Predicting the spatio-temporal spread of West Nile virus in Europe

West Nile virus is a widely spread arthropod-born virus, which has mosquitoes as vectors and birds as reservoirs. Humans, as dead-end hosts of the virus, may suffer West Nile Fever (WNF), which sometimes leads to death. In Europe, the first large-scale epidemic of WNF occurred in 1996 in Romania. Since then, human cases have increased in the continent, where the highest number of cases occurred in 2018. Using the location of WNF cases in 2017 and favorability models, we developed two risk models, one environmental and the other spatio-environmental, and tested their capacity to predict in 2018: 1) the location of WNF; 2) the intensity of the outbreaks (i.e. the number of confirmed human cases); and 3) the imminence of the cases (i.e. the Julian week in which the first case occurred). We found that climatic variables (the maximum temperature of the warmest month and the annual temperature range), human-related variables (rain-fed agriculture, the density of poultry and horses), and topo-hydrographic variables (the presence of rivers and altitude) were the best environmental predictors of WNF outbreaks in Europe. The spatio-environmental model was the most useful in predicting the location of WNF outbreaks, which suggests that a spatial structure, probably related to bird migration routes, has a role in the geographical pattern of WNF in Europe. Both the intensity of cases and their imminence were best predicted using the environmental model, suggesting that these features of the disease are linked to the environmental characteristics of the areas. We highlight the relevance of river basins in the propagation dynamics of the disease, as outbreaks started in the lower parts of the river basins, from where WNF spread towards the upper parts. Therefore, river basins should be considered as operational geographic units for the public health management of the disease.

Download Full-text

Spatiotemporal Analysis of West Nile Virus Epidemic in South Banat District, Serbia, 2017–2019

Animals ◽

10.3390/ani11102951 ◽

2021 ◽

Vol 11 (10) ◽

pp. 2951

Author(s):

Sonja Radojicic ◽

Aleksandar Zivulj ◽

Tamas Petrovic ◽

Jakov Nisavic ◽

Vesna Milicevic ◽

...

Keyword(s):

West Nile Virus ◽

Negative Binomial ◽

Climatic Factors ◽

The United States ◽

Wild Birds ◽

Water Levels ◽

Maximum Temperature ◽

Negative Binomial Regression Model ◽

West Nile Fever ◽

West Nile

West Nile virus (WNV) is an arthropod-born pathogen, which is transmitted from wild birds through mosquitoes to humans and animals. At the end of the 20th century, the first West Nile fever (WNF) outbreaks among humans in urban environments in Eastern Europe and the United States were reported. The disease continued to spread to other parts of the continents. In Serbia, the largest number of WNV-infected people was recorded in 2018. This research used spatial statistics to identify clusters of WNV infection in humans and animals in South Banat County, Serbia. The occurrence of WNV infection and risk factors were analyzed using a negative binomial regression model. Our research indicated that climatic factors were the main determinant of WNV distribution and were predictors of endemicity. Precipitation and water levels of rivers had an important influence on mosquito abundance and affected the habitats of wild birds, which are important for maintaining the virus in nature. We found that the maximum temperature of the warmest part of the year and the annual temperature range; and hydrographic variables, e.g., the presence of rivers and water streams were the best environmental predictors of WNF outbreaks in South Banat County.

Download Full-text

West Nile Virus in Slovenia

Viruses ◽

10.3390/v12070720 ◽

2020 ◽

Vol 12 (7) ◽

pp. 720

Author(s):

Nataša Knap ◽

Miša Korva ◽

Vladimir Ivović ◽

Katja Kalan ◽

Mateja Jelovšek ◽

...

