The outbreak of bluetongue disease in 2006 in Central Europe - Facts and questions

Im August 2006 brach die BTD erstmals in Mitteleuropa aus. Zunächst traten Fälle in Holland und Belgien auf, schnell folgten Deutschland und Frankreich, und schließlich auch Luxemburg. Betroffen waren vorwiegend Kühe und Schafe, vereinzelt Ziegen und Wildwiederkäuer. Überraschenderweise erkrankten neben Schafen auch zahlreiche Kühe schwer, und einige verendeten sogar. Als infektiöses Agens konnte der BTV-Serotyp 8 identifiziert werden, der niemals zuvor in Europa aufgetreten war. Bis zum Jahresende konnte sich die BTD insbesondere im Dreiländereck von Holland, Belgien und Deutschland weiter ausbreiten. Nach dem Animal Disease Notification System der EU waren Ende 2006 in den betroffenen fünf Ländern BTD-Ausbrüche in 2047 Viehwirtschaftsbetrieben bestätigt worden: Holland 456, Belgien 695, Deutschland 885, Frankreich 6 und Luxemburg 5 Obwohl die Hoffnung bestand, dass die Ceratopogoniden mit dem Einbruch des Winters verschwinden und keine Virustransmission mehr stattfinden würden, wurden neue Ausbrüche auch nachfolgend verzeichnet (75 weitere bis 1. Februar 2007, davon allein 67 in Deutschland; ProMED-Mail 2007), wobei bisher nicht klar ist, ob es sich tatsächlich um Neuinfektionen oder um verspätet diagnostizierte Infektionen aus 2006 handelt. Die Aktivitätsdichte der Gnitzen nahm gegen Ende 2006 mit sinkenden Temperaturen zwar ab, war jedoch zumindest bis zum 21. Dezember niemals gleich Null (Mehlhorn & al. 2007). Mit fortschreitender Dauer der Epizootie wurde auch eine geografische Ausbreitung nach Osten beobachtet. Anfang Februar 2007 waren fast alle deutschen Bundesländer von den BTD-Schutz- und Überwachungszonen betroffen (Abb. 1), in denen besondere Vorschriften für den Transport und Handel mit Wiederkäuern gelten (EU 2005).In August 2006, bluetongue disease, a ceratopogonid-borne viral infection of ruminants, broke out in Europe for the first time north of the Mediterranean distribution area of its most important Old World vector, Culicoides imicola. Up to the end of 2006, the disease was recorded at 2047 farms in Belgium, The Netherlands, France, Germany and Luxembourg where numerous cattle and sheep were affected. While 24 serotypes of the bluetongue virus have been characterized worldwide, the virus strain involved in the central European outbreak was classified as serotype 8. By contrast, in southern Europe, where the disease has been enzootic since 1998, serotypes 1, 2, 4, 9, and 16 have been found, but not serotype 8. The virus in question was most closely related to a strain isolated in 1982 in Nigeria, as confirmed by nucleotide sequencing data. It is still unclear when and how the virus was imported into central Europe although the import of infected ruminants from Africa is the most likely route. Indigenous ceratopogonid species presumed to be involved as vectors were those of the Culicoides obsoletus and C. pulicaris groups, which are distributed across much of Europe. In October 2006, the virus was isolated from C. dewulfi caught in The Netherlands, and later on from C. obsoletus collected in Germany. Although mechanisms enabling the virus to overwinter were discussed, it was hoped that the epizootic would disappear automatically as a consequence of the seasonal disappearance of the vectors. However, due to the mild winter temperatures (and possibly unknown biological peculiarities of the indigenous ceratopogonid fauna), ceratopogonids continued to be active at least until late December 2006 and new cases of bluetongue disease were still being recorded in early 2007

Activity of Culicoides spp. (Diptera: Ceratopogonidae) inside and outside of livestock stables in late winter and spring

