快速诊断疟疾胶体金免疫层析试条方法的建立与评价

目的 建立一种能区分恶性疟的快速、简便诊断疟疾的胶体金免疫层析试条方法，并对其进行评价。 方法 筛选基于恶性疟原虫乳酸脱氢酶制备的单克隆抗体对，采用柠檬酸三钠还原法制备胶体金颗粒，标记筛选到的单克隆抗体F4H12、G4C9和D8F7，并将其吸附于样品垫；将单克隆抗体B2G10（针对恶性疟原虫与间日疟原虫）和D6A7（只针对恶性疟原虫）分别划线包被于同一硝酸纤维素膜适当位置，制成免疫层析检测试条。用该试条检测疫区非疟疾发热病人血样（107份）和内脏利什曼病患者血样（17份）以评价其特异性，检测确诊的疟疾患者血样（间日疟110份， 恶性疟54份）以评价其敏感性。均用单盲法检测。 结果 检测107份疫区非疟疾发热病人血样和17份内脏利什曼病患者血样，有119份显示为阴性，特异性约为96.0%；其中17份内脏利什曼病患者血样全部为阴性。检测164份疟疾患者血样，阳性153份，敏感性为93.3%，其中间日疟检出率为92.7%（102/110），恶性疟检出率为94.4%（51/54）。 结论 研制出的快速诊断疟疾胶体金免疫层析试条敏感性、特异性均较高。     

两种鉴别诊断恶性疟和间日疟免疫层析试条检测效果评价

目的 对两种快速、简便能区分诊断恶性疟和间日疟的胶体金免疫层析试条的检测效果进行评价. 方法 筛选基于恶性疟原虫富组蛋白Ⅱ和恶性疟原虫乳酸脱氢酶制备的单克隆抗体对,采用柠檬酸三钠还原法制备胶体金颗粒,标记筛选到的单克隆抗体C6E9和G4C9,并将其同时吸附于样品垫;将单克隆抗体B2G10(针对恶性疟原虫与间日疟原虫)和C6H.(只针对恶性疟原虫)分别划线包被于同一硝酸纤维素膜适当位置,制成免疫层析检测试条.用该试条检测疫区非疟疾发热病人血样(120份)和内脏利什曼病患者血样(20份)以评价其特异性,检测确诊的疟疾患者血样(间日疟105份,恶性疟95份)以评价其敏感性.均用单盲法检测,同时用基于恶性疟原虫乳酸脱氢酶制备的单克隆抗体对制备的试条进行平行检测. 结果 检测120份疫区非疟疾发热病人血样和20份内脏利什曼病患者血样,有138份显示为阴性,特异性为98.6％,其中20份内脏利什曼病患者血样全部为阴性.检测200份疟疾患者血样,阳性190份,敏感性为95.0％,其中间日疟检出率为93.3％ (98/105),恶性疟检出率为96.8％ (92/95).基于恶性疟原虫乳酸脱氢酶制备的单克隆抗体对制备的试条检测的敏感性和特异性分别为93.5％ (187/200)和95.7％ (134/140),与本研究制备的基于恶性疟原虫富组蛋白Ⅱ和恶性疟原虫乳酸脱氢酶制备的单克隆抗体对的试条比较两者敏感性(x2=0.42,P＞0.05)和特异性(x2=1.09,P＞0.05)的差异均无统计学意义. 结论 研制出的基于恶性疟原虫富组蛋白Ⅱ和恶性疟原虫乳酸脱氢酶制备的单克隆抗体对的快速诊断疟疾胶体金免疫层析试条敏感性、特异性均较高.     

