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1.
To assess the validity of different clinical criteria in malaria patients, a small study including 92 children presented with fever or history of fever were examined in a highly endemic area of Papua New Gwinea. In 21 children parasitaemia was confirmed by microscopy examination of thick and thin smear stained with Giemsa method (9 cases of Plasmodium falciparum, 8 cases of Plasmodium vivax and 4 cases of mixed invasion Plasmodium falciparum and Plasmodium vivax). Only 4 from different 39 criteria analyzed in children with history of fever or hot skin showed significant association with parasitaemia (conscious disturbances, severe wasting, enlarged spleen and diarrhoea), however none of the criteria presented high sensitivity and could serve as good predictors for parasitaemia accept two (first and second one). These findings help to realize the importance of laboratory examination in diagnosis of malaria and explain difficulties in confirming or exclusion of malaria where microscopy is not available.  相似文献   

2.
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.  相似文献   

3.
We compared the performance of Paracheck-Pf, a new and cheap rapid malaria test, with ICT-Pf/PvR and microscopy in two malaria surveys in Thai villages on the Thai-Burmese border. The specificity, sensitivity, predictive positive and negative values of the Paracheck-PfR and ICT-PfR tests were calculated taking microscopy results as the gold standard. The 294 ICT-Pf/Pv tests resulted in two invalid (no control line) and 11 doubtful results. Both the ICT-Pf/PvR and Paracheck-PfR tests reliably detected P. falciparum infections. However, Paracheck-PfR failed to detect three P. falciparum cases and likewise, ICT-Pf/PvR failed to detect the same three cases and an additional four cases. These seven cases were detected by microscopy and had a parasitaemia under 150 parasites/microl. At a cost of c. US $1.00, the Paracheck-PfR test, based on the detection of the P. falciparum specific HRP-2 protein, is a reliable, easy to use and affordable tool for the diagnosis of P. falciparum malaria.  相似文献   

4.
The algorithm developed for the integrated management of childhood illness (IMCI) provides guidelines for the treatment of paediatric malaria. In areas where malaria is endemic, for example, the IMCI strategy may indicate that children who present with fever, a recent history of fever and/or pallor should receive antimalarial chemotherapy. In many holo-endemic areas, it is unclear whether laboratory tests to confirm that such signs are the result of malaria would be very relevant or useful. Children from a holo-endemic region of Tanzania were therefore checked for malarial parasites by microscopy and by using two rapid immunochromatographic tests (RIT) for the diagnosis of malaria (ICT Malaria P.f/P.v and OptiMal. At the time they were tested, each of these children had been targeted for antimalarial treatment (following the IMCI strategy) because of fever and/or pallor. Only 70% of the 395 children classified to receive antimalarial drugs by the IMCI algorithm had malarial parasitaemias (68.4% had Plasmodium falciparum trophozoites, 1.3% only P. falciparum gametocytes, 0.3% P. ovale and 0.3% P. malariae). As indicators of P. falciparum trophozoites in the peripheral blood, fever had a sensitivity of 93.0% and a specificity of 15.5% whereas pallor had a sensitivity of 72.2% and a specificity of 50.8%. The RIT both had very high corresponding sensitivities (of 100.0% for the ICT and 94.0% for OptiMal) but the specificity of the ICT (74.0%) was significantly lower than that for OptiMal (100.0%). Fever and pallor were significantly associated with the P. falciparum asexual parasitaemias that equalled or exceeded the threshold intensity (2000/microl) that has the optimum sensitivity and specificity for the definition of a malarial episode. Diagnostic likelihood ratios (DLR) showed that a positive result in the OptiMal test (DLR = infinity) was a better indication of malaria than a positive result in the ICT (DLR = 3.85). In fact, OptiMal had diagnostic reliability (0.93) which approached that of an ideal test and, since it only detects live parasites, OptiMal is superior to the ICT in monitoring therapeutic responses. Although the RIT may seem attractive for use in primary health facilities because relatively inexperienced staff can perform them, the high cost of these tests is prohibitive. In holo-endemic areas, use of RIT or microscopical examination of bloodsmears may only be relevant when malaria needs to be excluded as a cause of illness (e.g. prior to treatment with toxic or expensive drugs, or during malaria epidemics). Wherever the effective drugs for the first-line treatment of malaria are cheap (e.g. chloroquine and Fansidar), treatment based on clinical diagnosis alone should prove cost-saving in health facilities without microscopy.  相似文献   

