Anthony R. Fooks

Susceptibility of North American big brown bats (Eptesicus fuscus) to infection with European bat lyssavirus type 1

The aim of this study was to determine the susceptibility of insectivorous bats (using the big brown bat as a model) to infection with European bat lyssavirus type 1a (EBLV-1a), to assess the dynamics of host immune responses and to evaluate the opportunity for horizontal viral transmission within colonies. Two isolates of EBLV-1a, originating from Slovakia (EBLV-1aSK) and Germany (EBLV-1aGE), were tested. Four different routes of inoculation were used with isolate EBLV-1aSK [10(4.8) mouse intracerebral median lethal dose (MICLD(50)) in 50 mul]: intramuscular (i.m.) in the deltoid area or masseter region, per os (p.o.) and intradermal (i.d.) scratches. Isolate EBLV-1aGE (10(3.2) and 10(2.2) MICLD(50) in 20 mul) was inoculated via the intranasal (i.n.), i.m. (low- and high-dose groups, into pectoral muscles); p.o. and intracerebral (i.c.) routes. None of the bats infected by the i.n., p.o. or i.d. route with either virus isolate developed disease during the experiments (91 or 120 days, respectively). Incubation periods were 9-12 days for i.c.-inoculated bats (66 % mortality), 12-33 days for bats inoculated i.m. with the higher dose (23-50 % mortality) and 21-58 days in bats inoculated i.m. with the lower dose of virus (57 % mortality). Virus or viral RNA in bat saliva was detected occasionally, as early as 37 days before death. All i.d.-inoculated and the majority of i.m.-inoculated bats seroconverted within 7-10 days of inoculation. These observations suggest that exposure of bats to varying doses of EBLV-1 from rabid conspecifics via natural (i.d.) routes could lead to an abortive infection and serve as a natural mode of immunization resulting in the presence of virus-neutralizing antibodies in free-ranging bats.

Analysis of vaccine-virus-associated rabies cases in red foxes ( Vulpes vulpes ) after oral rabies vaccination campaigns in Germany and Austria

To eradicate rabies in foxes, almost 97 million oral rabies vaccine baits have been distributed in Germany and Austria since 1983 and 1986, respectively. Since 2007, no terrestrial cases have been reported in either country. The most widely used oral rabies vaccine viruses in these countries were SAD (Street Alabama Dufferin) strains, e.g. SAD B19 (53.2%) and SAD P5/88 (44.5%). In this paper, we describe six possible vaccine-virus-associated rabies cases in red foxes (Vulpes vulpes) detected during post-vaccination surveillance from 2001 to 2006, involving two different vaccines and different batches. Compared to prototypic vaccine strains, full-genome sequencing revealed between 1 and 5 single nucleotide alterations in the L gene in 5 of 6 SAD isolates, resulting in up to two amino acid substitutions. However, experimental infection of juvenile foxes showed that those mutations had no influence on pathogenicity. The cases described here, coming from geographically widely separated regions, do not represent a spatial cluster. More importantly, enhanced surveillance showed that the vaccine viruses involved did not become established in the red fox population. It seems that the number of reported vaccine virus-associated rabies cases is determined predominantly by the intensity of surveillance after the oral rabies vaccination campaign and not by the selection of strains.

Oral vaccination of foxes against rabies in Turkey between 2008 and 2010.

Following a sustained spill-over event from dogs to foxes, fox rabies spread rapidly in the Aegean region, Turkey. In order to control the outbreak a program of oral vaccination of foxes against rabies was introduced. In the selected vaccination area three annual campaigns between 2008 and 2010 were undertaken during the winter months whereby the vaccine baits were distributed exclusively by plane using a density of 18 baits per km2. Subsequently, fox rabies cases were reported only from locations bordering the non-vaccinated areas. Hence, it was shown that fox rabies control by means of oral rabies vaccination is feasible in Turkey. However, for the progress towards the elimination of fox-mediated rabies in Turkey to be maintained, it is necessary that political and financial support is secured to extend oral vaccination where infected foxes remain.