Culicoides Latreille, 1809 midge species are the putative vectors of Bluetongue virus (BTV) and Schmallenberg virus (SBV) in Europe. To gain a better understanding of the epidemiology of the diseases, basic knowledge about the overwintering of the vectors is needed. Therefore, we investigated culicoid activity in relation to air temperature at livestock stables during late winter and spring season. Ceratopogonids were captured weekly indoors and outdoors on three cattle farms, three horse farms and one sheep farm in the federal state of Brandenburg, Germany between January and May, 2015 by BG-Sentinel UV-light suction traps. First seasonal activity was measured inside a sheep barn and cattle stables in mid-March, suggesting the existence of a preceding vector-free period. The first species at all trapping sites were members of the Obsoletus Complex followed by Culicoides punctatus (Meigen), 1804 and Culicoides pulicaris (Linnaeus), 1758 simultaneously. In total, 160 collections were made, including 3465 Culicoides specimens with 2790 (80.6%) of them being members of the Obsoletus Complex. The remaining 675 individuals belonged to six other culicoid species. 59.8% of all Culicoides were collected indoors, and almost five times as many midges were sampled on cattle farms as on horse farms. Cattle farms harboured seven species while only two species were found on the horse and the sheep farms, respectively. Temperatures, husbandry practises and the presence/quality of potential breeding sites might be responsible for the difference in species and numbers of caught specimens between livestock holdings

Anophelinae (Diptera: Culicidae) in ausgewählten Marschgebieten Niedersachsens : Bestandserfassung, Habitatbindung und Interpolation

Nach HIRSCH (1883) war die Malariasituation im 19. Jahrhundert in Norddeutschland am schlimmsten in Schleswig-Holstein, an der Küste westlich der Elbe sowie in den Moorgebieten von Hannover und Oldenburg. Erst mit Beginn des 20. Jahrhunderts nahm dort die Zahl der Infektionen ab. Dieser Rückgang wurde vielfach auf die Trockenlegung von Marsch-, Sumpf- und Moorgebieten zurückgeführt (MAIER 2004). Aktuell wird deshalb in Teilen der Bevölkerung ein Wiederaufflackern der Malaria bzw. anderer Mückenassoziierter Krankheiten als indirekte Folge von Wiedervernässungsmaßnahmen befürchtet. Hinzu kommen Klima- und weitere Umweltveränderungen, welche nach MAIER et al. (2003) Ursache für neu auftretende oder wiederkehrende Krankheiten sein können. Mit dem Verschwinden der Malaria wurde in Deutschland kaum weitere Forschung zur Verbreitung und Ökologie der Culiciden betrieben. Das Fehlen von fundierten Daten zur Ökologie und Populationsentwicklung der präimaginalen Culicidenstadien in den heute vorhandenen Lebensräumen (z.B. Gräben, Polder, Wiedervernässungsflächen, Mooren) erschwert Aussagen und Prognosen zur Verbreitung potenzieller Vektoren. Die aktuellen Untersuchungen konzentrierten sich zunächst auf die Untersuchung der aquatischen Entwicklungsstadien von Anopheles-Arten (Diptera: Culicidae) in Entwässerungsgräben. Diese Biotope sind für die heutige Landschaftsstruktur der Marschengebiete im Nordwesten Niedersachsens typisch, stellen dort einen hohen Anteil der Wasserflächen dar und sind grundsätzlich als Brutgewässer geeignet (CRANSTON et al. 1987, MOHRIG 1969). Wesentliches Ziel der Untersuchung war zunächst die Darstellung historischer Fundgebiete, der abgesicherte Nachweis aktueller Brutgebiete verschiedener Anopheles-Arten und die Entwicklung einer standardisierten Methode zur Charakterisierung der betreffenden Biotope. Darauf aufbauend sollen mit GISTechniken, Classification and Regression Trees (CART) und Geostatistik zukünftig Möglichkeiten der Übertragung dieser Resultate auf ähnlich ausgestattete Landschaftsräume geprüft werden.The disappearance of malaria from Northern Germany in the middle of the 20th century was closely linked to a significant reduction of Anopheles breeding sites as a consequence of intense drainage of marshes, swamps and moors. Nature conservation activities and the reestablishment of swamps and wetland areas may nowadays lead to a converse effect and contribute to the multiplication and spread of culicid mosquitoes again. Therefore, the monitoring of their distribution and abundance is advisable. The presented investigation concentrates on typical Lower Saxony marshland ditches and on their suitability to provide breeding facilities for Culicidae in general, and for the former malaria vectors An. atroparvus and An. messeae in particular. The study area was fixed geographically with special reference to historical vector findings, former malaria regions and current archive data. To determine the habitat preferences of the mosquitoes, a structural mapping of single ditches was performed and essential abiotic factors were recorded. Anopheles specimens regularly were found in ditches with submerse and emerse macrophytes but never in ditches with a high degree of surface coverage by swimming plants. Conductivity, pHvalue and total phosphate in the water body appear to be further variables which correlate with the occurrence and abundance of Anopheles larvae and pupae and therefore can be used for predictions. By means of geographic information systems (GIS) and geostatistical procedures, a surface related assessment of the given Anopheles densities within the ditches should now be feasible. To this end, the multivariate correlations between the empirical data were analysed by Classification and Regression Trees. The relations detected serve to predict the empirical findings to biotopes similar to the sampling sites. Furthermore, recent climate predictions will be analysed with respect to possible effects climate change may have on the distribution of Anophilinae in Lower Saxon

