Transmission Dynamics of the West Nile Virus in Mosquito Vector Populations under the Influence of Weather Factors in the Danube Delta, Romania

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.

Letea Virus: Comparative Genomics and Phylogenetic Analysis of a Novel Reassortant Orbivirus Discovered in Grass Snakes (Natrix natrix)

“…The associations between some viruses and more than one vector family could be the result of "species jumps" permitted by fast evolution characteristic of RNA segmented viruses. Such occurrences in members of the Orbivirus genus would not necessarily run counter to the "coevolution" hypothesis [11,14,43,86], but possibly complement it.…”

“…As one of Europe's largest wetlands, the Danube Delta Biosphere Reserve (DDBR) located in the southeast of Romania, is a very biodiverse and heterogeneous complex of ecosystems [10]. The region is a major hub for bird migration along main African-Eurasian fly corridors, with ecoclimatic conditions suitable for abundant and diverse populations of arthropod vectors [11][12][13][14], which may allow pathogen import and maintenance [15][16][17][18].…”

The utility of LASSO-based models for real time forecasts of endemic infectious diseases: A cross country comparison

“…A further limitation is that, for simplicity, only weather information from the capitals were used in the study, but for countries like Japan, Thailand and Taiwan, there are great variation between climatic conditions in the North and the South. Prediction accuracy might improve if [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] incidence and weather information can be collected at a finer resolution. We suspect that even the accuracy of short term forecasts may be reduced should new epidemiological conditions replace those that the model was trained on.…”

“…Existing approaches to real-time forecasting include generalized linear regression, seasonal autoregressive integrated moving average (SARIMA) model or a simpler ARIMA form of it, phenomenological models like the logistic growth model and Richards model, and mechanistic models like the SIR models [19][20][21][22][23][24]. Often such approaches involve the challenge of integrating environmental factors including temperature, humidity and rainfall, which may influence pathogen transmission directly or affect the vector activities (for vector borne diseases), especially in temperate regions [25][26][27][28][29]. For instance, influenza virus is more transmissible in low temperature and low humidity conditions [30,31], while the primary vector of dengue, the yellow fever mosquito Aedes aegypti, favors higher temperature [32,33].…”

An updated checklist of the Culicidae (Diptera) of Morocco, with notes on species of historical and current medical importance

“…Culex modestus is considered to be highly susceptible to infection of West Nile virus (Hannoun et al 1964, Mouchet et al 1970, Hubálek 2000, Bodker et al 2014, Vaux et al 2015, Cotar et al 2016. This species has also been found to carry Japanese encephalitis virus in China (Anonymous 1980) and avian Plasmodium species in southern Spain (Ferraguti et al 2013).…”