5.
In Myanmar, we tested two rapid malaria immunochromatographic kits: the OptiMAL assay for the detection of parasite lactate dehydrogenase (pLDH), and the ICT Malaria P.f./P.v. test for histidine-rich protein 2 (PfHRP2) and panmalarial antigens. A total of 229 patients were examined, of whom 133 were found to be malaria positive by Giemsa microscopy. Both OptiMAL and ICT gave lower sensitivities than previously reported. ICT sensitivity for Plasmodium falciparum and non-falciparum parasites were 86.2 and 2.9%, respectively; specificity was 76.9 and 100%, respectively. OptiMAL sensitivity for P. falciparum and non-falciparum parasites were 42.6 and 47.1%, respectively; specificity was 97.0 and 96.9%, respectively. The sensitivity of both tests for the detection of both P. falciparum and non-falciparum parasites increased with parasite density. Several explanations for these results are explored. Our results raise particular concern over batch quality variations of malaria rapid diagnostic devices (MRDDs).  相似文献   

6.
The performance of the OptiMAL test, to detect and differentiate Plasmodium falciparum and P. vivax, was evaluated in central India. The subjects were either symptomatic patients, who presented at a referral hospital in urban Jabalpur, or the inhabitants of remote, tribal, forested villages where malaria is a major public-health problem. In each setting, the results of conventional microscopy were used as the 'gold standard'. Under hospital conditions, the test had excellent sensitivity (100%), good specificity (97%), a high positive predictive value (98%) and a high negative predictive value (100%). The corresponding values in the field-based study in the tribal villages (100%, 67%, 84% and 100%, respectively) were almost as good. The results of OptiMAL testing reveal the decline in parasitaemias (of P. falciparum or P. vivax) after drug administration. For monitoring the effectiveness of treatment, the test could therefore be a useful alternative to microscopy, particularly (1) in places where the facilities for microscopy are poor or non-existent and (2) among hospitalized patients with severe, complicated malaria (in whom parasitaemia and drug response need to be followed very carefully). Follow-up (within 28 days of diagnosis) of the 58 malaria cases detected in the field revealed that the OptiMAL test can be used to detect re-infection with a different Plasmodium sp. (sensitivity = 100%; specificity = 100%; J-index = 1) or recrudescence/re-infection with the same Plasmodium sp. (sensitivity = 83%; specificity = 100%; J-index = 0.83) accurately. The ability to use the test to distinguish P. falciparum from P. vivax, and to identify mixed infections of these two species, is of great significance in areas where the preferred and effective therapy for P. falciparum malaria differs from that for P. vivax.  相似文献   

7.
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.  相似文献   

8.
BACKGROUND: Modelling malaria parasitaemia as function of fever has been proposed as best alternative to estimate the attributable fraction of malaria fever and the sensitivity and specificity of different case definitions of malaria disease. OBJECTIVES: To determine the prevalence of fever and its relation to malaria parasitaemia and to establish a pyrogenic threshold for malaria disease in the area. METHODS: We conducted two cross-sectional surveys in children of 6 months to 9 years of age (2434 during the rainy season of 1993 and 2353 during the dry season of 1994) randomly selected from 21 areas of Bandiagara district, Mali. RESULTS: The relationship between fever and Plasmodium falciparum parasitaemia depends strongly on the season, thus affecting the malaria-attributable fraction of fever cases and the sensitivity and specificity of malaria case definitions. The overall proportion of fever attributable to malaria parasitaemia was 33.6% during the rainy season and 23.3% during the dry season, with the highest proportion occurring among the youngest children. The cut-off value, where the sensitivity curve crosses the specificity curve, was around 3200 pf/microl for all age categories during the rainy season and 200 pf/microl during the dry season. CONCLUSIONS: Malaria remains a main cause of fever in this area of Mali. The pyrogenic threshold of parasitaemia depends strongly on the season, and different cut-off levels of parasitaemia should be used during the two seasons to define malaria cases in this area.  相似文献   