Hantavirus (Seoul virus) in pet rats: a zoonotic viral threat

COLLEAGUES may be aware that a small number of human cases of acute kidney injury associated with hantavirus infection has been recorded in individuals who recreationally or occupationally handle rats in the UK. The UK public health authorities continue to investigate these cases in collaboration with the Animal and Plant Health Agency. Pet rats (including ‘fancy rats’), breeder rats and wild rats have been identified as the potential source of infection. The human cases had documented exposure to rats resulting in the probable transmission of the rat-associated hantavirus, Seoul virus (SEOV). Hantaviruses (family Bunyaviridae, genus Hantavirus ) are single-stranded RNA viruses. Unlike other members of the Bunyaviridae, hantaviruses are not transmitted by arthropods but are predominantly transmitted by rodents. Throughout Europe, six rodent-borne hantaviruses have been described, of …

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 Daubentons 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. Daubentons 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.

Surveillance to Establish Elimination of Transmission and Freedom from Dog-mediated Rabies

Background With a global target set for zero human deaths from dog-mediated rabies by 2030 and some regional programmes close to eliminating canine rabies, there is an urgent need for enhanced surveillance strategies suitable for declaring freedom from disease and elimination of transmission with known confidence. Methods Using exhaustive contact tracing across settings in Tanzania we generated detailed data on rabies incidence, rabid dog biting behaviour and health-seeking behaviour of bite victims. Using these data we compared case detection of sampling-based and enhanced surveillance methodologies and investigated elimination verification procedures. Findings We demonstrate that patients presenting to clinics with bite injuries are sensitive sentinels for identifying dog rabies cases. Triage of patients based on bite history criteria and investigation of suspicious incidents can confirm >10% of dog rabies cases and is an affordable approach that will enable validation of disease freedom following two years without case detection. Approaches based on sampling the dog population without using bite-injury follow-up were found to be neither sensitive nor cost-effective. Interpretation The low prevalence of rabies, and short window in which disease can be detected, preclude sampling-based surveillance. Instead, active case finding guided by bite-patient triage is needed as elimination is approached. Our proposed methodology is affordable, practical and supports the goal of eliminating human rabies deaths by improving administration of lifesaving post-exposure prophylaxis for genuinely exposed but untreated contacts. Moreover, joint investigations by public health and veterinary workers will strengthen intersectoral partnerships and capacity for control of emerging zoonoses.

Two EBLV-2 infected Daubenton's bats detected in the north of England

DUE to the presence of European bat lyssavirus type 2 (EBLV-2) in British bats, the APHA continues to test dead bats submitted by veterinary surgeons, the Bat Conservation Trust and members of the public. Most bat species in the British Isles are not associated with infection with lyssaviruses, although identification of individual species can be difficult (Banyard and others 2011). All bat species are protected by law and should not be disturbed. Further advice can be obtained from the Bat Conservation Trust (www.bats.org.uk/) or the UK governments website (www.gov.uk/guidance/rabies-in-bats). In August 2016, two bats that had been found at sites in the north of England tested positive for EBLV-2. The first bat was found by two members of the public on August 5 in west Yorkshire. The bat was alive but showed signs of being undernourished and dehydrated. It was offered milk formula and mealworms, but subsequently died in captivity on August 8 and was received for testing at the APHA on …

Rabies pre-exposure prophylaxis elicits long-lasting immunity in humans.