Contribution to the occurrence and distribution of culicid mosquitoes in Northrhine-Westphalia with special reference to the greater Bonn area

Mit dem Verschwinden der Malaria aus Deutschland in der Mitte des letzten Jahrhunderts sank auch das wissenschaftliche Interesse an Stechmücken. Seit Jahrzehnten sind keine großflächigen systematischen Studien zum Vorkommen und zur Verbreitung der einheimischen Culicidenarten mehr durchgeführt worden, da diese scheinbar keine Vektorfunktion mehr hatten. Lediglich saisonal bedingte Massenvermehrungen waren und sind Anlass zu gezielten Bekämpfungsaktionen, die auch aktuell regionale Daten zur Stechmückenfauna liefern (BECKER & KAISER 1995). Diese und weitere sporadische Studien aus den letzten Jahren (BASTIAN 2000; HERRMANN 2000; KAMPEN unveröffentl.) zeigen, dass potenzielle Malariaüberträger nach wie vor bei uns heimisch sind. Gerade die anhaltende Diskussion über ‚emerging and resurging infectious diseases’ in Verbindung mit möglichen Klima- und Umweltveränderungen (GRATZ 1999, 2004) sollte aber das allgemeine Interesse an den einheimischen (potenziellen) Vektoren wecken, um für Eventualitäten gewappnet zu sein. Der weltweite Massentourismus und Tierhandel sorgt nicht nur für ein permanentes Angebot an Infektionsquellen für einheimische hämatophage Arthropoden, sondern erleichtert auch die Einschleppung und Ausbreitung von allochthonen Vektoren. So gelangte etwa die Tigermücke Aedes albopictus, ein effizienter Gelbfieber- und Dengue-Vektor, zu Beginn der 1990er Jahre mit dem Gebrauchtreifenhandel nach Südeuropa (KNUDSEN et al. 1996) und wandert seitdem ständig weiter nach Norden (SCHAFFNER 2001; FLACIO et al. 2004; SCHOLTE et al. 2006). Doch auch Zugvögel bringen seit jeher Viren aus afrikanischen Ländern nach Europa undkönnen einheimische Vektoren infizieren (MALKINSON & BANET 2002). Bis auf wenige Ausnahmen blieben große Epidemien bisher aus. Nicht so in Nordamerika, wo 1999 auf bislang unbekanntem Wege das West Nil-Virus eingeschleppt wurde und sich bis 2003 über die gesamten Vereinigten Staaten ausbreitete (GOULD & FIKRIG 2004). Zahlreiche Todesfälle bei Menschen, Pferden und Vögeln, insbesondere auf eine Virusübertragung durch Culex pipiens zurückzuführen, waren die Folge. Mit dem Tahyna-, Sindbis- und West Nil-Virus kursieren mindestens drei pathogene Stechmückenassoziierte Viren auch in Europa (ASPÖCK 1996; LUNDSTRÖM 1999). Erst kürzlich wurde in toten Vögeln in Österreich erstmals das Usutu-Virus außerhalb Afrikas nachgewiesen (WEISSENBÖCK et al. 2002). Ob es humanpathogenes Potenzial hat, ist unbekannt. Schließlich sind Stechmücken als Überträger der caninen Filariose von Bedeutung, die gelegentlich auch den Menschen befallen kann und sich offenbar ebenfalls vom Mittelmeerraum nach Norden ausbreitet (MURO 1999; PAMPIGLIONE & RIVASI 2000). Die vorgestellte Studie soll einen Beitrag zur Aktualisierung unserer Kenntnisse zum Vorkommen, zur Verbreitung und zur Biologie einheimischer Culiciden liefern, die erforderlich sind, um auf autochthone Erregerübertragung in geeigneter Weise reagieren zu können.To update information on the indigenous culicid fauna (Diptera: Culicidae) of western Germany, aquatic mosquito stages were collected by water dipping and adults caught by specialized traps at various Northrhine-Westphalian localities in 2004. Out of 154 water basins checked, 75 turned out to be culicid breeding sites. 1404 larvae and pupae belonging to 17 species were collected. These comprised 7 Aedes-, 4 Culex-, 4 Anopheles- and 2 Culiseta-species. Cx. territans specimens added up to 44.7 % of the larval and pupal catches and together with the three other most abundant species, Cs. annulata (14.7 %), An. maculipennis s.s. (12.3 %) and Cx. torrentium (10 %), amounted to 81.8 % of all larvae and pupae collected. With regard to the adult stages, only 111 specimens belonging to 8 species were trapped probably owing to methodological reasons and/or to the particular mosquito-hostile climatic conditions in the summer of 2004. In contrast to the larval collections, the major part of the adults were Cx. torrentium with 34.2 %, followed by Cx. pipiens s.s. (21.6 %) and An. plumbeus (19.8 %), thus giving a completely different impression on the indigenous population abundances. 105 of the adults were caught by the BG sentinel, a newly developed odour trap emitting a quantified composition of selected mosquito attractants. The other 6 individuals were caught by a CO2-trap, whereas a mere light trap and an ovipositor trap were never successfu

