Evidence of West Nile virus circulation among humans in central northern Algeria

West Nile Virus (WNV) is the most widely distributed flavivirus worldwide. It is a mosquito-borne virus, and birds constitute its natural reservoir. Humans and equines are considered accidental hosts. Human WNV infections are usually asymptomatic or express as a mild febrile syndrome; however, in around 1% of cases they are responsible for more serious neurological diseases with a potentially lethal outcome. In the Mediterranean basin the virus circulation is regarded as endemic. Outbreaks of WNV meningoencephalitis are regularly notified, especially during summer and autumn seasons. In Algeria, although some surveys have reported WNV activity in the Sahara, to date few data are available about virus circulation in the northern part of the country. We conducted this study to detect possible WNV activity in this part of Algeria. For this purpose, in 2010 a total of 164 human sera were collected from native patients of the Algiers district and surrounding areas, then tested retrospectively for IgG anti-WNV by ELISA. Plaque reduction neutralization technique (PRNT) was used for result confirmation. In this cohort, 9.8% of the 164 collected sera returned positive for anti-WNV IgG; after confirmation by PRNT; 6.7% had specific neutralizing antibodies. No statistically significant difference was observed according to the sex or transfusion status of the patients. In conclusion, these data show for the first time serological evidence of WNV circulation in Algiers and its surrounding areas. They also highlight the need for implementing an integrated surveillance programme covering all aspects of WNV disease in order to better understand the circulation dynamics of WNV in this region. Other flaviviruses antigenically related to WNV should be investigated, given the evidence of serological cross-reaction, as specific IgG antibodies decrease after PRNT confirmation. Keywords: Algeria, circulation, ELISA, north central, sero-neutralization (PRNT), West Nile viru

Resonance-driven random lasing

4 pages, 4 figures.-- Supplementary material available at http://dx.doi.org/10.1038/nphoton.2008.102: Fig. 1: Ohm's law fit for photonic glass, Fig. 2: Two dyes photonic glass reference sample.A random laser is a system formed by a random assembly of elastic scatterers dispersed into an optical gain medium. The multiple light scattering replaces the standard optical cavity of traditional lasers and the interplay between gain and scattering determines the lasing properties. All random lasers studied to date have consisted of irregularly shaped or polydisperse scatterers, with a certain average scattering strength that was constant over the frequency window of the laser. In this letter we consider the case where the scattering is resonant. We demonstrate that randomly assembled monodisperse spheres can sustain scattering resonances over the gain frequency window, and that the lasing wavelength can therefore be controlled by means of the diameter and refractive index of the spheres. The system is therefore a random laser with an a priori designed lasing peak within the gain curve.The work was financially supported by the European Commission (EC) (LENS) under contract number RII3-CT-2003-506350, by the European Union (EU) through the Network of Excellence IST-2-511616-NOE (PHOREMOST), CICyT NAN2004-08843-C05, MAT2006-09062, the Spanish MEC Consolider-QOIT CSD2006-0019 and the Comunidad de Madrid S-0505/ESP-0200.Peer reviewe