Rapid detection of multiple respiratory viruses based on microfluidic isothermal amplification and a real-time colorimetric method

Respiratory viruses are major threats causing development of acute respiratory tract infections, which are common causes of illness and death throughout the world. Here, an integrated microsystem based on real-time colorimetry was developed for diagnosing multiple respiratory viruses. The microsystem employed magnetic beads for nucleic acid extraction and an eight-channel microfluidic array chip integrated with a loop-mediated isothermal amplification system for point-of-care screening of respiratory viruses. The overall detection process (including sample collection, nucleic acid extraction, sample loading, real-time detection, and signal output) could be completed within 1 h. Our results show that the developed method could specifically recognize influenza A virus subtypes (H1N1, H3N2, H5N1, and H7N9), influenza B virus, and human adenoviruses. The results obtained with 109 clinical samples indicate that the developed method has high specificity (100%, confidence interval 94.9-100.0) and sensitivity (96%, confidence interval 78.1-99.9). The integration of magnetic bead-based pre-treatment techniques and microfluidic isothermal amplification provides an effective solution for rapidly detecting etiological agents of respiratory diseases. The strategy of using a closed chip system and real-time colorimetry reduced aerosol contamination and ensured the accuracy of the results. The developed method provides an effective alternative for rapid point-of-care screening for viruses that cause respiratory disease syndromes and further aids in accurate and timely detection to control and prevent the spread of respiratory diseases caused by such pathogens.

Epidemiological and etiological characteristics of hand, foot, and mouth disease in Henan, China, 2008-2013

Hand, foot, and mouth disease (HFMD) is a common childhood illness caused by enteroviruses. HFMD outbreaks and reported cases have sharply increased in China since 2008. Epidemiological and clinical data of HFMD cases reported in Henan Province were collected from 2008 to 2013. Clinical specimens were obtained from a subset of these cases. Descriptive epidemiological methods were used to analyze the time, region and population distribution. The VP1 gene from EV71 and CA16 isolates was amplified, and the sequences were analyzed. 400,264 cases of HFMD were reported in this study, including 22,309 severe and 141 fatal cases. Incidence peaked between April and May. Laboratory confirmation was obtained for 27,692 (6.9%) cases; EV71, CA16, and other enteroviruses accounted for 59.5%, 14.1%, 26.4%, respectively. Phylogenetic analysis revealed that EV71 belonged to the C4a evolution branch of C4 sub-genotype and CA16 belonged to subtype B1a or B1b. The occurrence of HFMD in Henan was closely related to season, age and region distribution. Children under five were the most affected population. The major pathogens causing HFMD and their genotypes have not notably changed in Henan. The data strongly support the importance of EV71 vaccination in a high population density area such as Henan, China.