1. Hookworms 鉤蟲 Distribution between 45oN and 30oS
Approximately 9 billion people infected
Over 20 million showed clinical manifestations
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

2. Between 45oN and 30oS A. duodenale 十二指腸鉤蟲 N. americanus 美洲鉤蟲
Middle East
Mediterranean countries
North China
Africa
South-East Asia
South America
Pacific Islands
A. duodenale 十二指腸鉤蟲
Far East
South Asia
Tropical Africa
Central and South America
N. americanus 美洲鉤蟲

3. 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

4. Posterior end of N. americanus
雄美洲鉤蟲 9~11 x 0.4 mm
雌美洲鉤蟲 7~9 x 0.3 mm
Anus
Bursa
交尾囊

5. Copulatory bursa 交尾囊 externo-dorsal ray 外背側枝 ventral ray 腹面枝
Spicules
交尾刺
postero-
latero ray
後側枝
medio-lateral
ray 內側枝
externo-lateral
ray
ventral ray
腹面枝
dorsal ray
背面枝
externo-dorsal
ray 外背側枝

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

7. Filariform larva (L3) 絲狀幼蟲
Lungs
Circulation
Penetrates skin
Egg in faeces
2nd stage
larva (L2) in soil
Rhabditiform larva
hatches 桿狀幼蟲
Swallowed
Pharynx
Trachea
EXTERNAL
ENVIRONMENT
Diagnostic
stage
診斷期
Infective
感染期
Attached to
small intestine
4~6 wks
2~3 wks
1 wk
3 days
MAN

8. Clinical Pathology Pentration of skin by F- form larvae (L3)
Skin reaction (uritcaria 蕁痲疹 )at the site of larval pentration
Stinging sensation followed by irration, erythea,
oedema and papulovesicular eruption
Gound itch
A. braziliense and A. caninum wandering through the
cutaneous layer (cutaneous larva migrans) cause
intense irritation and iflammaton.
Most of the larva die in the skin.
Creeping eruptions 匍行性疹

9. Clinical Pathology Migration of F-form larvae (L3) In lungs
During invasion of the circulation: Usually no ill-effects
During 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 tract
Coughing due to irritation of the
bronchial and
tracheal mucous membranes

10. Clinical Pathology Established intestinal infection by adult worms
Epigastric duodenal-type pain, indigestion, loss of appetite or diarrhoea
Hookworm anaemia (HWA)
Losses of blood, iron and proteins
Occassionally associated with folate deficiency
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)

11. Laboratory Diagnosis Direct smear for eggs
Egg culture for 1st stage larva (L1)
Colourless with a thin shell which appears as a black line aroung the ovum
Oval in shape, measuring about 65 x 40 mm
Contains an ovum which usually appears segmented
Larva may be seen inside in some specimen