Keyword(s):

West Nile Virus ◽

Urine Sample ◽

Whole Genome ◽

Igg Antibodies ◽

West Nile Fever ◽

West Nile ◽

The North ◽

Neuroinvasive Disease ◽

First Case ◽

Dead End

West Nile virus (WNV) is a flavivirus transmitted by mosquitoes. Birds are the reservoir for the virus; humans, horses and other mammals are dead-end hosts. Infections caused by WNV in humans can vary from asymptomatic infections to West Nile fever (WNF) or West Nile neuroinvasive disease (WNND). In 1995, a serosurvey was performed in Slovenia on forest workers, and WNV specific IgG antibodies were confirmed in 6.8% of the screened samples, indicating that WNV is circulating in Slovenia. No human disease cases were detected in Slovenia until 2013, when the first case of WNV infection was confirmed in a retrospective study in a 79-year old man with meningitis. In 2018, three patients with WNND were confirmed by laboratory tests, with detection of IgM antibodies in the cerebrospinal fluid of the patients. In one of the patients, WNV RNA was detected in the urine sample. In 2017, 2018 and 2019, a mosquito study was performed in Slovenia. Mosquitoes were sampled on 14 control locations and 35 additional locations in 2019. No WNV was detected in mosquitoes in 2017 and 2019, but we confirmed the virus in a pool of Culex sp. mosquitoes in 2018. The virus was successfully isolated, and complete genome sequence was acquired. The whole genome of the WNV was also sequenced from the patient’s urine sample. The whole genome sequences of the WNV virus detected in Slovenian patient and mosquito indicate the virus most likely spread from the north, because of the geographic proximity and because the sequences cluster with the Austrian and Hungarian sequences. A sentinel study was performed on dog sera samples, and we were able to confirm IgG antibodies in 1.8% and 4.3% of the samples in 2017 and 2018, respectively. Though Slovenia is not a highly endemic country for WNV, we have established that the virus circulates in Slovenia.

Download Full-text

Environmental Predictors of Human West Nile Virus Infections, Colorado

Emerging Infectious Diseases ◽

10.3201/eid1311.070506 ◽

2007 ◽

Vol 13 (11) ◽

pp. 1788-1790 ◽

Cited By ~ 20

Author(s):

Jennifer L. Patnaik ◽

Lara Juliusson ◽

Richard L. Vogt

Keyword(s):

West Nile Virus ◽

Virus Infections ◽

Environmental Predictors ◽

West Nile ◽

Human West Nile Virus

Download Full-text

Increase in human West Nile and Usutu virus infections, Austria, 2018

Eurosurveillance ◽

10.2807/1560-7917.es.2018.23.43.1800545 ◽

2018 ◽

Vol 23 (43) ◽

Cited By ~ 40

Author(s):

Stephan W. Aberle ◽

Jolanta Kolodziejek ◽

Christof Jungbauer ◽

Karin Stiasny ◽

Judith H. Aberle ◽

...

Keyword(s):

West Nile Virus ◽

Blood Donors ◽

Blood Donation ◽

Virus Infections ◽

West Nile Fever ◽

West Nile ◽

Usutu Virus ◽

Neuroinvasive Disease ◽

Human West Nile Virus ◽

Imported Cases

Between 28 June and 17 September 2018, 27 cases of human West Nile virus infections were recorded in Austria; four cases of West Nile neuroinvasive disease, 11 cases of West Nile fever, six infections detected by blood donation screening and six imported cases. In addition, 18 cases of human Usutu virus infections (all blood donors) were recorded. This is the highest number of annual infections recorded in Austria since the introduction of both viruses.

Download Full-text

Artificial Intelligence Predicts and Explains West Nile Virus Risks Across Europe: Extraordinary Outbreaks Determined by Climate and Local Factors

10.1101/2020.07.24.20146829 ◽

2020 ◽

Author(s):

Albert A Gayle

Keyword(s):

