Serological evidence of West Nile virus, Usutu virus and Sindbis virus infection of birds in the UK

Abstract

The introduction and rapid dispersal of the African flavivirus West Nile virus (WNV) throughout North America, and the high fatality rate due to encephalitis in birds, horses, other wildlife species and humans, has attracted major attention worldwide. Usutu virus, another flavivirus, came to prominence in 2001, when it was identified as the agent responsible for a drop in the bird population in Austria; previously this encephalitic virus was found only in birds and mosquitoes in Africa. Sindbis virus, a pathogenic alphavirus that causes arthritis, is widespread throughout Africa, Europe, Asia and Australia, infecting a range of arthropods and vertebrates and is genetically related to encephalitic viruses in North America. Currently there is no evidence that any of these viruses cause disease in the UK. Here the presence of virus-specific neutralizing antibodies is reported in the sera of resident and migrant birds in the UK, implying that each of these viruses is being introduced to UK birds, possibly by mosquitoes. This is supported by nucleotide sequencing that identified three slightly different sequences of WNV RNA in tissues of magpies and a blackbird. The detection of specific neutralizing antibodies to WNV in birds provides a plausible explanation for the lack of evidence of a decrease in the bird population in the UK compared with North America. The potential health risk posed to humans and animals by these viruses circulating in the UK is discussed.

Prevalence of West Nile Virus Neutralizing Antibodies in Wild Birds from the Camargue Area, Southern France

“…Within the passerines, the prevalence of antibody-positive birds was significantly higher for long-distance migrants (7.0%) than for residents and short-distance migrants (0.8%) (x 2 57.36, P,0.01). These data support other studies in England (Buckley et al, 2003), Spain (Lopez et al, 2008), and other European countries that suggest migrants frequently have antibodies to flaviviruses. Conversely, only three of the 201 Cattle Egret nestlings sampled from site two had WNV neutralizing antibodies; titers ranged from 40 to 320 (Table 1).…”

Usutu Virus Sequences inCulex pipiens(Diptera:Culicidae), Spain

“…This decrease in USUV-associated bird deaths was attributed to herd immunity in the bird population No. studied H 2001 170 24 23 23 35 0 232 28 27 27 23 2 2002 150 18 17 17 35 1 149 10 9 10 39 3 2003 218 20 20 21 43 1 177 17 18 17 65 12 2004 215 23 23 24 47 2 221 5 5 5 70 14 2005 222 29 29 29 62 2 217 7 7 7 60 12 2006 240 23 24 24 68 2 278 2 3 2 in the United Kingdom without causing an obvious reduction in the bird population (7). From May through October 2006, monitoring of fl aviviruses in mosquitoes was performed in the northeast region of Spain (Catalonia).…”

Sindbis Virus Infection in Resident Birds, Migratory Birds, and Humans, Finland

“…SINV is present throughout the Old World but has never been found in the New World (the Americas). SINV seropositivity in humans has been reported in various areas, and antibodies to SINV have also been found from various bird (3)(4)(5) and mammal (6,7) species. The virus has been isolated from several mosquito species, frogs (8), reed warblers (9), bats (10), ticks (11), and humans (12)(13)(14).…”