疟疾胶体金免疫层析试条在间日疟流行区的诊断评价

目的 在现场评价疟疾胶体金免疫层析试条 （简称试条） 的诊断性能。 方法 2008年9～10月采集安徽省间日疟流行区蒙城县5个乡镇医院门诊部所有就诊的发热病人血样,用双盲法比较镜检法和试条测试的结果。 结果 共采集发热病人血样292份,镜检法检出疟原虫阳性181份,均为间日疟;试条检出疟原虫阳性163份,亦均为间日疟。两法检测结果一致的血样占92.8%（271/292）,其中均为阳性的163份,均为阴性的108份。两法检测结果不一致的21份血样中,镜检阳性的、试条检测阴性的有18份,镜检阴性的、试条检测阳性的有3份。原虫密度在＞1 000 个/μl、100～1 000 个/μl和＜100 个/μl时,试条检测阳性率分别为93.5%（115/123）、86.0%（43/50）和62.5%（5/8）。 结论 该快速诊断疟疾胶体金免疫层析试条在疟疾流行区对间日疟有一定的诊断价值。     

套式/多重PCR方法应用于疟疾诊断与监测的初步评价

目的 与镜检法比较评价标签引物-套式/多重PCR（UT-PCR）在疟疾监测中的应用价值。 方法 在海南、云南省恶性疟和间日疟混合流行区和广西疟疾控制区的疟疾监测中,采集初诊为疟疾或疑似疟疾的发热患者的血片与滤纸血样400份,在双盲条件下比较镜检法与UT-PCR的初检结果,对结果不一致的血片再次镜检复查,同时对其滤纸血样重复PCR 2～3次;评估UT-PCR与镜检法的敏感性和特异性。 结果 400例发热患者血样中,镜检法初检检出疟原虫阳性234例,其中恶性疟125例,间日疟109例;UT-PCR检出疟原虫阳性235例,其中恶性疟124例,间日疟109例;恶性疟和间日疟混合感染2例。两法初检结果一致的血样占92.5%（370/400）,其中阴性154例,阳性216例（间日疟117例,恶性疟99例）。复查25份初检结果不一致的血样,包括镜检阴性PCR阳性11例,镜检阳性PCR阴性10例,镜检为恶性疟PCR为间日疟3例,镜检为间日疟而PCR为混合感染1例,其中15份与UT-PCR的初检结果一致,7份“假阳性”原因不明,仅3份为PCR的假阴性。根据复查结果评估PCR的敏感性为99.6%,特异性为98.8%。 结论 采用更敏感的UT?鄄PCR疟疾诊断方法有助于解决疟疾诊断与鉴别诊断中的疑难问题,提高疟疾监测的质量和效率。     

单克隆抗体3A3、2E7用于恶性疟Dipstick检测的初步研究

目的建立一种快速、简便,适用于基层的恶性疟免疫诊断方法.方法将抗恶性疟原虫HRP-Ⅱ的单克隆抗体3A3、2E7纯化后经配对筛选,利用Dipstick-免疫胶体金技术,制成诊断恶性疟的Dipstick层析条.用该层析条对115份疟疾患者血样,20份非疟疾病人血样及10份正常人血样进行检测,评价其敏感性和特异性,并对其稳定性、重复性等进行了初步研究.结果用该法检测145份血样,其对恶性疟的敏感性和特异性分别为83.1%及97.5%,已包被抗原、抗体的Dipstick条在4 C及室温下可保存3个月以上,对30份血样重复检测4次结果完全一致.结论Dipstick-免疫胶体金模式快速、简便,适用于基层应用,为疟疾的快速诊断提供了新的有效的手段.     

恶性疟原虫乳酸脱氢酶的快速电泳法检测及影响因素

目的建立一种敏感、特异的恶性疟快速诊断方法。方法：应用快速电泳法检测恶性疟病人血样中恶性疟原虫乳酸脱氢酶（ＬＤＨ－Ｐ），并对可能影响检测结果的几种因素进行观察。结果：检测４０份恶性疟病人血样，３８份检测出ＬＤＨ－Ｐ，阳性率为９５％，假阴性率为５％；同时检测４０份间日疟病人血样和２０份正常人血样，均为阴性，无假阳性；血样反复冻融可使ＬＤＨ－Ｐ受到破坏，蛋白酶抑制剂对保存血样中的ＬＤＨ－Ｐ保护作用明显；新鲜血样中加否蛋白酶抑制剂，检测结果差异不明显。结论：快速电泳法检测ＬＤＨ－Ｐ诊断恶性疟，方法简便、敏感性和特异性高，具有很好的现场应用价值。检测新鲜血样中ＬＤＨ－Ｐ效果好。     

