West Nile virus in horses during the summer and autumn seasons of 2015 and 2016, Portugal.

West Nile fever (WNF) is an emergent disease in Europe, under surveillance in the European Union. Following a 5-year period of apparent silence (autumn 2010 to summer 2015), West Nile virus (WNV) reemerged in the South of Portugal, in July 2015. Here we present data from the onset, geographic location within mainland Portugal, and outcome of clinical cases of WNV infection in horses in 2015 and 2016. During the transmission seasons of 2015 and 2016, twenty-seven horses, most symptomatic (n=20) were found positive to IgM, pr-E immunoglobulins and VNT, leading to the subsequent report to Animal Disease Notification System of the European Commission (ADNS) by the Portuguese National Authority for Animal Health. Outbreaks occurred in the middle summer (August) and early/mid autumn (October/November) of 2015 and 2016, in the southern regions of the country (Alentejo and Algarve). Compared with the previous WNV transmission seasons of 2004 and 2010, a higher number of cases were reported in 2015 and 2016. The results of our study contribute to increase information concerning the geographic areas affected and time period for WNV transmission risk in Portugal.

Spatial and temporal distribution of Culicoides species in mainland Portugal (2005-2010). Results of the Portuguese Entomological Surveillance Programme.

Bluetongue virus (BTV) is transmitted by Culicoides biting midges and causes an infectious, non-contagious disease of ruminants. It has been rapidly emerging in southern Europe since 1998. In mainland Portugal, strains of BTV belonging to three serotypes have been detected: BTV-10 (1956-1960), BTV-4 (2004-2006 and 2013) and BTV-1 (2007-2012). This paper describes the design, implementation and results of the Entomological Surveillance Programme covering mainland Portugal, between 2005 and 2010, including 5,650 caches. Culicoides imicola Kieffer was mostly found in central and southern regions of Portugal, although it was sporadically detected in northern latitudes. Its peak activity occurred in the autumn and it was active during the winter months in limited areas of the country. Obsoletus group was present at the highest densities in the north although they were found throughout the country in substantial numbers. Culicoides activity occurred all year round but peaked in the spring. A generalized linear mixed model was developed for the analysis of the environmental factors associated with activity of the species of Culicoides suspected vectors of BTV in the country. For C. imicola Kieffer, the most important variables were month, diurnal temperature range (DTR), the number of frost days (FRS) and median monthly temperature (TMP). For the Obsoletus group, the most important factors were month, diurnal temperature range (DTR), and linear and quadratic terms for median monthly temperature (TMP). The results reported can improve our understanding of climatic factors in Culicoides activity influencing their distribution and seasonal pattern.