江西省农村居民肠道寄生虫感染调查及蛔虫生物流行病学研究

目的探讨江西农村居民肠道寄生虫感染现状及蛔虫病生物流行病学特点.方法采用粪检、化疗驱虫后收集虫体等方法对江西进贤县鹿塘试区625名居民进行了研究.结果该试区居民感染9种肠道寄生虫,总感染率为72.80%,其中蛔虫、钩虫、鞭虫卵的阳性率分别为51.52%、11. 80%和34.60%.以噻嘧啶对全体居民治疗后,在59.40%的居民中检获蛔虫,感染者平均虫荷为2.97条(范围1～32条),10.00%的排虫者可见未成熟蛔虫,推算人群每月蛔虫再感染率为5.13%.对粪检虫卵假阴性人群的分析显示,仅有单性蛔虫寄生者(单雄或单雌)占82.93%,有1条未成熟雌虫和1～4条雄虫寄生者占17.03%.粪检虫卵假阴性率随着寄生蛔虫数的增加而减少,当感染6条以上蛔虫时,无假阴性出现.结论该社区人群肠道寄生虫感染率高,蛔虫再感染严重,有必要进行反复治疗以巩固防治效果;由于单性感染或未成熟蛔虫的缘故,居民实际蛔虫感染率要高于Kato-Katz法检查所见.     

蛔虫的种群动力学和药物控制效果的研究

实验村社区居民蛔虫感染率为53.5％。125个阳性居民的蛔虫平均虫荷数为1.9条。用数学模型算得的种群动力学参数负二项分布值(K)、密度依赖限制值(Z)和基本繁殖率值(R)分别为0.54,0.92及1.17。蛔虫感染者经药物治疗后第4、7及12个月的再感染率分别为14.3％、30.8％和40.7％。再感染者的EPG值分别为13000、17500和22600。理论感染率分别为22.2％、35.5％和42.6％。理论平均虫负荷数分别为0.430、0.676和0.967。据此认为,单纯运用化疗措施控制和消灭蛔虫病流行的效果不理想。     

Genetic analysis of susceptibility to infection with Ascaris lumbricoides.

Epidemiologic studies of helminthic infections have shown that susceptibility to these parasites frequently aggregates in families, suggesting the possible involvement of genetic factors. This paper presents a genetic epidemiologic analysis of Ascaris lumbricoides infection in the Jirel population of eastern Nepal. A total of 1,261 individuals belonging to a single pedigree were assessed for intensity of Ascaris infection at two time points. Following an initial assessment in which all individuals were treated with albendazole, a follow-up examination was performed one year later to evaluate reinfection patterns. Three measures of worm burden were analyzed, including eggs per gram of feces, direct worm counts, and worm biomass (weight). For all traits, variance component analysis of the familial data provided unequivocal evidence for a strong genetic component accounting for between 30% and 50% of the variation in worm burden. Shared environmental (i.e., common household) effects account for between 3% and 13% of the total phenotypic variance.     

部分肠道线虫病的免疫交叉反应研究

以ＳＤＳ－ＰＡＧＥ酶联免疫印渍技术对蛔虫、钩虫、鞭虫及犬弓蛔虫的免疫交叉反应进行了研究。结果显示，钩虫病、鞭虫病及犬弓蛔虫病患者血清都与人、猪蛔虫可溶性成虫抗原发生较强的免疫反应。人蛔虫可溶性成虫抗原和猪蛔虫可溶性成虫抗原间无明显差别。人、猪蛔虫可溶性成虫抗原与钩虫病患者血清反应的主要抗原成份分子量为３５、４４、５２．５、６４和８５ｋＤａ。两种抗原与鞭虫病患者血清反应带位于２２．２ｋＤａ和２０５ｋＤａ之间。两种抗原与犬弓蛔虫病患者血清反应形成多条反应带，其抗原分子量在３５．５ｋＤａ和１９５ｋＤａ之间。本研究表明，在某些线虫之间的确存在免疫交叉反应。     