The role of the blackbird (Turdus merula), redwing (Turdus iliacus) and song trush (Turdus philomelos) as blood hosts for ticks (Acari: Ixodidae) and reservoir hosts for four genospecies of the Borrelia burgdorferi-complex

Vögel spielen vor allem aufgrund ihrer Häufigkeit in natürlichen und anthropogenen Habitaten sowie ihrer von anderen Wirbeltieren unübertroffenen Mobilität als natürliche Reservoire von Krankheitserregern eine bedeutende infektionsepidemiologische Rolle. Darüber hinaus können Zugvögel während ihrer Migration Erreger wie Vektoren über hunderte oder tausende von Kilometern transportieren und in ihrer Verbreitung extrem begünstigen. Dass Vögel neben anderen Tiergruppen eine wichtige Wirtsfunktion für Zecken besitzen, ist bekannt. Ebenso wird Vögeln eine Reservoirfunktion für bestimmte Genospezies des Borrelia burgdorferi-Artenkomplexes zugesprochen (GERN et al. 1998; GYLFE et al. 2000). In welchem Maße verschiedene Vogelarten an der geographischen Verbreitung dieser Bakterienarten beteiligt sind, ist jedoch noch weitgehend unklar. In dieser Studie sollte durch die Untersuchung von an Vögeln abgesammelten Zecken (Ixoes ricinus) die Bedeutung von drei Drosselarten (Turdidae) für den Lebenszyklus der Borrelien genauer untersucht werden. Des Weiteren wurde die Reservoirfunktion dieser Vogelarten für vier verschiedene Genospezies des B. burgdorferi-Komplexes geprüft.In spring 2003, 251 specimens of the three bird species, blackbird (Turdus merula), redwing (Turdus iliacus) and song trush (Turdus philomelos) that had been trapped on the Greifswalder Oie, a small German island in the Baltic sea, were examined for ticks (I. ricinus). 806 ticks (305 larvae, 508 nymphs) were removed from the birds and stored in 80% ethanol or, in the case of full engorgement, kept alive until moulting. The infestation prevalences of the three bird species ranged from 39,5 % to 68,2 % demonstrating the important role of these species as tick hosts. Out of 377 ticks, 104 were tested DNA-positive for B. burgdorferi sensu lato by a polymerase chain reaction assay. The increasing infection prevalences of larvae (19,7 %), nymphs (30,0 %) and adults obtained from repleted nymphs (38,9 %) display the reservoir function of the birds for B. burgdorferi s.l.. The Borrelia-positive tick specimens were additionally tested for the respective B. burgdorferi-genospecies present, B. burgdorferi sensu stricto, B. afzelii, B. garinii and/or B. valaisiana, via DNA-hybridisation. 94,8 % of the ticks were found positive for B. garinii or B. valaisiana. Although these two genospecies are known to be bird-specific, so far there is little evidence on different bird species having different kinds of reservoir competence. According to the results of this study, however, a special correlation between infecting genospecies and avian reservoir host species appears to be likely and has to be proven by further epidemiological and immunological studies