Despite the availability of safe and effective human vaccines, rabies remains a global threat, with an estimated 60,000 human deaths annually attributed to rabies. Pre-exposure prophylaxis against rabies infection is recommended for travelers to countries where rabies is endemic, and also for those with a higher risk of exposure. In this study, the rabies-specific neutralising antibody responses in a cohort of rabies-vaccinated recipients over a period of twenty years have been assessed. In particular, the antibody response to primary vaccinations and boosters, and the waning of antibody post primary vaccination and post booster were investigated. The significance of gender, age at vaccination, vaccine manufacturer and vaccination intervals were also evaluated. These data confirm that rabies vaccination can elicit a neutralising antibody response that can remain at detectable levels for a number of years, without additional booster vaccinations. The antibody response following both primary vaccination and booster was significantly influenced by the gender of the subject (p=0.002 and 0.03 respectively), with supportive data that suggests an effect by the make of vaccine administered following primary vaccination, with significantly higher VNA titres observed for one vaccine manufactured prior to 2006 (p<0.001) in a small subset of recipients (n=5). Additionally, the decay rate was demonstrated through the overall decline in antibody titre for all individuals, which was a 37% and 27% reduction per 2-fold change in time following primary and booster vaccination respectively. Individuals within older age groups demonstrated a significantly faster decline in antibody titre following the primary vaccination course (p=0.012). Rate of decline in antibody titre was also significantly influenced by the vaccine make following primary course (p<0.001). The assessment of neutralising antibody titre decline has also provided an insight into the most appropriate timing for booster administration, and enabled the prediction of long term titres from post-vaccination antibody titres.

Pathogenesis of bat rabies in a natural reservoir: comparative susceptibility of the straw-colored fruit bat ( Eidolon helvum ) to three strains of Lagos bat virus

Rabies is a fatal neurologic disease caused by lyssavirus infection. People are infected through contact with infected animals. The relative increase of human rabies acquired from bats calls for a better understanding of lyssavirus infections in their natural hosts. So far, there is no experimental model that mimics natural lyssavirus infection in the reservoir bat species. Lagos bat virus is a lyssavirus that is endemic in straw-colored fruit bats (Eidolon helvum) in Africa. Here we compared the susceptibility of these bats to three strains of Lagos bat virus (from Senegal, Nigeria, and Ghana) by intracranial inoculation. To allow comparison between strains, we ensured the same titer of virus was inoculated in the same location of the brain of each bat. All bats (n = 3 per strain) were infected, and developed neurological signs, and fatal meningoencephalitis with lyssavirus antigen expression in neurons. There were three main differences among the groups. First, time to death was substantially shorter in the Senegal and Ghana groups (4 to 6 days) than in the Nigeria group (8 days). Second, each virus strain produced a distinct clinical syndrome. Third, the spread of virus to peripheral tissues, tested by hemi-nested reverse transcriptase PCR, was frequent (3 of 3 bats) and widespread (8 to 10 tissues positive of 11 tissues examined) in the Ghana group, was frequent and less widespread in the Senegal group (3/3 bats, 3 to 6 tissues positive), and was rare and restricted in the Nigeria group (1/3 bats, 2 tissues positive). Centrifugal spread of virus from brain to tissue of excretion in the oral cavity is required to enable lyssavirus transmission. Therefore, the Senegal and Ghana strains seem most suitable for further pathogenesis, and for transmission, studies in the straw-colored fruit bat.

Molecular approaches for blood meal analysis and species identification of mosquitoes (Insecta: Diptera: Culicidae) in rural locations in southern England, United Kingdom

Thirty-four species of Culicidae are present in the UK, of which 15 have been implicated as potential vectors of arthropod-borne viruses such as West Nile virus. Identification of mosquito feeding preferences is paramount to the understanding of vector-host-pathogen interactions which, in turn, would assist in the control of disease outbreaks. Results are presented on the application of DNA barcoding for vertebrate species identification in blood-fed female mosquitoes in rural locations. Blood-fed females (n = 134) were collected in southern England from rural sites and identified based on morphological criteria. Blood meals from 59 specimens (44%) were identified as feeding on eight hosts: European rabbit, cow, human, barn swallow, dog, great tit, magpie and blackbird. Analysis of the cytochrome c oxidase subunit I mtDNA barcoding region and the internal transcribed spacer 2 rDNA region of the specimens morphologically identified as Anopheles maculipennis s.l. revealed the presence of An. atroparvus and An. messeae. A similar analysis of specimens morphologically identified as Culex pipiens/Cx. torrentium showed all specimens to be Cx. pipiens (typical form). This study demonstrates the importance of using molecular techniques to support species-level identification in blood-fed mosquitoes to maximize the information obtained in studies investigating host feeding patterns.