Genes on chromosomes 1 and 13 have significant effects on Ascaris infection

Nematode parasites show a characteristic aggregated distribution among hosts. This observation has important implications for pathogenesis, immunology, and control of these infections, but the relative roles of environment and genetics in determining these patterns have remained uncertain. This paper presents the results of the first genome scan for susceptibility to infection with roundworm (Ascaris lumbricoides). Data on 375 genetic markers were generated for each of 444 members of a genetically isolated Nepalese population, the Jirels. Ascaris worm burden as assessed by egg counts was measured in these same individuals by using the Kato Katz thick smear method. The extensive genealogical data available for the population allowed assignment of all 444 individuals to a single pedigree that contained 6,209 pairs of relatives that were informative for genetic analysis. A variance components linkage analysis resulted in the unequivocal localization of two genes (one on chromosome 1 and another on chromosome 13) with clear, significant effects on susceptibility to Ascaris infection. This is the first evidence that individual quantitative trait loci influence variation in Ascaris burden in humans.     

Fatal human ascariasis following secondary massive infection

More than 796 Ascaris lumbricoides worms weighing 550 g were recovered at autopsy from a 2-year-old black South African girl. Most of the worms were taken from necrotic small intestine, but worms were also in the stomach, esophagus, intrahepatic and extrahepatic bile ducts, and gallbladder. The worms had caused torsion and gangrene of the ileum, which was interpreted as the cause of death. Worms were formalin-fixed and individually weighed. There were 796 intact worms and 112 appreciably large (greater than 0.2 g) fragments of worms. Statistical analysis of the weights revealed 2 distinct populations of worms: 16 large worms (0.5-2.3 g) and 778 small worms (0.03-0.95 g). The difference in weight between these 2 groups of worms was significant (male and female worms treated separately; P less than 0.05 to P less than 0.001). These observations reveal that the patient acquired a massive and fatal infection with A. lumbricoides while hosting a relatively burden.     

复方阿苯达唑驱除肠道线虫的现场观察

目的：观察复方阿苯达唑（每片含阿苯达唑６７ｍｇ和噻嘧啶８３．３ｍｇ基质）的驱虫效果。方法：对成人钩虫感染者１８６４例、蛔虫感染者１５６８例和鞭虫感染者１７８５例及儿童蛲虫感染者３７３例，随机分组，比较服用单剂复方阿苯达唑３片或２片与单剂阿苯达唑４００ｍｇ或噻嘧啶３０ｍｇ（含基质１０ｍｇ）／ｋｇ的驱虫效果和副作用。结果：成人复方阿苯达唑３片和２片的虫卵阴转率，钩虫分别为６５．０％和５２．７％（Ｐ＜０．０１），蛔虫均为１００％，鞭虫分别为２６．５％和１９．２％（Ｐ＜０．０１）。３片的驱钩虫效果显著优于阿苯达唑和噻嘧啶组（Ｐ均＜０．０１）。２片的驱钩虫效果亦优于噻嘧啶（Ｐ＜０．０１），与阿苯达唑无显著性差异，但驱鞭虫效果低于阿苯达唑。２－６岁儿童服复方阿苯达唑１．５片的，蛲虫卵阴转率为１００％，显著优于噻嘧啶（Ｐ＜０．０１）。复方阿苯达唑的驱虫作用快速，副作用轻，对血象、肝肾功能和心电图无显著影响。结论：复方阿苯达唑具有阿苯达唑和噻嘧啶两药的协同作用。     

我国蛔虫病传播数学模型的建立与应用

目的建立我国蛔虫病传播数学模型并用于现场预测。方法选择四川翠屏、江西进贤和湖南岳阳3个调查点,通过现场调查获取基线、服药后1月和1年后人群蛔虫感染率及平均虫负荷,构建蛔虫种群动力学、分布及感染率等传播数学模型。由现场数据获得模型参数,代入模型后预测1年后的感染水平,与实际调查数据比较,针对与药物驱虫措施相关的因素进行敏感性分析。结果翠屏、进贤、岳阳3个调查点蛔虫基线感染率分别为28.79%、20.35%和20.72%,平均虫负荷分别为1.32、0.65和0.48,药物驱虫后1年感染率分别为30.10%、7.51%和0.94%,平均虫负荷分别为1.04、0.56和0.34。服药1年后感染率和平均虫负荷均在实际观察值的95%可信区间内。敏感性分析结果显示服药覆盖率和治疗频次是影响疾病收益（平均虫负荷、感染率）的重要因素。结论本研究建立的蛔虫病传播数学模型较好地拟合了现场数据,可为制定蛔虫病控制规范和优化防治策略提供理论依据。     