Buzzing Homes: Using Citizen Science Data to Explore the Effects of Urbanization on Indoor Mosquito Communities

Urbanization has been associated with a loss of overall biodiversity and a simultaneous increase in the abundance of a few species that thrive in urban habitats, such as highly adaptable mosquito vectors. To better understand how mosquito communities differ between levels of urbanization, we analyzed mosquito samples from inside private homes submitted to the citizen science project ‘Mückenatlas’. Applying two urbanization indicators based on soil sealing and human population density, we compared species composition and diversity at, and preferences towards, different urbanization levels. Species composition between groups of lowest and highest levels of urbanization differed significantly, which was presumably caused by reduced species richness and the dominance of synanthropic mosquito species in urban areas. The genus Anopheles was frequently submitted from areas with a low degree of urbanization, Aedes with a moderate degree, and Culex and Culiseta with a high degree of urbanization. Making use of citizen science data, this first study of indoor mosquito diversity in Germany demonstrated a simplification of communities with increasing urbanization. The dominance of vector-competent species in urban areas poses a potential risk of epidemics of mosquito-borne diseases that can only be contained by a permanent monitoring of mosquitoes and by acquiring a deeper knowledge about how anthropogenic activities affect vector ecology

Blood parasites in vectors reveal a united blackfly community in the upper canopy.

Chakarov N, Kampen H, Wiegmann A, Werner D, Bensch S. Blood parasites in vectors reveal a united blackfly community in the upper canopy. Parasites & vectors. 2020;13(1): 309.BACKGROUND: The behaviour of blood-sucking arthropods is a crucial determinant of blood protozoan distribution and hence of host-parasite coevolution, but it is very challenging to study in the wild. The molecular identification of parasite lineages in vectors can be a useful key to understand the behaviour and transmission patterns realised by these vectors.; METHODS: In this study, we collected blackflies around nests of three raptor species in the upper forest canopy in central Europe and examined the presence of vertebrate DNA and haemosporidian parasites in them. We molecularly analysed 156 blackfly individuals, their vertebrate blood meals, and the haemosporidian parasite lineages they carried.; RESULTS: We identified nine species of Simulium blackflies, largely belonging to the subgenera Nevermannia and Eusimulium. Only 1% of the collected specimens was visibly engorged, and only 4% contained remains of host DNA. However, in 29% of the blackflies Leucocytozoon lineages were identified, which is evidence of a previous blood meal on an avian host. Based on the known vertebrate hosts of the recorded Leucocytozoon lineages, we can infer that large and/or abundant birds, such as thrushes, crows, pigeons, birds of prey, owls and tits are the main targets of ornithophilic blackflies in the canopy. Blackfly species contained similar proportions of host group-specific parasite lineages and thus do not appear to be associated with particular host groups.; CONCLUSIONS: The Leucocytozoon clade infecting thrushes, crows, and pigeons present in most represented blackfly species suggests a lack of association between hosts and blackflies, which can increase the probability of host switches of blood parasites. However, the composition of the simuliid species differed between nests of common buzzards, goshawks and red kites. This segregation can be explained by coinciding habitat preferences between host and vector, and may lead to the fast speciation of Leucocytozoon parasites. Thus, subtle ecological preferences and lack of host preference of vectors in the canopy may enable both parasite diversification and host switches, and enforce a habitat-dependent evolution of avian malaria parasites and related haemosporidia

In memory of Professor Dr Werner Mohrig (*17 December 1937 – †26 April 2019)

