Dena Adachi

Sensitivity of Rapid Influenza Diagnostic Testing for Swine-Origin 2009 A (H1N1) Influenza Virus in Children

BACKGROUND: The rapidly evolving pandemic of novel 2009 swine-origin influenza A (H1N1) virus (S-OIV) demands that accurate and practical diagnostics be urgently evaluated for their potential clinical utility. OBJECTIVE: To determine the diagnostic accuracy of a rapid influenza diagnostic test (RIDT) and direct fluorescent antibody (DFA) assay for S-OIV by using reverse-transcription polymerase chain reaction (RT-PCR) as the reference standard. METHODS: We prospectively recruited children (aged 0–17 years) assessed in the emergency department of a pediatric referral hospital and a community pediatric clinic for influenza-like illness between May 22 and July 25, 2009. RIDT (performed on-site) and DFA were compared with RT-PCR to determine their sensitivity and specificity for S-OIV. We also compared the sensitivity of RIDT for S-OIV to that for seasonal influenza over 2 preceding seasons. RESULTS: Of 820 children enrolled, 651 were from the emergency department and 169 were from the clinic. RIDT sensitivity was 62% (95% confidence interval [CI]: 52%–70%) for S-OIV, with a specificity of 99% (95% CI: 92%–100%). DFA sensitivity was 83% (95% CI: 75%–89%) and was superior to that of RIDT (P < .001). RIDT sensitivity for S-OIV was comparable to that for seasonal influenza when using DFA supplemented with culture as the reference standard. RIDT sensitivity for influenza viruses was significantly higher in children 5 years of age or younger (P = .003) and in patients presenting ≤2 days after symptom onset (P < .001). CONCLUSIONS: The sensitivity of RIDT for detection of S-OIV is higher than recently reported in mixed adult-pediatric populations but remains suboptimal.

The Complete Sequence of a Human Parainfluenzavirus 4 Genome

Although the human parainfluenza virus 4 (HPIV4) has been known for a long time, its genome, alone among the human paramyxoviruses, has not been completely sequenced to date. In this study we obtained the first complete genomic sequence of HPIV4 from a clinical isolate named SKPIV4 obtained at the Hospital for Sick Children in Toronto (Ontario, Canada). The coding regions for the N, P/V, M, F and HN proteins show very high identities (95% to 97%) with previously available partial sequences for HPIV4B. The sequence for the L protein and the non-coding regions represent new information. A surprising feature of the genome is its length, more than 17 kb, making it the longest genome within the genus Rubulavirus, although the length is well within the known range of 15 kb to 19 kb for the subfamily Paramyxovirinae. The availability of a complete genomic sequence will facilitate investigations on a respiratory virus that is still not completely characterized.

COMPARISON OF HUMAN METAPNEUMOVIRUS INFECTION WITH RESPIRATORY SYNCYTIAL VIRUS INFECTION IN CHILDREN

We aimed to validate a direct immunofluorescence assay (DFA) for the detection of human metapneumovirus (hMPV) from nasal swabs and to determine the incidence and clinical features of this viral infection in a pediatric population. One hundred twenty-one of 3026 nasal swabs were positive for hMPV by DFA (4.0%). Compared with reverse transcriptase polymerase chain reaction, the sensitivity and specificity of DFA were 90%, and 100%, respectively. Compared with RSV, hMPV infection was more common in children with congenital abnormalities, particularly those with cardio-pulmonary dysplasia and was associated with an increased ventilatory requirement.

Comparison of the IMDx Influenza A Virus, Influenza B Virus, and Respiratory Syncytial Virus A/B Assay on the m2000 Platform with Real-Time Reverse Transcriptase PCR Assays

The increasing demand for timely respiratory virus testing for both diagnostic and surveillance purposes emphasizes the need to strike a sustainable approach for testing clinical specimens. Streamlined automated approaches allow clinically relevant diagnosis while avoiding pitfalls (e.g., subjective

Calibration of qualitative HBsAg assay results for quantitative HBsAg monitoring

Evidence is accumulating that quantitative hepatitis B surface antigen monitoring may be useful in managing patients with chronic HBV infection on certain treatment regimens. Based on these results with the Abbott Architect qualitative and quantitative HBsAg assays, it seems feasible to convert qualitative to quantitative HBsAg values for this purpose.

Discrepant HIV results resolved by human DNA testing

A high-risk patient was informed of a positive HIV antibody/antigen test. However, follow-up samples taken 2-3 months later for HIV RNA and anti-HIV antibodies were negative. Human DNA testing confirmed that all samples were from this patient, excluding a sample mix-up. Laboratory investigations revealed a likely splash-over contamination event.