Spatial and temporal dynamics of West Nile virus between Africa and Europe
Giulia Mencattelli,
Marie Henriette Dior Ndione,
Andrea Silverj
et al.
Abstract:It is unclear whether West Nile virus (WNV) circulates between Africa and Europe, despite numerous studies supporting an African origin and high transmission in Europe. We integrated genomic data with geographic observations and phylogenetic and phylogeographic inferences to uncover the spatial and temporal viral dynamics of WNV between these two continents. We focused our analysis towards WNV lineages 1 (L1) and 2 (L2), the most spatially widespread and pathogenic WNV lineages. Our study shows a Northern-West… Show more
“…The same lineage was identified in mosquitoes and animals [ 17 ]. This lineage was reported in Sub-Saharan Africa and Madagascar, before spreading to Europe, and no genetic flow in the opposite direction was reported [ 4 ]. Currently, in Italy, the circulation of both Lineage 1 and 2 has been documented [ 17 ].…”
Section: Discussionmentioning
confidence: 97%
“…Currently, Europe has no specific surveillance programs to monitor seroprevalence, and testing is only indicated on clinical suspicion of infection [12]. However, the identification of WNV in animals (i.e., mosquitoes, horses, and birds) requires public health measures to prevent human-to-human transmission through contaminated blood donations [4]. According to the EU Blood Safety Directive, a negative individual donor nucleic acid test, or 28 days of deferral from donation, is required if the donor has returned from areas in which human cases of WNV infection have been detected [13].…”
Section: Introductionmentioning
confidence: 99%
“…Environmental factors have been considered as potential regulators of the annual incidence rate; in fact, increased temperatures shorten the replication cycle of vectors, and feeding increases accordingly (accompanied by increased biting frequency) [ 3 ]. Symptomatic disease is more common in horses than in humans, and the neuroinvasive form has a mortality rate of 33% [ 4 ]. Human cases are thought to be the tip of the iceberg since most are asymptomatic, and full recovery is usual [ 5 , 6 ].…”
Section: Introductionmentioning
confidence: 99%
“…At least nine lineages of WNV have been described worldwide, with Lineages 1 (L1) and 2 (L2) being the most prevalent in Europe [ 10 ]. WNV L1 was first introduced from Northern–Western African countries to Italy and France in 1988 and 2000, respectively, while WNV L2 was identified in Hungary in 2004 [ 4 ]; since 2008, it has spread across central Europe and the eastern Mediterranean region, becoming more virulent in vertebrates [ 11 ].…”
West Nile virus (WNV) is a public health concern in Europe. Rising temperatures and the migration of potential vectors promote the spread of viruses to previously unaffected areas. In 2023, the Apulia region of Southern Italy experienced an unexpected increase in West Nile neuroinvasive disease (WNND); no such cases had been reported in the previous 10 years. Overall, eight autochthonous cases of WNV infection were identified between July and October 2023, six of which were WNND. All cases were male (median age, 73 years). Two of the cases were blood donors. All WNND cases were hospitalized and all recovered within a few weeks. Surveillance data showed that, in the Apulia region, WNV Lineage 2 was detected in humans, mosquitoes, and horses. Based on the number of WNND cases reported, we can assume that a high number of infections occurred during the summer period. Changes in the climate in the region over recent years could be considered among the main drivers of the rapid increase in WNV infections. Therefore, integrated surveillance should be strengthened to avoid the potential massive spread of WNV in Southern Italy. Moreover, the implementation of whole-genome sequencing of WNV strains, as well as seroepidemiological studies in the area, will facilitate a better understanding of circulation dynamics.