9.
BACKGROUND: In Africa, fever is often treated presumptively as malaria, resulting in misdiagnosis and the overuse of antimalarial drugs. Rapid diagnostic tests (RDTs) for malaria may allow improved fever management. METHODS: We compared RDTs based on histidine-rich protein 2 (HRP2) and RDTs based on Plasmodium lactate dehydrogenase (pLDH) with expert microscopy and PCR-corrected microscopy for 7000 patients at sites of varying malaria transmission intensity across Uganda. RESULTS: When all sites were considered, the sensitivity of the HRP2-based test was 97% when compared with microscopy and 98% when corrected by PCR; the sensitivity of the pLDH-based test was 88% when compared with microscopy and 77% when corrected by PCR. The specificity of the HRP2-based test was 71% when compared with microscopy and 88% when corrected by PCR; the specificity of the pLDH-based test was 92% when compared with microscopy and >98% when corrected by PCR. Based on Plasmodium falciparum PCR-corrected microscopy, the positive predictive value (PPV) of the HRP2-based test was high (93%) at all but the site with the lowest transmission rate; the pLDH-based test and expert microscopy offered excellent PPVs (98%) for all sites. The negative predictive value (NPV) of the HRP2-based test was consistently high (>97%); in contrast, the NPV for the pLDH-based test dropped significantly (from 98% to 66%) as transmission intensity increased, and the NPV for expert microscopy decreased significantly (99% to 54%) because of increasing failure to detect subpatent parasitemia. CONCLUSIONS: Based on the high PPV and NPV, HRP2-based RDTs are likely to be the best diagnostic choice for areas with medium-to-high malaria transmission rates in Africa.  相似文献   

10.
OBJECTIVES: To compare the sensitivity, specificity and post-treatment persistence of three commonly used rapid antigen detection methods. METHOD: We studied 252 Vietnamese patients aged from 4 to 60 years, 157 with falciparum and 95 with vivax malaria and 160 healthy volunteers. An initial blood sample was taken for microscopy, and OptiMAL, immunochromatographic test (ICT) malaria P.f./P.v. and Paracheck-Pf tests. Patients with falciparum malaria were treated with an artesunate-based combination regimen and those with vivax malaria received chloroquine. Eighty-seven patients with falciparum malaria who were initially positive for one of the antigen tests and who remained blood smear-negative underwent follow-up testing over 28 days. RESULTS: Paracheck-Pf was the most sensitive test for Plasmodium falciparum (95.8% vs. 82.6% for ICT malaria P.f./P.v. and 49.7% for OptiMAL). Specificities were all 100%. For vivax malaria, OptiMAL performed better than ICT malaria P.f./P.v. (sensitivities 73.7% and 20.0%, respectively), with 100% specificity in both cases. All tests had low sensitivities (< or = 75.0%) at parasitaemias < 1000/microl regardless of malaria species. During follow-up, Paracheck-Pf remained positive in the greatest proportion of patients, especially at higher parasitaemias (> 10,000/microl). Residual OptiMAL positivity occurred only in a relatively small proportion of patients (< 10%) with parasitaemias > 10,000/microl during the first 2 weeks after treatment. CONCLUSIONS: Although microscopy remains the gold standard for malaria diagnosis, Paracheck-Pf may prove a useful adjunctive test in uncomplicated falciparum malaria in southern Vietnam. OptiMAL had the lowest sensitivity for P. falciparum but it might have a use in the diagnosis of vivax malaria and perhaps to monitor efficacy of treatment for falciparum malaria where microscopy is unavailable.  相似文献   

11.
Two hundred and forty-six apparently healthy pregnant women aged 19-40 years, without symptoms were recruited (147 recruited during the dry season and 99 recruited during the rainy season) for the present study. Blood examinations for malaria parasites, Plasmodium falciparum specific-IgG concentration and serological reactivity with P. falciparum-histidine rich protein-2 (HRP-2) antigens were conducted on all the pregnant women during the dry and rainy seasons of the year. During the dry season, 109 (74%) of the recruited pregnant women without symptoms had P. falciparum parasitaemia, while 79 (80%) of the recruited pregnant women without symptoms had P. falciparum parasitaemia during the rainy season. However, the P. falciparum malaria parasites density was significantly raised during the dry season compared with that of in the rainy season (p < 0.05). Serological analysis with P. falciparum histidine rich protein-2 antigen (HRP-2) showed 108 (73%) and 71 (77%) of the pregnant women without symptoms as seropositive during the dry and rainy seasons respectively. The P. falciparum specific-IgG concentration was similar during both seasons in the HRP-2 seropositive pregnant women without symptoms (p > 0.05). The results showed no seasonal tide in the incidences of asymptomatic P. falciparum parasitaemia; however, the significantly raised parasitaemia during the dry season may suggest possible increased parasites tolerance. The P. falciparum specific-IgG concentration during both seasons may not be the primary effector mechanism offering tolerance in asymptomatic parasitaemia in pregnant women.  相似文献   

12.
A rapid new immunochromatographic test (ICT malaria P.f/P.v) for diagnosis of Plasmodium falciparum and P.vivax was evaluated against thick blood smears in forest villages of Chhindwara, Madhya Pradesh, where both Plasmodium falciparum and P.vivax are prevalent. 344 symptomatic patients (Gond ethnic tribe) in five villages were screened by field staff of the Malaria Research Centre in October 1999. For P.falciparum, the ICT was 97.5% sensitive and 88% specific, with a positive predictive value (PPV) of 87.6% and a negative predictive value (NPV) of 97.6%. For P.vivax the sensitivity was only 72%, the specificity 99%, with a PPV of 92% and an NPV of 96%. Although a negative test result was inadequate to exclude parasitaemia < or = 300/microl for P.falciparum and < or = 1500/microl for P.vivax, the test is potentially useful in remote areas.  相似文献   

