Hookworms Distribution between 45 o N and 30

Hookworms 鉤蟲 Distribution between 45 o. N and 30 o. S 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

Between 45 o. N and 30 o. S 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 Far East South Asia Pacific Islands Tropical Africa Central and South America

Posterior end of N. americanus 雌美洲鉤蟲 7~9 x 0. 3 mm Anus 雄美洲鉤蟲 9~11 x 0. 4 mm Bursa 交尾囊

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

Transmission Active penetration of skin by infective filariform larvae (L 3) Ingesting of infective larvae in A. duodenale Transmammary transmission of larvae in A. duodenale infective filariform larvae (L 3)

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

Clinical Pathology Pentration of skin by F- form larvae (L 3) Gound itch Skin reaction (uritcaria 蕁痲疹 )at the site of larval pentration Stinging sensation followed by irration, erythea, oedema and papulovesicular eruption Creeping eruptions 匍行性疹 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.

Clinical Pathology Migration of F-form larvae (L 3) 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) In lungs Haemorrhages and leukocytic or eosinophilic infiltrations In respiratory tract Coughing due to irritation of the bronchial and tracheal mucous membranes

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)

Clinical Pathology Cubbled Fingers & Ascites

Laboratory Diagnosis Direct smear for eggs Egg culture for 1 st stage larva (L 1) 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

Early stage Advanced stage Gastrula stage Embryonated stage

Hookworm Rhabditiform Larva Hookworm Filariform Larva