1. Nematode The intestinal nematodes Ascaris Hook worms Pin worm
Whip worm
The blood- and tissue dwelling nematodes
The filaria
Trichinella

2. Ascaris lumbricoides 似蚓蛔线虫

3. Introduction
The first representative and the most common intestinal parasite
Cosmopolitan in distribution
Rural > urban
Children > adults

4. Morphology Adult Looks like an earthworm
Female (20-35 cm); Male (12-30 cm)
3 lips which carry minute teeth

5. A pair of female and male worms of A. lumbricoides
A pair of female and male worms of A. lumbricoides. Notice the vulvar waist(arrow)of the female worm and the coiled end of the male worm.

6.
Ascaris female worm

7.
A scanning electron micrograph of Ascaris showing the three prominent “lips”

8. Egg
Fertilized egg
Unfertilized egg

9. A. lumbricoides, fertilized egg (6050 micrometer)
Egg shell
Ovum
Albuminous layer
A. lumbricoides, fertilized egg (6050 micrometer)

10. A. lumbricoides, fertilized egg
A. lumbricoides, fertilized egg

11. A. lumbricoides unfertilized egg
A. lumbricoides unfertilized egg 

12. The life cycle of A. lumbricoides
The life cycle of A. lumbricoides

13. HOST MAN Living site Adults in small intestine Migration
Larvae migrate though the lungs
Diagnostic stage
Undeveloped eggs in feces
Method of infection
Infective eggs are ingested
Infective stage
Eggs embryonate in soil by 2-3 wks

14. Symptomatology
Larva
Pneumonitis
Asthma attacks
Loeffler’s syndrome

15. Adult The presence of few worms may be asymptomatic (85%)
The most common symptoms are vague abdominal pain
Large numbers of worms may cause malnutrition and present signs and symptoms of obstruction

16. Migration of adult worms may cause signs and symptoms of perforation, peritonitis, appendicitis or extrahepatic biliary obstruction.

17. A.lumbricoides in common bile duct

18. Cross section of a liver specimen contains many adult worms of A
Cross section of a liver specimen contains many adult worms of A.lumbricoides obstructing the intrahepatic and extrahepatic bile ducts.

19. Ascarid chronic pancreatitis

20.
A large mass of Ascaris lumbricoides that was passed from the intestinal tract.  The ruler at the bottom of the image is 4 cm (about 1.5 inches) in length.

21. An autopsy specimen shows intestinal obstruction by many adult worms of A.lumbricoides. Notice the markedly distended intestinal loop, the thin intestinal wall with hemorrhage and worms protruding from the perforated wound.

22. Peritonitis caused by intestinal perforation due to Ascaris
Resected bowel and the adult female from the peritoneal cavity

23. Diagnosis
Microscopic identification eggs in the stool a direct wet mount examination of the specimen (200,000 eggs/female/day)
Macroscopic identification of adults passed in stool or through the mouth or nose

24. Epidemiology
Worldwide distribution, throughout the temperate and tropical areas
1,000,000,000 people in the world
40% population in Africa and Asia
600,000,000 in China (1992)

25. Treatment Albendazole a single oral dose of 400 mg
Mebenazole 100 mg orally twice daily for 3 days

26. Prevention
Avoid contacting soil that may be contaminated with human feces
Do not defecate outdoors
Dispose of diapers properly

27. Wash hands with soap and water before handling food
When traveling to areas where sanitation and hygiene are poor, avoid water or food that may be contaminated
Wash, peel or cook all raw vegetables and fruits before eating

28. Hook worms 钩虫

29. Ancylostoma duodenale 十二指肠钩口线虫 Necator americanus 美洲板口线虫

30. Pinworm 蛲虫 Enterobius vermicularis 蠕形住肠线虫

31. Whip worm 鞭虫 Trichuris trichiura 毛首鞭形线虫

32. Adult worms of Ancylostoma duodenale
Adult worms of Ancylostoma duodenale

33. Adult worms of Necator americanus
Adult worms of Necator americanus

34. Morphology Adult Cylindrical with the head bent sharply backwards
Males are smaller than the females and possess a bursa at their posterior end

35. http://wwhttp://www. biosci. ohio-state. edu/~parasite/hookworm_adults
Scanning electron micrograph of the oral opening of Ancylostoma duodenale, another species of human hookworm.  Note the presence of four cutting "teeth," two on each side.

