No abstract

Mosquitoes were collected in the Danube Delta during the active seasons of 2011-2013. For Culex spp. mosquitoes, the abundance was calculated. Culex pipiens (sensu lato), (s.l.) and Culex modestus pools were tested for the presence of West Nile virus (WNV) genome, and the maximum likelihood of the infection rate was established. Mean daily temperatures and precipitation were obtained for the closest meteorological station. A negative binominal model was used to evaluate linkages between the temperature/precipitation and mosquito population size. A zero-inflated negative binomial model was used to test the relationship between the temperature and the infection rate. A single complex model for infection rate prediction was also used. The linkages were calculated for lag 0 and for 10 days earlier (lag 1), 20 days earlier (lag 2), and 30 days earlier (lag 3). Significant positive linkages (P < 0.001) were detected between temperature and mosquito population size for lag 1, lag 2, and lag 3. The linkages between temperature and infection rates were positive and significant for lag 2 and lag 3. Negative significant (P < 0.001) results were detected between precipitation and infection rates for lags 1, 2, and 3. The complex model showed that the best predictors for infection rate are the temperature, 20 days earlier (positive linkage) and the precipitation, 30 days earlier (negative linkage). Positive temperature anomalies in spring and summer and rainfall decrease contributed to the increase in the Culex spp. abundance and accelerated the WNV amplification in mosquito vector populations in the following weeks.

BackgroundThere is a growing concern that global climate change will affect the potential for pathogen transmission by insect species that are vectors of human diseases. One of these species is the former European malaria vector, Anopheles atroparvus. Levels of population differentiation of An. atroparvus from southern Europe were characterized as a first attempt to elucidate patterns of population structure of this former malaria vector. Results are discussed in light of a hypothetical situation of re-establishment of malaria transmission.MethodsGenetic and phenotypic variation was analysed in nine mosquito samples collected from five European countries, using eight microsatellite loci and geometric morphometrics on 21 wing landmarks.ResultsLevels of genetic diversity were comparable to those reported for tropical malaria vectors. Low levels of genetic (0.004

Lineage 2 West Nile virus (WNV), previously found only in sub-Saharan Africa and Madagascar, was identified in Hungary in 2004 and has rapidly expanded in Europe in the past decade. Following a significant outbreak of West Nile fever with neurological cases caused by lineage 1 WNV in Romania in 1996, scattered cases have been recorded in the south-east of the country in each transmission season. Another outbreak, affecting a larger area and caused by lineage 2 WNV, was recorded in 2010. We analysed human sera from neuroinvasive West Nile fever cases and mosquitoes, sampled in south-eastern Romania between 2011 and 2013, for the presence of WNV genome, and obtained partial NS5 and envelope glycoprotein sequences. Human- and mosquito-derived WNV sequences were highly similar (99%) to Volgograd 2007 lineage 2 WNV and differed from isolates previously detected in central and southern Europe. WNV was detected in one pool of Culex pipiens s.l. males, documenting vertical transmission. Lineage 4 WNV, of unknown pathogenicity to mammals, was found in the amphibian-feeding mosquito Uranotaenia unguiculata from the Danube Delta. Our results present molecular evidence for the maintenance of the same isolates of Volgograd 2007-like lineage 2 WNV in south-eastern Romania between 2011 and 2013.

During an entomological investigation carried out in Bucharest and surroundings in fall of 2012, 45 adult mosquitoes (38 females and 7 males) of Aedes albopictus were collected in a neighborhood from the southern area of the city. The morphological identification of the species was further confirmed by sequencing 2 mitochondrial DNA markers: the cytochrome c oxidase subunit I and NADH dehydrogenase subunit 5 genes. Aedes albopictus was collected again in 2013 in the same area from July until October. During late summer the species was found also in another location in the city, downtown Bucharest. Larvae were found in water barrels and other types of household containers, as well as in rain catch basins. In 2014, following a nuisance complaint of a Bucharest inhabitant, the entomological investigation found aggressive Ae. albopictus adults on his property that harbored many mosquito larvae in container-type breeding habitats. These findings are the 1st records of this invasive species and of its breeding population in Romania, and show maintenance of the species over 2 winter seasons. Surveillance of the species outside the area of the capital city was not performed, therefore it is not known whether Ae. albopictus has been introduced in other regions of the country. The presence of Ae. albopictus has been reported every year (2012-14) to competent public health authorities, stressing on the importance of surveillance and of implementation of control measures.