West Nile Virus ◽

Large Scale ◽

Predictive Accuracy ◽

Local Effect ◽

Research Literature ◽

West Nile ◽

Priority Direction ◽

Minimal Data ◽

Novel Method ◽

Using Data

Year-to-year emergence of West Nile virus has been sporadic and notoriously hard to predict. In Europe, 2018 saw a dramatic increase in the number of cases and locations affected. In this work, we demonstrate a novel method for predicting outbreaks and understanding what drives them. This method creates a simple model for each region that directly explains how each variable affects risk. Behind the scenes, each local explanation model is produced by a state-of-the-art AI engine. This engine unpacks and restructures output from an XGBoost machine learning ensemble. XGBoost, well-known for its predictive accuracy, has always been considered a "black box" system. Not any more. With only minimal data curation and no "tuning", our model predicted where the 2018 outbreak would occur with an AUC of 97%. This model was trained using data from 2010-2016 that reflected many domains of knowledge. Climate, sociodemographic, economic, and biodiversity data were all included. Our model furthermore explained the specific drivers of the 2018 outbreak for each affected region. These effect predictions were found to be consistent with the research literature in terms of priority, direction, magnitude, and size of effect. Aggregation and statistical analysis of local effects revealed strong cross-scale interactions. From this, we concluded that the 2018 outbreak was driven by large-scale climatic anomalies enhancing the local effect of mosquito vectors. We also identified substantial areas across Europe at risk for sudden outbreak, similar to that experienced in 2018. Taken as a whole, these findings highlight the role of climate in the emergence and transmission of West Nile virus. Furthermore, they demonstrate the crucial role that the emerging "eXplainable AI" (XAI) paradigm will have in predicting and controlling disease.

Download Full-text

Human cases of West Nile Virus Infection in north-eastern Italy, 15 June to 15 November 2010

Eurosurveillance ◽

10.2807/ese.16.33.19949-en ◽

2011 ◽

Vol 16 (33) ◽

Author(s):

L Barzon ◽

M Pacenti ◽

R Cusinato ◽

M Cattai ◽

E Franchin ◽

...

Keyword(s):

West Nile Virus ◽

West Nile Virus Infection ◽

West Nile Fever ◽

Antibody Prevalence ◽

Igg Antibody ◽

West Nile ◽

The Third ◽

Neuroinvasive Disease ◽

Northern Areas ◽

North Eastern

In 2010, for the third consecutive year, human cases of West Nile virus (WNV) infection, including three confirmed cases of neuroinvasive disease and three confirmed cases of West Nile fever, were identified in north-eastern Italy. While in 2008 and 2009 all human cases of WNV disease were recorded in the south of the Veneto region, cases of WNV disease in 2010 additionally occurred in two relatively small northern areas of Veneto, located outside those with WNV circulation in the previous years. WNV IgG antibody prevalence in blood donors resident in Veneto was estimated as ranging from 3.2 per 1,000 in areas not affected by cases of WNV disease to 33.3 per 1,000 in a highly affected area of the Rovigo province. No further autochthonous human cases of WNV disease were notified in Italy in 2010. The recurrence of human cases of WNV infection for the third consecutive year strongly suggests WNV has become endemic in north-eastern Italy.

Download Full-text

WEST NILE FEVER IN THE SARATOV REGION IN 2013-2015

Voprosy Virusologii ◽

10.18821/0507-4088-2017-62-5-219-226 ◽

2017 ◽

Vol 62 (5) ◽

pp. 219-226

Author(s):

E. V. Kazorina ◽

T. Yu. Krasovskaya ◽

A. V. Kazantsev ◽

E. V. Naydenova ◽

I. N. Sharova ◽

...

Keyword(s):

West Nile Virus ◽

Clinical Samples ◽

West Nile Fever ◽

West Nile ◽

Saratov Region ◽

Stable Domain ◽

Field Samples ◽

Live Stock ◽

Regional Population ◽

The City

West Nile virus (WNV) circulation in the territory of Saratov region and its role in the infectious pathology were investigated. For this purpose, in studies conducted in 2013-2015, suspensions of bloodsucking arthropods, organs of birds and small mammals were analyzed for the presence of WNV markers (antigens and/or RNA). The seroprevalence level in live-stock animals and population of the region was evaluated; clinical samples from patients with symptoms compatible with West Nile fever (WNF) were analyzed. As a result of the investigations, WNV markers were detected in field samples gathered in natural biotopes and in the city of Saratov. Immunity to WNV was detected in horses. A stable domain of persons with immunity to this agent was revealed among regional population. Patients with WNF have been annually registered in the region since 2012. The obtained results confirm active circulation of WNF in the Saratov region, as well as formation of stable natural and anthropourgic foci.

