Gudrun Wibbelt

Inoculation of bats with European Geomyces destructans supports the novel pathogen hypothesis for the origin of white-nose syndrome.

White-nose syndrome (WNS) is an emerging disease of hibernating bats associated with cutaneous infection by the fungus Geomyces destructans (Gd), and responsible for devastating declines of bat populations in eastern North America. Affected bats appear emaciated and one hypothesis is that they spend too much time out of torpor during hibernation, depleting vital fat reserves required to survive the winter. The fungus has also been found at low levels on bats throughout Europe but without mass mortality. This finding suggests that Gd is either native to both continents but has been rendered more pathogenic in North America by mutation or environmental change, or that it recently arrived in North America as an invader from Europe. Thus, a causal link between Gd and mortality has not been established and the reason for its high pathogenicity in North America is unknown. Here we show that experimental inoculation with either North American or European isolates of Gd causes WNS and mortality in the North American bat, Myotis lucifugus. In contrast to control bats, individuals inoculated with either isolate of Gd developed cutaneous infections diagnostic of WNS, exhibited a progressive increase in the frequency of arousals from torpor during hibernation, and were emaciated after 3–4 mo. Our results demonstrate that altered torpor-arousal cycles underlie mortality from WNS and provide direct evidence that Gd is a novel pathogen to North America from Europe.

Pan-European Distribution of White-Nose Syndrome Fungus (Geomyces destructans) Not Associated with Mass Mortality

Background The dramatic mass mortalities amongst hibernating bats in Northeastern America caused by “white nose-syndrome” (WNS) continue to threaten populations of different bat species. The cold-loving fungus, Geomyces destructans, is the most likely causative agent leading to extensive destruction of the skin, particularly the wing membranes. Recent investigations in Europe confirmed the presence of the fungus G. destructans without associated mass mortality in hibernating bats in six countries but its distribution remains poorly known. Methodology/Principal Findings We collected data on the presence of bats with white fungal growth in 12 countries in Europe between 2003 and 2010 and conducted morphological and genetic analysis to confirm the identity of the fungus as Geomyces destructans. Our results demonstrate the presence of the fungus in eight countries spanning over 2000 km from West to East and provide compelling photographic evidence for its presence in another four countries including Romania, and Turkey. Furthermore, matching prevalence data of a hibernaculum monitored over two consecutive years with data from across Europe show that the temporal occurrence of the fungus, which first becomes visible around February, peaks in March but can still be seen in some torpid bats in May or June, is strikingly similar throughout Europe. Finally, we isolated and cultured G. destructans from a cave wall adjacent to a bat with fungal growth. Conclusions/Significance G. destructans is widely found over large areas of the European continent without associated mass mortalities in bats, suggesting that the fungus is native to Europe. The characterisation of the temporal variation in G. destructans growth on bats provides reference data for studying the spatio-temporal dynamic of the fungus. Finally, the presence of G. destructans spores on cave walls suggests that hibernacula could act as passive vectors and/or reservoirs for G. destructans and therefore, might play an important role in the transmission process.

White-Nose Syndrome Fungus (Geomyces destructans) in Bats, Europe

Unlike bats in North America, bats in Europe are not killed by this fungus.

Temperature-dependent growth of Geomyces destructans, the fungus that causes bat white-nose syndrome

White-nose syndrome (WNS) is an emergent disease estimated to have killed over five million North American bats. Caused by the psychrophilic fungus Geomyces destructans, WNS specifically affects bats during hibernation. We describe temperature-dependent growth performance and morphology for six independent isolates of G. destructans from North America and Europe. Thermal performance curves for all isolates displayed an intermediate peak with rapid decline in performance above the peak. Optimal temperatures for growth were between 12.5 and 15.8°C, and the upper critical temperature for growth was between 19.0 and 19.8°C. Growth rates varied across isolates, irrespective of geographic origin, and above 12°C all isolates displayed atypical morphology that may have implications for proliferation of the fungus. This study demonstrates that small variations in temperature, consistent with those inherent of bat hibernacula, affect growth performance and physiology of G. destructans, which may influence temperature-dependent progression and severity of WNS in wild bats.

Pathophysiology of white-nose syndrome in bats: a mechanistic model linking wing damage to mortality.

