Airborne Transmission of Influenza Virus in a Hospital of Qinhuangdao During 2017-2018 Flu Season.

The 2017-2018 flu season is considered to be one of the most severe, with numerous influenza outbreaks worldwide. In an infectious disease hospital of Qinhuangdao, air samples were collected daily from outpatient hall, clinical laboratory, fever clinic, children's ward (Children's Ward I/Children's Ward II), and adult ward during 23-29 January 2018 (peak flu activity) and 9-15 April 2018 (low flu activity). The air samples were collected with SLC-SiOH magnetic beads using impingement samplers. Real-time PCR assay was used to detect the RNA of airborne influenza (IFVA and IFVB) in the 91 collected aerosol samples. The results indicated that the air samples collected from the children's wards, adult ward and fever clinic were detected with airborne influenza viruses. However, the samples collected from outpatient hall and clinical laboratory were absence of influenza viruses. In addition, the subtypes of pH1N1/IFVA, H3N2/IFVA, yamagata/IFVB, and victoria/IFVB were detected among the samples with positive IFVA and IFVB. Notably, a new developed subtype of pH1N1 (an epidemic in 2018) was detected in the aerosol samples. In summary, this study profiled the distribution of airborne influenza in an infectious hospital in Qinhuangdao during 2017-2018 flu season. Patients infected with influenza could release airborne particles containing the virus into their environment. Healthcare workers and visitors in those places might have frequent exposure to airborne influenza virus. Therefore, we recommend some protective measures such as air disinfection and mask wearing to prevent and control the transmission of airborne influenza in hospital.

Epidemiological and clinical characteristics of Dengue virus outbreaks in two regions of China, 2014 - 2015.

Dengue virus (DENV), a single-stranded RNA virus and Flaviviridae family member, is transmitted by Aedes aegypti and Aedes albopictus mosquitoes. DENV causes dengue fever, which may progress to severe dengue. Hospital-based surveillance was performed in two Chinese regions, Guangzhou and Xishuangbanna, during the dengue epidemics in 2014 and 2015, respectively. Acute-phase serum was obtained from 133 patients with suspected dengue infections during the peak season for dengue cases. Viremia levels, virus sero-positivity, serotype distribution, infection type, clinical manifestations and virus phylogenetics were investigated. Of the 112 DENV-confirmed cases, 92(82.14%) were IgM antibody-positive for DENV, and 69(51.88%) were positive for DENV RNA. From these cases, 47(41.96%) were classified as primary infections, 39(34.82%) as secondary infections and 26 (23.21%) as undetermined infections. The viremia levels were negatively correlated with IgM presence, but had no relationship with the infection type. DENV-1 genotype V dominated in Guangzhou, whereas the DENV-2 Cosmopolitan genotype dominated in Xishuangbanna, where fewer DENV-1 genotype I cases occurred. DENV-2 is associated with severe dengue illness with more serious clinical issues. The strains isolated during 2014-2015 are closely related to the isolates obtained from other Chinese regions and to those isolated recently in Southeast Asian countries. Our results indicate that DENV is no longer an imported virus and is now endemic in China. An extensive seroepidemiological study of DENV and the implementation of vector control measures against it are now warranted in China.

No MERS-CoV but positive influenza viruses in returning Hajj pilgrims, China, 2013-2015.

BACKGROUND: There is global health concern that the mass movement of pilgrims to and from Mecca annually could contribute to the international spread of Middle East Respiratory Syndrome Coronavirus (MERS-CoV). In China, about 11,000 Muslim pilgrims participate in the Hajj gathering in Mecca annually. This is the first report of MERS-CoV and respiratory virus molecular screening of returning pilgrims at points of entry in China from 2013 to 2015. METHODS AND RESULTS: A total of 847 returning Hajj pilgrims participated in this study. The test results indicated that of the travelers, 34 tested positive for influenza A virus, 14 for influenza B virus, 4 for metapneumo virus, 2 for respiratory syncytial virus, and 3 for human coronavirus. There was a significant difference in the rates of positive and negative influenza virus tests between Hajj pilgrims with symptoms and those without. The detection rates of influenza virus were not significantly different among the three years studied, at 5.3, 6.0 and 6.3% for 2013, 2014 and 2015, respectively. DISCUSSION AND CONCLUSION: The MERS-CoV and respiratory viruses detection results at points of entry in China from 2013 to 2015 indicated that there were no MERS-CoV infection but a 5.7% positive influenza viruses in returning Chinese pilgrims.

A multiplex PCR assay for the detection of five influenza viruses using a dual priming oligonucleotide system.

