Dataset Information

Field Evaluation of Capillary Blood Samples as a Collection Specimen for the Rapid Diagnosis of Ebola Virus Infection During an Outbreak Emergency.

ABSTRACT:

Background

Reliable reverse transcription polymerase chain reaction (RT-PCR)-based diagnosis of Ebola virus infection currently requires a blood sample obtained by intravenous puncture. During the current Ebola outbreak in Guinea, we evaluated the usability of capillary blood samples collected from fingersticks of patients suspected of having Ebola virus disease (EVD) for field diagnostics during an outbreak emergency.

Methods

A total of 120 venous and capillary blood samples were collected from 53 patients admitted to the Ebola Treatment Centre in Guéckédou, Guinea, between July and August 2014. All sample specimens were analyzed by RT-PCR using the RealStar Filovirus Screen RT-PCR Kit 1.0 from altona Diagnostics (Germany). We compared samples obtained by venipuncture and those obtained by capillary blood sampling absorbed onto swab devices.

Results

The resulting sensitivity and specificity of tests performed with capillary blood samples were 86.8% (95% confidence interval [CI], 71.9%-95.6%; 33/38 patients) and 100% (95% CI, 84.6%-100%; 22/22 patients), respectively.

Conclusions

Our data suggest that capillary blood samples could serve as an alternative to venous blood samples for the diagnosis of EVD in resource-limited settings during a crisis. This can be of particular advantage in cases when venipuncture is difficult to perform-for example, with newborns and infants or when adult patients reject venipuncture for cultural or religious reasons.

SUBMITTER: Strecker T

PROVIDER: S-EPMC4530726 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature

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Publications

Field Evaluation of Capillary Blood Samples as a Collection Specimen for the Rapid Diagnosis of Ebola Virus Infection During an Outbreak Emergency.

Strecker Thomas T Palyi Bernadett B Ellerbrok Heinz H Jonckheere Sylvie S de Clerck Hilde H Bore Joseph Akoi JA Gabriel Martin M Stoecker Kilian K Eickmann Markus M van Herp Michel M Formenty Pierre P Di Caro Antonino A Becker Stephan S

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 20150519 5

<h4>Background</h4>Reliable reverse transcription polymerase chain reaction (RT-PCR)-based diagnosis of Ebola virus infection currently requires a blood sample obtained by intravenous puncture. During the current Ebola outbreak in Guinea, we evaluated the usability of capillary blood samples collected from fingersticks of patients suspected of having Ebola virus disease (EVD) for field diagnostics during an outbreak emergency.<h4>Methods</h4>A total of 120 venous and capillary blood samples were ...[more]

