Necator americanus 美洲鉤蟲

Ancylostoma duodenale 十二指腸鉤蟲

Ancylostoma caninum 犬鉤蟲

Ancylostoma braziliense 巴西鉤蟲

Ancylostoma ceylanicum 鍚蘭鉤蟲

Ancylostoma malayanium 馬來亞鉤蟲

Hookworms 鉤蟲Distribution between 45oN and 30oSApproximately 9 billion people infected

Over 20 million showed clinical manifestations

Middle EastMediterranean countriesNorth ChinaAfricaSouth-East AsiaSouth AmericaPacific Islands

A. duodenale 十二指腸鉤蟲

Far EastSouth AsiaPacific IslandsTropical AfricaCentral and South America

N. americanus 美洲鉤蟲

Between 45oN and 30oS

A. duodenale 十二指腸鉤蟲

腹齒附齒

次腹齒刀

N. americanus 美洲鉤蟲

腹齒板

雄美洲鉤蟲 9~11 x 0.4 mm

雌美洲鉤蟲 7~9 x 0.3 mm

Anus

Bursa

Posterior end of N. americanus

交尾囊

Copulatory bursa 交尾囊

Spicules 交尾刺

postero-latero ray後側枝 medio-lateral

ray 內側枝

externo-lateralray

ventral ray腹面枝

dorsal ray背面枝

externo-dorsalray 外背側枝

Transmission

Active penetration of skin by infective filariform larvae (L3)Ingesting of infective larvae in A. duodenaleTransmammary transmission of larvae in A. duodenale

infective filariform larvae (L3)

Filariform larva (L3) 絲狀幼蟲

Lungs

Circulation

Penetrates skin

Egg in faeces

2nd stagelarva (L2) in soil

Rhabditiform larvahatches (L1) 桿狀幼蟲

SwallowedPharynx

EXTERNAL ENVIRONMENT

Diagnosticstage診斷期

Infectivestage感染期

Attached tosmall intestine

4~6 wks

2~3 wks

1 wk

3 days MAN

Trachea

Pentration of skin by F- form larvae (L3)Clinical Pathology

Skin reaction (uritcaria 蕁痲疹 )at the site of larval pentrationStinging sensation followed by irration, erythea,oedema and papulovesicular eruption

Gound itch

A. braziliense and A. caninum wandering through the cutaneous layer (cutaneous larva migrans) causeintense irritation and iflammaton.Most of the larva die in the skin.

Creeping eruptions 匍行性疹

Migration of F-form larvae (L3)Clinical Pathology

During invasion of the circulation: Usually no ill-effectsDuring migration through the lungs: Pneumonitis (肺炎) with cough (咳嗽), wheeze (哮喘), fever (發燒 ), transient X-ray shadows (Not as severe as Ascaris)

Haemorrhages and leukocytic or eosinophilic infiltrations

In lungs

In respiratory tractCoughing due to irritation of the

bronchial and tracheal mucous membranes

Established intestinal infection by adult wormsClinical Pathology

Epigastric duodenal-type pain, indigestion, loss of appetite or diarrhoea

Adult worms attach to duodenum and jejunum by teeth or cutting plates (mechanical)

Worms move every 4-6 hours (blood leaking)Worrms feed on blood from cut vessels and

mucosal tissue (chronic blood loss)

Hookworm anaemia (HWA)Losses of blood, iron and proteins

Occassionally associated with folate deficiency

Clubbed Fingers & AscitesClinical Pathology

Laboratory Diagnosis

Colourless with a thin shell which appears as a black line aroung the ovumOval in shape, measuring about 65 x 40 µmContains an ovum which usually appears segmentedLarva may be seen inside in some specimen

Direct smear for eggsEgg culture for 1st stage larva (L1)

Embryonated stage Gastrula stage

Advanced stage Early stage

Hookworm Filariform Larva (L3)

Hookworm RhabditiformLarva (L1)