儿童手部清洁卫生与蛔虫感染的关系

目的　探讨儿童手部清洁卫生与蛔虫感染之间关系。　方法　基线调查中所有蛔虫感染者均予一次性驱虫治疗。实验组开展洗手活动 ,对照组不开展洗手活动。 1年中每 2个月用加藤 (Kato)厚涂片法检查受试者粪便 1次 ,比较实验组和对照组中 ,试验前蛔虫感染阴性者 ,每次复查的新感染率 (即两组新感染率比较 ) ;试验前蛔虫感染阳性治毕半月复查转阴者 ,每次复查的再感染率 (即两组再感染率比较 )。　结果　每 2个月复查 1次 ,按每次复查累计计算的新感染率与再感染率 ,实验组均非常显著低于对照组 (P <0 0 0 1)。 1年后复查 ,蛔虫感染率实验组为 35 2 % ,比项目前的 6 8 3%下降 4 8 5 % ;对照组为 73 7% ,比项目前的 4 1 4 %上升了 78 0 %。　结论　每日用香皂洗手保持手部清洁卫生 ,可以显著降低蛔虫感染率。     

人群蛔虫感染调查粪检与驱虫结果比较

目的探讨社区人群蛔虫感染调查中粪检与驱虫结果的关系。方法选择江西省南昌县塘南乡张溪村为试点,采用Kato Katz法粪检,双羟萘噻嘧啶化疗驱虫后收集虫体,对两者结果进行比较分析。结果共检测1 019名村民,人群实际蛔虫感染率为30.23%,其中粪检阳性率为20.41%,淘虫阳性率为23.75%。淘虫阳性感染者平均虫荷2.64条,虫荷数高的感染者所占比例较低。感染者虫荷数越多,检出虫卵的概率越高,当感染者寄生7条以上蛔虫,虫卵检出率为100%。粪检虫卵假阴性者中,感染雄虫者占61.00%,感染雌虫幼虫并有或无雄虫者占7.00%,感染成熟雌虫者占32.00%。人群粪检虫卵漏检率为32.47%。其中,因不排虫卵(生物学)漏检率为22.08%,Kato Katz法(方法学)漏检率为10.39%。结论人群蛔虫感染调查中粪检阳性率较实际感染率偏低,粪检虫卵检出率与感染虫荷数有关。     

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。     

Heterogeneity in the expression of surface-exposed epitopes among larvae of Ascaris lumbricoides

Quantitative immunofluorescence was used to examine differences in the binding of antibody to the surfaces of individual living infective stage larvae of Ascaris lumbricoides. Using rabbit antisera, it was first established that larvae cultured for 48 h after artificial hatching were relatively uniform in their levels of antibody binding and in minimal exposure of epitopes expressed by later larval stages. Aliquots from a pool of larvae were probed with serum from individual infected people living in an endemic area of Nigeria. The larvae used were derived from parasites collected in the same geographical area in which serum donors were living. Two principal points emerged. First, serum donors varied considerably in the degree to which their antibody bound to the larvae. Secondly, the binding of antibody from a given donor revealed remarkable heterogeneity in surface epitope expression. Such intra-specific variability in antigen expression has considerable implications for the development of immunity to parasitic nematodes.     

Hookworm, Ascaris lumbricoides infection and polyparasitism associated with poor cognitive performance in Brazilian schoolchildren

Objective  To investigate the relationship between hookworm and Ascaris lumbricoides infection and performance on three subsets of the Wechsler Intelligence Scale for Children – third edition (WISC-III) (Digit Span, Arithmetic and Coding) and Raven Colored Progressive Matrices.
Methods  Cross-sectional study of 210 children between the ages of 6 and 11 years in Americaninhas, Minas Gerais, Brazil. Separate proportional odds models were used to measure the association between the intensity of helminth infections and poor performance on each of the four cognitive tests.
Results  After adjusting for sex, age, socioeconomic status and other helminth infections, moderate-to-high-intensity hookworm infection was associated with poor performance on the WISC-III Coding subtest [OR = 3.20; 95% confidence interval (CI) = 1.43–7.17], low intensity of hookworm infection was associated with poor performance on the WISC-III Coding subtest [odds ratio (OR) = 3.71; 95% CI = 1.80–7.66] and moderate-to-high-intensity A. lumbricoides infection was associated with poor performance on the Raven test (OR = 2.03; 95% CI = 1.04–3.99), all in comparison with uninfected children. Children co-infected with A. lumbricoides infection and hookworm infection had greater odds of poor performance on some WISC-III subtests than children with only A. lumbricoides infection.
Conclusions  These findings suggest that hookworm infection may be associated with poorer concentration and information processing skills, as measured on the WISC-III Coding subtest, and that A. lumbricoides infection may be associated with poorer general intelligence, as measured through the Raven Colored Progressive Matrices. This study also presents evidence that polyparasitized children experience worse cognitive outcomes than children with only one helminth infection.     