蛔虫提取物对小鼠Lewis肺癌细胞的细胞毒性作用

目的探讨蛔虫提取物对小鼠Lewis肺癌细胞(LLC)的细胞毒作用。方法选用8种浓度的蛔虫提取物诱导小鼠Lewis肺癌细胞,分别在诱导后24、48、72 h采用四氮唑盐酶还原法(MTT)测A492值,计算细胞存活率和抑制率。结果不同浓度的蛔虫提取物分别作用LLC细胞24、48和72 h,对LLC细胞的增殖均有明显的抑制作用,呈剂量依赖,且以48 h抑制作用最强,之后随着作用时间的延长,BEAL对肿瘤细胞的抑制作用降低。结论蛔虫提取物对小鼠Lewis肺癌细胞具有细胞毒性作用,能够诱导LLC细胞发生凋亡。     

Endoscopic management of biliary ascariasis

Cholangitis and pancreatitis have resulted from migration of Ascaris lumbricoides up the biliary tree. We report our experience with the endoscopic management of 11 patients who presented with cholangitis and pancreatitis. Successful endoscopic worm extraction with or without sphincterotomy was achieved for worms located in the biliary tree but endoscopic worm extraction from the pancreas was technically difficult. Anthelminthic therapy is indicated to eradicate the gut infestation and prevent recurrent disease.     

Intestinal parasites among Karitiana Indians from Rond?nia State, Brazil.

Gravity sedimentation parasitological examinations were performed in stool samples from 111 Karitiana Indians from Rond?nia State, Brazilian Amazon Basin. Intestinal parasites were found in 43 samples (38.7%). Ascaris lumbricoides was the most prevalent helminth species (18.9%). Egg counts in samples positive for Ascaris suggested an overdispersed distribution of worm burdens in the host population. Age-distribution pattern of intestinal parasites among Karitiana Indians was found to be rather unusual: the highest prevalence (60.0%) was detected in the 12- to 16-year-old age group.     

Esophageal space-occupying lesion caused by Ascaris lumbricoides

Ascaris lumbricoides is the largest intestinal nematode parasite of man, which can lead to various complications because of its mobility. As the esophagus is not normal habitat of Ascaris, the report of esophageal ascariasis is rare. An old female presented with dysphagia after an intake of several red bean buns and haw jellies. The barium meal examination revealed a spherical defect in the lower esophagus. Esophageal bezoar or esophageal carcinoma was considered at the beginning. The patient fasted, and received fluid replacement treatment as well as some oral drugs such as proton pump inhibitor and sodium bicarbonate. Then upper gastrointestinal endoscopy was done to further confirm the diagnosis and found a live Ascaris lumbricoides in the gastric antrum and two in the duodenal bulb. The conclusive diagnosis was ascariasis. The esophageal space-occupying lesion might be the entangled worm bolus. Anthelmitnic treatment with mebendazole improved patient's clinical manifestations along with normalization of the radiological findings during a 2-wk follow-up. Authors report herein this rare case of Ascaris lumbricoides in the esophagus, emphasizing the importance of awareness of this parasitic infection as it often presents with different and unspecific symptoms.     

Intestinal parasites in University of Dacca students.

Nine hundred and thirty three students of Dacca University were examined: mean haemoglobin levels were 80.5 per cent for men and 70.0 per cent for women. Five hundred and thirty three (57.3%) of the students had single or multiple intestinal parasitic infections, of which Ascaris lumbricoides (366), Entamoeba histolytica (113) and Trichuris trichiura (99) were the commonest. It is suggested that chronic nutritional deficiencies are compounded by these parasites, leading to low weights, and low haemoglobins.     

Effects of Ascaris infection on human nutrition

The role of Ascaris lumbricoides infection in human nutrition was investigated in 12 children 5-10 years of age. Daily levels of dietary protein intake varied from 1-2.8 g/kg body weight but were kept constant for each child as was caloric intake. Nitrogen, fat balance, and d-xylose absorption determinations were done before and after deworming. A mean reduction in fecal nitrogen excretion of 230 mg/day was noted after worm removal. In 7 children harboring 48 or more parasites, the reduction in fecal nitrogen amounted to 7.2% of the dietary nitrogen. In 3 children receiving 1 g of protein/kg body weight, the improved nitrogen absorption after deworming led to an increased nitrogen retention. In 8 children the infection was associated with moderate steatorrhea (13.4% of dietary fat) and impairment of d-xylose absorption; the former was markedly reduced, and the latter was partially improved following treatment. It is concluded that Ascaris infection in children can lead to marked nutritional impairment when a high parasite load is associated with a low protein intake.     

