascaris lumbricoides (roundworm)
Ascaris adult

14. Ascaris lumbricoides (roundworm)
The commonest human helminthes infection.
Found in jejunum and upper part of ileum.
Female ± 20 cm longer than male ± 10 cm
Feed on semi digested food.

15. Ascaris lumbricoides

16. Ascaris lumbricoides (roundworm)
LIFE CYCLE

17. Ascaris lumbricoides (roundworm)
Ascaris egg
(embryonated)

18. Ascaris eggs
Ascaris larva emerging from egg
Ascaris egg
(embryonated)

19. Ascaris lumbricoides (roundworm)
Pathology:
1-Adult worm:
Light infection : asymptomatic.
Heavy infection : intestinal obstruction
Migrating adult : to bile duct -jaundice
2-Larvae: Loeffler`s syndrome
Pneumonia, cough with bloody sputum
Eosinophilia, urticaria

20. Ascaris lumbricoides (roundworm)
Loeffler`s syndrome: Larvae in lung
pnumonia,cough ,bloody sputum

21. Ascaris lumbricoides (roundworm)
Ascaris larva in lung

22. Ascaris lumbricoides (roundworm)
Diagnosis:
-eggs in stool.
-larvae in sputum.
-adult may pass with stool.
Treatment: Albendazole , Mebendazole

23. Trichuris trichiura (Whipworm)

24. Trichuris trichiura (Whipworm)
LIFE CYCLE

25. Trichuris trichiura (Whipworm)
World wide ,common in poor sanitation.
It coexists with Ascaris because of similar requirement.
Adult live in large intestine especially caecum and appendix –in heavy infection the whole length of large intestine affected.
Male and female worm have narrow anterior portion penetrate the intestinal mucosa

26. Trichuris trichiura (Whipworm)
Pathology
light infection : asymptomatic
heavy infection :abdominal pain ,bloody diarrhea. Rectal prolapse in children is a common complication.
-Diagnosis: egg in stool characterized by its barrel shape with mucoid plugs at each pole .
Treatment :Albendazole.

27. Trichuris trichiura (Whipworm)
Embryonated egg Unembryonated egg
Infective stage Diagnostic stage

28. Trichuris trichiura (Whipworm)
-Diagnosis: egg in stool characterized by its barrel shape with mucoid plugs at each pole .
Treatment :Albendazole.

29. Ancylostoma dudenale &Necator americanus
Hook worms
Ancylostoma dudenale &Necator americanus

30. 1- Buccal cavity with intestinal mucosa 2- B
1- Buccal cavity with intestinal mucosa B.cavity with teeth &cutting plates anemia

32. Ancylostoma dudenale &Necator americanus
Hook worms
Ancylostoma dudenale &Necator americanus
LIFE CYCLE

33. Ancylostoma dudenale &Necator americanus
Hook worms
Ancylostoma dudenale &Necator americanus
A common cause of anemia.
Found in small intestine mainly jejunum.
Its buccal capsule (mouth) lined with hard hooks, triangular cutting plates and anticoagulant glands.

34. Ancylostoma dudenale &Necator americanus
Hook worms
Ancylostoma dudenale &Necator americanus
pathology& clinical picture:
- larvae:
i-At the site of entry of larvae
(ground itch).
ii- Migration phase:
cough with bloody sputum
pneumonia, eosinophilia,urticaria.
- Adult worm:
•low worm burden: no symptoms.
•Moderate to heavy burden:
epigastric pain, vomiting ,simulating
duodenal ulcer, hemorrhagic enteritis.

35. Ancylostoma dudenale &Necator americanus
Hook worms
Ancylostoma dudenale &Necator americanus
• Protein loss: hypoproteinaemia edema.
• Anemia: due to withdrawal of blood by parasites and hemorrhage from punctured sites lead to sever anemia = microcytic hypochromic .

36. Ancylostoma dudenale &Necator americanus
Hook worms
Ancylostoma dudenale &Necator americanus
Diagnosis:
-Eggs in stools.;
-occult blood (+)
Treatment: Albendazol, Mebendazole

37. Strongyloides stercoralis
Widely distributed in tropical region worldwide .
fetal opportunistic in immuno-compromised host.
It is smallest pathogenic nematodes
± 2.5mm.
adult live in mucous membrane of duodenum jejunum

38. Strongyloides stercoralis

39. Strongyloides stercoralis
LIFE CYCLE

40. Strongyloides stercoralis
Pathology and clinical picture:
1-Cutaneous little reaction on penetration.
sever dermatitis at perianal region in
case of external autoinfection.
2- Migration :same as hook worms .
3- Intestinal: inflammation of upper intestinal mucosa, diarrhea, upper abdominal pain clicky in nature.
Disseminated strongyloidiasis : in patient with immunodeficiency ,uncontrolled diarrhea –granulomatus changes –necrosis--perforation--peritonitis--death.