BACKGROUND: A cost-effective, accurate and rapid simultaneous multiplex assay is required for testing and diagnoses of conventional and emerging viruses in clinical virology laboratories. We developed and optimized a dual priming oligonucleotide (DPO) multiplex PCR assay for detecting influenza viruses including seasonal H1N1, 2009 pandemic H1N1, H3N2, influenza B and H5N1. METHODS: The optimized multiplex DPO PCR was used to detect 233 clinical human samples. The results were compared to those obtained with RT-qPCR, conventional PCR and immunochromatographic assay. RESULTS: Specificity analysis revealed that the DPO PCR assay amplified each target virus without any cross-amplification. Statistical analysis demonstrated that the multiplex DPO-PCR sensitivity was higher than for the immunochromatographic assay and lower than for qPCR, while no significant difference was observed compared with conventional PCR, when detecting influenza A and B. Additional experiments using the same sample panel indicated no significant differences between the number of positive samples detected by multiplex DPO PCR and RT-qPCR when applying a Cq with a value lower than 30. CONCLUSIONS: The five-targeted simultaneous multiplex DPO PCR assay could be easily adopted into routine practice. This approach is cost effective with a short running time, low technical requirements for the detection of influenza virus and early diagnosis in clinical laboratories.

First confirmation of imported dengue virus serotype 2 complete genome in urine from a Chinese traveler returning from India.

Dengue virus (DENV) is a mosquito-borne virus that has four serotypes. Collection of serum from patients is time- and labor- consuming, and presents a high injury risk for infants and children. The genomic and serological diagnosis of imported dengue fever from a urine sample was used as a non-invasive diagnostic method in this study. A serum sample was collected on disease day 5, and a serum and urine sample were collected on disease day 8 and 18. The results of serological tests for DENV IgM revealed that the serum samples were positive for DENV. The results of RT-qPCR assay revealed that the serum sample collected on day 5 was DENV-positive; however, the serum sample collected on day 8 and 18 were negative for DENV. The urine sample collected on day 8 and 18 were DENV-positive. We also sequenced the complete DENV genome (10723 bp) from the urine sample (GenBank KF479233). The results of phylogenetic and epidemiological analysis indicated strong confirmation that the strain was located within the DENV-2 group with a 100% bootstrap value. In this report, we (1) provided the first evidence of a DENV infection that was imported from India to a non-endemic city of China, (2) investigated the DENV genome detection having a longer timeframe for positive detection in urine sample compared to previous studies, (3) provided the sequence results for the complete DENV-2 genome from a concentrated urine sample (4) discussed how virus-typing results could be used to manage the risk of sero-specific and re-infected travel-associated dengue fever.

[Evaluation of a self-prepared anti-WNV-IgG diagnostic ELISA kit with a panel of serum samples collected from the people from areas in which West Nile fever is endemic].

In view of that there is no report of west Nile virus infection cases in our country, evaluation the self-prepared anti-WNV-IgG diagnostic ELISA kit should be employed with the establishment of the serum sample panel collected from the entry personnel. All individuals of entry personnel were traveled from epidemic area of infectious west Nile disease. In our study, the serum samples were both detected by self-prepared anti-WNV-IgG diagnostic ELISA kit and the FDA certified kits ,which are FOCUS West Nile Virus IgG Dxselect and Panbio Dengue IgG Capture ELISA kits. The self-prepared kit and FDA certified kits were compared and assessed simultaneously. Furthermore, the specificity, repeatability and stability of the kits were also evaluated. The results indicated that no significant difference of detective rates (35. 6% for self-prepared kit vs. 32.5% for FOCUS kit, χ2 = 3. 05, P > 0.05) and good consistency (Kappa = 0.8372) between the self-prepared kit and FDA certified kits. Also, the positive coincidence rate, the negative coincidence rate and the total coincidence rate were calculated as 91.18%, 95.34% and 92.66%, respectively. The laboratory self-developed kit presented similar quality as the counterpart kits with FDA certificate. The development of our self-prepared anti-WNV-IgG diagnostic ELISA kit will provide technical support for the prevention and control of west Nile virus entry.

[Transmission electron microscopy investigation of the denudation of the envelope of influenza virus treated with Nonidet P-40 and the binding influence of antibody].

OBJECTIVE: Through observing the morphological changes of the prepared influenza viruses (H1N1) treated with the different concentration of Nonidet P-40 solutions and added with antibody against the influenza virus using transmission electron microscopy (TEM), to explore the principle of application of the internal antibody for immunoassay of influenza virus. METHODS: Through treating the virus samples with serial diluted Nonidet P-40 solutions from 0.01% to 0.2% and/or not adding antibody against the influenza virus, then investigating the samples by TEM to obtain the morphological changes of the virions. RESULTS: The serial images show that the denudation degree of the virions is proportional with the rise of NP-40 concentration, and partly denuded virion image appeared at 0.1% NP-40 treatment, also under this condition no influence was observed on antibody binding to the virus. CONCLUSION: This work demonstrated the interaction between influenza virion and its antibody under nonionic surfactants existing, which supports the advantages of sample preparation for immunoassay enveloped virus using internal antibody theoretically.