Eurosurveillance - Volume 17, Issue 27, 05 July 2012

We report the first documented cases of sandfly fever virus infection in travellers returning from Malta to Switzerland in autumn 2011. These cases illustrate the importance of considering sandfly-borne viral infection in the differential diagnosis of febrile patients from the Mediterranean island Malta. Raising awareness among physicians is relevant especially now at the beginning of the summer tourist season.

In Réunion, a French overseas territory located in the southern hemisphere, increase in influenza activity is generally observed several months earlier than in Europe. Influenza activity is monitored in Réunion through a multi-source surveillance system including sentinel practitioners network, hospital emergency department, laboratory and mortality. Since 2009, three successive influenza epidemics occurred on the island. The largest was observed in 2009 while epidemics in 2010 and 2011 were much weaker. In terms of circulating strains, B viruses were predominant at the beginning of the 2009 epidemic but they were completely evicted once A(H1N1)pdm09 circulation started. In 2010, A(H1N1)pdm09 virus was predominant again, but a constant co-circulation of B viruses was observed. In 2011, A(H3N2) virus circulated. The same viruses were identified a few months later in mainland France in the respective seasons. Since 2009, virus circulation, epidemiological trends and health impact of influenza have been similar to those observed in Europe. Influenza surveillance in Réunion may therefore give reliable early information which should be considered apart from the surveillance in mainland France. Then, it might be even a more suitable predictor for Europe than other temperate southern hemisphere countries. .

Although oseltamivir-resistant pandemic influenza A(H1N1)pdm09 is uncommon in immunocompetent individuals, a recent report from Newcastle, Australia, showed the first sustained community spread, from June to August 2011, of oseltamivir-resistant influenza A(H1N1)pdm09 virus carrying the H275Y neuraminidase (NA) mutation. To determine the frequency and the extent of this viral variant spread in the nearest major city to Newcastle, we performed a sequence-based genotypic assessment on samples from 143 oseltamivir untreated and 23 oseltamivir post-treatment individuals with influenza collected contemporaneously in Sydney, 120 km southwest of Newcastle. The detection of two of 143 (1.4%) community-derived samples containing H275Y suggests a low prevalence of oseltamivir-resistant influenza A(H1N1)pdm09 virus in the general community and no convincing evidence of spread of the NA H275Y-bearing influenza A(H1N1)pdm09 virus. In oseltamivir treated patients, oseltamivir-resistant influenza A(H1N1)pdm09 virus continue to emerge with three of 23 (13%) post-treatment samples containing the H275Y mutation. The observation of signature mutations and distinct phylogenetic relationship in full-length sequences of haemagglutinin and neuraminidase genes derived from 2011 strains against 2009 strains indicates continued genetic evolution and antigenic drift of the influenza A(H1N1)pdm09 viruses circulating in Australia.

This article describes the data obtained by the Portuguese Laboratory Network, reactivated following the World Health Organization declaration of the 2009 influenza pandemic, on the diagnoses of influenza A(H1N1)pdm09 infection during the pandemic (2009/10) and post-pandemic (2010/11) influenza seasons. The laboratories analysed and reported cases of influenza-like illness (ILI) and severe acute respiratory infection (SARI) to the National Influenza Reference Laboratory, which performed more detailed antigenic and genetic characterisation of the virus isolates. In 2009/10, a total of 62,089 ILI cases, distributed in two peaks, were analysed, 25,985 of which were positive for influenza A(H1N1)pdm09. Children aged 5-14 years were the most affected. Viruses were both antigenically and genetically similar to the pandemic strain A/California/7/2009, included in the 2009/10 pandemic vaccine. During the post-pandemic season, 1,496 ILI cases were tested for influenza A(H1N1)pdm09, 572 of which were positive. Infection was mainly diagnosed in adolescent and adults. Although the 2010/11 viruses remained antigenically similar to A/California/7/2009, increased genetic variation was observed. During the two seasons, two viruses with the neuraminidase H275Y amino acid substitution, associated with oseltamivir resistance, were detected. The Laboratory Network made an important contribution to the description of the influenza activity in the two seasons. .