寄生虫脑病课件

Epidemiology of parasitic infection in CNS Schistosoma japonicum Schistosomiasis is a global disease that remains a major public health problem in many countries of the world. World Health Organisation (WHO) estimates indicate that approximately 200 million persons residing in rural and agricultural areas are currently infected with schistosome parasites, and a further 600 million persons are potentially exposed to the risk of infection. Schistosoma japonicum, is recognised as the most difficult to control because of its zoonotic nature. Several million people are afflicted with schistosomiasis japonica with significant endemic foci in China. The first diagnosed case of S. japonicum infection was made by an American physician in 1905 while working in the Dongting Lake region of China. Epidemiological characteristics 1. The geography of the Dongting Lake region and the S. japonicum focus: Dongting Lake, covering a surface water area of 2691 km2, is located at 28402950N and 1150 11310E in the south of China. The lake region is 25 50 m above sea level and has a warm climate with abundant rainfall. Dongting Lake plays an important role in regulating the amount of water in the Yangtze River. The natural surface area of lake water was 6000 km2 in 1850, 5400 km2 (10% reduction) in 1915, 4350 km2 (28% reduction) in 1950 and 2691 km2 (55% reduction) in 1987. The Dongting Lake region, covering a total area of 15 000 km2, has a population of approximately 3.2 million, and it is recognised as a severe endemic area for S. japonicum in China. Re-infection and incidence of S. japonicum after mass praziquantel treatment of exposed residents in Wu-Yi community, Dongting Lake region YearTreatment for infected cases Treatment for non- infected casesTotal ExposedRe- infectedExposedIncidenceExposed Re- infected and incidence % No.%No.%No. 19916524.618518.925020.4 19926740.321516.728222.3 19938151.97422.915538.1 19941139.71304.62437.0 19953842.19013.312821.9 Total36430.869415.3105820.6 Water exposure and human infection with S. japonicum There is a close relationship between the prevalence of human infection and the frequency of contact with water contaminated with schistosome cercariae. Well-defined studies on human water contact are limited for S. japonicum in China. Our recent work in the lake region has shown that most water contact occurs in males 18 49 years of age. Further, human water exposure is occupationally driven, as more than 90% of houses in the study area have been provided with a good water supply. Dynamics of S. japonicum transmission ecology, water level and infected nails by month in the Dongting Lake in 1992 Dynamics of S. japonicum transmission ecology, water level and infected nails by month in the Dongting Lake in 1992. . Age by mean+S.D. intensity and meanS.D. water exposure in 213 cohort subjects from the Dongting Lake region of China (19961998) The snail intermediate host of S. japonicum belongs to the genus Oncomelania and family Pomatiopsidae. A total of 29 species and subspecies have been identified, based primarily on the characteristics of the outer shell, which is highly polymorphic . There are six subspecies found throughout the Far East, but O. h. hupensis is the sole vector transmitting human schistosomiasis in the lake region. Paragonimiasis Paragonimiasis is a disease caused by species of lung flukes of the genus Paragonimus. Eight species have been identified which use man as a host, and the disease has a range of Asia, Africa, and the Americas. The most predominant infective species are P. westermani and P. kellicotti. International Distribution Paragonimus species are endemic to Southeast Asia, Latin America (most commonly in Peru), and Africa (most commonly in Nigeria). Paragonimiasis is less commonly found in West Africa and Central and South America.2 An estimated 22 million people are infected worldwide. Prevalence of infection in endemic areas ranges from 0.1-23.75%. Prevalences of human paragonimiasis according to a range of national and provincial surveys in China ProvinceYear of samplingNo. of samples testedPrevalence (%) Anhui200410801.9 Chongqing200241921.9 Fujian20062438.6 Heilongjiang200290141.46 Hubei200452551.54 Hunan1995335010.8 Jiangxi200221320.66 Jilin200012532 Liaoning20024651.9 Shanghai20033904.62 Sichuan199546 69819.7 Yunnan19866917.83 Race Paragonimiasis is most common in Asians, Africans, and Hispanics. Sex Prevalence of infection is higher among