The spatiotemporal dynamics of Crimean-Congo haemorrhagic fever virus in enzootic Iberian scenarios

Resumen del trabajo presentado a la Joint Virtual Conference of the WDA and EWDA, celebrada del 31 de agosto al 2 de septiembre de 2021.Peer reviewe

The spatiotemporal dynamics of exposure of wild ungulates to Flavivirus shapes the patterns of West Nile virus outbreaks in Spain

Resumen del póster presentado a la Joint Virtual Conference of the WDA and EWDA, celebrada del 31 de agosto al 2 de septiembre de 2021.West Nile virus (WNV) is a neuropathic virus for humans, horses and birds transmitted by mosquitoes. The recent increase of clinical cases in Spain shows the need to better understand the ecology of this Flavivirus, not only in urban areas, but also where birds, WNV and mosquitoes interact with wild ungulates, to better predict/prevent WNV outbreaks. We analysed the dynamics of exposure of wild ungulates to Flavivirus along 15 years (2005-2019) in a south-to-north gradient in 5 areas where WNV cases occur since 2007. Sera of 2,418 wild ungulates (Cervus elaphus &Sus scrofa) from Doñana National Park (A1), Western Sierra Morena (A2), Central Sierra Morena (A3), Guadiana river Valley (A4) and Toledo Mounts (A5) were analysed with a blocking ELISA highly specific for WNV. Weather conditions were gathered from two climatically and environmentally contrasting areas: i) A1, a thermo-Mediterranean wetland; and ii) A4, a Mediterranean continental forest/shrubland. The risk of Flavivirus exposure of ungulates was modelled with weather covariates (average winter/spring/summer temperatures and annual/winter-spring/spring/summer rainfall) by logistic binary regression. The proportion of exposed ungulates was higher in A1 (33.5%) and A2 (35.3%) than in A3 (18.7%), A4 (20.3%) and A5 (18.7%), shaping the contrasting reported incidence of WNV outbreaks in southern (n=189) and south-central (n=2) Spain. The annual patterns of exposure of ungulates also shaped the temporal emergence of WNV outbreaks. Higher winter temperature associated positively to the risk of exposure in A1 whereas in A4 the risk increased with annual rainfall whereas it decreased with increasing spring precipitation. These preliminary results point out that whereas in wetlands, where water is abundant, smoother winter temperatures better predict WNV circulation, annual rainfall seems to be a better predictor for WNV infection risk in dry continental Mediterranean areas. Wild ungulates additionally prove to be efficient predictors for Flavivirus spatiotemporal dynamics.Peer reviewe

Mapping the risk of exposure to Crimean-Congo haemorrhagic fever virus in the Iberian Peninsula using Eurasian wild boar (Sus scrofa) as a model

