Update: Influenza Activity - United States and Worldwide, May 22-September 10, 2016

Thymic stromal lymphopoietin limits primary and recall CD8+ T-cell anti-viral responses

Thymic stromal lymphopoietin (TSLP) is a cytokine that acts directly on CD4+ T cells and dendritic cells to promote progression of asthma, atopic dermatitis, and allergic inflammation. However, a direct role for TSLP in CD8+ T-cell primary responses remains controversial and its role in memory CD8+ T cell responses to secondary viral infection is unknown. Here, we investigate the role of TSLP in both primary and recall responses in mice using two different viral systems. Interestingly, TSLP limited the primary CD8+ T-cell response to influenza but did not affect T cell function nor significantly alter the number of memory CD8+ T cells generated after influenza infection. However, TSLP inhibited memory CD8+ T-cell responses to secondary viral infection with influenza or acute systemic LCMV infection. These data reveal a previously unappreciated role for TSLP on recall CD8+ T-cell responses in response to viral infection, findings with potential translational implications.

Viral detection profile in children with severe acute respiratory infection

Objectives

The role of viral co-detection in children with severe acute respiratory infection is not clear. We described the viral detection profile and its association with clinical characteristics in children admitted to the Pediatric Intensive Care Unit (PICU) during the 2009 influenza A(H1N1) pandemic.

Method

Longitudinal observational retrospective study, with patients aged 0–18 years, admitted to 11 PICUs in Rio de Janeiro, with suspected H1N1 infection, from June to November, 2009. The results of respiratory samples which were sent to the Laboratory of Fiocruz/RJ and clinical data extracted from specific forms were analyzed.

Results

Of 71 samples, 38% tested positive for H1N1 virus. Of the 63 samples tested for other viruses, 58 were positive: influenza H1N1 (43.1% of positive samples), rhinovirus/enterovirus (41.4%), respiratory syncytial vírus (12.1%), human metapneumovirus (12.1%), adenovirus (6.9%), and bocavirus (3.5%). Viral codetection occured in 22.4% of the cases. H1N1-positive patients were of a higher median age, had higher frequency of fever, cough and tachypnea, and decreased leukometry when compared to H1N1-negative patients. There was no difference in relation to severity outcomes (number of organic dysfunctions, use of mechanical ventilation or amines, hospital/PICU length of stay or death). Comparing the groups with mono-detection and co-dection of any virus, no difference was found regarding the association with any clinical variable.

Conclusions

Other viruses can be implicated in SARI in children. The role of viral codetection has not yet been completely elucidated.

Respiratory Syncytial Virus Surveillance System in Japan: Assessment of Recent Trends, 2008-2015

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract illness in infants and young children. In Japan, surveillance for RSV infection started in 2003 based on approximately 3,000 pediatric sentinel sites. In recent years, RSV notifications have increased, but the interpretation of trends has been challenging due to a suspected increase in testing frequency and the expansion of the insurance coverage for RSV testing to include certain outpatients in late 2011. Therefore, we evaluated RSV surveillance data during 2008-2015, considering the number of sites that reported at least one RSV case during a surveillance year and restricting to sites that had continuous reporting status since 2008. While annual RSV notifications had increased, the number of sites reporting also increased. And the same magnitude of increase was not observed when the number of cases reported was restricted to the 1,372 sites that had continuous reporting status since 2008. Additionally, in the year following the insurance expansion, RSV notifications increased more remarkably for clinics than for hospitals. These results suggested that some of the recent increases in notifications might be due to an increase in testing frequency.

Antiviral Drug-Resistant Influenza B Viruses Carrying H134N Substitution in Neuraminidase, Laos, February 2016

In February 2016, three influenza B/Victoria/2/87 lineage viruses exhibiting 4- to 158-fold reduced inhibition by neuraminidase inhibitors were detected in Laos. These viruses had an H134N substitution in the neuraminidase and replicated efficiently in vitro and in ferrets. Current antiviral drugs may be ineffective in controlling infections caused by viruses harboring this mutation.