Hookworm
Hookworm infection is widely distributed in tropical & subtropical,
where there are favorable environmental factor for hookworm
spreading, including warm weather, high rainfall, soil pollution by
human defection or fertilization with human feces and person walking
with bare feet.
Hookworm infection is second only to ascariasis as the most common
helminthic infection.
Hookworm infection has almost eradicated from Europe and United
States.
Ancylostoma duodenale(十二指肠钩虫)----------- the small intestine
Necator americanus (美洲板口线虫)--------------the small intestine
Ancylostoma cerlanicum (锡兰钩口线虫)---rarely infects human beings
Ancylostoma caninum(犬钩口线虫)-------rarely infects human beings
Ancylostoma braziliense巴西钩口线虫----creeping erupting,
幼虫可感染人，引起幼虫移行症
The common species are 十二指肠钩虫& 美洲板口线虫,
these worms are similar in morphology & life cycle.
钩虫是一类口囊发达的线虫，并在口囊内有锐利的切器，
可损伤肠粘膜，吸食血液和组织液，使患者长期慢性失血，
造成严重危害。钩虫寄生小肠引起钩虫病
Hookworm infection is contracted mainly by penetration of the
skin or oral mucosa by the filariform larvae ( infective stage)
of hookworm. Thus, barefoot farmers & children walking on
contaminated soil or eating contaminated vegetables may
become infected.
形态
Morphology
Adult:The adult are
cylindrical with the
head bent sharply
backwards,
giving them a hooked appearance.
The mouth of hookworm were well developed, with a pair of
teeth or a pair of cutting plate.
The adults of A.duodenale are somewhat large than those of
N. americanus.
The posterior end of the male has an umbrella shaped bursa, with
riblike rays.
十二指肠钩虫
大小
体形
稍大，♀>♂
“（”形，头尾向背侧仰伸
口囊
背肋分支
阴门
尾刺
两对钩齿
远端分2支，再分3支
体中部略后
+
美洲钩虫
稍小，♀>♂
“∫”形，头向背仰伸，
尾向腹侧弯曲
一对切板
基部分2支，再分2支
体中部略前
-
Egg (虫卵)
Egg of two species are nearly indistinguishable. They are ovoid with a
thin transparent shell and, measure 60 m X 40 m, a clear space that
separates the shell from the yolk cells. The number of yolk cells in
egg found in the stool varies from two to eight.
?
?
Larva
a rhabditiform larva (杆状蚴): 275 X 16 m
The newly hatched larva feed actively upon bacteria &
organic debris, grow rapidly to a size of 500 to 700 m
in 5 days
a filariform larva (丝状蚴 ): slender, nonfeeding the active
filarform larva frequent the upper half-inch of soil and project
from the surface-------infective stage
头端
咽管矛
鞘膜横纹
尾端
Ad 丝状蚴
Na 丝状蚴
扁平，中间微凹
不明显
不明显
逐渐变细
圆形，无凹陷
明显
明显
骤然变尖
十二指肠钩虫和美洲钩虫的分布 /致病力/药敏性各异
They survive best in shaded localities, such as light sandy
or alluvial soil or loam covered by vegetation,
they are protected from dry or excessive wetness
at 0° C larva survive less than 2 wks
at 11° C less than 24 hrs
at 45° C less than 1 hr
Life cycle
Humans almost exclusively are hosts for both hookworm, while dogs also
are common host for N. americanus.
When eggs are expelled with feces, under optimal conditions ( temperature
of 23-33°C, shade, and sandy soil rich in organic material), a rhabditiform
larva matures in 1-2 days & hatches from the thin shelled egg, feeds on
bacteria & organic material in the soil. After two molts, it becomes a
non-feeding, infective, filariform larva.
成虫
卵
杆状蚴
丝状蚴（感染期）
经皮肤
粘膜
移行途径
皮肤
小血管
右心
肺
食道
肺部微血管
咽
肺泡
小气管
Adult worm
egg
rhabdifiform larva
transmission
filariform
larva
(5-6 wk)
skin
mucosa
Transmission:
Skin
lymphatic vessels
small intestine
right side of heart
lung
pulmonary capillary
tracheobronchial
alveoli
成虫寄生部位和摄食
Adult worm in small intestine
产卵量 Ova product
A.duodenale produces 10000 to 30000 eggs per day
N.americanus produces 5000 to 10000 eggs per day
丝状蚴具有向上性、向湿性、向温性
character of filariform larva : strong thigmotaxis,
moisture, thermotaxis (1-2 cm)
Penetration skin or oral mucosa (A.d), migration,
development
A.d of filariform larva may invade host skeletal musculature
致病
Pathogenicity
钩虫感染
钩虫病
The course of human hookworm disease can be divided into three phases:
invasion phase
migration phase
intestinal phase
Invasion phase
幼虫所致病变和症状 larval invasion of skin
1. 钩蚴性皮炎
itching, erythematous papular,
vesicular eruption ( with or without edema or
enlargement of lymph nodes),
secondary bacterial infection
creeping eruption
2.
