METHODS: This prospective cross-sectional study consecutively recruited 494 patients with suspected dengue from a health clinic in Malaysia. Both RDTs were performed onsite. The evaluated ELISA and reference tests were performed in a virology laboratory. The reference tests comprised of a reverse transcription-polymerase chain reaction and three ELISAs for the detection of dengue NS1 antigen, IgM and IgG antibodies, respectively. The diagnostic performance of evaluated tests was computed using STATA version 12.
RESULTS: The sensitivity and specificity of ViroTrack were 62.3% (95%CI 55.6-68.7) and 95.0% (95%CI 91.7-97.3), versus 66.5% (95%CI 60.0-72.6) and 95.4% (95%CI 92.1-97.6) for SD NS1 ELISA, and 52.4% (95%CI 45.7-59.1) and 97.7% (95%CI 95.1-99.2) for NS1 component of SD Bioline, respectively. The combination of the latter with its IgM and IgG components were able to increase test sensitivity to 82.4% (95%CI 76.8-87.1) with corresponding decrease in specificity to 87.4% (95%CI 82.8-91.2). Although a positive test on any of the NS1 assays would increase the probability of dengue to above 90% in a patient, a negative result would only reduce this probability to 23.0-29.3%. In contrast, this probability of false negative diagnosis would be further reduced to 14.7% (95%CI 11.4-18.6) if SD Bioline NS1/IgM/IgG combo was negative.
CONCLUSIONS: The performance of ViroTrack Dengue Acute was comparable to SD Dengue NS1 Ag ELISA. Addition of serology components to SD Bioline Dengue Duo significantly improved its sensitivity and reduced its false negative rate such that it missed the fewest dengue patients, making it a better point-of-care diagnostic tool. New RDT like ViroTrack Dengue Acute may be a potential alternative to existing RDT if its combination with serology components is proven better in future studies.
OBJECTIVE: to describe a case of Nipah virus encephalitis in a pig farm worker from Malaysia.
STUDY DESIGN: the clinical, laboratory and radiological findings of this patient were scrutinized. Special emphasis was placed on the electron microscopic analysis of the cerebrospinal fluid (CSF) specimen from this patient.
RESULTS: the neurological deficits indicative of cerebellar involvement were supported by the magnetic resonance imaging that showed prominent cerebellar and brainstem lesions. CSF examination provided further evidence of viral encephalitis. Complement fixation and/or RT-PCR assays were negative for Japanese encephalitis, herpes simplex, measles and mumps viruses. ELISA for detecting IgM and IgG antibodies against Hendra viral antigens were equivocal for the CSF specimen, and tested initially negative for the first serum sample but subsequently positive for the repeat serum sample. Transmission electron microscopy of negatively-stained preparations of CSF revealed enveloped virus-like structures fringed with surface projections as well as nucleocapsids with distinctive helical and herringbone patterns, features consistent with those of other paramyxoviruses, including Hendra virus.
CONCLUSION: this case report reiterates the relevant and feasible role of diagnostic electron microscopy for identifying and/or classifying novel or emerging viral pathogens for which sufficiently specific and sensitive tests are lacking.