13.
For diagnosis of malaria, popular brands of rapid test kits collectively termed as "dipsticks" were subject to field evaluation in northeastern India for their comparative sensitivity and specificity vis-à-vis conventional microscopic results. Dipsticks based on Plasmodium falciparum-specific histidine-rich protein (Pf HRP-2) antigen capture assay revealed 100% sensitivity and high specificity (94-100%); thus, they were concluded to be reliable tools for confirmed diagnosis of malarial infection. However, an advanced version of the same kit, having incorporated additional pan-malarial monoclonal antibody, was found to be less sensitive (71%) for non-falciparum infections. Besides, Pf HRP-2-based kits continued to show positive results up to day 7, even after clearance of parasitemia on account of persistent antigenemia. This very limitation seemed to have been overcome by parasite-specific lactate dehydrogenase (pLDH) enzyme-based kit. This kit was observed to have high sensitivity (81-89%) and specificity (100%) for both falciparum and non-falciparum malaria, but cannot distinguish mono-infection from mixed infections. It is concluded that the rational use of these kits would accord health benefits in terms of early detection and prompt treatment, reduce drug pressure, and possibly delay the emergence and spread of multi-drug-resistant strains of malarial parasites.  相似文献   

14.
The OptiMAL assay, a new immunochromatographic "dipstick" test for malaria based on detection of Plasmodium lactate dehydrogenase (pLDH), is purported to detect infections of approximately 200 parasites/microL of blood and to differentiate between Plasmodium falciparum and non-P. falciparum. We evaluated OptiMAL performance by comparing the test strip interpretations of two independent readers with consensus results obtained independently by expert malaria microscopists. Unbiased measures of sensitivity were derived by applying the OptiMAL test for detection and differentiation of light, asymptomatic infections by P. falciparum and Plasmodium vivax. OptiMAL readings were separated in time to determine whether the reaction signal was stable. Microscopy identified infections in 225 of 505 individuals screened; those with P. falciparum (n = 170) averaged 354 asexual forms/microL and P. vivax/Plasmodium malariae (n = 112) averaged 216 asexual forms/microL of blood. Concordance between OptiMAL and microscopy was 81% and 78% by the two independent readings. The assay's sensitivity for detection of any malaria species was 60.4% and 70.2% respectively and specificity was 97% and 89%. Most cases identified by microscopy as P. falciparum were graded as negative or non-falciparum by both OptiMAL readers. OptiMAL false negatives as well as misidentifications were related to low parasitemias (< 500/microL). The OptiMAL assay demonstrated 88-92% sensitivity for detecting infections of 500-1,000 parasites/microL, a range covering the mean parasitemia of primary symptomatic P. falciparum infections in malaria-na?ve Indonesian transmigrants. This device was markedly less sensitive than expert microscopy for discriminating between malaria species and is presently unsuited for use as an epidemiological screening tool. The OptiMAL assay is not approved for diagnostic use but is commercially available for research purposes only.  相似文献   

15.
BACKGROUND & OBJECTIVES: Plasmodium falciparum cerebral malaria remains a major health problem in India. The efficacy of treatment of cerebral malaria lies in its early diagnosis through rapid diagnostic methods. ParaSights-F test detects HRP-2 antigen secreted by parasitised red blood cells and quantitative buffy coat assay (QBC) is examination of buffy coat for the presence of malarial parasite stained with acridine orange. This study was performed to evaluate the effectiveness of ParaSight-F test and QBC assay as diagnostic methods in the patients of cerebral malaria. METHODS: Fifty clinically diagnosed patients of cerebral malaria were included in the study. ParaSight-F test, QBC and conventional blood smear examination was done. Patients who were in coma and there were no obvious features of bacterial or viral etiology were investigated for cerebral malaria by these diagnostic methods. RESULTS: ParaSight-F test, QBC and peripheral blood smears were examined. Patients were followed-up for signs of clinical recovery. ParaSight-F test was positive in 47 patients, QBC in 46 while blood smear examination was positive in 28 cases. INTERPRETATION & CONCLUSION: Sensitivity and specificity of ParaSight-F test were found to be 96.6 and 94% while QBC showed 97.8 and 100% respectively. ParaSight-F test and QBC were found to be novel methods for diagnosis of cerebral malaria especially in the cases where diagnosis can not be made by conventional blood smear examination due to low parasitaemia. These rapid diagnostic methods help in early therapeutic intervention.  相似文献   