Crimean-Congo haemorrhagic fever (CCHF) virus (CCHFV) is a tick-borne zoonotic pathogen that can cause a lethal haemorrhagic disease in humans. Although the virus appears to be endemically established in the Iberian Peninsula, CCHF is an emerging disease in Spain. Clinical signs of CCHFV infection are mainly manifested in humans, but the virus replicates in several animal species. Understanding the determinants of CCHFV exposure risk from animal models is essential to predicting high-risk exposure hotspots for public health action. With this objective in mind, we designed a cross-sectional study of Eurasian wild boar (Sus scrofa) in Spain and Portugal. The study analysed 5,291 sera collected between 2006 and 2022 from 90 wild boar populations with a specific double-antigen ELISA to estimate CCHFV serum prevalence and identify the main determinants of exposure probability. To do so, we statistically modelled exposure risk with host- and environment-related predictors and spatially projected it at a 10 × 10 km square resolution at the scale of the Iberian Peninsula to map foci of infection risk. Fifty-seven (63.3 %) of the 90 populations had at least one seropositive animal, with seroprevalence ranging from 0.0 to 88.2 %. Anti-CCHFV antibodies were found in 1,026 of 5,291 wild boar (19.4 %; 95 % confidence interval: 18.3–20.5 %), with highest exposure rates in southwestern Iberia. The most relevant predictors of virus exposure risk were wild boar abundance, local rainfall regime, shrub cover, winter air temperature and soil temperature variation. The spatial projection of the best-fit model identified high-risk foci as occurring in most of western and southwestern Iberia and identified recently confirmed risk foci in eastern Spain. The results of the study demonstrate that serological surveys of CCHFV vector hosts are a powerful, robust and highly informative tool for public health authorities to take action to prevent human cases of CCHF in enzootic and emergency settings.This study was funded by the regional Government of Castilla-La Mancha (JCCM) and the EU-European Social Fund (ESF) through project SBPLY/19/180501/000321 and by MCIN/AEI/10.13039/501100011033 and the European Regional Development Fund (EU-ERDF) through project CGL2017–89866-R. We also acknowledge funding by MCIN/AEI/10.13039/501100011033 and by the European Union "Next Generation EU"/PRTR Recovery, Transformation and Resilience Plan-Next Generation EU” through the TED2021–132599B-C21/22 project, by EU-ERDF (POPE 2014–2020) project LifeWATCH INDALO-Scientific Infrastructures for Global Change Monitoring and Adaptation in Andalusia (LIFEWATCH-2019–04-AMA-01) and by “Instituto de Salud Carlos III”, MCIN/AEI/10.13039/501100011033 and EU-Next Generation EU funds through “CIBER-Consorcio Centro de Investigación Biomédica en Red (CB 2021/13/00083)”. SB-F and CH acknowledge funding by JCCM and EU-ESF contracts PREJCCM2019/11 and SUPLY/19/180501/000487, respectively. AP-M was funded by the University of Castilla-La Mancha (UCLM) and EU-ERDF through 2019-PREDUCLM-10932 contract whereas RC-M received funding from MCIN, EU-ERDF and UCLM at PRE2018–083801 contract. DJ-M holds a PhD contract granted by the Own Research Plan of the University of Cordoba and SC-S is supported by an FPU grant from the Spanish Ministry of Universities (FPU19/06,026). This study has been partially funded by the Department of Economic Development and Infrastructures of the Basque Government. AC was supported by a ‘Ramón y Cajal’ post-doctoral grant RYC2021–033084-I funded by MCIN/AEI/10.13039/501,100,011,033 and by European Union NextGenerationEU/PRTR. RM is supported by a postdoctoral contract Margarita Salas Reference MS-23 (University of Extremadura) from the Program of Requalification of the Spanish University System (Spanish Ministry of Universities) financed by the European Union-NextGenerationEU.Peer reviewe

The relevance of the wild reservoir in zoonotic multi-host pathogens: The links between Iberian wild mammals and Coxiella burnetii

Q fever is a worldwide zoonosis caused by an obligate intracellular bacterium, Coxiella burnetii, with only anecdotal reports of human-to-human transmission. The cause of human Q fever infections is the circulation of C. burnetii in animal reservoirs. Infected livestock, particularly goats and sheep, may cause Q fever outbreaks in humans. However, wildlife is the origin of several human Q fever cases. Human impacts on habitats, biodiversity and climate are responsible for changes in the patterns of interaction between domestic animals, wildlife and humans, allowing wild animals to play an increasingly relevant role as Q fever reservoirs. In the Iberian Peninsula, human impacts on the environment combined with a high biodiversity, which could maintain high transmission rates of this multi-host pathogen, make wild reservoirs an important piece in Q fever epidemiology. In this study, we review the reporting of C. burnetii infections and exposure in Iberian wild mammals and analyse the link between the diversity of wild mammals and the frequency of C. burnetii notifications in wildlife. For it, the number of wild mammal species per UTM 10 × 10-km grid in mainland Spain and Portugal was estimated as a potential predictor of C. burnetii transmission. The results of non-linear regression analysis showed a quadratic relationship between the number of wild mammal species per grid and the presence of C. burnetii cases reported in the literature both by serology (R2 = 0.86) and polymerase chain reaction (R2 = 0.83). Increasing wild mammal diversity was linked to increasing C. burnetii transmission until an intermediate level when the relationship was inverted. Thus, at high levels of wild mammal diversity, the risk of C. burnetii transmission was lower. These observations show a role of wild mammal biodiversity in C. burnetii ecology that needs to be further explored to better prevent the negative impact of Q fever in livestock and human health in Iberia.We acknowledge partial funding support from the Spanish Ministry for the Science and Innovation (MCI) and the European Social Fund (ESF) through project CGL2017-89866-R. DGB is funded by MCI-ISCIII through ‘Sara Borrell’ (CD19CIII/00011) postdoctoral fellowship. AJC is supported by a ‘Juan de la Cierva’ contract (IJC2020-042629-I) funded by MCIN/AEI/10.13039/501100011033 and by the European Union Next Generation.Peer reviewe