White-nose syndrome is devastating North American bat populations but we lack basic information on disease mechanisms. Altered blood physiology owing to epidermal invasion by the fungal pathogen Geomyces destructans (Gd) has been hypothesized as a cause of disrupted torpor patterns of affected hibernating bats, leading to mortality. Here, we present data on blood electrolyte concentration, haematology and acid–base balance of hibernating little brown bats, Myotis lucifugus, following experimental inoculation with Gd. Compared with controls, infected bats showed electrolyte depletion (i.e. lower plasma sodium), changes in haematology (i.e. increased haematocrit and decreased glucose) and disrupted acid–base balance (i.e. lower CO2 partial pressure and bicarbonate). These findings indicate hypotonic dehydration, hypovolaemia and metabolic acidosis. We propose a mechanistic model linking tissue damage to altered homeostasis and morbidity/mortality.

White-nose syndrome: is this emerging disease a threat to European bats?

White-nose syndrome (WNS) is a newly emergent disease that potentially threatens all temperate bat species. A recently identified fungus, Geomyces destructans, is the most likely causative agent of this disease. Until 2009, WNS and G. destructans were exclusively known from North America, but recent studies have confirmed this fungus is also present in Europe. We assembled an international WNS consortium of 67 scientists from 29 countries and identified the most important research and conservation priorities to assess the risk of WNS to European bats. Here, we review what is known about WNS and G. destructans and detail the conservation and research recommendations aimed at understanding and containing this emerging infectious disease.

Rat-to-elephant-to-human transmission of cowpox virus.

To the Editor: Despite the eradication of smallpox in the past century, other orthopoxviruses, such as monkeypox virus, vaccinia virus in Brazil, and cowpox virus (CPXV) in Europe (1), still infect humans. CPXV has been restricted to the Old World with wild rodents as its natural reservoir (2,3). Human CPXV infections are commonly described in relation to contact with diseased domestic cats, rarely directly from rats (2,4). Human infections usually remain localized and self-limiting but can become fatal in immunosuppressed patients (5). CPXV infections in captive exotic animals have been reported to be transmitted by rodents (2,6). In February 2007, a circus elephant (Elephas maximus) in northern Germany exhibited disseminated ulcerative lesions of the skin and mucosal membranes (Figure, panel A) caused by CPXV infection; the elephant was euthanized after treatment attempts failed. Electron micrographs of negative-stained biopsy specimens of tongue lesions showed orthopoxvirus particles. The presence of orthopoxvirus after routine virus isolation in Hep2 cells was confirmed in direct immunofluorescence assay with orthopox-specific antibodies. The morphologic feature of hemorrhagic pocks on the chorioallantoic membrane (CAM) of infected embryonated hen’s eggs indicated CPXV. This finding was confirmed by sequence analysis of the complete hemagglutinin (HA) open reading frame (ORF), which showed 99% homology of 921 bp to CPXV isolated in 1984 from an elephant in Hamburg, Germany (Figure, panel B). A serum sample was drawn from the elephant 2 weeks before euthanasia. An indirect fluorescent antibody test (IFAT) detected immunoglobulin (Ig) G antibodies against the new corresponding elephant virus isolate (termed CPXV GuWi) with a titer of 1,260. According to the owner, the >40-year-old female elephant had never been vaccinated with vaccinia virus. Figure Route of cowpox virus (CPXV) transmission and phylogenetic analysis of orthopoxviruses. A) Disseminated ulcerative lesions of the skin around the eye of the circus elephant. Although transmission of CPXV has been confirmed from cats and cows to humans ... Eight days after the elephant’s death, a circumscribed lesion developed on the back of the right hand of a 19-year-old immunocompetent, healthy, unvaccinated animal keeper. CPXV was isolated from lesion fluid and was found to be homologous by using the HA ORF to CPXV GuWi. A convalescent-phase serum sample from the keeper taken 3 weeks later showed a significant increase in IgM (from 40 to 2,560), IgG (from 20 to 10,240), and neutralizing antibody (from <5 to 80) titers. Further simultaneous investigations were undertaken to determine the source of infection. Because no felids were kept on the circus premises, the focus centered on wild rodents that had propagated and infested the area because of the mild winter. Six days after the elephant’s death, 4 rats (Rattus norvegicus) were caught and tested for orthopoxvirus antibodies. Although none of the rats had epidermal lesions or other pathologic changes indicative of a poxvirus infection, all were tested by IFAT and found to be serologically positive (IgG titers 40, 320, 2,560, and >10,240; IgM titers <5, <5, 160, and 2,560), indicating a recent infection in at least 2 animals. CPXV-typical pock morphologic features on the CAM could be visualized after homogenized liver and spleen of the animal with the highest titer was passaged 3 times. Infected CAM and original organ tissues (liver and spleen) showed CPXV by PCR and subsequent sequencing. The corresponding HA ORF displayed perfect homology to the viruses isolated from the elephant and the animal keeper. We report CPXV infection in humans transmitted from an elephant, with rats as a probable source of the elephant’s infection (Figure, panel A). Although the animal keeper was infected by direct contact with the elephant, the exact transmission route from rat to elephant remains unclear. Nevertheless, rats have proven to be a natural reservoir for CPXV (4,7), and infections persisting for >3 weeks were shown for other rodents (8). No data about CPXV prevalence in rats are available, and no data for CPXV isolates from rats have been published in Germany. Therefore, further studies on rats as CPXV reservoir are needed to estimate the potential risk for infection among humans and exotic animals. Zoo and circus animals, especially elephants, seem to be highly susceptible to generalized CPXV infections. Although modified vaccinia virus Ankara was authorized in Germany to be used in vaccinating exotic animals (9), this case highlights the need for increased efforts toward general vaccination of potentially susceptible exotic animals in Europe. The sequence identity of the HA ORFs also demonstrates a low mutation rate of CPXV after it crosses species barriers. As the Figure, panel B, infers, there is a phylogenetic difference between CPCV GuWi and CPXV from a human patient living in the same geographic area (CPXV #2), which indicates the cocirculation of >1 CPXV variant (9,10). Considering the extremely high virus load in infected animals, the broad host range of CPXV, and the abandoned vaccination against smallpox, this case emphasizes the risk among humans of acquiring CPXV infection (6). It also highlights the need for increased awareness regarding clinical features of orthopoxvirus infections and the importance of developing new antiviral drugs against orthopoxviruses.