Der deutsche Zoologe Werner Mohrig verstarb im Alter von 81 Jahren am 26. April 2019 in Gießen (Hessen). Als Professor für Allgemeine Zoologie lehrte er am Zoologischen Institut und Museum der Ernst-Moritz-Arndt-Universität in Greifswald. In dieser Zeit erwarb sich Professor Dr. Mohrig vor allem bei der Ausbildung und Förderung des dipterologischen und immunbiologischen Nachwuchses große Verdienste. Bei den Entomologen ist er vor allem durch seine umfangreichen taxonomisch-systematischen Studien über die niederen Diptera (Cecidomyiidae, Culicidae, Sciaridae) weltweit bekannt. Die vorliegende Arbeit gibt neben dem biographischen Abriss seines Lebens eine Publikationsliste, die 201 wissenschaftliche Arbeiten aus der Entomologie und Immunologie sowie zu anthropologischen und demographischen Problemen zusammenfasst. Den Abschluss bildet eine Liste der von Werner Mohrig beschriebenen Taxa, in der 3 präokkupierte Namen ersetzt und 15 Arten in eine andere Gattung kombiniert werden.The German zoologist Werner Mohrig died on the 26th April 2019, at the age of 81, in Gießen (Hesse). As professor of general zoology he taught at the Zoological Institute and Museum of the Ernst Moritz Arndt University in Greifswald. In this capacity, Professor Dr Mohrig was responsible for the education and training of many young dipterists and immunobiologists. Among entomologists, he is known worldwide for his extensive taxonomic and systematic studies on the lower Diptera (Cecidomyiidae, Culicidae, Sciaridae). In addition to a biographical sketch of his life, this paper lists his 201 scientific papers on entomology and immunology, as well as anthropological and demographic topics. The final part is a list of taxa described by Werner Mohrig, in which 3 preoccupied names are replaced and 15 species names are newly combined with a different genus

Drivers of spatio-temporal variation in mosquito submissions to the citizen science project ‘Mückenatlas’

Intensified travel activities of humans and the ever growing global trade create opportunities of arthropod-borne disease agents and their vectors, such as mosquitoes, to establish in new regions. To update the knowledge of mosquito occurrence and distribution, a national mosquito monitoring programme was initiated in Germany in 2011, which has been complemented by a citizen science project, the ‘Mückenatlas’ since 2012. We analysed the ‘Mückenatlas’ dataset to (1) investigate causes of variation in submission numbers from the start of the project until 2017 and to (2) reveal biases induced by opportunistic data collection. Our results show that the temporal variation of submissions over the years is driven by fluctuating topicality of mosquito-borne diseases in the media and large-scale climate conditions. Hurdle models suggest a positive association of submission numbers with human population, catch location in the former political East Germany and the presence of water bodies, whereas precipitation and wind speed are negative predictors. We conclude that most anthropogenic and environmental effects on submission patterns are associated with the participants’ (recording) behaviour. Understanding how the citizen scientists’ behaviour shape opportunistic datasets help to take full advantage of the available information

Recently discovered Aedes japonicus japonicus (Diptera: Culicidae) populations in The Netherlands and northern Germany resulted from a new introduction event and from a split from an existing population

BACKGROUND: Originally native to East Asia, Aedes japonicus japonicus, a potential vector of several arboviruses, has become one of the most invasive mosquito species in the world. After having established in the USA, it is now spreading in Europe, with new populations emerging. In contrast to the USA, the introduction pathways and modes of dispersal in Europe are largely obscure. METHODS: To find out if two recently detected populations of Ae. j. japonicus in The Netherlands and northern Germany go back to new importations or to movements within Europe, the genetic makeup of mosquito specimens from all known European populations was compared. For this purpose, seven microsatellite loci from a representative number of mosquito specimens were genotyped and part of their mitochondrial nad4 gene sequenced. RESULTS: A novel nad4 haplotype found in the newly discovered Dutch population of Ae. j. japonicus suggests that this population is not closely related to the other European populations but has emanated from a further introduction event. With five nad4 haplotypes, the Dutch population also shows a very high genetic diversity indicating that either the founder population was very large or multiple introductions took place. By contrast, the recently detected North German population could be clearly assigned to one of the two previously determined European Ae. j. japonicus microsatellite genotypes and shows nad4 haplotypes that are known from West Germany. CONCLUSION: As the European populations of Ae. j. japonicus are geographically separated but genetically mixed, their establishment must be attributed to passive transportation. In addition to intercontinental shipment, it can be assumed that human activities are also responsible for medium- and short-distance overland spread. A better understanding of the processes underlying the introduction and spread of this invasive species will help to increase public awareness of the human-mediated displacement of mosquitoes and to find strategies to avoid it