PMID: 25991465

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Project description:BackgroundThroughout the Ebola virus disease (EVD) epidemic in West Africa, field laboratory testing for EVD has relied on complex, multi-step real-time reverse transcription PCR (RT-PCR) assays; an accurate sample-to-answer RT-PCR test would reduce time to results and potentially increase access to testing. We evaluated the performance of the Cepheid GeneXpert Ebola assay on clinical venipuncture whole blood (WB) and buccal swab (BS) specimens submitted to a field biocontainment laboratory in Sierra Leone for routine EVD testing by RT-PCR ("Trombley assay").Methods and findingsThis study was conducted in the Public Health England EVD diagnostic laboratory in Port Loko, Sierra Leone, using residual diagnostic specimens remaining after clinical testing. EDTA-WB specimens (n = 218) were collected from suspected or confirmed EVD patients between April 1 and July 20, 2015. BS specimens (n = 71) were collected as part of a national postmortem screening program between March 7 and July 20, 2015. EDTA-WB and BS specimens were tested with Xpert (targets: glycoprotein [GP] and nucleoprotein [NP] genes) and Trombley (target: NP gene) assays in parallel. All WB specimens were fresh; 84/218 were tested in duplicate on Xpert to compare WB sampling methods (pipette versus swab); 43/71 BS specimens had been previously frozen. In all, 7/218 (3.2%) WB and 7/71 (9.9%) BS samples had Xpert results that were reported as "invalid" or "error" and were excluded, leaving 211 WB and 64 BS samples with valid Trombley and Xpert results. For WB, 22/22 Trombley-positive samples were Xpert-positive (sensitivity 100%, 95% CI 84.6%-100%), and 181/189 Trombley-negative samples were Xpert-negative (specificity 95.8%, 95% confidence interval (CI) 91.8%-98.2%). Seven of the eight Trombley-negative, Xpert-positive (Xpert cycle threshold [Ct] range 37.7-43.4) WB samples were confirmed to be follow-up submissions from previously Trombley-positive EVD patients, suggesting a revised Xpert specificity of 99.5% (95% CI 97.0%-100%). For Xpert-positive WB samples (n = 22), Xpert NP Ct values were consistently lower than GP Ct values (mean difference -4.06, 95% limits of agreement -6.09, -2.03); Trombley (NP) Ct values closely matched Xpert NP Ct values (mean difference -0.04, 95% limits of agreement -2.93, 2.84). Xpert results (positive/negative) for WB sampled by pipette versus swab were concordant for 78/79 (98.7%) WB samples, with comparable Ct values for positive results. For BS specimens, 20/20 Trombley-positive samples were Xpert-positive (sensitivity 100%, 95% CI 83.2%-100%), and 44/44 Trombley-negative samples were Xpert-negative (specificity 100%, 95% CI 92.0%-100%). This study was limited to testing residual diagnostic samples, some of which had been frozen before use; it was not possible to test the performance of the Xpert Ebola assay at point of care.ConclusionsThe Xpert Ebola assay had excellent performance compared to an established RT-PCR benchmark on WB and BS samples in a field laboratory setting. Future studies should evaluate feasibility and performance outside of a biocontainment laboratory setting to facilitate expanded access to testing.

Project description:Early infant diagnosis is an important step in identifying children infected with HIV during the perinatal period or in utero. Multiple factors contribute to delayed antiretroviral treatment initiation for HIV-infected children, including delays in the early infant HIV diagnosis cascade.We conducted a retrospective study to evaluate early infant diagnosis turnaround times in Lesotho. Trained staff reviewed records of HIV-exposed infants (aged-6-8 weeks) who received an HIV test during 2011. Study sites were drawn from Highlands, Foothills and Lowlands regions of Lesotho. Central laboratory database data were linked to facility and laboratory register information. Turnaround time geometric means (with 95% CI) were calculated and compared by region using linear mixed models.1,187 individual infant records from 25 facilities were reviewed. Overall, early infant diagnosis turnaround time was 61.7 days (95%CI: 55.3-68.7). Mean time from specimen collection to district laboratory was 14 days (95%CI: 12.1-16.1); from district to central laboratory, 2 days (95%CI 0.8-5.2); results from central laboratory to district hospital, 23.3 days (95%CI: 18.7-29.0); from district hospital to health facility, 3.2 days (95%CI 1.9-5.5); and from health facility to caregiver, 10.4 days (95%CI, 7.9-13.5). Mean times from specimen transfer to the central laboratory and for result transfer from central laboratory to district hospital were significantly shorter in the Lowlands Region (0.9 and 16.2 days, respectively), compared to Highlands Region (6.0 [P = 0.030] and 34.3 days [P = 0.0099]. Turnaround time from blood draw to receipt of results was significantly shorter for HIV infected infants compared to HIV uninfected infants [p = 0.0036] at an average of 47.1 days (95%CI: 38.9-56.9) and 62 days (95%CI: 55.9-68.7) respectively. Of 47 HIV-infected infants, 36 were initiated on antiretroviral therapy at an average of 1.3 days (95%CI: 0.3, 5.7) after caregiver received the result.HIV-infected infants received results earlier and were rapidly initiated on antiretroviral therapy once the result was delivered to caregiver. However, average early infant diagnosis turnaround time was two months; the longest period of delay was transfer of results from central laboratory to district hospital. Turnaround time of results based on geographical regions or between hospitals and health centres varied but did not reach statistical significance.

Dataset Information

Field Evaluation of Capillary Blood Samples as a Collection Specimen for the Rapid Diagnosis of Ebola Virus Infection During an Outbreak Emergency.

Background

Methods

Results

Conclusions

Publications

Field Evaluation of Capillary Blood Samples as a Collection Specimen for the Rapid Diagnosis of Ebola Virus Infection During an Outbreak Emergency.

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