Viral Hemorrhagic Fever Diagnostics.

There are 4 families of viruses that cause viral hemorrhagic fever (VHF), including Filoviridae. Ebola virus is one virus within the family Filoviridae and the cause of the current outbreak of VHF in West Africa. VHF-endemic areas are found throughout the world, yet traditional diagnosis of VHF has been performed in large reference laboratories centered in Europe and the United States. The large amount of capital needed, as well as highly trained and skilled personnel, has limited the availability of diagnostics in endemic areas except in conjunction with governmental and nongovernmental entities. However, rapid diagnosis of VHF is essential to efforts that will limit outbreaks. In addition, increased global travel suggests VHF diagnoses may be made outside of the endemic areas. Thus, understanding how to diagnose VHF is imperative for laboratories worldwide. This article reviews traditional and current diagnostic modalities for VHF.

Detection of intracellular parasites by use of the CellaVision DM96 analyzer during routine screening of peripheral blood smears.

Conventional microscopy is the gold standard for malaria diagnosis. The CellaVision DM96 is a digital hematology analyzer that utilizes neural networks to locate, digitize, and preclassify leukocytes and characterize red blood cell morphology. This study compared the detection rates of Plasmodium and Babesia species on peripheral blood smears utilizing the CellaVision DM96 with the rates for a routine red blood cell morphology scan. A total of 281 slides were analyzed, consisting of 130 slides positive for Plasmodium or Babesia species and 151 negative controls. Slides were blinded, randomized, and analyzed by CellaVision and microscopy for red cell morphology scans. The technologists were blinded to prior identification results. The parasite detection rate was 73% (95/130) for CellaVision and 81% (105/130) for microscopy for positive samples. The interobserver agreement between CellaVision and microscopy was fair, as Cohen's kappa coefficient equaled 0.36. Pathologist review of CellaVision images identified an additional 15 slides with parasites, bringing the total number of detectable positive slides to 110 of 130 (85%). Plasmodium ovale had the lowest rate of detection at 56% (5 of 9); Plasmodium malariae and Babesia spp. had the highest rate of detection at 100% (3/3 and 6/6, respectively). The detection rate by CellaVision was 100% (23/23) when the parasitemia was ≥2.5%. The detection rate for <0.1% parasitemia was 63% (15/24). Technologists appropriately classified all negative specimens. The percentage of positive specimens detectable by CellaVision (73%) approaches results for microscopy on routine scan of peripheral blood smears for red blood cell morphology.

Comparison of FilmArray and Quantitative Real-Time Reverse Transcriptase PCR for Detection of Zaire Ebolavirus from Contrived and Clinical Specimens.

Rapid, reliable, and easy-to-use diagnostic assays for detection of Zaire ebolavirus (ZEBOV) are urgently needed. The goal of this study was to examine the agreement among emergency use authorization (EUA) tests for the detection of ZEBOV nucleic acids, including the BioFire FilmArray BioThreat (BT) panel, the FilmArray BT-E panel, and the NP2 and VP40 quantitative real-time reverse transcriptase (qRT) PCR assays from the Centers for Disease Control and Prevention (CDC). Specimens used in this study included whole blood spiked with inactivated ZEBOV at known titers and whole-blood, plasma, and urine clinical specimens collected from persons diagnosed with Ebola virus disease (EVD). The agreement for FilmArray and qRT-PCR results using contrived whole-blood specimens was 100% (6/6 specimens) for each ZEBOV dilution from 4 × 10(7) to 4 × 10(2) 50% tissue culture infective dose (TCID50)/ml, as well as the no-virus negative-control sample. The limit of detection for FilmArray and qRT-PCR assays with inactivated ZEBOV, based on duplicate positive results, was determined to be 4 × 10(2) TCID50/ml. Rates of agreement between FilmArray and qRT-PCR results for clinical specimens from patients with EVD were 85% (23/27 specimens) for whole-blood specimens, 90% (18/20 specimens) for whole-blood specimens tested by FilmArray testing and matched plasma specimens tested by qRT-PCR testing, and 85% (11/13 specimens) for urine specimens. Among 60 specimens, eight discordant results were noted, with ZEBOV nucleic acids being detected only by FilmArray testing in four specimens and only by qRT-PCR testing in the remaining four specimens. These findings demonstrate that the rapid and easy-to-use FilmArray panels are effective tests for evaluating patients with EVD.

Long-term stability of CMV DNA in human breast milk.