套式/多重PCR诊断疟疾的敏感性、特异性和稳定性初探

目的 提高标签引物?鄄套式/多重PCR诊断疟疾的敏感性、特异性与稳定性。 方法 用滤纸法采集非疟疾发热病人血样30份及其他传染病（感冒， 流感， 伤寒， 肝炎等）患者血样20份；抽取恶性疟和间日疟各1例患者血4 m1，进行系列稀释制备不同疟原虫含量的感染血样；健康者血样作对照。用热裂解法制备DNA模板，用线粒体细胞色素氧化酶基因作为靶基因，应用相关软件和网络资源（Primer Premier 5.0, PUBMED, NCBI-BLAST和Mfold服务器）设计和优化标签引物?鄄套式/多重PCR，并用于检测所采集制备的各种血样。 结果 间日疟与恶性疟患者血系列稀释为含 1 000、100、10和1个虫/μl后经标签引物?鄄套式/多重PCR检测，恶性疟和间日疟患者各稀释含虫血样分别在611 bp和255 bp出现1条带，能检测到原虫密度均为1个虫/μl血；非疟疾发热病人血样30份及其他传染病患者血样均为阴性；健康者血样未出现扩增条带，每种血样反复测试3次以上均获得同样结果。 结论 经优化的标签引物-套式/多重PCR在疟疾诊断中具有较高的敏感性、特异性和稳定性。     

单克隆抗体3A3、2E7用于恶性疟Dipstick检测的初步研究

目的 建立一种快速、简便，适用于基层的恶性疟免疫诊断方法。方法 将抗恶性疟原虫HRP－Ⅱ的单克隆抗体3A3、2E7纯化后经配对筛选，利用Dipstick-免疫胶体金技术，制成诊断恶性疟的Dipstick层析条。用该层析条对115份疟疾患者血样，20份非疟疾病人血样及10份正常人血样进行检测，评价其敏感性和特异性，并对其稳定性、重复性等进行了初步研究。结果 用该法检测145份血样，其对恶性疟的敏感性和特异性分别为83．1％及97．5％，已包被抗原、抗体的Dipstick条在4℃及室温下可保存3个月以上，对30份血样重复检测4次结果完全一致。结论 Dipstick-免疫胶体金模式快速、简便，适用于基层应用，为疟疾的快速诊断提供了新的有效的手段。     

万孚疟疾快速诊断试剂盒效果评价

目的评价万孚恶性疟快速检测试剂盒的检测效果。方法以镜检法为金标准,采用单盲法检测临床"四热"患者血样。结果使用万孚恶性疟快速检测试剂盒检测"四热"患者547例,检出疟疾阳性323例。敏感性和特异性分别为95.00%和100.00%,与镜检符合率为96.89%。结论万孚恶性疟快速检测试剂盒敏感性和特异性高,质量稳定,适合于恶性疟流行区使用。     

试纸法检测血液中富组氨酸蛋白Ⅱ快速诊断恶性疟的初步观察

本文报道了应用试纸法检测感染恶性疟后血内富组氨酸蛋白Ⅱ，用以诊断恶性疟。对镜检确诊的恶性疟病人进行了检测，阳性检出率为９５％，检测全过程需５～７ｍｉｎ。应用改良法检测全血或血浆仅需２～３ｍｉｎ；同时对间日疟病人血样和非疟疾病人血样进行了检测，结果全部阴性，特异性为１００％。应用试纸法诊断疟疾无须任何仪器，诊断快速、方便，对临床早期确诊病人并给于及时治疗、减少传播和病死率有重要意义。     

Identification of cryptic coinfection with Plasmodium falciparum in patients presenting with vivax malaria.

