Understanding Spatio-Temporal Variability in the Reproduction Ratio of the Bluetongue (BTV-1) Epidemic in Southern Spain (Andalusia) in 2007 Using Epidemic Trees
| Autor: | Napp, S., Allepuz, A., Purse, B. V., Casal, J., García-Bocanegra, I., Burgin, L. E., Searle, K. R. |
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| Rok vydání: | 2021 |
| Předmět: |
RNA viruses
0301 basic medicine Culicoides imicola Veterinary medicine Spatial Epidemiology Epidemiology Range (biology) Culicoides obsoletus lcsh:Medicine Pathology and Laboratory Medicine law.invention Geographical Locations 0403 veterinary science law Reoviruses Medicine and Health Sciences lcsh:Science media_common Mammals Multidisciplinary Goats Spatial epidemiology Culicoides Agriculture Ruminants 04 agricultural and veterinary sciences 3. Good health Insects Europe Infectious Diseases Transmission (mechanics) Medical Microbiology Viral Pathogens Viruses Vertebrates Pathogens Reproduction Research Article Infectious disease epidemiology Farms Livestock Arthropoda Infectious Disease Control 040301 veterinary sciences media_common.quotation_subject Cattle Diseases Biology Microbiology Bluetongue Models Biological Colicoides Infectious Disease Epidemiology Ecology and Environment 03 medical and health sciences Bluetongue Virus Infectious disease control Animals Microbial Pathogens Goat Diseases Sheep lcsh:R Organisms Biology and Life Sciences Outbreak biology.organism_classification Invertebrates 030104 developmental biology Agriculture and Soil Science Spain 13. Climate action People and Places Cattle lcsh:Q Bluetongue virus |
| Zdroj: | Recercat: Dipósit de la Recerca de Catalunya Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) PLOS ONE PLoS ONE, Vol 11, Iss 3, p e0151151 (2016) PLoS ONE 11(3): e0151151 (2016) Helvia. Repositorio Institucional de la Universidad de Córdoba instname Recercat. Dipósit de la Recerca de Catalunya Dipòsit Digital de Documents de la UAB Universitat Autònoma de Barcelona PLoS ONE |
| Popis: | Andalusia (Southern Spain) is considered one of the main routes of introduction of bluetongue virus (BTV) into Europe, evidenced by a devastating epidemic caused by BTV-1 in 2007. Understanding the pattern and the drivers of BTV-1 spread in Andalusia is critical for effective detection and control of future epidemics. A long-standing metric for quantifying the behaviour of infectious diseases is the case-reproduction ratio (Rt), defined as the average number of secondary cases arising from a single infected case at time t (for t>0). Here we apply a method using epidemic trees to estimate the between-herd case reproduction ratio directly from epidemic data allowing the spatial and temporal variability in transmission to be described. We then relate this variability to predictors describing the hosts, vectors and the environment to better understand why the epidemic spread more quickly in some regions or periods. The Rt value for the BTV-1 epidemic in Andalusia peaked in July at 4.6, at the start of the epidemic, then decreased to 2.2 by August, dropped below 1 by September (0.8), and by October it had decreased to 0.02. BTV spread was the consequence of both local transmission within established disease foci and BTV expansion to distant new areas (i.e. new foci), which resulted in a high variability in BTV transmission, not only among different areas, but particularly through time, which suggests that general control measures applied at broad spatial scales are unlikely to be effective. This high variability through time was probably due to the impact of temperature on BTV transmission, as evidenced by a reduction in the value of Rt by 0.0041 for every unit increase (day) in the extrinsic incubation period (EIP), which is itself directly dependent on temperature. Moreover, within the range of values at which BTV-1 transmission occurred in Andalusia (20.6°C to 29.5°C) there was a positive correlation between temperature and Rt values, although the relationship was not linear, probably as a result of the complex relationship between temperature and the different parameters affecting BTV transmission. Rt values for BTV-1 in Andalusia fell below the threshold of 1 when temperatures dropped below 21°C, a much higher threshold than that reported in other BTV outbreaks, such as the BTV-8 epidemic in Northern Europe. This divergence may be explained by differences in the adaptation to temperature of the main vectors of the BTV-1 epidemic in Andalusia (Culicoides imicola) compared those of the BTV-8 epidemic in Northern Europe (Culicoides obsoletus). Importantly, we found that BTV transmission (Rt value) increased significantly in areas with higher densities of sheep. Our analysis also established that control of BTV-1 in Andalusia was complicated by the simultaneous establishment of several distant foci at the start of the epidemic, which may have been caused by several independent introductions of infected vectors from the North of Africa. We discuss the implications of these findings for BTV surveillance and control in this region of Europe. |
| Databáze: | OpenAIRE |
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