Hookworm is a parasitic nematode that infects the small intestine and is a major cause of iron-deficiency anemia globally. Two species infect humans - Ancylostoma duodenale and Necator americanus. The worms attach to the small intestine where the female lays thousands of eggs daily that are passed in feces. If soil contaminated with feces comes into contact with human skin, larvae can penetrate and migrate through tissues before reaching the intestine. This causes a rash and eosinophilia. In the intestine, the worms feed on blood, causing microcytic anemia. Over 900 million people are infected worldwide, especially in tropical areas with

1. Ms Mary Mwinga

2. INTRODUCTION
 Widely distributed in tropical and sub tropical countries
 One of small intestine nematodes
 Important cause of Iron deficiency anaemia
 Named so – anterior end of adult worm is bent
 Belongs to family Ancylostomatidae
 2 important human Spp: Ancylostoma duodenale
Necator americanus

3. Ancylostoma duodenale
 Also called old world hookworm
 Causes ancylostomiasis
 Dubini in 1843 described the parasite
 Arthur Loss in 1896 described pathogenesis and mode of
infection

4. EPIDEMIOLOGY
 Globally 900 million people infected. Necator- 835 million &
Ancylostoma- 135 million
 Hookworm infection is prevalent in the tropics and subtropical
countries – Asia, Africa, America, China and Southern Europe
 In India – prevalent in Punjab, Uttar Pradesh and Bihar
 Males & young adults commonly affected
 Anaemia severe in children & pregnant women

5. MORPHOLOGY
 Adult worm and egg
Adult Worm:
- small, greyish white and cylindrical
- Anterior end- bent dorsally = hence name hookworm
- Oral aperture- directed towards dorsal surface
- Buccal capsule- has 6 teeth, 4 hook-like on the ventral surface
and 2 knob-like on the dorsal surface.
- Male worm differs from female worm

6. Differences between Adult male and female A.
duodenale
Characteristic Male Female
Size Smaller- 5 to 11 mm long x
0.4 mm wide
larger /longer than male
9 to 13 mm long x 0.6 mm
wide
Posterior end Expanded in an umbrella
like fashion
Named as copulatory
bursa
Tapering and no
expanded bursa
Genital opening Posterior and opens with
cloacae
Present at junction of
posterior and middle
third of body

8.  Copulatory bursa
- Present in male
- For attachment with female during copulation
- Consists of 3 lobes, one dorsal and two lateral lobes
- Each lobe: supported by chitinous rays= 13
3 at dorsal lobe and 10 at the two lateral lobes
- Dorsal ray is partially divided at tip
- Each division is tripartite
- Life span adult worm in human intestine: 3 to 4 years

10. EGG
 Oval shaped
 Size: 65 µm long x 40 µm wide
 Colourless- non-bile stained
 Surrounded by a thin transparent hyaline shell-membrane
 Contains a segmented ovum with four (4) blastomeres
 Clear space between egg shell and segmented ovum.
 Egg floats in saturated salt solution
 Single female worm- lays about 25 000 to 30 000 eggs/day
 Eggs are excreted in faeces 4-7 weeks after infection

12. Life cycle of Hookworm
 Definite host: man
In small intestines: Adult worm inhabit small intestine
of man
Attachment to mucous membrane by help of mouth
parts
Eggs contain segmented ova with 4 blastomeres-
passed out in faces of infected person (non-infective)

13. In soil: rhabditiform larva hatches from each egg (24-
48 hours)
size: 250 µm x 17 µm.
moults twice on 3rd and 5th day
develops into filariform larva.
size: 500-700 µm long
is the infective form- penetrates unbroken skin (of
toes, dorsum of foot and medial aspect of sole)
 Remains infective up to 6 weeks

15.  People at risk
- Walking barefoot on soil containing filariform larva
- Farm workers: larva penetrates skin of hands
reaches subcutaneous tissues and enters lymphatics or small
venules
Lymph to venous circulation into right heart
 into pulmonary capillaries- break through and enters alveolar
spaces
 migrates to bronchi, trachea and larynx- crawl over the
epiglottis to pharynx  gets swallowed
During migration through oesophagus undergo 3rd moulting

16. Settles in small intestines undergo 4th moulting and
develop into adult worms.
Attach to small intestine by their mouth parts
After 6 weeks- mature sexually
Fertilization occurs
Female begin to lay eggs in faeces  cycle repeats

18. Pathogenesis and clinical manifestations
 Infective form: filariform larva
 Portal of entry- skin
 Worm causes hookworm disease- characterized by anaemia.
 Effects are due to –migrating larva or adult worm
Migrating larva lesions:
- Ancylostoma dermatitis or ground itch
- Creeping eruption or cutaneous larva migrans
- Lesions in lungs

19. 1. Ancylostoma dermatitis/ground itch
 Occurs at site of entry
 Entry of filariform in skin cause dermatitis
 Leads to intense itching and burning
 Followed by erythema and oedema of the area
 Develop into papular and vesicular eruptions
 Disappears within 1 to 2 weeks.
 Common in N. americanus

20. 2. Creeping eruption/cutaneous larva migrans
 Condition where filariform larva wander about the skin
-producing reddish itchy papule along path traversed by the worm
Seen mostly in animal (cats, dogs and others)
- Animal filariform cannot penetrate below level of stratum
germinativum and stratum corneum
Animal agents: - Ancylostoma braziliense (dogs and cats)
- A. caninum (dog hookworm)
- Uncinaria stenocephalia (dog hookworm)
- Bunostomum phlebotomum (cattle hookworm)
- Gnathostoma sp.