Non-invasive management of Ascaris lumbricoides biliary tact migration: a prospective study in 69 patients from Ecuador

Ascariasis is one of the most common helminthic diseases. Its most feared complication is migration into the biliary tree. Some authors recommend immediate duodenoscopy in all cases of biliary migration, with sphincterotomy for the extraction of the parasites, and surgical extraction in case of intrahepatic ascariasis. We followed prospectively 69 patients with ultrasonographical evidence of migration. Initial treatment consisted of intravenous analgesics and antispasmodics, and albendazole 800 mg by mouth. Only patients with persisting symptoms or with high amylasaemia underwent duodenoscopy, with extraction in case of a visible worm. Surgery was limited to cases with persistent or progressive complications. In 97% of our cases the worms disappeared with noninvasive therapy alone. A duodenoscopy was done in 30 (42%) cases; in 10 (14%) a worm was found in the ampulla of Vater and extracted without sphincterotomy. In none of the 6 cases with A. lumbricoides in the intrahepatic biliary tree did the parasite persist. Only one patient required surgical intervention. Treatment of A. lumbricoides migration to the biliary tract should be principally medical. Duodenoscopy with extraction of a visible worm should be limited to cases with persisting pain and/or hyperamylasaemia. Invasive methods like sphincterotomy and surgery should be restricted to patients who do not respond to conservative treatment.     

Ecological covariates of Ascaris lumbricoides infection in schoolchildren from rural KwaZulu-Natal, South Africa

OBJECTIVES: To identify environmental factors that could serve to predict Ascaris lumbricoides infection patterns and thus guide control efforts in the absence of epidemiological information; to assess whether A. lumbricoides infection is positively associated with the soil clay content. METHODS: Information on A. lumbricoides infection and re-infection in a cohort of primary schoolchildren and interview data on their socioeconomic background and behaviour were combined with environmental data using a geographical information system (GIS). Multivariate models served to explore the covariation of environmental and infection patterns adjusted for possible confounders. RESULTS: Prevalence maps and spatial statistics revealed considerable spatial clustering of infection in the small study area. Logistic multivariate regression models showed strong positive associations of infection with vegetation density measured as the normalized difference vegetation index (NDVI) at baseline [odds ratio (OR) for a 10% increase: 1.82; 95% confidence interval (95% CI): 1.24-2.68; P=0.002] and after re-infection (OR: 2.22; 95% CI: 1.71-2.87; P<0.001). We also found a strong negative association of re-infection with the sun exposure of the soil surface as estimated from digital elevation models (OR: 0.78; 95% CI: 0.88; P<0.001). The soil clay content was only moderately positively associated with infection and re-infection. Socioeconomic and behavioural variables, although correlated with A. lumbricoides infection, did not appear to confound the above associations in the demographically homogeneous study area. Spatial analysis of the model residuals suggested that as the models accounted for most of the spatial pattern, the model standard errors should not be affected by spatial clustering. CONCLUSION: NDVI seems to have a high potential for the prediction of A. lumbricoides infection as it was strongly associated with infection patterns in the study area. Further advantages are that NDVI information is easy to use, affordable and available with global coverage.     

IgE cross-reactivity between Ascaris lumbricoides and mite allergens: possible influences on allergic sensitization and asthma

Nematode infections such as Ascariasis are important health problems in underdeveloped countries, most of them located in the tropics where environmental conditions also promote the perennial co-exposure to high concentrations of domestic mite allergens. Allergic diseases are common, and most of patients with asthma exhibit a predominant and strong IgE sensitization to mites. It is unknown whether co-exposure to Ascaris lumbricoides and the domestic mites Blomia tropicalis and Dermatophagoides pteronyssinus potentiates Th2 responses and IgE sensitization, thereby modifying the natural history of allergy. Recently, we obtained experimental evidence of a high cross-reactivity between the allergenic extracts of these invertebrates, involving well-known allergens such as tropomyosin and glutathione transferases. There is indirect evidence suggesting that the clinical impact of these findings may be important. In this review, we discuss the potential role of this cross-reactivity on several aspects of allergy in the tropics that have been a focus of a number of investigations, some of them with controversial results.     