BACKGROUND: Human cytomegalovirus (CMV) is the leading cause of intrauterine and perinatal viral infection. The most common route of CMV transmission in newborns is through breastmilk and this can lead to infant morbidity and mortality. Breast milk that has been frozen for an extended period may need to be tested for CMV DNA to determine the source of infection. It has been a challenge for clinical laboratories to ensure the stability of CMV DNA in frozen breast milk for accurate viral load measurement. OBJECTIVES: To evaluate the stability of CMV DNA in breast milk by testing quantitative viral loads over a 28-day period for breast milk stored at 4 °C and a 90-day period for breast milk stored at -20 °C. STUDY DESIGN: Baseline viral loads were determined on day 0 and the samples stored at 4 °C underwent extraction and amplification at four time points, up to 28 days. The samples stored at -20 °C underwent extraction and amplification at five time points up to 90 days. Log10 values were calculated and t-test, Pearson's coefficient, and concordance correlation coefficient were calculated. RESULTS: There was no statistically significant difference between the time points by t-test, and correlation coefficients showed greater than 90% concordance for days 0 and 28 as well as days 0 and 90 at both storage temperatures tested. CONCLUSIONS: The concentration of CMV DNA in breast milk was stable for 28 days at 4 °C and 90 days at -20 °C as the concentrations did not differ significantly from the baseline viral loads.

Identification of bacterial pathogens from formalin-fixed, paraffin-embedded tissues by using 16S sequencing: retrospective correlation of results to clinicians' responses.

16S sequencing on formalin-fixed, paraffin-embedded (FFPE) material has been used to identify bacteria when culture-based phenotyping techniques have not worked. The objective of this study was to determine how frequently 16S sequencing used in FFPE material was helpful to clinicians in the diagnosis and treatment of infectious diseases. Requests for testing occurred upon consultation between an infectious disease pathologist and a surgical pathologist or an infectious disease physician. A selected paraffin block from each case was referred for 16S sequencing. Retrospectively, we correlated clinical history and management decisions on 27 cases that were tested by paneubacterial 16S sequencing. Samples included 24 surgical specimens, 1 autopsy, and 2 cytology blocks. Seventeen (63%) of the 27 cases had a positive 16S sequencing. Acute inflammation was present in 10 of these cases, and organisms were observed using special stains in 3. In 11 (65%) of the 17 cases, clinicians considered the organism identified by 16S sequencing to be the cause or possible cause of the infectious process. Organisms included common (Citrobacter) and fastidious bacteria (Haemophilus, Fusobacterium). In 3 cases, clinicians changed antibiotic treatment based on the bacteria identified, whereas in 8 (including 2 where no organism was found), clinicians continued the antibiotic treatment. The use of 16S sequencing on FFPE identified specific bacteria even when organisms were not observed histopathologically. 16S results had an impact in infectious disease management decisions.

Fecal microbiota transplant protocol for clostridium difficile infection.

Fecal microbiota transplant has become more acceptable as a therapeutic for recurrent Clostridium difficile infection. The FDA has an enforcement discretion policy for practitioner's performing this therapy, which includes informed consent for this experimental treatment. This manuscript describes a typical procedure that can be followed that includes the important aspects of this preparation and treatment.

ß-Globin gene sequencing of hemoglobin Austin revises the historically reported electrophoretic migration pattern.

CONTEXT: Hemoglobin (Hb) Austin was defined in 1977, using amino acid sequencing of samples from 3 unrelated Mexican-Americans, as a substitution of serine for arginine at position 40 of the ß-globin chain (Arg40Ser). Its electrophoretic migration on both cellulose acetate (pH 8.4) and citrate agar (pH 6.2) was reported between Hb F and Hb A, and this description persists in reference literature. OBJECTIVES.-To review the clinical features and redefine the diagnostic characteristics of Hb Austin. DESIGN: Eight samples from 6 unrelated individuals and 2 siblings, all with Hispanic surnames, were submitted for abnormal Hb identification between June 2010 and September 2011. High-performance liquid chromatography, isoelectric focusing (IEF), citrate agar electrophoresis, and bidirectional DNA sequencing of the entire ß-globin gene were performed. RESULTS: DNA sequencing confirmed all 8 individuals to be heterozygous for Hb Austin (Arg40Ser). Retention time on high-performance liquid chromatography and migration on citrate agar electrophoresis were consistent with that identification. Migration on IEF, however, was not between Hb F and Hb A, as predicted from the report of cellulose acetate electrophoresis. By IEF, Hb Austin migrated anodal to ("faster than") Hb A. CONCLUSIONS: Hemoglobin Austin (Arg40Ser) appears on IEF as a "fast," anodally migrating, Hb variant, just as would be expected from its amino acid substitution. The cited historic report is, at best, not applicable to IEF and is probably erroneous. Our observation of 8 cases in 16 months suggests that this variant may be relatively common in some Hispanic populations, making its recognition important. Furthermore, gene sequencing is proving itself a powerful and reliable tool for definitive identification of Hb variants.