“…The same lineage was identified in mosquitoes and animals [ 17 ]. This lineage was reported in Sub-Saharan Africa and Madagascar, before spreading to Europe, and no genetic flow in the opposite direction was reported [ 4 ]. Currently, in Italy, the circulation of both Lineage 1 and 2 has been documented [ 17 ].…”
Section: Discussionmentioning
confidence: 97%
“…Currently, Europe has no specific surveillance programs to monitor seroprevalence, and testing is only indicated on clinical suspicion of infection [12]. However, the identification of WNV in animals (i.e., mosquitoes, horses, and birds) requires public health measures to prevent human-to-human transmission through contaminated blood donations [4]. According to the EU Blood Safety Directive, a negative individual donor nucleic acid test, or 28 days of deferral from donation, is required if the donor has returned from areas in which human cases of WNV infection have been detected [13].…”
Section: Introductionmentioning
confidence: 99%
“…Environmental factors have been considered as potential regulators of the annual incidence rate; in fact, increased temperatures shorten the replication cycle of vectors, and feeding increases accordingly (accompanied by increased biting frequency) [ 3 ]. Symptomatic disease is more common in horses than in humans, and the neuroinvasive form has a mortality rate of 33% [ 4 ]. Human cases are thought to be the tip of the iceberg since most are asymptomatic, and full recovery is usual [ 5 , 6 ].…”
Section: Introductionmentioning
confidence: 99%
“…At least nine lineages of WNV have been described worldwide, with Lineages 1 (L1) and 2 (L2) being the most prevalent in Europe [ 10 ]. WNV L1 was first introduced from Northern–Western African countries to Italy and France in 1988 and 2000, respectively, while WNV L2 was identified in Hungary in 2004 [ 4 ]; since 2008, it has spread across central Europe and the eastern Mediterranean region, becoming more virulent in vertebrates [ 11 ].…”
West Nile virus (WNV) is a public health concern in Europe. Rising temperatures and the migration of potential vectors promote the spread of viruses to previously unaffected areas. In 2023, the Apulia region of Southern Italy experienced an unexpected increase in West Nile neuroinvasive disease (WNND); no such cases had been reported in the previous 10 years. Overall, eight autochthonous cases of WNV infection were identified between July and October 2023, six of which were WNND. All cases were male (median age, 73 years). Two of the cases were blood donors. All WNND cases were hospitalized and all recovered within a few weeks. Surveillance data showed that, in the Apulia region, WNV Lineage 2 was detected in humans, mosquitoes, and horses. Based on the number of WNND cases reported, we can assume that a high number of infections occurred during the summer period. Changes in the climate in the region over recent years could be considered among the main drivers of the rapid increase in WNV infections. Therefore, integrated surveillance should be strengthened to avoid the potential massive spread of WNV in Southern Italy. Moreover, the implementation of whole-genome sequencing of WNV strains, as well as seroepidemiological studies in the area, will facilitate a better understanding of circulation dynamics.
“…Birds can indirectly spread pathogens via feces, by contaminating water, and by carrying ticks, etc. [ 15 , 16 , 17 , 18 , 19 ]. As a typical zoonotic bacterial pathogen, Campylobacter is widely detected and researched in wild and domestic animals, particularly poultry and livestock, such as chicken, pigs, cattle, sheep, and the corresponding food products [ 20 , 21 , 22 , 23 ].…”
Campylobacter species, especially C. jejuni and C. coli, are the main zoonotic bacteria causing human gastroenteritis. A variety of Campylobacter species has been reported in wild birds, posing a potential avian–human transmission pathway. Currently, there has been little surveillance data on Campylobacter carriage in migratory birds in China. In the current work, fresh fecal droppings from individual migratory birds were collected at four bird wintering/stopover sites in China from May 2020 to March 2021. Nucleic acid was extracted and tested for Campylobacter with PCR-based methods. Overall, 73.8% (329/446) of the samples were positive for Campylobacter, demonstrating location and bird host specificity. Further speciation revealed the presence of C. jejuni, C. coli, C. lari, C. volucris, and an uncharacterized species, which all harbored a variety of virulence factors. Phylogenetic analysis performed on concatenated 16S rRNA-atpA-groEL genes elucidated their genetic relationship, demonstrating both inter- and intra-species diversity. The wide distribution and high diversity of Campylobacter spp. detected in migratory birds in China indicated potential transmission across territories. The existence of virulence factors in all of these species highlighted their public health importance and the necessity of monitoring and controlling Campylobacter and other pathogens carried by migratory birds.
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