我国西南彝族农村地区HIV与血吸虫 蛔虫及鞭虫感染现状调查

目的 目的 了解我国西南彝族农村地区HIV、 血吸虫、 蛔虫及鞭虫感染状况, 调查是否存在混合感染。 方法 方法 在我 国西南部某山区随机选取一个彝族乡开展横断面调查, 检测村民HIV、 血吸虫、 蛔虫及鞭虫感染情况; 并对村民进行问卷 调查, 了解HIV及寄生虫感染的危险因素。 结果 结果 我国西南彝族农村地区居民HIV、 血吸虫、 蛔虫和鞭虫感染率分别为 2.33%、 2.05%、 13.47%和30.59%, 鞭虫与蛔虫共同感染检出率为7.08%, HIV与蛔虫和鞭虫共同感染检出率均为0.23%。 男性以及吸毒是HIV感染的危险因素 ［OR = 3.26, 95% CI：（0.97, 10.95）; OR = 72.86, 95% CI： （18.51, 286.76）］; 厕所与蛔 虫和鞭虫感染间均存在负相关关系 ［OR = 0.51, 95% CI：（0.27, 0.98）; OR = 0.48, 95% CI：（0.28, 0.80）］。与居住在村4的 居民相比, 村1村民感染蛔虫风险较高 ［OR = 3.14, 95% CI：（1.35, 7.27）］; 与居住在村4的居民相比, 居住在村2和村3的 村民鞭虫感染风险较高 ［OR = 3.73,95% CI：（1.92, 7.26）; OR = 4.53, 95% CI：（2.12, 9.68）］。此外, 11～20岁年龄组村民 鞭虫感染风险高于>50岁村民 ［OR = 3.72, 95% CI：（1.59, 8.67）］; 蛔虫与鞭虫感染间存在相关关系 ［OR = 3.11, 95% CI： （1.63, 5.93）］, 未发现与血吸虫感染相关的因素。 结论 结论 我国西南彝族农村居民HIV及寄生虫感染率尤其是鞭虫感染 率较高; 应进一步探索HIV与寄生虫感染, 尤其是与血吸虫感染间的关系。     

江苏省农村人群蛔虫感染变化及影响因素

目的调查江苏省农村人群蛔虫感染变化情况及其影响因素,为制定控制蛔虫感染对策提供依据。方法统计苏南、苏中和苏北1990~2002年间3次调查的农村人群蛔虫感染率、集体服药率、人均收入和自来水及卫生厕所使用率,探讨影响蛔虫感染率下降的主要因素。结果13年来,3个片区人群蛔虫感染率均持续大幅度下降,2002年平均感染率2.14%,下降率为94.58%。苏中感染率最低,仅0.41%,下降率达98.92%;苏北感染率最高,为5.09%,下降率最低,为89.97%。累计集体服药率苏中为159.00%,显著高于苏南的103.00%和苏北的105.00%。居民人均收入、自来水和卫生厕所使用率由北向南逐渐升高,3个片区间差异有统计学意义。结论集体服药防治和经济卫生条件共同影响农村人群蛔虫感染率变化,尤其集体服药防治的作用更显著。     

Humoral responses to a secretory Onchocerca volvulus protein: differences in the pattern of antibody isotypes to recombinant Ov20/OvS1 in generalized and hyperreactive onchocerciasis

The Onchocerca volvulus secretory protein Ov20/OvS1 represents a dominant antigen expressed in the infective larvae, microfilariae and adult stages of the parasite. The humoral responses to this protein have not yet been analysed in the polar clinical and immunological forms of onchocerciasis. Analysis by ELISA of class and subclass antibodies to Ov20/OvS1 in persons with the generalized or the hyperreactive form of onchocerciasis revealed similar strong responses of IgG1, IgG4 and IgM antibody levels in both forms of onchocerciasis and significant differences were observed in the IgE and IgA antibody classes. Computation of the ratios of antibodies showed that persons with the generalized form exhibited significantly higher ratios of IgG4 to IgG1, IgG4 to IgE, and IgM to IgE than patients with the hyperreactive form. To investigate the isotype recognition of antigenic sites on Ov20/OvS1 protein, three recombinantly expressed fragments (F1-3) of Ov20/OvS1 were probed using sera which strongly reacted with intact recombinant Ov20/OvS1. Epitope(s) on F1 comprising amino acid residues 1-63 were significantly recognized by IgG1 and IgE, while IgM recognized epitopes on all three fragments. The strongest reaction of IgM occurred with epitope(s) formed by residues 108-171 (F3). In contrast, IgG4 type antibodies were not reactive with either of the three OvS1 fragments, but they reacted with intact Ov20/OvS1 protein. Generalized onchocerciasis, unable to eliminate microfilariae, and hyperreactive onchocerciasis, with a high potency to eliminate or to reduce parasite loads, can be distinguished by a distinct pattern of isotype responses to Ov20/OvS1.     

