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A cross-sectional study was conducted to assess the circulation and risk factors associated with West Nile virus (WNV) exposure in equine and wild bird populations following the largest epidemic outbreak ever reported in Spain. A total of 305 equids and 171 wild birds were sampled between November 2020 and June 2021. IgG antibodies against flaviviruses were detected by blocking enzyme-linked immunosorbent assay (bELISA) in 44.9% (109/243) and 87.1% (54/62) of unvaccinated and vaccinated equids, respectively. The individual seroprevalence in unvaccinated individuals (calculated on animals seropositive by both bELISA and virus microneutralization test [VNT]) was 38.3% (95%CI: 33.1-43.4). No IgM antibodies were detected in animals tested (0/243; 0.0%; 95%CI: 0.0-1.5) by capture-ELISA. The main risk factors associated with WNV exposure in equids were age (adult and geriatric), breed (crossbred) and the absence of a disinsection programme on the facilities. In wild birds, IgG antibodies against flaviviruses were found in 32.7% (56/171; 95%CI: 26.8-38.6) using bELISA, giving an individual WNV seroprevalence of 19.3% (95%CI: 14.3-24.3) after VNT. Seropositivity was found in 37.8% of the 37 species analysed. Species group (raptors), age (1-year old) and size (large) were the main risk factors related to WNV seropositivity in wild birds. Our results indicate high exposure and widespread distribution of WNV in equid and wild bird populations in Spain after the epidemic outbreak in 2020. The present study highlights the need to continue and improve active surveillance programmes for the detection of WNV in Spain, particularly in those areas at greatest risk of virus circulation.

Background Identifying pig farms infected with hepatitis E virus (HEV) is a key aspect to implement surveillance programmes for this emerging zoonotic agent. Detection of HEV in blood has several drawbacks, including animal handling, economic costs and animal stress. The objective of this study was to evaluate the effectiveness of a non-invasive screening approach for determining the HEV status of pig farms under different management systems. Methods Forty stool samples randomly collected from the pen floor of 17 intensive pig farms and the yard of nine extensive ones were tested for HEV RNA. The invasive method used to confirm the HEV status of the farm was HEV RNA analysis of serum samples randomly collected from 40 animals on each farm. Results Twenty-one HEV-positive farms were detected by invasive and non-invasive methods. No positive serum or stool samples were detected on five intensive farms. A high intertest agreement (K=1; P Conclusion This non-invasive screening approach could be reliably applied in a large-scale surveillance programme for determining the HEV status of pig farms under different management systems.

Pigs are considered important reservoirs of HEV and so constitute a major risk of transmission to humans, either via direct contact or by consuming raw or undercooked contaminated pork products. Once the scale of this disease on European pig farms has been estimated, the identification of risk factors associated with HEV infection in these species could help determine contingency strategies to minimize the risk of transmission to humans. Our objective was to evaluate risk factors associated with HEV in pigs under different production systems. We included 1040 pigs from 26 farms. The prevalence of HEV infection in the study population, evaluated by RT-qPCR, was calculated, then studied according to animal and farm characteristics. Factors associated with HEV infection were analyzed by multivariate analysis. One hundred and seventy-two pigs were infected by HEV, which gave an individual prevalence of 16.5% (95% CI: 14.4%–18.9%). Factors associated with higher prevalence of HEV infection were: extensive farming [23.9%; OR = 2.239 (1.036–4.837)], absence of sanitary ford [33.8%; OR = 3.597 (1.649–7.850)], no quarantine period [20.8%; OR = 2.723 (1.450–5.112)], and contact with domestic species [24.5%; OR = 3.893 (1.453–10.431)]. Our evidence showed that pigs reared on extensive farms are at a higher risk of HEV infection than those reared intensively. The use of control measures could reduce the risk of HEV infection in pigs and minimize the risk of zoonotic transmission.

West Nile virus (WNV) is recognized as an emerging zoonotic pathogen, whose incidence in horses, humans and birds has increased significantly in different European countries in the last decade. A serosurvey study was carried out in non vaccinated horses to determine the geographical distribution of WNV in Andalusia (Southern Spain), and to assess the factors that influence the risk of WNV infection in horses. Antibodies to WNV were detected in 54 out of 510 horses analyzed by a blocking ELISA, of which 36 were confirmed by micro virus neutralization test (7.1%; CI(95%): 4.9-9.3). A total of 28 out of the 348 equine herds (8.3%; CI(95%): 5.4-11.2) had at least one seropositive animal. A generalized estimating equations model showed that the main risk factors associated to WNV seroprevalence were: number of horses within the holding (low), transport of the horse within the last six months (Yes) and presence of mosquitoes in the holding (Yes). The results demonstrated that WNV circulation in Andalusia was more widespread than previously reported. Besides, the distribution of WNV infections was not homogeneous as significant differences among provinces were observed. The results show the need to improve the active surveillance in Spain, so that the early detection of WNV circulation allows the establishment control measures such as vaccination and implementation of vector control programs during the risk period.

West Nile virus (WNV) is a mosquito-transmitted flavivirus recognized as an emerging and re-emerging pathogen in different countries. This study describes the monitoring of the first WNV epidemic in Spain between 2010 and 2011. Between September and December 2010, 36 outbreaks of WNV in horses were reported in three different provinces of Andalusia (southern Spain), with no apparent spread outside this area. The temporal distribution and the clinical signs observed during the WNV epidemic in Spain were, in general, similar to those reported in Europe and in the Mediterranean Basin. Morbidity, mortality and fatality rate in the affected herds were 4.6, 1.4 and 35.3%, respectively. Thirty-six of 75 (47.4%) suspected herds investigated presented at least one IgM seropositive animal. The individual seroprevalence in unvaccinated animals from the infected holdings was 51.7%. RNA WNV lineage 1 virus was confirmed from blood and cerebrospinal fluid samples in a lethally infected horse. The entomological survey showed that the most abundant mosquito species detected in the affected area was Culex pipiens. A cross-sectional study was carried out in non-suspected herds between April 2010 and February 2011 in the affected area. The individual seroprevalence was 11.0%, and six of the 38 herds sampled (15.8%) presented at least one seropositive animal. The results showed active WNV circulation several months before the first outbreak was reported in horses. The seropositivity found in municipalities where clinical cases were not reported indicates a higher geographical dissemination of the virus. Significantly higher seroprevalences were detected in areas close to Morocco. Furthermore, 90 wild ruminants were tested for the presence of antibodies against WNV, but the results were all negative.