Emerging diseases in Chiroptera: Why bats?

A conference entitled ‘2nd International Berlin Bat Meeting: Bat Biology and Infectious Diseases’ was held between the 19 and 21 of February 2010 in Berlin, Germany. Researchers from two major disciplines, bat biologists and disease specialists, met for the first time in an interdisciplinary event to share their knowledge about bat-associated diseases. The focus of the meeting was to understand why in particular bats are the hosts of so many of the most virulent diseases globally. During several sessions, key note speakers and participants discussed infectious diseases associated with bats, including viral diseases caused by Henipa-, Filo-, Corona- and Lyssaviruses, the spread of white-nose syndrome in North American bats, bat immunology/immunogenetics, bat parasites, and finally, conservation and human health issues.

Novel Paramyxoviruses in Free-Ranging European Bats

The zoonotic potential of paramyxoviruses is particularly demonstrated by their broad host range like the highly pathogenic Hendra and Nipah viruses originating from bats. But while so far all bat-borne paramyxoviruses have been identified in fruit bats across Africa, Australia, South America, and Asia, we describe the detection and characterization of the first paramyxoviruses in free-ranging European bats. Moreover, we examined the possible impact of paramyxovirus infection on individual animals by comparing histo-pathological findings and virological results. Organs from deceased insectivorous bats of various species were sampled in Germany and tested for paramyxovirus RNA in parallel to a histo-pathological examination. Nucleic acids of three novel paramyxoviruses were detected, two viruses in phylogenetic relationship to the recently proposed genus Jeilongvirus and one closely related to the genus Rubulavirus. Two infected animals revealed subclinical pathological changes within their kidneys, suggestive of a similar pathogenesis as the one described in fruit bats experimentally infected with Hendra virus. Our findings indicate the presence of bat-born paramyxoviruses in geographic areas free of fruit bat species and therefore emphasize a possible virus–host co-evolution in European bats. Since these novel viruses are related to the very distinct genera Rubulavirus and Jeilongvirus, a similarly broad genetic diversity among paramyxoviruses in other Microchiroptera compared to Megachiroptera can be assumed. Given that the infected bats were either found in close proximity to heavily populated human habitation or areas of intensive agricultural use, a potential risk of the emergence of zoonotic paramyxoviruses in Europe needs to be considered.

Genome Analysis of Bat Adenovirus 2: Indications of Interspecies Transmission

ABSTRACT The genome of bat adenovirus 2 was sequenced and analyzed. It is similar in size (31,616 bp) to the genomes of bat adenovirus 3 and canine adenoviruses 1 and 2. These four viruses are monophyletic and share an identical genome organization, with one E3 gene and four E4 genes unique to this group among the mastadenoviruses. These findings suggest that canine adenoviruses may have originated by interspecies transfer of a vespertilionid bat adenovirus.