肺部损害
Migration phase the major features are pulmonary manifestation
severe cases: Loffler’s syndrome
or
coughing, dyspnea, pulmonary infiltrate, eosinophilia
nausea, vomiting ------------ Wakana disease
成虫所致病变
Intestinal phase
消化系统的症状 nausea, vomiting, abdominal pain, diarrhea,
constipation --------intestinal complaints
by buccal capsule & ‘teeth’ to burrow through the mucosa, feeding upon
blood ------ anemia 慢性失血引起贫血
贫血的原因：
成虫吸血： 吸血量
吸血同时，咬附部位粘膜渗血：咬附点渗血量
虫体吸血可以经常更换咬附部位，造成新的损伤，
原伤口还继续渗血 移位伤口渗血量
造血物质吸收障碍；小细胞低色素性贫血
Salivary secretions of the worms contain anticoagulants
that facilitate blood feeding
A.d 0.15 –0.26 ml/worm/24 hrs (6-8 yrs)
egg
output 20000/d
N.a 0.03 –0.05 ml/worm/24 hrs (2 yrs)
egg output 10000/d
progressive cardiac insufficiency ----- congestive heart failure
3 ml to 100 ml/day in mild or severe infection
另外与患者原来的健康状况
异嗜症 也许是钩虫病诊断的一个线索
Geophagy
craving to eat soil, wood, charcoal, paper-----pico
Infection in infant or children severe stunted growth die
婴儿钩虫病：贫血严重、发育极差、合并症多、死亡率高。
经胎盘
经乳汁
经皮肤
诊断 Laboratory Diagnosis
identification of eggs in the stool
粪便检查
直接涂片法
饱和盐水浮聚法
钩蚴培养法： 定量检查
PCR检测
一个虫卵即可诊断，并可区别虫种
Brine floatation method
Culture of hookworm larva
DNA (PCR) can be amplified from a single egg and identity species
流行 Epidemiology
Hookworm is worldwide distributed.
N. americanus is found mainly in moist tropical region such as Southeast
Asia,
h
A. duodenale is found mainly in dry tropical region such as North
Africa, North China
传染源：患者、带虫者
传播因素：
a.适宜虫卵、幼虫发育、存活的条件
A shaded sandy or loam soil, which is a favorable culture medium
for hookworm larva.
A warm climate, which favors the development of the eggs and
larva and promiscuous defecation
Moisture, especially during the worm season of the years when egg
and larva development are possible
b.粪便污染土壤
Contamination of the soil by egg-containing feces
c.生产、生活方式
person walking with bare feet.
d.个体抵抗力
防治原则 Prevention & Treatment
治疗病人和带虫者
mebendazole
100mg Bid×3days
albendazole
400mg once
同时纠正贫血
Treatment of infected individuals
mebendazole 100 mg Bid for 3 days
albendazole 400 mg once
for severe anemia administration of iron
粪管
Sanitary disposal of human excrement
预防感染
Protective measures to prevent contact with infective larva
蛲虫
蛲虫(pinworm)，学名蠕形住肠线虫（Enterobius
vermicularis)，成虫寄生在盲肠、阑尾、
直肠等处引起蛲虫病(enterobiasis)。
一.
形态
（一）成虫
（二）虫卵
二. 生活史
成虫
卵
感染期卵
幼虫
the egg may survive for some days in dry dust
airborne eggs may infect person at some distance
a type of autoinfection described as “retrofection”
三.致病
是常见的小儿科疾病
pinworms or their eggs have occasionally been reported from other
ectopic sites, such as liver and lung
蛲虫性阑尾炎
蛲虫性泌尿生殖系统炎症
四.实验诊断
发现虫卵或成虫即可诊断
从粪便中检出虫卵率低于5-15%，为什么？
透明胶纸粘贴法、棉签拭子法
cross sections of Enterobius vermicularis
in appendix
五.流行
蛲虫病是世界性分布的常见寄生虫病。
传播方式
1.经口感染 直接
间接
2.吸入感染
3.逆行感染 retrofection
Pinworm is by all odds the most common helminth parasite of those
temperate regions where sanitation measures are relatively rigorous
as much as 10% of the pediatric population may be infected in these area
less attention is paid to pinworm in the tropical areas, probably because
of the relative prevalence of more important parasites
蛲虫病分布广泛的原因
生活史简单
虫卵抵抗力强，一般浓度消毒液不能杀死虫卵
卫生习惯不良
六. 防治原则
1.普治共治，集体治疗
2.注意环境卫生、家庭卫生、个人卫生及防止相互感染。
3.治疗病人 albendazole：200mg(儿童)
400mg(成人)
mebendazole：100mg bid ×3days