Seasonal and inter-annual drivers of yellow fever transmission in South America.
In the last 20 years yellow fever (YF) has seen dramatic changes to its incidence and geographic extent, with the largest outbreaks in South America since 1940 occurring in the previously unaffected South-East Atlantic coast of Brazil in 2016-2019. While habitat fragmentation and land-cover have pre...
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2021-01-01
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| Series: | PLoS Neglected Tropical Diseases |
| Online Access: | https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0008974&type=printable |
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| author | Arran Hamlet Katy A M Gaythorpe Tini Garske Neil M Ferguson |
| author_facet | Arran Hamlet Katy A M Gaythorpe Tini Garske Neil M Ferguson |
| author_sort | Arran Hamlet |
| collection | DOAJ |
| description | In the last 20 years yellow fever (YF) has seen dramatic changes to its incidence and geographic extent, with the largest outbreaks in South America since 1940 occurring in the previously unaffected South-East Atlantic coast of Brazil in 2016-2019. While habitat fragmentation and land-cover have previously been implicated in zoonotic disease, their role in YF has not yet been examined. We examined the extent to which vegetation, land-cover, climate and host population predicted the numbers of months a location reported YF per year and by each month over the time-period. Two sets of models were assessed, one looking at interannual differences over the study period (2003-2016), and a seasonal model looking at intra-annual differences by month, averaging over the years of the study period. Each was fit using hierarchical negative-binomial regression in an exhaustive model fitting process. Within each set, the best performing models, as measured by the Akaike Information Criterion (AIC), were combined to create ensemble models to describe interannual and seasonal variation in YF. The models reproduced the spatiotemporal heterogeneities in YF transmission with coefficient of determination (R2) values of 0.43 (95% CI 0.41-0.45) for the interannual model and 0.66 (95% CI 0.64-0.67) for the seasonal model. For the interannual model, EVI, land-cover and vegetation heterogeneity were the primary contributors to the variance explained by the model, and for the seasonal model, EVI, day temperature and rainfall amplitude. Our models explain much of the spatiotemporal variation in YF in South America, both seasonally and across the period 2003-2016. Vegetation type (EVI), heterogeneity in vegetation (perhaps a proxy for habitat fragmentation) and land cover explain much of the trends in YF transmission seen. These findings may help understand the recent expansions of the YF endemic zone, as well as to the highly seasonal nature of YF. |
| format | Article |
| id | doaj-art-dab6bc76b99e476eae2d0361bd9249a1 |
| institution | DOAJ |
| issn | 1935-2727 1935-2735 |
| language | English |
| publishDate | 2021-01-01 |
| publisher | Public Library of Science (PLoS) |
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| series | PLoS Neglected Tropical Diseases |
| spelling | doaj-art-dab6bc76b99e476eae2d0361bd9249a12025-08-20T02:55:14ZengPublic Library of Science (PLoS)PLoS Neglected Tropical Diseases1935-27271935-27352021-01-01151e000897410.1371/journal.pntd.0008974Seasonal and inter-annual drivers of yellow fever transmission in South America.Arran HamletKaty A M GaythorpeTini GarskeNeil M FergusonIn the last 20 years yellow fever (YF) has seen dramatic changes to its incidence and geographic extent, with the largest outbreaks in South America since 1940 occurring in the previously unaffected South-East Atlantic coast of Brazil in 2016-2019. While habitat fragmentation and land-cover have previously been implicated in zoonotic disease, their role in YF has not yet been examined. We examined the extent to which vegetation, land-cover, climate and host population predicted the numbers of months a location reported YF per year and by each month over the time-period. Two sets of models were assessed, one looking at interannual differences over the study period (2003-2016), and a seasonal model looking at intra-annual differences by month, averaging over the years of the study period. Each was fit using hierarchical negative-binomial regression in an exhaustive model fitting process. Within each set, the best performing models, as measured by the Akaike Information Criterion (AIC), were combined to create ensemble models to describe interannual and seasonal variation in YF. The models reproduced the spatiotemporal heterogeneities in YF transmission with coefficient of determination (R2) values of 0.43 (95% CI 0.41-0.45) for the interannual model and 0.66 (95% CI 0.64-0.67) for the seasonal model. For the interannual model, EVI, land-cover and vegetation heterogeneity were the primary contributors to the variance explained by the model, and for the seasonal model, EVI, day temperature and rainfall amplitude. Our models explain much of the spatiotemporal variation in YF in South America, both seasonally and across the period 2003-2016. Vegetation type (EVI), heterogeneity in vegetation (perhaps a proxy for habitat fragmentation) and land cover explain much of the trends in YF transmission seen. These findings may help understand the recent expansions of the YF endemic zone, as well as to the highly seasonal nature of YF.https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0008974&type=printable |
| spellingShingle | Arran Hamlet Katy A M Gaythorpe Tini Garske Neil M Ferguson Seasonal and inter-annual drivers of yellow fever transmission in South America. PLoS Neglected Tropical Diseases |
| title | Seasonal and inter-annual drivers of yellow fever transmission in South America. |
| title_full | Seasonal and inter-annual drivers of yellow fever transmission in South America. |
| title_fullStr | Seasonal and inter-annual drivers of yellow fever transmission in South America. |
| title_full_unstemmed | Seasonal and inter-annual drivers of yellow fever transmission in South America. |
| title_short | Seasonal and inter-annual drivers of yellow fever transmission in South America. |
| title_sort | seasonal and inter annual drivers of yellow fever transmission in south america |
| url | https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0008974&type=printable |
| work_keys_str_mv | AT arranhamlet seasonalandinterannualdriversofyellowfevertransmissioninsouthamerica AT katyamgaythorpe seasonalandinterannualdriversofyellowfevertransmissioninsouthamerica AT tinigarske seasonalandinterannualdriversofyellowfevertransmissioninsouthamerica AT neilmferguson seasonalandinterannualdriversofyellowfevertransmissioninsouthamerica |