36. Adult mouthpart of Necator americanus
Adult mouthpart of Necator americanus
Note : The large buccal capsule is open dorsally with one pair of cutting plate teeth.

37. Lift A. duodenale; Right N. americanus
Bursa of hookworms
Lift A. duodenale; Right N. americanus

38. Tridigitate at the terminus
A.d
N.a
Size
Larger
Smaller
Shape
“C”
“S”
Buccal capsule
4 hooklets
2 plates
Bursa
Round
Broader
Dorsal ray
Tridigitate at the terminus
Bidigitate at the base
Spicules
Separated
Fused at terminal
Mucron
Present
Absence

39. Enterobius vermicularis adult female
cm.in length , spindle-shaped with a long pointed posterior end. Anterior part has dorsoventral bladder-like expansions of cuticula (cervical alae). Rhabditiform esophagus. The greater part of the body is occupied by the uterus filled with eggs.
Enterobius vermicularis adult female
cm.in length , spindle-shaped with a long thin sharply tail. The greater part of the body is occupied by the uterus filled with eggs.

40. Trichuris trichiura adults.
Trichuris trichiura adults. 

42. Egg (indistinguishable between the 2 species)
Median size (like the ascaris egg)
Elliptical
Transparent
Thin shell
4-cell stage when discharge

43.
Enterobius vermicularis egg. Note the thick shell and characteristic shape; approximate length = 55 µm.

44. Egg < Ascaris egg Non-symmetrical ellipse; D shaped Transparent
Thick transparent shell
Tadpole-like embryo when discharged

45.
Trichuris vulpis egg

46.
The third stage larva initiates the infection by penetrating the shin and passing into the blood circulation,. Through the blood it is carried to the right heart and then to pulmonary blood vessels. It soon breaks out of the pulmonary blood vessels into the alveoli. It then crawls up the trachea and is is swallowed with saliva to re-enter the intestinal tract.

47. Life Cycle Host -man No intermediate host 钩虫: Egg Larva (free-living)
Larvae migrate from skin to the lungs
蛲虫:Egg takes 6 hours to be infective stage
鞭虫: Similar to Ascaris but no pulmonary migration . There are reservoir hosts.

48. Parasitic site: 蛔虫: small intestinal
钩虫: upper small intestine; Duodenum, jejunum
蛲虫: colon
Gravid female adult deposits its eggs on the anus and perianal skin.
鞭虫: ileo-caecal region

49. 蛲虫: infective egg ( Egg takes 6 hours to be infective stage)
Infection stage
蛔虫: infective egg
钩虫: infective larva
蛲虫: infective egg ( Egg takes 6 hours to be infective stage)
infective mode: Anus-Hand-Mouth
Auto-infection/Cross-infection
鞭虫: infective egg

50. Digestive disturbances /Allotriophagy
Pathogenic stage:
蛔虫: adult worm /larva
钩虫:adult worm
Digestive disturbances /Allotriophagy
Microcytic hypochromic anemia
(sucking, oozing, discharging) A.d ml/d; N.a ml/d
larva:Dermatitis ‘ground itch’ Pneumonitis and Bronchitis

51. Pathogenic stage: 蛲虫:adult worm 鞭虫:adult worm
Anal itching (migration of gravid females)
Ectopic infection
Digestive disturbances
鞭虫:adult worm
Anemia

52.
Erythema /eri’thi:ma/ 红斑
Trichuris trichiura in the large intestine.  Many worms are present, each with its anterior end embedded in the intestinal mucosa, resulting in the erythema. 

53. Etiologic dignosis: 蛔虫:fecal direct smear 钩虫:Brine floatation
Larva cultivation
Egg counting(to estimate infection intensity)
蛲虫: Collect eggs from perianal region by anal swab on the cellophane tape. Search adult female in the perianal region when the child is sleeping.
鞭虫: Brine floatation

54. Prevention and Control
钩虫:Distribution
Cosmopolitan
0.4 billion humans are infected in China
Natural factors
Soil contamination
Night soil as fertilizer
Suitable climate dry-land vegetable- raising & mine

55. Prevention and Control蛲虫
Readily endemic in children concentrated units
Should put the prevention in first
Mebendazole (100mg repeated after 2 weeks) 鞭虫
Principles same as for ascaris

56. Mebendazole 100mg/次 2次/d 连服3天
Drug:
Albendazole 400mg/d
阿苯达唑/丙硫咪唑/肠虫清
Mebendazole mg/次 次/d 连服3天
(600mg repeated after 2 weeks)