article : More Know about Hookworm

The hookworms cause hookworm disease, which is one of the five major parasitic disease in China(malaria, shistosomiasis, filariasis, kala- azar and hookworm disease). At least two species of hookworms infect man, Necator americanus and Ancylostoma duodenale. They live in small intestine.

Morfology

Adults: They look like an odd piece thread and are about 1cm. They are white or light pinkish when living. ♀is slightly larger than♂.The male’s posterior end is expanded to form a copulatory bursa.

Eggs: 60×40 µm in size, oval in shape, shell is thin and colorless.

Content is 2-8cells.

The Morphological Differences between Two species of Hookworms

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A. duodenale N. americanus

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Size larger smaller

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Shape single curve, looks like C double curves, looks like S

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Mouth 2 pairs of ventral teeth 1peir of ventral cutting plates

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Copulatory circle in shape oval in shape

Bursa (a top view) (a top view)

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Copulatory 1pair with separate 1pair of which unite to form

spicule endings a terminal hooklet

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caudal spine present no

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vulva position post-equatorial pre-equatorial

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Lyfe cycle

1. Final host: man

2. Inf. Stage: Larva 3 or filariform larva

3. Inf. Route: by skin

4. Food: blood and tissue fluid

5. Site of inhabitation: small intestine

6. Life span: Ad 15years, Na 3-7years

7. Blood-lung migration:

skin, cavum, right heart, lungs

nPathogenesis & Clinical manifestation

Larval migration

(1) Dermatitis, known as "ground itch" or "stool poison".The larvae penetrating the skin cause allergic reaction, petechiae 0r papule with itching and burning sensation. Scratching leads to secondary infection.

(2) pneumonitis (allergic reaction), Loeffier's syndrome: cough, asthma, low fever, biood-tinged sputum or hemoptysis, chest-pain, inflammation shadows in lungs under X-ray. These manifestations go on about 2 weeks.

Adults in small intestine

(1) Epigastric pain as that of a duodenal ulcer.

(2) A large worm burden results in microcytic hypochromatic anemia (character manifestation). The symptoms are lassitude, edema, palpitation of the heart. In severe case, death may result from cardiac failure or physical exhaustion.

(3) Allotriophagy (orpica) is due to the lack of trace element iron (4) Amenorrhea, sterility, abortionmay take place in women.

(5) Gastrointestinal bleeding

(6) Infantile hookworm disease

Diagnosis

Criterion: 1. hemoglobin is lower than 120g/L in man,
110g/L in woman. 2. find hookworm egg

Method:

1. saturated brine flotation technique

2. direct fecal smear

3. culture of larvae

Treatment

1. Albendazole
2. Mebedazole

Epidemiology

worldwide distribution. 22-26℃ is the optimal temperature for Ancylostoma duodenale development, Ancylostoma duodenale mainly prevalent in north of China. 31-35℃ is suitable for Necator americanus, it is mainly prevalent in south of China

Prevention

Unified measures:
1. sanitary disposal of night soil,
2. individual protection,
3. health education,
4. cultivate hygienic habits,
5. treat the patients and carriers.