1. Hookworms
Associated prof. Tian

2. Background
1. Hookworms are the voracious blood feeders of the nematode world
Hookworms parasitize more than 900 million people worldwide.
2. Ancylostomiasis is second only to ascariasis in infections by parasitic worms.

3. 3. There are two species of hookworms of medical importance
Ancylostoma duodenale: - Africa, India, China and South East Asia (Asia hookworms)
Necator americanus: - First reported in Brazil, then Texas, but since found in Africa, India and South East Asia.
(American hookworms)

4. Morphology
Adult:
The adult parasites are small cylindrical worms, cm long (Ancylostoma duodenale being slightly larger than Necator americanus ).
A. duodenale
N. americanus

5. buccal capsule(mouth capsule)
The anterior end of the parasites are formed into a buccal capsule
Curved teeth
Ancylostoma duodenale

6. cutting plates
(semilunar)
Necator
americanus

7. The posterior end of the male worm is equip with a characteristic copulatory bursa

8. (umbrella-shaped bursa)
Copulatory bursa of male of A.duodenale

9. Copulatory bursa of male of N.americanus

10. Comparison of Hookworms
N. americanes A. duodenale
Size (lenth) about 10 mm slight larger
Shape “ S ” “ C ”
buccal capsule a pair of two pair of
cutting plates curved teeth

11. Eggs: shell Morula(4-8cell) Size 57-76 µm by 35-47 µm
Oval or ellipsoidal shape Thin shell, colorless. The eggs usually contain 4-8 cells in feces

12. A: Hookworm egg, advanced cleavage (iodine). B: Embryonated hookworm egg.

13. Contact host and penetrate the skin into the body
Life cycles
warm moist shaded soil
adult
egg
Rhabditiform larvae
Intestinallumen
Are passed in the stool
hatching 24-48h,
Contact host and penetrate the skin into the body
5-8days
adult
Filariform larvae
Migrant by lungs

14. The route of larvae migrant
Skin lungs trachea
Oesophagus stomach intestine

15. Life Cycle

16. Soil polluted with human excreta is commonly responsible for exposure to infection with human hookworms
Individuals become infected, usually by walking bare footed across contaminated soil

17. Penetration of the intact skin by filariform larvae of hookworm, on coming in contact with fecal polluted soil.

18. A, B: Hookworm rhabditiform larva (wet preparation).
A, B: Hookworm filariform larva (wet preparation).

19. A, B, C: Hookworm filariform larva (A and B, wet preparations; C, iodine).  Larva tail is depicted in Figures B and C.

20. Pathogenesis and clinical manifestation
Cutaneous or invasive phase:
by hookworm larvae
Dermatitis(ground itch):
irritation and itching

21. The larva of a hookworm is visible in the center of this photograph

22. (2) Pulmonary phase: by hookworm larvae
Local haemorrhaging, pneumonitis
Symptoms in respiratory system
cause a cough and a sore throat.

23. (3) Intestinal phase: By adult worm
A)the intestinal mucosa are damaged
B)Anemia:
Protein and iron in-take is insufficient
Blood loss
Hypochromic microcytic anemia

24. Blood loss
a)Ingestion of the blood by the worm
b)Seepage of the blood around the site of attachment of the worm
c)Oozing of the blood from the burrowed site previously attached by the worm
d)Anticoagulants

25. This is a photograph of the hookworm's appearance against the lining of the intestine (intestinal mucosa).

26. Clinical features of hookworm disease
Site
Symptoms
Pathogenesis
Dermal
Local erythema, macules, papules (ground itch)
Cutaneous invasion and subcutaneous migration of larva
Pulmonary
Bronchitis, pneumonitis and, sometimes, eosinophilia
Migration of larvae through lung, bronchi, and trachea
Gastro- intestinal
Anorexia, epigastric pain and gastro-intestinal hemorrhage
Attachment of adult worms and injury to upper intestinal mucosa
Hematologic
Iron deficiency, anemia, hypoproteinemia, edema, cardiac failure
Intestinal blood loss

27. Diagnosis Laboratory diagnosis
It includes parasitic diagnosis and immunodiagnosis
l) Microscopy Direct smear examination of feces is adequate to detect moderate or severe infections.