SDS－PAGE酶联免疫印渍实验对人、猪蛔虫抗原特性的分析

以ＳＤＳ－ＰＡＧＥ方法对人蛔虫和猪蛔虫成虫可溶性抗原分析发现，在分子量１４ｋＤ～２３０ｋＤ之间两种抗原有许多相同蛋白带，未见明显的特异性蛋白带存在。应用ＳＤＳ－ＰＡＧＥ酶联免疫印渍方法发现以该两种抗原制备的兔抗血清均能从两种抗原中辨认出多个蛋白带。猪蛔虫成虫可溶性抗原中分子量２１．７ｋＤ和３４ｋＤ蛋白带能被部分兔抗血清所识别，而人蛔虫成虫可溶性抗原未出现这２条反应带。以人蛔虫感染者血清进行酶联免疫印渍也发现人蛔虫、猪蛔虫成虫可溶性抗原相似。两抗原中许多蛋白带可被病人血清所识别，其主要蛋白带为６６ｋＤ，提示蛔虫病人血清中含有大量抗体。另外，其中一份病人血清能从猪蛔虫成虫可溶性抗原中识别出４８．５ｋＤ蛋白带，而在人蛔虫抗原中未发现有该蛋白带。     

Cellular responses and cytokine profiles in Ascaris lumbricoides and Trichuris trichiura infected patients

The impact of intestinal helminth infection, i.e. Ascaris lumbricoides and Trichuris trichiura, on cellular responsiveness and cytokine production was investigated in young adults. Ascaris-specific cellular responsiveness was higher in parasite-free endemic controls than in patients infected with T. trichiura, or A. lumbricoides, or patients co-infected with both parasites. Also, mitogen-induced tumour necrosis factor (TNF)-alpha, interleukin (IL)-12 and interferon (IFN)-gamma secretion by peripheral blood mononuclear cells (PBMC) was higher in negative endemic controls than in infected individuals. Ascaris antigen-specific production of TNF-alpha, IL-12 and IFN-gamma was low in singly Ascaris as well as in co-infected patients, whereas secretion of IL-10 and IL-13 was elevated and similarly high in all patient groups. The detection of Trichuris-specific and Ascaris-specific IgG4 revealed significantly higher serum antibody levels in Trichuris or Ascaris patients when compared to endemic controls (P < 0.05), whereas parasite-specific IgE antibody levels were similarly high in infected individuals and in endemic controls. In summary, chronically infected Ascaris and Trichuris patients with a high parasite load presented reduced cellular reactivity and lower type 1 TNF-alpha, IFN-gamma and IL-12 responses when compared with endemic controls, whereas type 2 IL-10 and IL-13 productions were similar in all groups from the endemic area. The former may support parasite persistence, whereas substantial type 2 cytokine release may promote protective immunity, suggesting an adaptation of the host to control the parasite burden while minimizing immune-mediated host self-damage.     

Quantitative assessment of Ascaris lumbricoides infection in school children from a slum in Visakhapatnam, south India

An epidemiological study was conducted on 217 school children aged between 7-13 years, from Relliveedhi a slum in Visakhapatnam, Andhra Pradesh, south India, during August 1993 to August 1994. The children belonged to a socioeconomically backward community-parental occupation being fishing or waged labor. Intensity and prevalence estimations for Ascaris lumbricoides were done indirectly by formalin-ethyl-acetate sedimentation technic and directly by worm expulsions following albendazole administration at a single oral dose of 400 mg/child. Prevalence rate was 73% while the intensity of infection ranged between low to moderate. Boys had severe infection than girls due to their outdoor activities and behavioral habits. Nine year old children had the highest prevalence rates. Mean Ascaris worm intensity was 2.2 (+/-1.91) with an over-dispersed distribution of the parasite in the host population. Reinfection study over a period of nine month showed that the prevalence rates exceeded the pre-intervention level but the intensity of infection was very low. Dual species intensity correlation between Ascaris and Trichuris was consistently strong.     