females. An increase in infection in men, most notably those who are middle aged, because of their traditional culinary habits, has been observed in Japan. Age Prevalence reportedly increases with age and peaks in older adolescents and young adults; prevalence then declines progressively with age. By the sixth decade of life, prevalence is less than 25% of its peak in young adulthood Age Prevalence Rate Mortality/Morbidity Death may occur during the acute phase of infection. For those who survive the acute phase, spontaneous recovery usually occurs within 1-2 months, but symptoms may recur intermittently over several years. Complications of untreated heavy infection include interstitial pneumonia, bronchitis, and bronchiectasis. Secondary complications may include bronchopneumonia, lung abscess, pleural effusion, or empyema. Untreated cerebral paragonimiasis has a mortality rate of approximately 5%. Neurocysticercosis Neurocysticercosis is the most common parasitic infection of the central nervous system (CNS). Approximately 2.5 million people worldwide carry the adult tapeworm, and many more are infected with cysticerci. In the United States, neurocysticercosis is mainly a disease of immigrants, and the disease is prevalent in the states of California, Texas, and New Mexico. Neurocysticercosis represents a major cause of morbidity among the Hispanic population. Although most of the cases have been diagnosed in persons of Hispanic origin, the incidence is increasing in nonendemic countries because of travel to zones of endemic disease. Native cases have also been reported, presumably because of ingestion of infected food that was handled by carriers of T solium. The incidence of neurocysticercosis has been steadily increasing in the United States. Although still mostly prevalent in the southwestern United States, imported cases have been reported throughout the country. Globally, neurocysticercosis is endemic in Central and South America, sub-Saharan Africa, and in some regions of the Far East, including the Indian subcontinent, Indonesia, and China, reaching an incidence of 3.6% in some regions. This disease is rare in Eastern and Central Europe, in North America (with the exception of Mexico), and in Australia, Japan, and New Zealand, as well as in Israel and in the Muslim countries of Africa and Asia. Cysticercosis can be seen in immigrant populations with a relatively high frequency, as in the US Southwest and South Africa, and subcutaneous cysticercosis is more common in Asian populations than in other peoples of other areas of endemic disease. It is not clear whether this is due to variations in parasite strain or to those in the host. Sex: Although neurocysticercosis appears to affect men and women equally, there is some evidence to suggest that inflammation around the parasites may be more severe in women than in men. Age Neurocysticercosis appears to be the most frequent cause of seizures in children and adults and peak incidence in between 30-40 years,the exact incidence in children is not known Sparganosis Sparganosis is an infection of humans and animals caused by the plerocercoid larvae (spargana) of various diphyllobothroid tapeworms belonging to the genus Spirometra. Sparganosis has been reported sporadically around the world, and a higher prevalence of the disease occurs in several Asian countries, including South Korea, Japan, Thailand, and China. To date, a total of more than 1000 cases of human sparganosis have been reported in 25 provinces in mainland China. Sparganosis is emerging in mainland China because of food consumption habits and the unusual practice of treating wounds or other lesions with poultices of frog or snake flesh. In China, human sparganosis has occurred sporadically, and the majority of cases have been reported from southern provinces, such as Guangdong, Guangxi, Fujian, and Hunan. From January 2000 to September 2010 and found a total of 164 recorded cases of human sparganosis, mainly from the provinces of Guangdong, Henan, Fujian, Hunan, Guangxi, and Hubei Reported cases of human sparganosis from the different provinces of mainland China since 2000 ProvinceBrain and spineEye Face and neck Breast and abdomenLimbs Other positionsTotal Guangdong101374025 Henan2001201024 Fujian28412118 Hunan33223114 Guangxi2111038 Hubei5102008 Jilin0004127 Anhui4010117 Jiangxi4020017 Shanghai3001026 Zhejiang1301005 Data were extracted from 110 articles published in Chinese