28. 2) Concentration Concentration of stool by formalin-ether or simple salt floatation stool is essential to detect light hookworm infection.
3) Third-stage larvae in the fecal culture

29. Epidemiology Distribution
Hookworm diseases is widely epidemic parasitic disease in the world. Hookworm distribute these areas between northern latitude 45○ to southern latitude 30○. A.duodenale is chiefly found in tropic areas and subtropic areas, N.americanus is commonly found in warm zone.

30. Distribution of Hookworm in china

31. Hookworm: World Distribution
                                                                                                                                                                               
Hookworm: World Distribution

32. Reservoir, source and transimission of infection
Human is the only reservoir of infection
Human feces is the only source of infection

33. Prevention and control
l ) Sanitary disposal of human feces;
2) Treatment of infected persons;
3) Health education with improved use of sanitary latrines and use of foot wears

34. Treatment of hookworm infection consists of
a) treatment of worm infection by anthelmintics such as mebendazole;
b)treatment of anemia.

36. TRICHINELLA SPIRALIS

37. Trichinosis is related to the quality of pork and consumption of poorly cooked meat. Autopsy surveys indicate about 2 percent of the population is infected.

38. Morphology
Adult worm The adult worms are very small and slender with slightly tapered anterior ends, white and just to the naked eye. female 2.2 mm in length, males 1.2 mm;
female
male

39. male
papilla

40. pharynx
female
Its pharynx is one third or half of worm body long, and posterior part of pharynx consists of a column of cells called of stichocytes.
juveniles

41. Cyst (larvae)
The cyst are found in skeletal muscle commonly, its size is about 0.25~0.5

42. Larvae in Muscle Section
Larvae in Muscle Press

43. Larvae of Trichinella, freed from their cysts, typically coiled; length: 0.8 to 1.0 mm. 

44. Trichinella spiralis: Electron microscopy

45. Life cycles adult larvae adult larvae cycst dischargeing ( 1 month)
Into skeletal via bloodstream
dischargeing
adult
larvae
cycst
( 1 month)
Intestine of the humans、pigs、rats、cats、dogs
Swallowed by
another host
adult
larvae

47. cyst
cyst
adult
lavae

48. Trichinellosis is acquired by ingesting meat containing cysts (encysted larvae) of Trichinella.
  After exposure to gastric acid and pepsin, the larvae are released
from the cysts and invade the small bowel mucosa where they develop into adult worms
(life span in the small bowel: 4 weeks).

49. After 1 week, the females release larvae
that migrate to the striated muscles where they encyst

50. Life Cycle
< Infection occurs by ingesting encysted larvae in undercooked meat.
< Larvae penetrate the intestinal wall and move to muscle tissue where they encyst in individual cells (nurse cells).  Active muscles, such as the diaphragm and tongue, often have the greatest numbers of larvae.
< Adults attach to the intestinal mucosa and being to release larvae in one week.  The adults live for about 4 weeks and may release more than 1000 larvae.

51. Pathogenesis and clinical manifestation
The process of pathological change can be divided three phases.
1)Invade phase : intestinal inflammation
intestinal inflammation
For invading of larvae and adult worms, the wall of intestine is damaged
Gastrointestinal signs

52. 2) Migratory phase : toxic and allergic
severe systemic disease
allergic phenomena such as edema, pneumonitis, and pleural transudate
3) Encystation of the larvae and tissue
repair formation of cyst

53. clinical manifestation (Symptoms)
Infection with Trichinella spiralis may be asymptomatic, especially in light infections.  Adults in the intestine may cause diarrhea, abdominal pain, and vomiting.  Larvae moving into the tissues may cause facial swelling, fever, muscle pain, splinter hemorrages (under fingernails) or rashes.
Heavy infections may lead to heart problems or central nervous system involvement.  Large numbers of larvae in other muscles may lead to soreness and weakness which often lessens over time.

54. Diagnosis
clinical manifestations with a history of ingesting meat that may contain larvae;
immunodiagnosis;
muscle biopsy.
The definitive diagnosis is made by demonstration of free or encapsulated Trichinella larvae in the skeletal muscles obtained either in biopsy or at autopsy.

55. Epidemiology

56. Trichinella spiralis (T-1) (green) is the most common member of the genus. The world distribution as depicted is almost certainly an under-representation

57. Prevention and control
avoidance of eating raw or undercooked pork and meat of other wild animals; and avoidance of feeding raw garbage to pigs will prevent transmission of infection to man.