蛔虫抗原基因ALAg表达载体的构建及其重组蛋白诱导小鼠的免疫保护研究

目的 目的 确定蛔虫基因工程疫苗候选基因。方法 方法 连接经BamH I和EcoR I酶切的pMD18?T?ALAg和pET?28a(+)质粒的纯化回收产物, 将连接产物pET?28a(+)?ALAg表达载体转化表达菌株BL21(DE3)进行诱导表达, 并纯化重组蛋白 (rALAg)。30只小鼠分成免疫组、 佐剂组和对照组, 每组10只, 各组分别接种重组蛋白与弗氏完全佐剂(FCA)混合物、 FCA以及磷酸盐缓冲液 （PBS） 后, 采用蛔虫感染性虫卵进行攻击(3 600个/只), 观察各组小鼠体内虫体数, 并采用间接ELISA法检测小鼠血清中抗体IgG。结果 结果 rALAg能被兔抗蛔虫阳性血清所识别。免疫组小鼠的肝脏和肺脏中的蛔虫幼虫数量（25.30±4.55） 比对照组 （57.60±5.76） 减少了69.26%, 与对照组和佐剂组比较差异有统计学意义(P < 0.01); 免疫组IgG抗体水平检测血清吸光度值A450 （0.858±0.003） 与对照组 （0.149±0.004）、 佐剂组比较 （0.134±0.004） 差异有统计学意义(P < 0.01)。结论 结论 ALAg基因可作为蛔虫基因工程疫苗的候选基因。     

Intestinal helminthiases and their control with albendazole among primary schoolchildren in riverine communities of Ondo State,Nigeria

A study to establish the prevalence of intestinal helminthiases among schoolchildren of riverine communities in the Ilaje-Ese Odo Local Government Area of Ondo State, Nigeria was conducted. Ninety-four percent of the children studied were infected with intestinal helminths. Trichuris trichiura infection was the commonest (84%), followed by Ascaris lumbricoides (75.3 %) and hookworm (7.6 %). Dual helminthic infections were recorded, with Ascaris-Trichuris having the highest prevalence among the children. Poor environmental sanitation and personal hygiene combined with the absence of potable water and a lack of awareness of the effects of nematode infection were identified as the possible reasons for the high rate of infection. Treatment with albendazole (200 mg) brought about reductions in the level of Trichuris trichiura (to 41.7%), Ascaris lumbricoides (to 4.2%) and Hookworm (to 0.7%). The estimated rates of reduction were 94.4%, 49.7%, and 90.2% for Ascaris lumbricoides, Trichuris trichiura and hookworm respectively. Post-treatment helminthic reduction, as found in this study, is expected to enhance the mental and physical development of the children. Community mobilization with health education messages aimed at improving personal and community hygiene was initiated with an emphasis on creating a sustained reduction in the burden of helminthic infection.     

Ascaris lumbricoides among children in rural communities in the Northern Area,Pakistan: prevalence,intensity, and associated socio-cultural and behavioral risk factors

The prevalence and intensity of Ascaris lumbricoides in 492 children from five rural villages in the Northern Area of Pakistan was examined. The overall prevalence of A. lumbricoides was 91% (95%CI 88.6-93.6) with geometric mean (GM) egg count intensities of 3985 eggs per g (epg). The most intense A. lumbricoides infections were found in children aged 5-8 years. We also investigated selected socio-cultural and behavioral variables for A. lumbricoides infections that might be relevant for the design of appropriate prevention and control programs. Univariate analysis associated A. lumbricoides intensity with age (P=0.004), location of household (P<0.01), defecation practices (P=0.02), soil eating habit (P<0.01), hand washing after defecation (P<0.01), and living with children under 5 years old (P=0.02). Multivariate analysis identified the children's age 5-8 (P<0.01), location of household in Surngo, Askole, and Stakchun where the pilot health care model activities were not done (P<0.01), and living with children under 5 years old (P=0.03) as variables statistically associated with the intensity of A. lumbricoides. The results indicated that there were certain clear risk factors in A. lumbricoides transmission, and that its intensity was influenced by age-related behavioral and environmental factors that contribute to exposure.