Modelización y proyección de la abundancia de garrapatas de vida libre a pequeña escala espacial

Resumen del trabajo presentado al XV Congreso de la Sociedad Española para la Conservación y Estudio de los Mamífero (SECEM), celebrado en Córdoba del 4 al 7 de diciembre de 2021.Las garrapatas juegan un papel importante en la dinámica de las poblaciones y el éxito reproductivo de los animales de los que se alimentan, ya sea por las enfermedades transmitidas o por la propia infestación en los hospedadores. Debido al papel que éstas desempeñan tanto en salud animal como humana, estudiar los factores que afectan a su distribución y abundancia a diferentes escalas espacio-temporales es de especial interés. El objetivo de este trabajo es conocer qué factores determinan la distribución espacial de las garrapatas de vida libre que pueden participar en el mantenimiento del virus de la fiebre hemorrágica de Crimea-Congo (VFHCC), entre otros patógenos, a una escala espacial pequeña. Para ello, se realizaron 15 transectos lineales de 1200 metros distribuidos espacialmente en Los Quintos de Mora (QM; 6.864 has; Toledo) durante el mes de mayo de 2021 para estimar la abundancia de garrapatas, coincidiendo con el pico de actividad de las principales especies de garrapatas en la zona. Los modelos de abundancia de garrapatas fueron estimados utilizando variables de uso de suelo (cobertura de bosque, matorral, pasto y vegetación mixta) y de disponibilidad de recursos para ungulados (distancia a siembras y fuentes de agua - charcas y arroyos-). Un total de 278 garrapatas fueron capturadas. La abundancia de garrapatas estuvo estrechamente correlacionada con la distancia a siembras realizadas como suplemento alimentario para rumiantes silvestres. El modelo resultante fue proyectado a una escala espacial de 250x250m. para todo QM para establecer las zonas de mayor riesgo de interacción con garrapatas en función de su abundancia. Esta información, unida a estimas pendientes de prevalencia de infección por el VFHCC en las garrapatas, permitirá conocer qué factores modulan la abundancia de garrapatas a una escala espacial pequeña y, así, identificar las zonas donde es más probable infectarse con el VFHCC y otros patógenos transmitidos por garrapatas. Esta información ayudará a tomar mejores medidas de prevención para evitar la transmisión de enfermedades por garrapatas.Peer reviewe

Insights into the spatiotemporal dynamics of West Nile virus transmission in emerging scenarios

The incidence of West Nile fever (WNF) is highly variable in emerging areas, making it difficult to identify risk periods. Using clinical case records has important biases in understanding the transmission dynamics of West Nile virus (WNV) because asymptomatic infections are frequent. However, estimating virus exposure in sentinel species could help achieve this goal at varying spatiotemporal scales. To identify the determinants of inter-annual variation in WNV transmission rates, we designed a 15-year longitudinal seroepidemiological study (2005–2020) in five environmentally diverse areas of southwestern Spain. We modeled individual annual area-dependent exposure risk based on potential environmental and host predictors using generalized linear mixed models. Further, we analyzed the weight of predictors on exposure probability by variance partitioning of the model components. The analysis of 2418 wild ungulate sera (1168 red deer - Cervus elaphus - and 1250 Eurasian wild boar - Sus scrofa) with a highly sensitive commercial blocking ELISA identified an average seroprevalence of 24.9% (95% confidence interval (CI): 23.2–26.7%). Antibody prevalence was slightly higher in wild boar (27.5%; CI: 25.1–30.1%) than in deer (22.2%; CI: 19.8–24.7%). We observed a spatial trend in exposure, with higher frequency in the southernmost areas and a slight, although area-dependent, increasing temporal trend. Host-related predictors were important drivers of exposure risk. The environmental predictor with the highest weight was annual cumulative precipitation, while temperature variations were also relevant but with less weight. We observed a coincidence of spatiotemporal changes in exposure with the notification of WNF outbreaks in horses and humans. That indicates the usefulness of wild ungulates as sentinels for WNV transmission and as models to understand its spatiotemporal dynamics. These results will allow the development of more accurate predictive models of spatiotemporal variations in transmission risk that can inform health authorities to take appropriate action

