scholarly journals Challenges in Laboratory Diagnosis of Malaria in a Low-Resource Country at Tertiary Care in Eastern Nepal: A Comparative Study of Conventional vs. Molecular Methodologies

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Pragyan Dahal ◽  
Basudha Khanal ◽  
Keshav Rai ◽  
Vivek Kattel ◽  
Satish Yadav ◽  
...  
Keyword(s):  
Real Time ◽  
Sensitivity And Specificity ◽  
Malaria Elimination ◽  
Real Time Pcr ◽  
Febrile Illness ◽  
Diagnostic Tools ◽  
Acute Febrile Illness ◽  
Gold Standard Method ◽  
Blood Samples ◽  
Ct Value

For ongoing malaria elimination programmes, available methods such as microscopy and rapid diagnostic tests (RDTs) cannot detect all malaria cases in acute febrile illness. These methods are entirely dependent on the course of infection, parasite load, and skilled technical resources. Our study objectives were to estimate the performance of light microscopy and a RDT as well as real-time PCR for the detection of the Plasmodium parasite. Altogether, 52 blood samples collected from patients with acute febrile illness were tested by microscopy, RDT, and real-time PCR. The results were compared in terms of sensitivity and specificity. Microscopy detected the malaria parasite in 5.8% of the blood samples whereas 13.5% were detected by the RDT and 27% by real-time PCR. Considering real-time PCR as the gold standard method, microscopy had a sensitivity of 21.4% and a specificity of 100%, and the RDT had a sensitivity of 28.6% and a specificity of 92.1%. Microscopy together with the RDT successfully detected malaria positive cases in blood samples of Ct value below 20, but both were unable to detect malaria cases between 26–40 Ct value ranges amplified by real-time PCR. Despite various diagnostic tools being available, microscopy still remains the method of choice for diagnosis, while the RDT is user-friendly when applied at the point of care. However, our preliminary results emphasize the need to implement the test with higher sensitivity and specificity in the context of a malaria elimination programme. Such programmes can be a crucial opportunity to understand the species prevalent in a low-endemic region. However, these results should be further verified with a large cohort study to document the submicroscopic infection.

scholarly journals Challenges in laboratory diagnosis of Malaria in a low resource country among cases of acute febrile illness at tertiary care hospital in eastern Nepal: Comparative study on Conventional Vs Molecular approach

2020 ◽  
Author(s):  
Pragyan Dahal ◽  
Basudha Khanal ◽  
Keshav Rai ◽  
Vivek Kattel ◽  
Satish Yadav ◽  
...  
Keyword(s):  
Real Time ◽  
Sensitivity And Specificity ◽  
Malaria Elimination ◽  
Real Time Pcr ◽  
Gold Standard ◽  
Febrile Illness ◽  
Acute Febrile Illness ◽  
Low Resource ◽  
Elimination Programme ◽  
Low Resource Country

Abstract Background For ongoing malaria elimination programme, available methods like microscopy and rapid diagnostic test (RDT) are not able to detect all the cases of malaria in acute febrile illness. These methods are entirely dependent on the course of infection, parasite load and skilled technical resources thus the study was carried out to compare performance of microscopy and RDT which are commonly used in a low resource country along with reference to real-time PCR. Methods Altogether 52 blood samples collected from patients with acute febrile illness were tested by microscopy, RDT and real-time PCR. The results were compared in terms of sensitivity and specificity. Results The test results were as follows: 5.8% positivity by Microscopy, 13.5% positivity by RDT and 27% by real time PCR. Taking into consideration of PCR as a gold standard method microscopy showed 21.4% sensitivity and 100% specificity. Likewise, RDT results revealed 28.6% sensitivity and 92.1% specificity. Conclusion Despite of various diagnostic tools available, microscopy stills remains the gold standard for the diagnosis and RDT is the user friendly to execute the test under the tree, but our preliminary results emphasized the need to implement the test with the higher sensitivity and specificity in context of malaria elimination programme which could be another important opportunity to understand the parasite circulation in case of low endemic region. However, these results should be further verified with the large study cohort in order to document the submicroscopic infection.