In Thailand, approximately 8% of patients treated for vivax malaria are found subsequently to have coinfection with Plasmodium falciparum. A P. falciparum histidine rich protein 2 (PfHRP-2) dipstick test was evaluated as a predictor of mixed infections with subpatent P. falciparum in a prospective study of 238 patients admitted to the hospital with acute vivax malaria. Of these, 23 (10%) had subsequent development of falciparum malaria without reexposure. Patients with cryptic P. falciparum infection had a significantly lower mean (standard deviation) hematocrit than those with P. vivax alone: 29.6 (7.6%) versus 37.2 (6.4%) (P < 0.0001). Using microscopic appearance of P. falciparum after the start of treatment as the reference standard, the PfHRP-2 test was 74% sensitive and 99% specific in predicting mixed infections with subpatent P. falciparum parasitemia at presentation. The PfHRP-2 dipstick test may be a useful adjunct to microscopy in areas where mixed infections are common.     

Evaluation of a dipstick test for the rapid diagnosis of imported malaria among patients presenting within the network TropNetEurop.

Lack of experience on the part of involved laboratory personnel frequently complicates swift diagnosis of imported falciparum malaria in non-endemic areas. Diagnostic tools based on the dipstick principle for the detection of plasmodial histidine-rich protein 2 have been marketed for several years and have been extensively evaluated. Recently, a test kit capable of detecting antigen of Plasmodium falciparum and P. vivax has been introduced. In order to evaluate this newly available tool, specimens from 664 patients were screened during the course of a prospective multicentre study within the European Network on Imported Infectious Disease Surveillance (TropNetEurop). Among the screened specimens, samples from 82 patients (12.3%) were positive for falciparum malaria using expert microscopy. A further 17 samples were positive for vivax malaria. The evaluated test kit performed with a sensitivity of 87.8% and a specificity of 99% for detection of falciparum malaria. Respective values for vivax malaria were 76.5% and 100%. Dipstick tests have the potential of improving the speed and accuracy of the diagnosis of falciparum malaria, especially if non-specialized laboratories are involved. However, decreased values of sensitivity and specificity, in comparison with expert microscopy, still impose a clear limit on the usefulness of the currently available kits.     

Community-based program for malaria case management in the Brazilian Amazon.

In areas of drug-resistant malaria, control programs may restrict chemotherapy until malaria has been confirmed via microscopy to contain costs and toxicity. In Brazil, patients travel to centralized laboratory posts (FNS) at great cost for diagnosis and treatment. A program was established through the bars of a mining town offering free dipstick diagnosis and mefloquine treatment on a 24-hr basis; falciparum malaria dipstick tests are accurate and easy to use. Outcomes were compared with historical data and results of a neighboring non-intervention village. Guidelines for dipstick use and treatment were followed for 98% of visits. The number of FNS visits was reduced from 2,316 (expected) to 1,097 (observed) with 626 dipstick tests applied. Ninety-five percent of those who visited the FNS experienced onset of malaria symptoms in the town where the FNS was located. There was an unexpected doubling of the malaria hospital admission rate. We demonstrate that dipstick testing can be used in a sustainable, community-based program that should be applicable in a wide variety of settings.     

Microscopic and sub-microscopic Plasmodium falciparum infection, but not inflammation caused by infection, is associated with low birth weight