Testing the efficiency of capture methods for questing Hyalomma lusitanicum (Acari: Ixodidae), a vector of Crimean-Congo hemorrhagic fever virus

Available methods to census exophilic tick populations have limitations in estimating true population size due to their inability to capture a high proportion of the actual tick population. We currently ignore the efficacy of these methods to capture questing Hyalomma spp. ticks, vectors of the Crimean-Congo hemorrhagic fever virus. To address the need of accurately estimating questing densities of Hyalomma spp., we designed a field experiment to test the efficacy of blanket dragging, blanket flagging, CO2-baited traps, and an ad hoc designed method, absolute surface counts, in capturing adult Hyalomma lusitanicum ticks from known numbers of preset fluorescent-marked ticks. The experiment was designed in 2 stages to estimate the point (1-day sampling) and cumulative (3-day serial sampling) efficacy of the methods under varying sampling effort and habitat. Tick survival, host interference, and weather effects on efficacy were controlled for in multiple regression models. There was high variability in method efficacy for capturing ticks, which was also modulated by effort, habitat, tick density, hosts, and soil temperature. The most effective method was absolute surface counts for both point estimates (39%) and cumulative efficacy (83%). CO2-baited traps reached a maximum efficacy of 37%, while blanket dragging and blanket flagging captured a maximum of the 8% of the marked ticks. Our results reveal the strengths and weaknesses of the different tick capture methods applied to adult H. lusitanicum and lay the groundwork for more accurate inferences about the true size of exophilic tick populations.This study is the result of funding by the Spanish Ministry for the Science and Innovation/Spanish Research Agency (MCIN/AEI/10.13039/501100011033/) and EU Regional Development Fund (EU-RDF) through projects CGL2017-89866-R and E-RTA2015-0002-C02-02, and by the Regional Government of Castilla-La Mancha and the EU European Social Fund (EU-ESF) through project SBPLY/19/180501/000321. R.C.-M., L.C.-M., A.P.-M., and S.B.-F. acknowledge the support of MCIN/AEI, EU-ESF, JCCM, and the University of Castilla-La Mancha through contracts PRE2018-083801, PEJ2018-003155-A, 2019-PREDUCLM-10932, and PREJCCM2019/11, respectively.Peer reviewe

Modelización espacial de la abundancia de tres especies de garrapatas parásitas de ungulados silvestres en el Parque Nacional de Doñana