scholarly journals Development of a TaqMan Array Card for Acute-Febrile-Illness Outbreak Investigation and Surveillance of Emerging Pathogens, Including Ebola Virus

2015 ◽  
Vol 54 (1) ◽  
pp. 49-58 ◽  
Author(s):  
Jie Liu ◽  
Caroline Ochieng ◽  
Steve Wiersma ◽  
Ute Ströher ◽  
Jonathan S. Towner ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Salmonella Enterica ◽  
Ebola Virus ◽  
Febrile Illness ◽  
Fever Virus ◽  
Outbreak Investigation ◽  
Acute Febrile Illness ◽  
Content Type ◽  
Taqman Array

Acute febrile illness (AFI) is associated with substantial morbidity and mortality worldwide, yet an etiologic agent is often not identified. Convalescent-phase serology is impractical, blood culture is slow, and many pathogens are fastidious or impossible to cultivate. We developed a real-time PCR-based TaqMan array card (TAC) that can test six to eight samples within 2.5 h from sample to results and can simultaneously detect 26 AFI-associated organisms, including 15 viruses (chikungunya, Crimean-Congo hemorrhagic fever [CCHF] virus, dengue, Ebola virus, Bundibugyo virus, Sudan virus, hantaviruses [Hantaan and Seoul], hepatitis E, Marburg, Nipah virus, o'nyong-nyong virus, Rift Valley fever virus, West Nile virus, and yellow fever virus), 8 bacteria (Bartonellaspp.,Brucellaspp.,Coxiella burnetii,Leptospiraspp.,Rickettsiaspp.,Salmonella entericaandSalmonella entericaserovar Typhi, andYersinia pestis), and 3 protozoa (Leishmaniaspp.,Plasmodiumspp., andTrypanosoma brucei). Two extrinsic controls (phocine herpesvirus 1 and bacteriophage MS2) were included to ensure extraction and amplification efficiency. Analytical validation was performed on spiked specimens for linearity, intra-assay precision, interassay precision, limit of detection, and specificity. The performance of the card on clinical specimens was evaluated with 1,050 blood samples by comparison to the individual real-time PCR assays, and the TAC exhibited an overall 88% (278/315; 95% confidence interval [CI], 84% to 92%) sensitivity and a 99% (5,261/5,326, 98% to 99%) specificity. This TaqMan array card can be used in field settings as a rapid screen for outbreak investigation or for the surveillance of pathogens, including Ebola virus.

scholarly journals Use of Multiplex Real-Time PCR To Diagnose Scrub Typhus

2017 ◽  
Vol 55 (5) ◽  
pp. 1377-1387 ◽  
Author(s):  
Wiwit Tantibhedhyangkul ◽  
Ekkarat Wongsawat ◽  
Saowaluk Silpasakorn ◽  
Duangdao Waywa ◽  
Nuttawut Saenyasiri ◽  
...  
Keyword(s):  
Early Diagnosis ◽  
Real Time ◽  
Real Time Pcr ◽  
Scrub Typhus ◽  
Febrile Illness ◽  
Asia Pacific ◽  
Diagnostic Tools ◽  
Pcr Assay ◽  
Content Type ◽  
Serologic Tests

ABSTRACTScrub typhus, caused byOrientia tsutsugamushi, is a common cause of acute undifferentiated febrile illness in the Asia-Pacific region. However, its nonspecific clinical manifestation often prevents early diagnosis. We propose the use of PCR and serologic tests as diagnostic tools. Here, we developed a multiplex real-time PCR assay using hydrolysis (TaqMan) probes targetingO. tsutsugamushi47-kDa,groEL, and human interferon beta (IFN-β gene) genes to improve early diagnosis of scrub typhus. The amplification efficiency was higher than 94%, and the lower detection limit was 10 copies per reaction. We used a human gene as an internal DNA quality and quantity control. To determine the sensitivity of this PCR assay, we selected patients with confirmed scrub typhus who exhibited a clear 4-fold increase in the level of IgG and/or IgM. The PCR assay result was positive in 45 of 52 patients, indicating a sensitivity of 86.5% (95% confidence interval [CI]: 74.2 to 94.4). The PCR assessment was negative for all 136 non-scrub typhus patients, indicating a specificity of 100% (95% CI: 97.3 to 100). In addition, this test helped diagnose patients with inconclusive immunofluorescence assay (IFA) results and using single blood samples. In conclusion, the real-time PCR assay proposed here is sensitive and specific in diagnosing scrub typhus. Combining PCR and serologic tests will improve the diagnosis of scrub typhus among patients presenting with acute febrile illness.

scholarly journals Evaluating Performance of Multiplex Real Time PCR for the Diagnosis of Malaria at Elimination Targeted Low Transmission Settings of Ethiopia.