Pregnancy-associated malaria is one of the leading causes of low birth weight in malaria endemic areas. In this study, 145 parturient women residing in areas endemic for Plasmodium falciparum in Lambaréné, Gabon, were recruited into the study after delivery, and the association of maternal P. falciparum infection, inflammatory response, and birth weight was studied. At delivery, 10% (15) of the mothers (12 were positive in both peripheral and placental blood smears, 1 was positive in peripheral blood only, and 2 were positive in placenta blood only) were positive for P. falciparum by microscopy and 23% (30) by real-time polymerase chain reaction (PCR). The level of C-reactive protein (CRP) was significantly elevated in microscopically P. falciparum-positive pregnant women (34 mg/L; 95% CI: 3-458) but not in those with sub-microscopic infections (6 mg/L; 95% CI: 1-40) compared with those free of P. falciparum infection (7 mg/L; 95% CI: 1-43). In a multivariate analysis, the presence of microscopic (adjusted OR = 28.6, 95% CI = 4.8-169.0) or sub-microscopic (adjusted OR = 13.2, 95% CI = 2.4-73.0) P. falciparum infection in pregnant women and age of mothers < 21 years (adjusted OR = 9.7 CI = 1.0-89.7), but not CRP levels, were independent predictors for low birth weight. This finding may have important operational implications and emphasizes the need for appropriate diagnostic methods in studies evaluating the outcome of pregnancy-associated malaria.     

Multicentre study, in patients with imported malaria, on the sensitivity and specificity of a dipstick test (ICT Malaria P.f./P.v.) compared with expert microscopy

A prospective, multicentre study was carried out in Italy to assess the sensitivity and specificity of a rapid dipstick test (ICT Malaria P.f./P.v.) in the diagnosis of imported malaria caused by Plasmodium falciparum and other Plasmodium spp. The test is based on the detection of histidine-rich protein-2 (HRP-2) from P. falciparum and 'panmalarial' antigen in peripheral blood. The 241 subjects were international travellers or immigrants from areas where malaria is endemic. When compared with the microscopical examination of bloodsmears (used as the 'gold standard'), the dipsticks were found to be 94.4% sensitive and 94.5% specific for pure infections with P. falciparum. The performance of the tests when used on patients infected with species other than P. falciparum or more than one Plasmodium spp. showed a high degree of variability. Although the dipsticks represent a very simple, rapid, and valuable diagnostic aid, they should not be considered a complete substitute for direct microscopical diagnosis using stained bloodsmears.     

The reliability of diagnostic techniques in the diagnosis and management of malaria in the absence of a gold standard

The accuracy of techniques for the diagnosis of malaria are usually compared with optical microscopy, which is considered to be a gold standard. However, microscopy is prone to error and therefore makes it difficult to assess the reliability of other diagnostic techniques. We did a systematic review to assess the specificity and sensitivity of diagnostic techniques in different settings, using a statistical method that avoided defining a gold standard. Performance varied depending on species of the malaria parasite, level of parasitaemia, and immunity. Overall, histidine-rich protein 2 (HRP2)-based dipsticks showed a high sensitivity (92.7%) and specificity (99.2%) for Plasmodium falciparum in endemic areas. The acridine orange test was more sensitive (97.1%) in detecting P falciparum in epidemiological studies, with a specificity of 97.9%. In the absence of a gold standard, HRP2 dipsticks and acridine orange could provide an alternative for detecting falciparum infections in endemic areas and epidemiological studies, respectively. Microscopy still remains more reliable in detecting non-falciparum infections.     

快速免疫色谱测试法诊断恶性疟的初步观察

目的：评价快速免疫色谱测试法（ＩＣＴ）在我国疟区门诊疟疾的适用性。方法：以镜检结果为对照，用ＩＣＴ方法检测门诊“四热”病人中的恶性疟。结果：ＩＣＴ检测恶性疟的敏感性和特异性分别为９４．７％和９０．３％，与间日疟无交叉，检测不同性别和民族人群阳性率间的差别无显著意义。结论：ＩＣＴ较镜检诊断恶性疟更为快速且简便，更适于在疟区门诊应用。     

