Eurosurveillance - Volume 19, Issue 4, 30 January 2014

The 2013/14 influenza season has started in Europe. Four countries have reported medium intensity influenza activity, with children under 15 years being the most affected age group. A growing number of countries see increasing rates of influenza-like illness or acute respiratory infection and increasing proportions of specimens positive for influenza A(H1)pdm09 virus. In previous seasons, this subtype was associated with higher reported numbers of severe and fatal cases. Clinicians should offer influenza vaccination to unvaccinated persons belonging to risk groups.

We present two cases of imported Zika fever to Japan, in travellers returning from French Polynesia, where an outbreak due to Zika virus (ZIKV) is ongoing since week 41 of 2013. This report serves to raise awareness among healthcare professionals, that the differential diagnosis of febrile and subfebrile patients with rash should include ZIKV infection, especially in patients returning from areas affected by this virus.

In November 2013, an acute Zika virus (ZIKV) infection was diagnosed in a German traveller returning from Thailand. The patient reported a clinical picture resembling dengue fever. Serological investigations revealed anti-ZIKV-IgM and -IgG, as well as ZIKV-specific neutralising antibodies in the patient's blood. In Europe, viraemic travellers may become a source of local transmission of ZIKV, because Aedes albopictus (Skuse) and Ae. aegypti (Linnaeus) are invasive mosquitoes and competent vectors for ZIKV. .

In March 2011, the German sentinel surveillance system for influenza (Arbeitsgemeinschaft Influenza (AGI)) was complemented by an Internet-based syndromic monitoring system (GrippeWeb) for acute respiratory infections (ARI) and influenza-like-illness (ILI). To assess representativeness of GrippeWeb participants, key demographic variables and lifetime prevalence of asthma and diabetes were compared with data from the general population of Germany. To 'validate' GrippeWeb, we compared weekly ARI and medically attended ARI (MAARI) rates, generated between weeks 35/2011 and 34/2012, with AGI MAARI rates and overlaid GrippeWeb ILI rates with the number of positive influenza samples obtained by the AGI. GrippeWeb had high weekly participation rates (62% of participants reported in ≥90% of possible weeks). Although it varied by age group, participants reported a mean of between 1.3 and 6.0 ARI episodes and between 0.1 and 2.4 ILI episodes during the study year. Estimated GrippeWeb MAARI incidence was very similar to the AGI MAARI incidence and influenza circulation was reflected well in the GrippeWeb ILI rates. GrippeWeb became a reliable monitoring system shortly after implementation, capturing the burden of ARI and ILI at general population level. The high degree of agreement between GrippeWeb's and AGI's MAARI data lends support to the validity of both systems. .

Following human infections with novel avian influenza A(H7N9) viruses in China, the European Centre for Disease Prevention and Control, the World Health Organization (WHO) Regional Office for Europe and the European Reference Laboratory Network for Human Influenza (ERLI-Net) rapidly posted relevant information, including real-time RT-PCR protocols. An influenza RNA sequence-based computational assessment of detection capabilities for this virus was conducted in 32 national influenza reference laboratories in 29 countries, mostly WHO National Influenza Centres participating in the WHO Global Influenza Surveillance and Response System (GISRS). Twenty-seven countries considered their generic influenza A virus detection assay to be appropriate for the novel A(H7N9) viruses. Twenty-two countries reported having containment facilities suitable for its isolation and propagation. Laboratories in 27 countries had applied specific H7 real-time RT-PCR assays and 20 countries had N9 assays in place. Positive control virus RNA was provided by the WHO Collaborating Centre in London to 34 laboratories in 22 countries to allow evaluation of their assays. Performance of the generic influenza A virus detection and H7 and N9 subtyping assays was good in 24 laboratories in 19 countries. The survey showed that ERLI-Net laboratories had rapidly developed and verified good capability to detect the novel A(H7N9) influenza viruses.