journals from January 2000 to September 2010. Full reference details are available from the corresponding author upon request. Total 42 case detected in brain and spinal cord disease involvement among 164 cases. Age incidence: The incidence of a cerebral sparganosis in children and young age adults was higher than the one in middle and old age adult. The possible reasons are the followings: the children and young people usually had more chances to get skin injury and ate infected cyclops water; because the immune system of children and young people was not intact, the sparganum and procercoid invading into their bodies could be survived easier; the blood brain barrier of children and young people was immature, so the sparganum and procercoid invading their bodies were more accessible to their brains. Age Prevalence Rate Sex incidence From the available patient information, the prevalence of sparganosis infection was higher among females than males, at a ratio of F:M=2:1 (27:15). Thank You 病因及发病机制 B.吞食生的或未煮熟的蛙、 蛇、鸡或猪肉。吞食的裂头 蚴即可穿过肠壁进入腹腔, 然后移行至其它部位; C.误食感染的剑水藻, 饮用生 水或游泳时误吞塘水, 裂头蚴进入大脑的途径不甚清楚 1.推测一种是可能:口消 化道腹腔胸腔、纵隔 颈部经神经血管周围 间隙向上移行通过枕大 孔、破裂孔或颈V孔颅 内, 2.第二种可能是:口消化 道胸壁血管血循环 脑部血管末梢定居发育。 脑裂头蚴病的病理学 裂头蚴幼虫在脑内迁徙游 走形成坏死隧道 释放蛋白酶毒素溶解周围 组织引起炎性反应 脑组织坏死后，局部炎性 细胞浸润和纤维胶质细胞 增生形成炎性肉芽肿，肉 芽肿内可见有一条或数条 虫体，虫体不分节，实 体、无体腔，具有特征性 的体壁结构是散在分布的 椭圆形石灰小体及束状纵 行肌纤维，前者可能为虫 体的残骸。 囊虫感染途径 人是猪带绦虫的中间宿主（囊 虫病）和终末宿主（绦虫病 ）。 内在自身感染：患有绦虫的 病人，由于呕吐或肠道逆蠕动 ，使绦虫妊娠节片回流至胃内 ，虫卵在十二指肠内孵化逸出 六钩蚴，钻过肠壁进入肠系膜 小静脉与淋巴循环而输送至全 身和脑，发育成囊虫蚴。 外在自身感染：绦虫病人的 手部沾染虫卵，污染食物，经 口而感染。 外来感染：病人自身并无绦 虫寄生，因摄入附有虫卵的蔬 菜或瓜果后而感染。 囊虫进入大脑的途径 绦虫卵经口进入 消化道，虫卵进入十二指 肠内孵化逸出六钩蚴，钻 入胃肠壁血管，蚴虫经血 液循环分布全身并发育成 囊尾蚴，寄生在脑实质、 脑室、蛛网膜下腔或脊髓 形成囊肿。 脑囊虫病的病理学 血吸虫病因及发病机制 脑血吸虫病理 脑肺吸虫病因及发病机制 脑肺吸虫病理 临床特点 Parasitoses of the central nervous system. AgentCerebral/spinal cord manifestations Imaging Taenia solium 猪带绦虫 Epilepsy, hydrocephalus, spastic paraparesis， arachnoiditis Parenchymal cysts Spirometra mansoni 裂头蚴 Headache, epilepsy, focal deficits,stroke, vasculitis Single, enhancing mass lesion, oedema, tunnel sign, atrophy, calcification Paragonimus westermani 卫氏并殖吸虫（肺吸虫） Headache, mental decline, seizures, weakness, ataxia, stroke Oedema, multiple, small, contrast-enhancing lesions, tumour-like lesions Schistosoma japonicum 日本血吸虫 Seizures, headache, mental retardation, stroke, focal deficits Multiple conglomerated, calcified masses or nodules, ring-like lesions Neurocysticerciasis arachnoiditis Cerebral cysticerciasisepilepsy (5070%); headache (40%) hydrocephalus (33%); meningitis stroke Intramedullary cysticerciasis（胸椎易受 累） paraparesis, paraspasticity, bowel or bladder incontinence, or sexual dysfunction Non-neural symptomsNodules in skins and muscles diminution of eye vision blood and CSF investigationsIgG antibodies in the serum or CSF(ELISA). Other CSF findings include elevated protein, low or normal glucose, moderate lymphocytic pleocytosis or Eosinophilia（33%） Neurosparganosis arachnoiditis neural clinical symptomsheadache epilepsy focal weakness sensory disturbances ischaemic stroke Intracerebral haemorrhage cerebral vasculitis Non-neural clinical symptomsspace-occupying lesion with mass effect in subcutis（皮下组织）, muscle， eye,urogenital tract（尿道生殖道）, gut blood and CSF investigationsIgG antibodies in the serum or CSF(ELISA). Other CSF findings include elevated protein, low or normal glucose, moderate lymphocytic pleocytosis or Eosinophilia Neuroparagonimiasis arachnoiditis neural clinical symptomsseizures haemorrhagic stroke headache dizziness spastic hemiplegia（偏瘫） hemianopsia（偏盲） mental retardation gait disturbance（步态异常） Non-neural clinical symptomsfever，gastro-intestinal symptoms（胃 肠道症状），hepatosplenomegaly（肝 脾肿大） cough，chest pain(lung lesions 40-70%) Nodules in skins （20%） blood and CSF investigationsIgG antibodies in the serum or CSF(ELISA). non-specific abnormalities in CSF Sputum and fecal investigationsFind the eggs Neuroschistosomiasis arachnoiditis neural clinical symptomsEpilepsy type Brain tumor type Stroke type Non-neural clinical symptomsFever，gastro-intestinal symptoms（胃肠 道症状），hepatosplenomegaly（肝脾肿 大），cough，chest pain blood and CSF investigationsIgG antibodies in the serum or CSF(ELISA). non-specific abnormalities in CSF urine or faeces investigationsova are excreted via the urine or faeces arachnoiditis MRI of Neurocysticerciasis Within a few weeks the larva transforms into a cysticercal cyst containing an invaginated scolex. Imaging hallmarks of this stage: 1.visualization of the scolex within a cyst 2. absence of enhancement or thin linear enhancement of the cyst wall. 3. The cyst fluid usually demonstrates the same signal intensity as cerebrospinal fluid (CSF) on all MR imaging/CT sequences。 