Download Full-text

Vectorial Competence Potential of Culex Quinquefasciatus (Say, 1923) from the Amazon Region to Transmit West Nile Virus Isolated in Brazil

10.21203/rs.3.rs-603135/v1 ◽

2021 ◽

Author(s):

Lúcia Aline Moura Reis ◽

Eliana Vieira Pinto da Silva ◽

Maria Nazaré Oliveira Freitas ◽

Rossela Damasceno Caldeira ◽

Pedro Arthur da Silva Araújo ◽

...

Keyword(s):

West Nile Virus ◽

Culex Quinquefasciatus ◽

Transmission Rate ◽

Amazon Region ◽

West Nile Fever ◽

West Nile ◽

Potential Vector ◽

Brazilian Strain ◽

Vectorial Competence ◽

Viral Titers

Abstract The West Nile virus is characterized as a neurotropic pathogen that causes the West Nile fever. It is transmitted by mosquitoes, mainly of the Culex genus. In 2018, the Evandro Chagas Institute carried out the first isolation of WNV strain from a horse brain sample and in 2021 the same institute also isolated the WNV in a pool of mosquitoes of the Culex spp. from the Carajás region (Pará). Thus, this study aimed to determine the vectorial competence of Culex quinquefasciatus from the Amazon region of Brazil for transmission the WNV Brazilian strain. Oral infection of Cx. quinquefasciatus females belonging to F1 generation was performed with infected blood with WNV. Subsequently, analysis of infection, dissemination and transmission rates was performed, as well as verification of viral titers in the samples. The study demonstrated that Cx. quinquefasciatus can act as a potential vector of WNV in Brazil, since it was found that the Brazilian strain was able to overcome the host's anatomical barriers and spread to various regions, among them in saliva, in which, despite the low viral titers identified, it had a transmission rate of 100% on the 21st day after infection.

Download Full-text

Procalcitonin measurement in West Nile virus neuroinvasive disease: a first case series

Official Journal of the Association of Medical Microbiology and Infectious Disease Canada ◽

10.3138/jammi-2020-0046 ◽

2021 ◽

pp. e20200046

Author(s):

Cheyanne Boehm ◽

Christopher Doig ◽

Justin Z Chen ◽

Wendy I Sligl ◽

Sean M Bagshaw ◽

...

Keyword(s):

West Nile Virus ◽

Antimicrobial Therapy ◽

Critically Ill Patients ◽

Bacterial Infections ◽

Viral Infections ◽

Case Series ◽

West Nile ◽

Neuroinvasive Disease ◽

First Case ◽

Low Serum

West Nile virus neuroinvasive disease (WNV-NID) is challenging to diagnose. Procalcitonin (PCT) is a useful diagnostic test to identify bacterial infections. We present four cases of WNV-NID with serum PCT measurements. Methods: Daily (days 1–7) serum PCT (bioMérieux) was examined for critically ill patients with sepsis enrolled in a provincial sepsis study. Patients with identified WNV-NID are descriptively analyzed in this case series. PCT values of ≥0.5 ng/mL were suggestive of bacterial infection. Results: Four patients with WNV-NID were identified. Those with viral infections alone had consistently low PCT values ranging from 0.09 ng/mL to 0.34 ng/mL. Those with documented bacterial co-infections had initially elevated PCT levels that decreased by more than 50% with antimicrobial therapy. Conclusion: These cases are the first to report serial PCT measurements in confirmed cases of WNV-NID and support a low serum PCT in WNV-NID.

Download Full-text