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.     

Collateral damage during antibiotic treatment of C. difficile infection in the aged host: Insights into why recurrent disease happens

Clostridium difficile infection (CDI) is one of the most common causes of healthcare-associated infections but an even bigger problem for the aging population. Advanced age leads to higher incidence, higher mortality, and higher recurrences. In our study, recently published in the Journal of Infectious Diseases, we investigated the effect of aging on CDI using a mouse model. We were able to demonstrate that aging leads to worse clinical outcomes, as well as lead to changes in microbiota composition and lower antibody production against C. difficile toxin A, but not toxin B. An association between advanced age and lower antibody production against C. difficile is a new finding which would explain the effect of aging on CDI outcome. Vancomycin, an anti-C. difficile antibiotic, led to similar changes in antibody response, suggesting a connection between microbiome and antibody response in the context of aging, which would require a much more nuanced look at the treatment of CDI.     

CXCL13/CXCR6信号通路在HBV感染中的研究进展及临床意义

[摘要]?HBV感染是人类面临的重大公共卫生问题,尽管有效的抗病毒治疗可延缓疾病进展,但仍很难实现“临床治愈”的目标。机体的适应性免疫应答在控制和清除病毒的过程中发挥关键作用。新近研究发现,趋化因子配体13（chemokine ligand 13, CXCL13）/趋化因子受体5（chemokine receptor 5, CXCR5）信号通路在调节HBV特异性体液免疫和细胞免疫应答中均发挥重要作用,这或是探索慢性乙型肝炎“临床治愈”的重要靶点。本文就CXCL13/CXCR5信号通路的生物学特点及其在HBV感染中的临床研究进展及意义进行综述。     

Influence of infection on malaria‐specific antibody dynamics in a cohort exposed to intense malaria transmission in northern Uganda

The role of submicroscopic infections in modulating malaria antibody responses is poorly understood and requires longitudinal studies. A cohort of 249 children ≤5 years of age, 126 children between 6 and 10 years and 134 adults ≥20 years was recruited in an area of intense malaria transmission in Apac, Uganda and treated with artemether/lumefantrine at enrolment. Parasite carriage was determined at enrolment and after 6 and 16 weeks using microscopy and PCR. Antibody prevalence and titres to circumsporozoite protein, apical membrane antigen‐1 (AMA‐1), merozoite surface protein‐1 (MSP‐1₁₉), merozoite surface protein‐2 (MSP‐2) and Anopheles gambiae salivary gland protein 6 (gSG6) were determined by ELISA. Plasmodium falciparum infections were detected in 38·1% (194/509) of the individuals by microscopy and in 57·1% (284/493) of the individuals by PCR at enrolment. Antibody prevalence and titre against AMA‐1, MSP‐1₁₉, MSP‐2 and gSG6 were related to concurrent (sub‐)microscopic parasitaemia. Responses were stable in children who were continuously infected with malaria parasites but declined in children who were never parasitaemic during the study or were not re‐infected after treatment. These findings indicate that continued malaria infections are required to maintain antibody titres in an area of intense malaria transmission.     

Impact of antihelminthic treatment on infection by Ascaris lumbricoides, Trichuris trichiura and hookworms in Covas, a rural community of Pernambuco, Brazil

This work aims to evaluate the impact of drug treatment on infection by Ascaris lumbricoides (Al), Trichuris trichiura (Tt) and hookworms (Hook) in a rural community from the sugar-cane zone of Pernambuco, Brazil. Four parasitological surveys were carried out from March 2001 to March 2002. Individual diagnosis was based on eight slides (four by the Kato-Katz method and four by the Hoffman method) per survey. Infected subjects were assigned to two groups for treatment with either albendazole (n = 62) or mebendazole (n = 57). Prevalence of infection fell significantly (p < 0.05) one month after treatment: Al (from 47.7% to 6.6%); Tt (from 45.7% to 31.8%) and Hook (from 47.7% to 24.5%). One year after treatment, infections by Tt and Hook remained significantly below pre-control levels. A substantial decrease in single-infection cases and multiple infections was found. Egg-negative rate was significant for Al (94.0%), Hook (68.3%) but not for Tt (45.5%), and did not differ significantly between subjects treated with mebendazole or albendazole. Egg counts fell significantly in the individuals remaining positive for Tt. It is recommended that antihelminthic treatment should be selective and given at yearly intervals preferably with albendazole, due to its cost-effectiveness.     

