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Incriminating bluetongue virus vectors with climate envelope models
Article first published online: 30 JUN 2007
DOI: 10.1111/j.1365-2664.2007.01342.x
Additional Information
How to Cite
PURSE, B. V., MCCORMICK, B. J. J., MELLOR, P. S., BAYLIS, M., BOORMAN, J. P. T., BORRAS, D., BURGU, I., CAPELA, R., CARACAPPA, S., COLLANTES, F., DE LIBERATO, C., DELGADO, J. A., DENISON, E., GEORGIEV, G., HARAK, M. E., DE LA ROCQUE, S., LHOR, Y., LUCIENTES, J., MANGANA, O., MIRANDA, M. A., NEDELCHEV, N., NOMIKOU, K., OZKUL, A., PATAKAKIS, M., PENA, I., SCARAMOZZINO, P., TORINA, A. and ROGERS, D. J. (2007), Incriminating bluetongue virus vectors with climate envelope models. Journal of Applied Ecology, 44: 1231–1242. doi: 10.1111/j.1365-2664.2007.01342.x
Publication History
- Issue published online: 30 JUN 2007
- Article first published online: 30 JUN 2007
- Received 21 September 2006; final copy received 29 March 2007; Editor: Philip Stephens
Keywords:
- bluetongue virus;
- climate;
- Culicoides imicola;
- C. obsoletus;
- C. pulicaris;
- environmental envelope
Summary
- 1The spread of vector-borne diseases into new areas, commonly attributed to environmental change or increased trade and travel, could be exacerbated if novel vector species in newly invaded areas spread infection beyond the range of traditional vectors.
- 2By analysing the differential degree of overlap between the environmental envelopes for bluetongue, a devastating livestock disease, and its traditional (Afro-Asian) and potential new (Palearctic) midge vectors, we have implicated the latter in the recent dramatic northward spread of this disease into Europe.
- 3The traditional vector of bluetongue virus, the Afro-Asian midge Culicoides imicola, was found to occur in warm (annual mean 12–20 °C), thermally stable locations that were dry in summer (< 400 mm precipitation). The Palearctic C. obsoletus and C. pulicaris complexes were both found to occur in cooler (down to 7 °C annual mean), thermally more variable and wetter (up to 700 mm summer precipitation) locations.
- 4Of 501 recorded outbreaks from the 1998–2004 bluetongue epidemic in southern Europe, 40% fall outside the climate envelope of C. imicola, but within the species’ envelopes of the C. obsoletus and C. pulicaris complexes.
- 5The distribution in multivariate environmental space of bluetongue virus is closer to that of the Palaearctic vectors than it is to that of C. imicola. This suggests that Palearctic vectors now play a substantial role in transmission and have facilitated the spread of bluetongue into cooler, wetter regions of Europe.
- 6Synthesis and applications. The risk to Northern Europe now depends on how much of the distributions of the widespread, abundant Palearctic midge vectors (the C. obsoletus and C. pulicaris complexes) bluetongue can occupy, perhaps determined by thermal constraints on viral replication. This was highlighted by the sudden appearance in summer 2006 of bluetongue virus at latitudes of more than 50° North – approximately 6° further North than previous outbreaks in southern Europe. Future surveillance for bluetongue and for related Culicoides-borne pathogens should include studies to record and explain the distributional patterns of all potential Palearctic vector species.