Resumen del trabajo presentado al XV Congreso de la Sociedad Española para la Conservación y Estudio de los Mamífero (SECEM), celebrado en Córdoba del 4 al 7 de diciembre de 2021.Las garrapatas son el segundo vector de patógenos más importante para animales y humanos a nivel mundial, y son los artrópodos que más agentes zoonóticos transmiten en el hemisferio norte. Varios estudios relacionan garrapatas con cambios en la dinámica poblacional y el éxito reproductivo de los animales hospedadores. Debido a este rol sanitario y ecológico, estudiar el nicho ecológico de las especies de garrapatas más abundantes y relevantes desde el punto de vista sanitario es de especial interés para conocer los factores que determinan su distribución y abundancia a diferentes escalas espacio-temporales. El objetivo de este trabajo es modelar la distribución espacial de Hyalomma lusitanicum, Rhipicephalus annulatus e Ixodes ricinus en sus hospedadores ungulados silvestres, así como identificar los factores que determinan esa distribución a pequeña escala espacial y determinar la existencia de variación inter-específica en el nicho. Para ello, se muestrearon ungulados silvestres del Parque Nacional de Doñana y sus garrapatas anualmente en 2010-2020. Un total de 1.965 animales fueron muestreados, en los que 51.429 garrapatas fueron estimadas. Los modelos de abundancia para las tres especies se estimaron utilizando variables ambientales (temperatura del suelo - ts - y NDVI), uso de suelo y variables bióticas (densidad de ganado, índices kilométricos de abundancia y uso del espacio de los ungulados silvestres), y se midió el solapamiento de nicho ecológico entre las tres especies. La abundancia de cada una de las especies estuvo determinada por factores ambientales (principalmente NDVI para H. lusitanicum y también con ts para I. ricinus) y de abundancia de hospedadores (vacuno para R. annulatus). Aunque el grado de solapamiento de nicho varió entre especies, no se observaron diferencias entre nichos a la escala de estudio. Esta información permite identificar zonas de riesgo a pequeña escala y así tomar medidas para prevenir los casos de enfermedades transmitidas por garrapatas tanto en animales silvestres como en el ganado y en humanos.Peer reviewe

Las relaciones hospedador-vector modulan la dinámica espaciotemporal de transmisión del virus de la fiebre hemorrágica de Crimea Congo en el Parque Nacional de Doñana

Resumen del trabajo presentado al XV Congreso de la Sociedad Española para la Conservación y Estudio de los Mamífero (SECEM), celebrado en Córdoba del 4 al 7 de diciembre de 2021.El virus de la fiebre hemorrágica de Crimea Congo (FHCC), una enfermedad humana emergente en España, circula de forma enzoótica y silenciosa, principalmente, en garrapatas y ungulados silvestres. Este estudio persigue comprender el efecto de las relaciones hospedador-vector en la dinámica de exposición al virus (VFHCC) en un espacio biodiverso y abundante en ungulados, el P.N. de Doñana (PND). Para ello, (1) se utilizaron resultados de la modelización espacial de la abundancia de Hyalomma lusitanicum, principal vector, a partir de estimas realizadas sobre ungulados silvestres, (2) se analizó la variación interanual en la incidencia de infecciones del VFHCC en ungulados silvestres (n=1.007) y (3) se analizó la prevalencia de infección en Hyalomma spp. recolectadas sobre ungulados silvestres (n=615). Modelizamos estadísticamente (1) la relación temporal entre incidencia en ungulados y prevalencia en garrapatas a escala anual y (2) la relación espacial entre abundancia de H. lusitanicum, incidencia en ungulados y prevalencia en garrapatas. Observamos que un 60% de los ungulados estuvo expuesto al VFHCC y que un 12,8% de las garrapatas estabas infectadas, siendo ambos parámetros variables entre años. El análisis estadístico mostró relación negativa entre incidencia en ungulados y prevalencia en garrapatas a escala anual. Esto sugiere que la estima de infección en garrapatas alimentadas no es un buen indicador de la presión de infección, al menos a la escala del estudio. Esta conclusión también se apoya en la ausencia de asociación espacial entre abundancia de H. lusitanicum y prevalencia del virus en garrapatas en contraste con la relación positiva entre esta y el riesgo de exposición al virus de los ungulados. La abundancia de ungulados y el ambiente modulan la abundancia de vectores y, con ello, el riesgo de exposición al VFHCC. El tercio norte del PND, donde coinciden alta densidad de ungulados silvestres y condiciones ambientales que favorecen la densidad de H. lusitanicum, sería la zona de mayor riesgo de transmisión del virus a personas. En estas zonas sería recomendable adoptar estrategias preventivas para visitantes y personal científico/técnico del PND.Peer reviewe

Spatial modelling of Hyalomma lusitanicum ticks shape Crimean-Congo haemorrhagic fever virus exposure in Doñana National Park, Spain

Resumen del trabajo presentado a la Joint Virtual Conference of the WDA and EWDA, celebrada del 31 de agosto al 2 de septiembre de 2021.Peer reviewe