21.  Human- infected by walking barefoot contacting
moist soil contaminated with animal faeces
 Creeping eruptions may occur occasionally by A.
duodenale and N. americanus.

22. 3. Lesions in the lungs
 Bronchitis and bronchopneumonia
 Marked eosinophilia occurs
 Caused by adult worm
 Disease= hookworm disease
 Features:- microcytic hypochromic anaemia
 Hookworm ingest blood
 Other features: cough, dyspnoea

23. Intestinal manifestations
 Attach to mucosa of small intestines
 Adult worm of A. duodenale sucks more blood (0.2
ml/day) than for N. americanus.
 Worm migrate to another site leaving small bleeding
points
 Worm secretions possess anticoagulant activity
bleeding from sites continue for sometime
 These leads to iron deficiency anaemia of microcytic,
hypochromic type

24.  Degree of anaemia depends on: - number of worms
- body iron store
- dietary iron
 Development of low grade fever, epigastric pain,
dyspepsia, vomiting and diarrhoea.
 Stool: reddish to black
 Symptoms and signs of anaemia present.

25. Laboratory Diagnosis
 Direct Methods:
- Stool examination: to find the adult worm or characteristic
hookworm eggs
- Stool concentration: required to detect light infections
- Larva- seen if stool is kept at room temperature after 24 hours
(not preserved)

26. May resemble Strongyloides larvae
Adult female hookworm- produce 2500 to 5000
eggs/day.
- Stool egg count: indicates number of adult
hookworms present
Indicates severity of infection
- Duodenal contents- reveals eggs or adult worms.

27. Indirect methods
 Blood examination: reveals microcytic, hypochromic
anaemia and eosinophilia
 Stool exam: shows occult blood and Charcot-Leyden
crystals

28. Stool culture
 Eggs hatch out and develop into filariform larva (L3) stage
 Takes place in 5-7 days
 Culture techniques used:
-Harada Mori filter paper tube method
- Petridish (slant culture) technique
- Baermann funnel technique
- Charcoal culture method
- Agar plate technique (more sensitive)
Other findings: hypochromic microcytic anaemia
Chest x-ray- show patchy infiltration of lungs

29. Necator americanus
 Has similar life cycle, pathogenesis and lab diagnosis
like for A. duodenale.
 Adult worm- slightly smaller than Ancylostoma
 Eggs of Ancylostoma and Necator are similar and
hence can be differentiated by morphological study of
adult worms and larvae

30. ADULT
WORMS
ANCYLOSTOMA
DUODENALE
NECATOR AMERICANUS
Size Large and thick Small and slender
Buccal
capsule
Large and oval
Contains 2 pairs of claw like
teeth on the ventral surface and 1
pair of knob like teeth on the
dorsal surface
Small and round
Contains 1 pair of chitinous plates
on ventral surface and 1 pair of
plates on the dorsal surface
Anterior end Bends in the same direction as
the body curvature
Bends in the opposite direction as
the body curvature
Posterior end Posterior spine present in female
worm
No posterior spine
Copulatory
bursa
Dorsal ray is single and
bifurcated
Each bifurcation again divides
into three rays
13 rays
Dorsal ray split form base
Each bifurcation is again divided
into two
12 rays
Vulva Present behind the middle of the
body
Present in front of the middle of
the body

33. BUCCAL CAPSULE

34. COPULATORY BURSA
ANCYLOSTOMA
DUODENALE
NECATOR AMERICANUS

35. EPIDERMIOLOGY
 Western world- Africa and America
 In India – all except in Punjab, Uttar Pradesh

36. Treatment
 Mebendazole- 100 mg twice daily for 3 days
 Albendazole- 400 mg single dose
 Pyrantal pamoate – 11 mg/kg for 3 days
 Mild iron-deficiency anaemia- oral iron
 Severe infections with protein loss and malabsorption:
nutritional support and oral or parenteral iron
replacement

37. PREVENTION
 Personal care: - improved personal hygiene
- proper disposal of faeces
- improved nutrition with dietary iron
- treatment of infected persons
 Prophylaxis: experimental animal vaccines: using larval or
adult stage antigen.
 Human trials: targeting Ancylostoma secreted proteins (ASP).