Passive surveillance of United Kingdom bats for lyssaviruses (2005-2015).

Passive surveillance for lyssaviruses in UK bats has been ongoing since 1987 and has identified 13 cases of EBLV-2 from a single species; Myotis daubentonii. No other lyssavirus species has been detected. Between 2005 and 2015, 10 656 bats were submitted, representing 18 species, creating a spatially and temporally uneven sample of British bat fauna. Uniquely, three UK cases originate from a roost at Stokesay Castle in Shropshire, England, where daily checks for grounded and dead bats are undertaken and bat carcasses have been submitted for testing since 2007. Twenty per cent of Daubenton's bats submitted from Stokesay Castle since surveillance began, have tested positive for EBLV-2. Phylogenetic analysis reveals geographical clustering of UK viruses. Isolates from Stokesay Castle are more closely related to one another than to viruses from other regions. Daubenton's bats from Stokesay Castle represent a unique opportunity to study a natural population that appears to maintain EBLV-2 infection and may represent endemic infection at this site. Although the risk to public health from EBLV-2 is low, consequences of infection are severe and effective communication on the need for prompt post-exposure prophylaxis for anyone that has been bitten by a bat is essential.

Population genetic structure of serotine bats (Eptesicus serotinus) across Europe and implications for the potential spread of bat rabies (European bat lyssavirus EBLV-1).

Understanding of the movements of species at multiple scales is essential to appreciate patterns of population connectivity and in some cases, the potential for pathogen transmission. The serotine bat (Eptesicus serotinus) is a common and widely distributed species in Europe where it frequently harbours European bat lyssavirus type 1 (EBLV-1), a virus causing rabies and transmissible to humans. In the United Kingdom, it is rare, with a distribution restricted to south of the country and so far the virus has never been found there. We investigated the genetic structure and gene flow of E. serotinus across the England and continental Europe. Greater genetic structuring was found in England compared with continental Europe. Nuclear data suggest a single population on the continent, although further work with more intensive sampling is required to confirm this, while mitochondrial sequences indicate an east-west substructure. In contrast, three distinct populations were found in England using microsatellite markers, and mitochondrial diversity was very low. Evidence of nuclear admixture indicated strong male-mediated gene flow among populations. Differences in connectivity could contribute to the high viral prevalence on the continent in contrast with the United Kingdom. Although the English Channel was previously thought to restrict gene flow, our data indicate relatively frequent movement from the continent to England highlighting the potential for movement of EBLV-1 into the United Kingdom.

Bat population genetics and Lyssavirus presence in Great Britain.

Most lyssaviruses appear to have bat species as reservoir hosts. In Europe, of around 800 reported cases in bats, most were of European bat lyssavirus type 1 (EBLV-1) in Eptesicus serotinus (where the bat species was identified). About 20 cases of EBLV-2 were recorded, and these were in Myotis daubentonii and M. dasycneme. Through a passive surveillance scheme, Britain reports about one case a year of EBLV-2, but no cases of the more prevalent EBLV-1. An analysis of E. serotinus and M. daubentonii bat genetics in Britain reveals more structure in the former population than in the latter. Here we briefly review these differences, ask if this correlates with dispersal and movement patterns and use the results to suggest an hypothesis that EBLV-2 is more common than EBLV-1 in the UK, as genetic data suggest greater movement and regular immigration from Europe of M. daubentonii. We further suggest that this genetic approach is useful to anticipate the spread of exotic diseases in bats in any region of the world.

Targeted surveillance for European bat lyssaviruses in English bats (2003-06).

In 2003-06, targeted (active) surveillance for European bat lyssaviruses (EBLVs) was undertaken throughout England, focusing on two species most likely to host these viruses, Myotis daubentonii and Eptesicus serotinus. Blood was sampled for the detection of EBLV-specific neutralizing antibodies and oropharyngeal swabs were taken for the detection of viral RNA or infectious virus in saliva. Between 2003 and 2006, 273 E. serotinus and 363 M. daubentonii blood samples were tested by the EBLV-1 or EBLV-2 specific modified fluorescent antibody neutralization test. The EBLV-2 antibody prevalence estimate was 1.0-4.1% (95% confidence interval [CI]; mean=2.2%) for M. daubentonii. European bat lyssavirus type 1-specific antibodies were detected only in a single E. serotinus. Other nontarget species (n=5) were sampled in small numbers (n=24), with no EBLV-specific antibody detected. No viral RNA or live virus was detected in any of the oropharyngeal swabs analyzed. Host RNA was detected from 83% of the oropharyngeal swabs analyzed (total swabs 2003-06: n=766). These data show that EBLV-2 is present in M. daubentonii in England. In contrast, there is insufficient evidence to suggest that EBLV-1 is present in E. serotinus in England, although further research is warranted.

EBLV-2 prevalence in the United Kingdom as determined by surveillance testing.

Five cases of EBLV-2 have been detected in the UK since 1996, with all wildlife cases in the Daubenton's bat: one on the south coast in Sussex in 1996, one in Lancashire in 2002, another in 2003, one in Surrey in 2004 and a human fatality in Angus, Scotland, in 2002. As a result of the human case, a seroprevalence study, aimed primarily at the Daubenton's bat was conducted in 2003 in Scotland and at some sites in England. In Scotland, 198 Daubenton's, 20 Natterer's and 6 pipistrelles were caught at 19 sites and analysed, while in England 67 Daubenton, 2 Brandts/ Whiskered and 4 pipistrelle bats were analysed from four sites in Lancashire. Analysis of blood was performed by a modified fluorescent antibody virus neutralisation test (mFAVN) to determine antibody titre to EBLV-2. Ignoring those sites where we had a priori reason to expect infected bats, the overall seroprevalence was between 0.7-5.1 % (95 % confidence interval), with a maximum likelihood estimate of 2.2 %. Mouth swabs were taken and tested for virus genome by RT-PCR and live virus by tissue culture isolation. All of the PCR and isolation results were negative suggesting that none of the bats sampled were actively excreting virus. This suggests a low level of active infection in Britain and raises the possibility that bats may recover following exposure to EBLV-2.

Effect of temperature and cultivar on pea aphid, Acyrthosiphon pisum (Hemiptera: Aphididae) life history.

Life history parameters of the pea aphid, Acyrthosiphon pisum were studied at five constant temperatures on two cultivars of peas, Scout and Sancho. The development and mortality of juveniles and the life-span, age-specific fecundity and survivorship of adult aphids were recorded and used to construct life tables. The juvenile development period (from birth to adulthood) was longest at 11.9 degrees C (16.8 days on cv. Scout and 16.2 days on cv. Sancho) and shortest at 26.7 degrees C (8.5 days on cv. Scout and 8.8 days on cv. Sancho). At all temperatures, except 26.7 degrees C, juveniles developed faster on cv. Sancho than on cv. Scout. On both pea varieties juvenile mortality was highest at temperatures above 19.6 degrees C and lowest at 19.6 degrees C. Highest cumulative juvenile mortality was recorded on cv. Scout at 26.7 degrees C when only 9% of aphids survived from birth to reproductively mature adults. Fecundity rates were unaffected by temperature in the range tested on cv. Sancho but increased with increasing temperatures between 11.9 and 19.6 degrees C on cv. Scout. These differences in life history parameters were reflected in the population growth (rm) of aphids on both pea cultivars which increased with increasing temperatures between 11.9 and 23.1 degrees C on cv. Sancho and 11.9 and 19.6 degrees C on cv. Scout, declining thereafter. Population growth was consistently greater at all temperatures for aphids reared on cv. Sancho than those reared on cv. Scout.