| PubMed Results |
| 1. | J Nepal Health Res Counc. 2012 Jan;10(1):16-9.Comparative study of sensitivity of rapid diagnostic (hexagon) test with calculated malarial parasitic density in peripheral blood.Shakya G, Gupta R, Pant SD, Poudel P, Upadhaya B, Sapkota A, Kc K, Ojha CR.Source
National Public Health Laboratory, DoHS, Teku, Kathmandu.
Abstract
Background: Different diagnostic test kits are used for rapid diagnosis of malaria. Most are based on antigen detection (pLDH, Pan Aldolase, HRP-2). In context of Nepal the diagnostic reliability and sensitivity of these tests is unknown. Hexagon Malaria Combi™ is one of the most commonly used test kit in Nepal for rapid diagnosis of malaria. The aim of the present study is to evaluate the sensitivity of the Hexagon malaria Combi test in comparison with parasitic density by microscopy technique Methods: A Cross sectional prospective study was conducted in three districts of Nepal from September to November 2009. Blood samples were collected from the suspected cases of malaria. Thick and thin smear were prepared from all the samples and Giemsa stain was done. Simultaneously RDT (hexagon) for malaria was done. When RDT was found to be positive, blood was serially diluted in 6 tubes as 1:2, 1:4, 1:8, 1:16, 1:32 and 1:64. RDT was done on diluted blood till RDT test gave negative result. Parasitic density was calculated for undiluted and diluted blood samples and sensitivity of RDT in various parasitic densities was calculated. Results: Hexagon malaria combi test is sensitive (86%) when malarial parasitic density is >500/μl. Sensitivity was found to be directly related to parasitic density. Its sensitivity is very low (2.9%) when parasitic density is less than 500/ μl. Conclusions: The sensitivity of rapid diagnostic test (hexagon Combi test detecting malarial pLDH antigen) is high only if the parasitic density is more than 500/μl. Keywords: rapid diagnostic test, parasitic density, malarial microscopy.
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| PMID: 22929630 [PubMed - in process] | |
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| 2. | Malar J. 2012 Aug 28;11(1):298. [Epub ahead of print]Genetic variation in histidine rich proteins among Indian Plasmodium falciparum population: possible cause of variable sensitivity malaria of rapid diagnostic tests.Kumar N, Singh JP, Pande V, Mishra N, Srivastava B, Kapoor R, Valecha N, Anvikar AR.Abstract
ABSTRACT:
BACKGROUND:
Rapid diagnostic tests (RDTs) have revolutionized the diagnosis of malaria. Among the various factors affecting RDTs sensitivity is genetic variation of the antigen used. The genetic variation in PfHRP2 and PfHRP3 proteins was studied among the Indian Plasmodium falciparum isolates.
METHODS:
One hundred and forty isolates of P. falciparum were collected from six geographical regions of India. Target genes encoding PfHRP2 and PfHRP3 antigens were sequenced to study genetic polymorphism. Minimum detection limit giving a positive rapid diagnostic test was also determined.
RESULTS:
Extensive variations were observed in amino acid repeat types of PfHRP2 and PfHRP3. PfHRP2 exhibited more polymorphism than PfHRP3. Significant relation was observed between type 2 and type 7 repeats and RDT detection rate as higher number of these repeats showed better sensitivity with RDTs.
CONCLUSION:
The results provide insights into the genetic diversity of Pfhrp2 and Pfhrp3 genes among Indian P. falciparum population and its relation to RDT sensitivity.
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| PMID: 22929537 [PubMed - as supplied by publisher] | |
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| 3. | Malar J. 2012 Aug 24;11(1):295. [Epub ahead of print]Performance of ¿VIKIA Malaria Ag Pf/Pan¿ (IMACCESS®), a new malaria rapid diagnostic test for detection of symptomatic malaria infections.Chou M, Kim S, Khim N, Chy S, Sum S, Dourng D, Canier L, Nguon C, Menard D.Abstract
ABSTRACT:
BACKGROUND:
Recently, IMACCESS[REGISTERED SIGN] developed a new malaria test (VIKIA Malaria Ag Pf/Pan[TRADE MARK SIGN]), based on the detection of falciparum malaria (HRP-2) and non-falciparum malaria (aldolase).
METHODS:
The performance of this new malaria rapid diagnostic test (RDT) was assessed using 1,000 febrile patients seeking malaria treatment in four health centres in Cambodia from August to December 2011. The results of the VIKIA Malaria Ag Pf/Pan were compared with those obtained by microscopy, the CareStart Malaria[TRADE MARK SIGN] RDT (AccessBio[REGISTERED SIGN]) which is currently used in Cambodia, and real-time PCR (as "gold standard").
RESULTS:
The best performances of the VIKIA Malaria Ag Pf/Pan[TRADE MARK SIGN] test for detection of both Plasmodium falciparum and non-P. falciparum were with 20--30 min reading times (sensitivity of 93.4% for P. falciparum and 82.8% for non-P. falciparum and specificity of 98.6% for P. falciparum and 98.9% for non-P. falciparum) and were similar to those for the CareStart Malaria[TRADE MARK SIGN] test.
