ANCYLOSTO

MIA

SIS

HOOKWORM

S

ANCYLOSTO

MA D

UODENALE

.

EMAN

KH

ALIF

A

P RO

F. O

F PA RA S I T

OLO

GY

ANCYLOSTOMA DUODENALE

Diseases: Ancylostomiasis, Hookworm disease Morphology:

Ancylostoma adults. At the anterior end there is

a big cup shaped mouth called buccal capsule.

They have a club shaped oesophagus

The male worm measures nearly 1 cm by 0.5 mm

and is provided with a copulatory bursa at the

posterior end with two free spicules

The female is larger and stouter (1.2 cm by 0.6

mm). The posterior end is straight and pointed.

24-Ancylostoma duodenale adult male

25-Ancylostoma duodenale adult female

The eggs Size: 60 X 40 in diameter ,

Shape: oval with blunt poles, thin-walled ,Colour: colourless

Content: four cell stage (immature).

ANCYLOSTOMA DUODENALE

Life cycle

Habitat: Adults live in the small intestine of man

attached by the mouth capsule to the mucosa. Eggs

passed in faeces mature rapidly, hatch and

produce the first stage rhabditiform larvae (250 )

in 1 to 2 days under favourable conditions

(humidity and temperature 25°C), feed actively

upon organic debris and grow rapidly to a size of

500 second stage rhabditiform larvae in 5 days.

 

They moult for a second time to become

infective ensheathed filariform larvae

(700 ) after about 7 days.

Mode of infection: Man is infected when

the filariform larva penetrates his intact

skin or mucous membrane of the

mouth.

Miners and farmers may acquire the infection on

the hands chiefly in the interdigital spaces,

dorsum of foot and between toes.

The filariform larva moves towards warmth (+ve

thermotropism), moist areas (+ve hygrotropism) and

host tissues (+ve histotropism) but against gravity (-

ve geotropism). The strong +ve histotropism

facilitates access to the host. The –ve geotropism

helps the larva to move towards the surface to reach

human skin.

The larvae enter the lymphatics or venules and

are carried in the blood through the heart to

the lungs, where they break out of the

capillaries into the alveoli. They ascend the

bronchi and trachea. Finally they are swallowed

and pass down to the intestine. This migration

takes about one week, during which the larvae

undergo a third moult and acquire a temporary

buccal capsule. The fourth moult occurs in the

intestine at about the 13th day. The egg-laying

females are developed in 5 to 6 weeks after

infection.

 

CLINICAL PICTURE

Invasion stage:

Larval penetration leads to local dermatitis and localized erythema, usually between the toes, dorsal surface of the foot. Itching is often severe. This

condition is known as “ground itch.”

Migration stage:

Passage of larvae in the lungs leads to minute haemorrhages and pneumonitis. There may be cough, expectoration, haemoptysis, fever, leucocytosis and eosinophilia (verminous pneumonia or Loeffler's syndrome).

INTESTINAL STAGE

:

Severe gastroenteritis often develops about 6 weeks after

infection due to ulceration of mucous membrane. The

gastroenteric phase is self-limited.

Symptoms due to the adult worms occur later only if anaemia

develops. An adult hookworm sucks about 0.3 ml blood / day.

The previous points of attachment bleed for sometime after

movement of the worms to new sites because adult secrets

antiplatelet agents that help the continuous oozing of blood,

this blood loss leads to hypochromic normocytic or

microcytic anaemia, which leads to dyspnoea on exertion,

palpitation, pallor, puffiness of the face, weakness and

dizziness .

Diagnosis:I- Clinical picture :

II- Laboratory:Direct :

Final diagnosis depends upon finding the eggs in the faeces

Infective stage of Ancylostoma duodenale is

Filariform larva

Egg containing four cell stage is the diagnostic stage of

Ancylostoma duodenale

Ancylostoma duodenale

Microcytic hypochromic anamia is a complication of

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