2021 ◽  
Author(s):  
Mahlet Belachew ◽  
Mistire Wolde ◽  
Desalegn Nega ◽  
Bokretsion Gidey ◽  
Legessie Negash ◽  
...  
Keyword(s):  
Light Microscopy ◽  
Real Time ◽  
Malaria Elimination ◽  
Real Time Pcr ◽  
Nucleic Acid Amplification ◽  
Molecular Testing ◽  
Pcr Assay ◽  
Blood Samples ◽  
Low Transmission ◽  
Highly Sensitive

Abstract Background: Malaria incidence has declined in Ethiopia in the past ten years. Current malaria diagnostic tests, including light microscopy and antigen-detecting rapid tests (RDTs) cannot reliably detect low-density infections. Studies have shown that nucleic acid amplification tests are highly sensitive and specific in detecting malaria infection. Thus, this study took place with the aim of evaluating the performance of multiplex real time PCR for the diagnosis of malaria using patient samples collected from health facilities located at malaria elimination targeted low transmission settings in Ethiopia. Methods: A health facility based cross sectional survey was conducted in selected malaria sentinel sites. Malaria suspected febrile outpatients referred to laboratory for malaria testing between December 2019 and March 2020 were enrolled into this study. Socio demographic information and capillary blood samples were collected from the study participants and tested at spot with RDTs. Additionally, five circles of dry blood sample (DBS) samples on Whatman filter paper and thick and thin smear were prepared for molecular testing and microscopic examination, respectively. Multiplex real time PCR assay was performed at EPHI malaria laboratory. The performance of multiplex real time PCR assay, microscopy and RDT for the diagnosis of malaria was compared and evaluated against each other.Results: Out of 271 blood samples, multiplex real time PCR identified 69 malaria cases as P. falciparum infection, 16 as P. vivax and 3 as mixed infections. Of the total samples, light microscopy detected 33 as Pf, 18 as PV and RDT detected 43 as Pf, 17 as PV, and one mixed infection. Using light microscopy as reference test, the sensitivity and specificity of multiplex real time PCR were 100% (95% CI [93-100]) and 83.2% (95% CI [77.6-87.9]), respectively. Using multiplex real time PCR as a reference, light microscopy and RDT had sensitivity of 58% (95% CI [46.9-68.4] and 67% (95% CI [56.2-76.7]); and 100% (95% CI [98-100] and 98.9 (95% CI (96-99.9), respectively. Substantial level of agreement was reported between microscopy and multiplex real time PCR results with kappa value of 0.65. Conclusions: Multiplex real time PCR had an advanced performance in parasite detection and species identification on febrile patients’ samples than did microscopy and RDT in low malaria transmission settings. It is highly sensitive malaria diagnostic method that can be used in malaria elimination program, particularly for community based epidemiological samples. Although microscopy and RDT had reduced performance when compared to multiplex real time PCR, still had an acceptable performance in diagnosis of malaria cases on patient samples at clinical facilities.

scholarly journals Detection of Streptococcus pneumoniae from culture-negative dried blood spots by real-time PCR in Nigerian children with acute febrile illness

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Pui-Ying Iroh Tam ◽  
Nelmary Hernandez-Alvarado ◽  
Mark R. Schleiss ◽  
Amy J. Yi ◽  
Fatimah Hassan-Hanga ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Real Time ◽  
Real Time Pcr ◽  
Febrile Illness ◽  
Dried Blood Spots ◽  
Acute Febrile Illness ◽  
Blood Spots ◽  
Nigerian Children ◽  
Culture Negative

scholarly journals Evaluating performance of multiplex real time PCR for the diagnosis of malaria at elimination targeted low transmission settings of Ethiopia