16.
快速免疫色谱测试卡诊断恶性疟和间日疟的效果评价   总被引:6,自引:1,他引:5  
目的: 评价快速免疫色谱测试卡( I C T) 在疟区诊断恶性疟和间日疟的效果。方法: 以疟原虫镜检结果为标准, 用 I C T 检测门诊“四热”病人中的恶性疟和间日疟。结果: I C T 检测恶性疟与间日疟的敏感性分别为967 % 和904 % , 特异性为986 % 。与原虫镜检结果的符合率为947 % 。恶性疟与间日疟之间无交叉反应。结论: 免疫色谱测试卡可同时检测恶性疟和间日疟, 较镜检法快速、简易。  相似文献   

17.
Microscopic examination of blood smears remains the gold standard for malaria diagnosis, but is labor-intensive and requires skilled operators. Rapid dipstick technology provides a potential alternative. A study was conducted in The Gambia to compare the performance of OptiMAL, an immunochromatographic antigen detection assay for the diagnosis of malaria using parasite lactate dehydrogenase, against standard microscopy in patients with suspected malaria. For initial diagnosis of Plasmodium falciparum, irrespective of stage, this assay had a sensitivity of 91.3%, a specificity of 92%, a positive predictive value of 87.2%, and a negative predictive value of 94.7%. The sensitivity of the test decreased markedly at parasitemias < 0.01%. This assay can be used for the diagnosis of malaria in areas where microscopy is not available and for urgent malaria diagnosis at night and at weekends, when routine laboratories are closed and when relatively inexperienced microscopists may be on duty.  相似文献   

18.
We report here the sensitivity and specificity of OptiMAL for the diagnosis of acute malaria in patients presenting to the Hospital for Tropical Diseases (HTD), a tertiary referral centre for Tropical and Infectious diseases. A sensitivity of 95.3% and a specificity of 100% for Plasmodium falciparum and a sensitivity of 96% and a specificity of 100% for Plasmodium vivax was obtained. The ability to follow the course of the parasitaemia using OptiMAL during treatment and its significance for use in areas where expert microscopy is not available is discussed.  相似文献   

19.
A rapid, immunochromatographic test for malaria diagnosis, 'Determine malaria pf', was evaluated by a field team in the epidemic-affected, forest setting of Chhindwara district, in Madhya Pradesh, central India. In all, 526 fever cases were screened for Plasmodium falciparum in October or November, 1999. Those found to be infected were treated with sulfadoxine-pyrimethamine and primaquine. Using microscopy as the gold standard, the new test had a sensitivity of 98% and a specificity of 87%. The positive and negative predictive values were 88% and 98%, respectively. Although follow-up of 64 subjects on day 7 post-treatment revealed that 20% of those who then appeared smear-negative were still antigenaemic, 34% of the subjects were still smear-positive, for asexual parasites, at that time. The Determine test was found to be very easy to perform and the results could be read reliably by field workers, without any supervision. The ease of use of the test indicates that it could be useful in the management of malaria, particularly in remote and inaccessible areas, provided that its accuracy can be assured and that it can be made affordable.  相似文献   

20.
The performance of two histidine-rich protein type-2-based malaria rapid diagnostic tests (mRDTs) was examined in a rural area with a high prevalence of malaria and human immunodeficiency virus type-1 (HIV-1) infection in 113 and 445 febrile patients ≥ 15 years of age with and without HIV-1 infection, respectively. Patients were tested for HIV-1 infection by using a standard assay and for Plasmodium falciparum by using two mRDTs and microscopy. When microscopy was used as the gold standard, both mRDTs performed similarly in patients with and without HIV-1 infection: Bioline SD Malaria Antigen P.f, sensitivity 94.4% (95% confidence interval [CI]: 81.3-99.3%) versus 97.1% (95% CI:92.8-99.2%) and specificity 50.6% (95% CI: 39.0-62.2%) versus 47.2% (95% CI: 41.4-53.1%); and ICT diagnostics Malaria Pf, sensitivity 94.4% (95% CI: 81.3-99.3%) versus 97.1% (95% CI: 92.8-99.2%) and specificity 50.6% (95% CI:39.0-62.2%) versus 50.3% (95% CI: 44.4-56.1%). Infection with HIV-1 does not appear to affect the performance of these histidine-rich protein type-2 (HRP-2)-based mRDTs.  相似文献   

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