复式PCR检测恶性疟原虫与间日疟原虫的研究

目的： 建立在同一次扩增中即可鉴别患者感染的疟原虫虫种的复式ＰＣＲ检测方法。方法： 根据恶性疟原虫（Ｐ．ｆ．）中度重复基因序列ｐＢＲＫ１－１４ 和间日疟原虫（Ｐ．ｖ．）线粒体细胞色素Ｃ氧化酶基因ＣＯＩＩＩ合成引物,采用经优化的ＰＣＲ反应体系, 对疟原虫ＤＮＡ模板进行扩增。结果： Ｐ．ｆ．与Ｐ．ｖ．分别被扩增出２０６ 和３７０ ｂｐ 大小的ＤＮＡ片段,与人白细胞ＤＮＡ 无交叉;用该反应体系至少可检测出原虫血症为５×１０－ ７的Ｐ．ｆ．感染和１．０２×１０－ ６ Ｐ．ｖ．感染; 自云南疟疾流行区采集的７８３份滤纸干血滴样本中, 复式ＰＣＲ法阳性检出率为８５．８％ , 误诊率为０, 漏诊率为０．１％ , 而镜检法依次分别为８４．９％ 、３．１％ 和１．０％ , 两者符合率为９５．８％ 。结论： 本复式ＰＣＲ检测疟原虫较镜检敏感、特异, 适用于我国恶性疟与间日疟混合流行区的疟疾诊断、流行病学调查、药物的疗效考核和献血员的筛选等。     

Application of the ParaSight-F dipstick test for malaria diagnosis in a district control program

A rapid test for the diagnosis of Plasmodium falciparum infections based on the detection of histidine-rich-protein II, the ParaSight-F test, was evaluated after introduction in a district malaria control program in Uganda. Suspected treatment failures, pregnant women and infants with clinical malaria and general fever cases were tested at health facilities in malaria hypo-, meso- and holoendemic areas. A total of 1326 tests were carried out by health unit staff, cross read by experienced laboratory staff and results compared with thick film microscopy as the standard. Rater agreement in reading the dipstick result between health unit staff and laboratory staff was high, kappa index 0.94 (0.88-0.99). Sensitivity was 99.6% (99.0-100) for parasite densities above 500/microl, 98.6% (97.7-99.6) for densities above 50/microl and 22.2% (8.6-42.3) for densities below 10/microl. With the applied testing strategies no differences were found between endemicity levels or patient categories. Specificity was 86.2% (83.3-88.8) overall, but significantly higher in general fever cases (92.7%) compared to the other patient groups (84.3%, P=0.009). At the given prevalences positive predictive values (ppv) were above 80% and negative predictive values (npv) above 90% in all cases except in pregnant women (ppv: 77.8%). We conclude that in certain situations this test is an alternative to microscopy to improve diagnostic facilities for case management in malaria control programs in endemic African countries.     

Imported malaria in Moselle: 75 cases in three years

PURPOSE: Imported malaria frequency is increasing in France. Moselle, a north-east French county, with high concentration of servicemen going in endemic areas, follows the same trend. METHODS: Clinical, epidemiological aspects and treatment of all malaria attacks diagnosed over 3 years (from 1st january 1996 to 31st january 1999) were studied. Data pertaining to antimalaria prophylaxis and the reasons for prophylaxis failure were analyzed. RESULTS: Seventy-five patients developed a paroxysmal episode of malaria. No severe malaria and no death were noted. Ninety-six percent of the patients came from Africa (96%), 64% of them coming from western Africa (Ivory coast, Senegal, and Togo). Plasmodium falciparum was responsible for 90% of the cases. Giemsa staining, quantitative buffy coat diagnosis system and parasight rapid dipstick antigen capture assay help guide diagnosis. Halofantrine (64%) and quinine (28.6%) were used as curative treatment. Investigation about prophylactic means showed than 37.9% of interviewed patients did not comply with the preventive treatment. The primary prophylaxis (avoiding bites) was in existent or badly done. CONCLUSION: Although the best choice for chemoprophylaxis is still debated, travelers going to endemic areas should be aware of the risks for malaria and persuaded to take a preventive treatment, even though its efficacy may not be complete. They also should wear insecticide-treated clothes in order to decrease the number of potentially infective mosquito bites.