41. Strongyloides stercoralis
Diagnosis:
rhabditiform larvae diagnostic stage in:
-Stool examination
-Duodenal aspirate
Treatment : Albandazole, Mebendazole

42. TISSUE NEMATODES
TISSUE NEMATODES

43. COMMON TISSUE NEMATODE INFECTIONS
Trichinella spiralis adults in small intestine larvae in tissues (mainly in muscles).
Toxocara canis (dog roundworm) larvae in organs (liver brain eyes), causing visceral larva migrans
Dracunculus medinensis (guinea worm) adult female in subcutaneous tissues
Filarial worms

44. Trichinella spiralis

45. Trichinosis

46. Most prevalent in areas where domestic pigs are allowed to roam freely.

47. Trichinosis Pathology: Adults cause mild gastroenteritis.
Larvae cause fever, myositis and multi-system involvement which may lead to death.
Diagnosis: serology, muscle biopsy.
Treatment: Albendazole or Mebendazole + corticosteroids

48. Trichinosis

49. Visceral larva migrans: Caused by Toxocara canis
Mainly affects children who eat soil contaminated with emberyonated (infective) eggs of Toxocara canis.
Larvae do not develop in humans but migrate continuously in viscera and encapsulate, causing tissue damage.

50. Toxocara canis

51. Pathology: Eosinophilia, hepatomegaly,
retinitis.
Diagnosis: serology, biopsy.
Treatment: Albendazole

52. Dracunculus medinensis

53. Caused by Dracunculus medinensis
Draunculiasis
Caused by Dracunculus medinensis
Adult female lives in subcutaneous tissues, causing a skin ulcer through which it protrudes its anterior end.
Main pathology due to secondary bacterial infection and allergic reactions.
Diagnosis: clinical picture.
Treatment: surgical removal.

54. FILARIAL WORMS: (Adult worms + microfilariae)
Onchocerca volvulus:
Adults in subcutaneous swellings Microfilariae : mainly in skin, eyes causing River blindness
2. Wuchereria bancrofti, Brugia malayi & B. timori:
Lymphatic filariasis (adults in lymphatics,
microfilariae in blood)
3. Loa loa:
Adults in subcutaneous and subconjunctival tissues, causing Calabar swellings.
Microfilariae in blood

55. FILARIALIASIS )

56. Loiasis

58. Onchocerciasis (river blindness)
Pathology:
Adults worms live in subcutaneous nodules.
Main pathology caused by microfilariae in:
Skin: dermatitis
Lymph nodes: lymphadenopathy
Eyes: blindness
Diagnosis: skin snip to identify microfilariae.
Treatment: Ivermectin

59. Ivermectin

60. LYMPHATIC FILARIASIS

61. Lymphatic Filariasis

62. LYMPHATIC FILARIASIS Mainly caused by Wuchereria bancrofti Pathology:
and Brugia malayi
Pathology:
Due to adult worm obstructing lymphatics.
Acute: lymphadenitis lymphatic varices
Chronic: lymphedema, hydrocele, chyluria.

64. LYMPHATIC FILARIASIS
Diagnosis: detection of microfilariae in blood in early stages of the disease:
Blood film, Knott’s method
( concentration of 1 ml of blood), best 10 pm to 2 am (nocturnal periodicity).
Immunological tests:
Treatment: diethylcarbamazine (DEC) or ivermectin

65. Loa loa

66. Loiasis
Pathology: Adult worm continously migration in subcutaneous and subconjuntival tissues, causing Calabar swellings (allergic reactions) and conjunctivitis.

67. Loiasis Diagnosis: detection of microfilariae in blood film.
Treatment: diethylcarbamazine (DEC) or ivermectin, surgical remonval.

68. NON-FILARIAL TISSUE NEMATODE INFECTIONS
treatment
Diagnosis
Location in human
Mode of transmission
Disease
Nematode species
Surgical extraction
clinical
Subcutaneous, mainly in lower limbs
Ingestion of infected cyclops in water
Dracunculiasis, Guinea worm disease
Dracunculus medinensis
albendazole
Serology, muscle biopsy
Muscles, lungs brain
ingestion larvae in under-cooked pork
Trichinellosis (trichinosis)
Trichinella spiralis
Serology, ELISA
Abdominal organs and brain
Ingestion of infective eggs in soil
Visceral larva migrans
Toxocara canis

69. MAJOR FILARIAL INFECTIONS OF HUMANS
Lab. diagnosis
vector
Location of microfilaria
Location of adult in humans
Geographic distribution
Disease
species
Blood film
mosquitoes
Blood (nocturnal periodicity)
Lymphatic vessels
Tropical and subtropical areas
elephantiasis
Wuchereria bancrofti
Asia
Brugia malayi
Skin snip
Simulium spp. (black fly)
Skin, eyes, no periodicity
Subcutaneous nodules
Africa, Central and South America, Yemen
Onchocerciasis (river blindness)
Onchocerca volvulus
Chrysops spp. (deer fly)
Blood (diurnal periodicity)
Moving in subcutaneous tissues
Central Africa
loiasis
Loa loa