The British Isles (population 63 million) form a fairly compact archipelago of > 6000 islands (between 49–61°N and 10°W−2°E) spanning ∼600 000 km2 with total land area > 300 000 km2, westward from continental Europe. The two main islands are Great Britain (politically subdivided between the States of England, Scotland and Wales, comprising the United Kingdom) and Ireland (politically divided between the Irish Republic, Eire, and Northern Ireland Province of the United Kingdom). Largest of many subsidiary islands are the Isle of Man, between Britain and Ireland, and the Channel Islands between Britain and France. Until ∼6000 years ago, when seas rose after the last glaciation, Great Britain was joined to continental Europe by a land bridge, now broken by the shallow English Channel ≥ 30 km wide.
Potential transmission of West Nile virus in the British Isles: an ecological review of candidate mosquito bridge vectors
Article first published online: 4 MAR 2005
Medical and Veterinary Entomology
Volume 19, Issue 1, pages 2–21, March 2005
How to Cite
Medlock, J. M., Snow, K. R. and Leach, S. (2005), Potential transmission of West Nile virus in the British Isles: an ecological review of candidate mosquito bridge vectors. Medical and Veterinary Entomology, 19: 2–21. doi: 10.1111/j.0269-283X.2005.00547.x
- Issue published online: 4 MAR 2005
- Article first published online: 4 MAR 2005
- Accepted 18 December 2004
- Aedes cinereus;
- Coquillettidia richiardii;
- Culex pipiens biotype molestus;
- Ochlerotatus cantans;
- Oc. caspius;
- Oc. detritus;
- Oc. japonicus;
- Oc. punctor;
- Stegomyia albopicta;
- arbovirus vectors;
- bridge vectors;
- emerging infections;
- West Nile virus;
- British Isles;
- United Kingdom
Abstract. West Nile virus (WNV) transmitted by mosquitoes (Diptera: Culicidae) infects various vertebrates, being pathogenic for birds, horses and humans. After its discovery in tropical Africa, sporadic outbreaks of WNV occurred during recent decades in Eurasia, but not the British Isles*. WNV reached New York in 1999 and spread to California by 2003, causing widespread outbreaks of West Nile encephalitis across North America, transmitted by many species of mosquitoes, mainly Culex spp. The periodic reappearance of WNV in parts of continental Europe (from southern France to Romania) gives rise to concern over the possibility of WNV invading the British Isles.
The British Isles have about 30 endemic mosquito species, several with seasonal abundance and other eco-behavioural characteristics predisposing them to serve as potential WNV bridge vectors from birds to humans. These include: the predominantly ornithophilic Culex pipiens L. and its anthropophilic biotype molestus Forskål; tree-hole adapted Anopheles plumbeus Stephens; saltmarsh-adapted Ochlerotatus caspius Pallas, Oc. detritus Haliday and Oc. dorsalis (Meigen); Coquillettidia richiardii Ficalbi, Culiseta annulata Schrank and Cs. morsitans (Theobald) from vegetated freshwater pools; Aedes cinereus Meigen, Oc. cantans Meigen and Oc. punctor Kirby from seasonal woodland pools. Those underlined have been found carrying WNV in other countries (12 species), including the rarer British species Aedes vexans (Meigen), Culex europaeus Ramos et al., Cx. modestus Ficalbi and Oc. sticticus (Meigen) as well as the Anopheles maculipennis Meigen complex (mainly An. atroparvus van Thiel and An. messeae Falleroni in Britain). Those implicated as key vectors of WNV in Europe are printed bold (four species).
So far there is no proof of any arbovirus transmission by mosquitoes in the British Isles, although antibodies to Sindbis, Tahyna, Usutu and West Nile viruses have been detected in British birds. Neighbouring European countries have enzootic WNV and human infections transmitted by mosquito species that are present in the British Isles. However, except for localized urban infestations of Cx. pipiens biotype molestus that can be readily eliminated, there appear to be few situations in the British Isles where humans and livestock are exposed to sustained risks of exposure to potential WNV vectors. Monitoring of mosquitoes and arbovirus surveillance are required to guard the British Isles against WNV outbreaks and introduction of more anthropophilic mosquitoes such as Stegomyia albopicta (Skuse) and Ochlerotatus japonicus (Theobald) that have recently invaded Europe, since they transmit arboviruses elsewhere.