Confirmation of the protective effect of Ascaris lumbricoides on Plasmodium falciparum infection: results of a randomized trial in Madagascar

A controlled randomized trial of anti-helminthic treatment was undertaken in 1996-1997 in a rural area of Madagascar where populations were simultaneously infected with Ascaris lumbricoides, Plasmodium falciparum, and Schistosoma mansoni. Levamisole was administered bimonthly to 107 subjects, whereas 105 were controls. Levamisole was highly effective in reducing Ascaris egg loads in the treated group (P < 10(-3) at all visits), whereas it had no effect on schistosomiasis. Subjects 5-14 years of age, treated with levamisole, had a significant increase of their P. falciparum densities compared with controls (P = 0.003). There was no effect of the treatment on children 6 months to 4 years of age, nor on adults > 15 years of age. This study confirms the results of a randomized trial, which showed a negative interaction in those > 5 years of age between Ascaris and malaria parasite density in another Malagasy population, submitted to a higher malaria transmission.     

Relationship between parasite-specific antibody responses and intensity of Opisthorchis viverrini infection in hamsters

The kinetics of parasite-specific antibody responses in relation to worm burden and egg output were investigated in hamsters infected with 25, 50 and 100 Opisthorchis viverrini metacercariae (MC). Levels of antibody to egg, excretory-secretory (ES) and somatic antigens were examined by ELISA on days 1, 3, 7, 14 and month 1 postinfection (p.i.), and repeated monthly up to 6 months. The antibody responses were first detected as early as 14 days after infection. Hamsters that were infected with 100 MC and 50 MC showed higher antibody levels than those of 25 MC, during early infection until 1 month p.i. Then, the antibody levels were increased rapidly to a plateau at approximately month 2 p.i. and, subsequently, were relatively stable in all groups. The average antibody levels to egg and somatic, but not to ES antigens, were significantly higher in hamsters infected with 25 MC than those of 50 MC and 100 MC. These antibody responses, particularly to egg and ES antigens, were not correlated with worm burden or egg output. Overall, higher antibody responses were found in the order: ES, somatic and egg antigens. The significant lower antibody responses in chronic and heavy infections than those with mild infection may a result of immunosuppression.     

Age-dependency of infection status and serum antibody levels in human whipworm (Trichuris trichiura) infection

This study examines the age-dependency of the relationships between human infection with whipworm (Trichuris trichiura) and parasite-specific antibody level measured by ELISA against an extract of adult worms after preincubation of the sera with Ascaris lumbricoides adult worm extract. The convex age-profile of parasite infection intensity is shown to be mirrored by an age-dependent change in age-class mean levels of IgG (all subclasses except IgG3), IgA, IgM and IgE. Mean antibody levels rise with increasing acquisition of infection in childhood and decline as the intensity of infection falls in adulthood. Immunoblot analysis of selected sera from different age-classes indicates that antigen recognition is similarly dependent on infection intensity. In individual children, antibody levels correlate positively with acquisition of infection, consistent with a simple model of antigen dosage specifying the magnitude of the humoral immune response. In adults, IgG4 correlates positively and IgA negatively with intensity of infection, suggesting involvement of these isotypes in functional roles of immune blockade or effector mechanisms, respectively.     

Isotypic variation in antibody responses in a community in Papua New Guinea to larval and adult antigens during infection, and following reinfection, with the hookworm Necator americanus

The natural infection of a community with the hookworm Necator americanus induces a vigorous humoral response to both larval and adult parasite antigens. This response occurs in all five human antibody isotypes, and data are presented to show that, at the population level, isotypes respond differently, following chemotherapy and during reinfection, to changes in antigen stimulation. The differential response probably reflects the fact that the parasite, during the course of its life cycle, presents different amounts of antigens at different anatomical locations. It is suggested that IgG and IgM responses against adult excretory-secretory (ES) products most accurately reflect the efficacy of chemotherapy, and the load of resident adult infection, while IgG responses against larval somatic antigens reflect continuous exposure to infection. These hypotheses should now be tested, at the level of the individual, in a longitudinal manner using more closely spaced sampling intervals. This repetitive sampling, and the inclusion of a measure of the exposure of the population to infective stages, will allow more definitive conclusions to be made about the role of the immune response in controlling worm burdens.