CONCLUSIONS:
This new RDT performs similarly well as other commercially available tests (especially the CareStart Malaria[TRADE MARK SIGN] test, used as comparator), and conforms to the World Health Organization's recommendations for RDT performance. It is a good alternative tool for the diagnosis of malaria in endemic areas.
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| PMID: 22920654 [PubMed - as supplied by publisher] | |
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| 4. | J Clin Microbiol. 2012 Aug 22. [Epub ahead of print]Direct blood PCR in combination with Nucleic Acid Lateral Flow Immuno-Assay for the detection of Plasmodium species in malaria endemic settings.Mens PF, de Bes HM, Sondo P, Laochan N, Keereecharoen L, van Amerongen A, Flint J, Sak JR, Proux S, Tinto H, Schallig HD.Source
Koninklijk Instituut voor de Tropen/Royal Tropical Institute, Meibergdreef 39, 1105AZ,Amsterdam, The Netherlands.
Abstract
Declining malaria transmission and known difficulties with current diagnostic tools for malaria, such as microscopy and rapid diagnostic tests (RDTs) in particular at low parasite densities, still warrant the search for sensitive diagnostic tests. Molecular tests need substantial simplification before implementation in clinical settings in endemic countries.Direct-blood (db)-PCR, circumventing DNA extraction, detecting Plasmodium was developed and adapted to be visualized by nucleic acid lateral flow immuno-assay (NALFIA). The assay was evaluated in the laboratory against samples from confirmed Sudanese patients (n=51), returning travelers (n=214) and samples of the Dutch Blood Bank (n=100), and in the field in Burkina Faso (n=283) and Thailand (n=381) on suspected malaria cases and compared to RDT and microscopy.The sensitivity and specificity of the db-PCR-NALFIA compared to the initial diagnosis in the laboratory was 94,4% (95% CI: 0.909- 0.969) and 97,4% (95% CI: 0.909- 0.969) respectively. In Burkina Faso the sensitivity was 94,8% (95% CI:.88,7%-97,9%) and specificity 82,4% (95% CI: 75,4%-87,7%) compared to microscopy and 93,3% (95% CI: 87,4%-96,7%) and 91.4% (95% CI: 85,2%-95.3%) compared to RDT. In Thailand the sensitivity and specificity was 93,4%(CI: 86,4%-97,1%) and 90,9 (95% CI: 86,7%-93,9%) respectively compared to microscopy and 95,6% (95% CI: 88,5%-98,6%) and 87.1 % (95% CI: 82,5-90,6) compared to RDT.db-PCR-NALFIA is highly sensitive and specific for easy and rapid detection of Plasmodium parasites and can be easily used in malaria endemic countries. The inability of the device to discriminate Plasmodium species needs further attention.
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| PMID: 22915610 [PubMed - as supplied by publisher] | |
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| 5. | Malar J. 2012 Aug 17;11(1):279. [Epub ahead of print]Development, validation and evaluation of a rapid PCR-nucleic acid lateral flow immuno-assay for the detection of Plasmodium and the differentiation between Plasmodium falciparum and Plasmodium vivax.Mens PF, Moers AP, de Bes LM, Flint J, Sak JR, Keereecharoen L, van Overmeir C, Verweij JJ, Hallett RL, Wihokhoen B,Proux S, Schallig HD, van Amerongen A.Abstract
ABSTRACT:
BACKGROUND:
Molecular tools are very sensitive and specific and could be an alternative for the diagnosis of malaria. The complexity and need for expensive equipment may hamper implementation and, therefore, simplifications to current protocols are warranted.
METHODS:
A PCR detecting the different Plasmodium species and differentiating between Plasmodium falciparum and Plasmodium vivax was developed and combined with a nucleic acid lateral flow immuno-assay (PCR-NALFIA) for amplicon detection. The assay was thoroughly evaluated for the analytical sensitivity and specificity in the laboratory, the robustness and reproducibility in a ring trial and accuracy and predictive value in a field trial.
RESULTS:
The analytical sensitivity and specificity were 0.978 (95% CI: 0.932-0.994) and 0.980 (95% CI: 0.924-0.997), respectively, and were slightly less sensitive for the detection of P. vivax than for P. falciparum. The reproducibility tested in three laboratories was very good (k = 0.83). This evaluation showed that the PCR machine used could influence the results. Accuracy was evaluated in Thailand and compared to expert microscopy and rapid diagnostic tests (RDTs). The overall and P. falciparum-specific sensitivity and specificity was good ranging from 0.86-1 and 0.95-0.98 respectively, compared to microscopy. Plasmodium vivax detection was better than the sensitivity of RDT, but slightly less than microscopy performed in this study.
CONCLUSION:
PCR-NALFIA is a sensitive, specific and robust assay able to identify Plasmodium species with good accuracy. Extensive testing including a ring trial can identify possible bottlenecks before implementation and is therefore essential to perform in additon to other evaluations.
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| PMID: 22900750 [PubMed - as supplied by publisher] | |
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