2022 ◽  
Vol 21 (1) ◽  
Author(s):  
Mahlet Belachew ◽  
Mistire Wolde ◽  
Desalegn Nega ◽  
Bokretsion Gidey ◽  
Legessie Negash ◽  
...  
Keyword(s):  
Light Microscopy ◽  
Real Time ◽  
Malaria Elimination ◽  
Real Time Pcr ◽  
Diagnostic Tests ◽  
Molecular Testing ◽  
Pcr Assay ◽  
Blood Samples ◽  
Low Transmission ◽  
Highly Sensitive

Abstract Background Malaria incidence has declined in Ethiopia in the past 10 years. Current malaria diagnostic tests, including light microscopy and rapid antigen-detecting diagnostic tests (RDTs) cannot reliably detect low-density infections. Studies have shown that nucleic acid amplification tests are highly sensitive and specific in detecting malaria infection. This study took place with the aim of evaluating the performance of multiplex real time PCR for the diagnosis of malaria using patient samples collected from health facilities located at malaria elimination targeted low transmission settings in Ethiopia. Methods A health facility-based, cross-sectional survey was conducted in selected malaria sentinel sites. Malaria-suspected febrile outpatients referred to laboratory for malaria testing between December 2019 and March 2020 was enrolled into this study. Sociodemographic information and capillary blood samples were collected from the study participants and tested at spot with RDTs. Additionally, five circles of dry blood spot (DBS) samples on Whatman filter paper and thick and thin smear were prepared for molecular testing and microscopic examination, respectively. Multiplex real time PCR assay was performed at Ethiopian Public Health Institute (EPHI) malaria laboratory. The performance of multiplex real time PCR assay, microscopy and RDT for the diagnosis of malaria was compared and evaluated against each other. Results Out of 271 blood samples, multiplex real time PCR identified 69 malaria cases as Plasmodium falciparum infection, 16 as Plasmodium vivax and 3 as mixed infections. Of the total samples, light microscopy detected 33 as P. falciparum, 18 as P. vivax, and RDT detected 43 as P. falciparum, 17 as P. vivax, and one mixed infection. Using light microscopy as reference test, the sensitivity and specificity of multiplex real time PCR were 100% (95% CI (93–100)) and 83.2% (95% CI (77.6–87.9)), respectively. Using multiplex real time PCR as a reference, light microscopy and RDT had sensitivity of 58% (95% CI 46.9–68.4) and 67% (95% CI 56.2–76.7); and 100% (95% CI 98–100) and 98.9% (95% CI 96–99.9), respectively. Substantial level of agreement was reported between microscopy and multiplex real time PCR results with kappa value of 0.65. Conclusions Multiplex real-time PCR had an advanced performance in parasite detection and species identification on febrile patients’ samples than did microscopy and RDT in low malaria transmission settings. It is highly sensitive malaria diagnostic method that can be used in malaria elimination programme, particularly for community based epidemiological samples. Although microscopy and RDT had reduced performance when compared to multiplex real time PCR, still had an acceptable performance in diagnosis of malaria cases on patient samples at clinical facilities.

scholarly journals Evaluation of the New BD Max GC Real-Time PCR Assay, Analytically and Clinically as a Supplementary Test for the BD ProbeTec GC Qx Amplified DNA Assay, for Molecular Detection of Neisseria gonorrhoeae

2015 ◽  
Vol 53 (12) ◽  
pp. 3935-3937 ◽  
Author(s):  
Daniel Golparian ◽  
Stina Boräng ◽  
Martin Sundqvist ◽  
Magnus Unemo
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Real Time ◽  
Sensitivity And Specificity ◽  
Real Time Pcr ◽  
Molecular Detection ◽  
Analytical Sensitivity ◽  
Pcr Assay ◽  
Content Type ◽  
Dna Assay ◽  
Supplementary Test

The new BD Max GC real-time PCR assay showed high clinical and analytical sensitivity and specificity. It can be an effective and accurate supplementary test for the BD ProbeTec GC Qx amplified DNA assay, which had suboptimal specificity, and might also be used for initial detection ofNeisseria gonorrhoeae.

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