Vesicular Stage活虫期 axial T1-weighted image (A), axial T2-weighted image (B) C.D：coronal T1-weighted images MRI of Neurocysticerciasis Long-T1+short-T2 T1-weighted postcontrast images also reveal a ring-enhancement pattern. T2 -weighted images frequently demonstrate adjacent edema and may show a rim of the cyst of low signal intensity。 Colloidal Vesicular Stage变性水肿期 axial T1-weighted image (A), axial T2-weighted image (B) C.：coronal T1-weighted images . MRI of Neurocysticerciasis As degeneration of the cysticercus progresses,the cyst decreases in size and transforms into a smaller nodular lesion. This process represents a degenerating, active form of cysticercosis. CT and MR imaging demonstrate enhancement of the nodular lesion or a small ring-enhancing lesion at this stage. Mild associated edema may be identified in adjacent brain parenchyma。 Granular Nodular Stage结节肉芽肿期 Left temporal lobe granular nodular stage neurocysticercosis. (A) Axial T2- weighted image demonstrates a small nodular lesion with lack of significant associated edema. (B) Axial postcontrast T1-weighted image reveals corresponding small ring-enhancing lesion consistent with degenerating cysticercus in granular nodular stage. CT (not shown) demonstrated absence of calcification within the lesion MRI of Neurocysticerciasis The nodular calcified stage is the end stage of cysticercal degeneration, with transformation into a small calcified granulomatouslesion. This process represents a degenerated, inactive formof cysticercosis.Usually no associated edema or enhancement is observed, representing a lack of immune response to this end-stage, nonviable lesion. CT is most sensitive for these lesions, revealing them as hyperdense parenchymal lesions . The lesions are hypointense on T1- and T2- weighted imaging, and may be difficult to identify。 Nodular Calcified Stage钙化死亡期 (A, B)Noncontrast axialCT images ofnumerous nodular calcified stage cysticercosis lesions. Coexisting vesicular stage cysticerci can also be seen on image A. Right insular nodular calcified stage cysticercosis. (A) Axial T1-weighted image demonstrates a hypointense nodular lesion. (B, C) Axial T2-weighted image and FLAIR image also demonstrate a hypointense lesion with lack of associated vasogenic edema. (D) Postcontrast T1-weighted image demonstrates thin, linear ring enhancement of the lesion. there have been recent reports of the reactivation of calcified neurocysticercosis manifesting as edema and enhancement associated with calcified lesions. In addition,these patients may experience associated seizure activity. It is thought that residual antigens within calcified lesions may periodically induce an inflammatory response. MRI of Neurocysticerciasis This form of neurocysticercosis frequently manifests as a solitary intraventricular cyst. The fourth ventricle is the most common location for this cystic lesion. The third ventricle is the second most common location, with the lateral ventricle and cerebral aqueduct of Sylvius less frequently involved. Typically the cysts move from the lateral ventricle to the third ventricle, then to the aqueduct of Sylvius and the fourth ventricle. This form of neurocysticercosis may therefore result in obstructive hydrocephalus as the cyst blocks the flow of CSF through the ventricular system. INTRAVENTRICULAR NEUROCYSTICERCOSIS A：T1 B.D:FLAIR C:T2 E:DWI F:ADC MRI of Neurocysticerciasis Neurocysticercosis of the subarachnoid spaces and the ventricular system is thought to result from hemotogenous dissemination of the larvae to these locations. 病灶处于蛛网膜与软脑膜之间的空 隙中，脑池多见，炎症反应可引起 周围组织病变，脑神经受累，软脑 膜因炎症反应可出现增强，以及交 通性脑积水（因蛛网膜吸收减慢， 不同意脑室内囊虫病引起的梗阻性 脑积水）.急性的脑膜炎症反应可 引起鞍上池脑动脉穿通支血管炎， 继而引起局灶脑梗死.偶尔可累及 大脑中动脉，引起血管炎，从而出 现大范围脑梗死 SUBARACHNOID AND MENINGEAL NEUROCYSTICERCOSIS A.B:T2 C:FLAIR DE:T1 F: Noncontrast CT MRI of Neurocysticerciasis Neurocysticercosis very rarely involves the spine, with fewer than 1% of all patients diagnosed with this form. Intramedullary cysticercosis may cause direct mass effect and elicit inflammatory response, with resulting cord edema. SPINAL NEUROCYSTICERCOSIS A:T2 MRI of Neurosparganosis A:CT B:T2 CD, Postcontrastand T1-weighted images EF, After 4 months 1.migration of the worm 2.Tunnel sign 3.Bead-shaped enhancement 4. cortica