1.0TBE Bookhttps://tbenews.com/tbeAdministrator adminhttps://tbenews.com/tbe/author/administrator-admin/rich600338<blockquote class="wp-embedded-content" data-secret="you9ipmMpx"><a href="https://tbenews.com/tbe/tbe12b24/">Norway</a></blockquote><iframe sandbox="allow-scripts" security="restricted" src="https://tbenews.com/tbe/tbe12b24/embed/#?secret=you9ipmMpx" width="600" height="338" title="“Norway” — TBE Book" data-secret="you9ipmMpx" frameborder="0" marginwidth="0" marginheight="0" scrolling="no" class="wp-embedded-content"></iframe><script> /*! This file is auto-generated */ !function(d,l){"use strict";l.querySelector&&d.addEventListener&&"undefined"!=typeof URL&&(d.wp=d.wp||{},d.wp.receiveEmbedMessage||(d.wp.receiveEmbedMessage=function(e){var t=e.data;if((t||t.secret||t.message||t.value)&&!/[^a-zA-Z0-9]/.test(t.secret)){for(var s,r,n,a=l.querySelectorAll('iframe[data-secret="'+t.secret+'"]'),o=l.querySelectorAll('blockquote[data-secret="'+t.secret+'"]'),c=new RegExp("^https?:$","i"),i=0;i<o.length;i++)o[i].style.display="none";for(i=0;i<a.length;i++)s=a[i],e.source===s.contentWindow&&(s.removeAttribute("style"),"height"===t.message?(1e3<(r=parseInt(t.value,10))?r=1e3:~~r<200&&(r=200),s.height=r):"link"===t.message&&(r=new URL(s.getAttribute("src")),n=new URL(t.value),c.test(n.protocol))&&n.host===r.host&&l.activeElement===s&&(d.top.location.href=t.value))}},d.addEventListener("message",d.wp.receiveEmbedMessage,!1),l.addEventListener("DOMContentLoaded",function(){for(var e,t,s=l.querySelectorAll("iframe.wp-embedded-content"),r=0;r<s.length;r++)(t=(e=s[r]).getAttribute("data-secret"))||(t=Math.random().toString(36).substring(2,12),e.src+="#?secret="+t,e.setAttribute("data-secret",t)),e.contentWindow.postMessage({message:"ready",secret:t},"*")},!1)))}(window,document); //# sourceURL=https://tbenews.com/tbe/wp-includes/js/wp-embed.min.js </script> https://tbenews.com/tbe/wp-content/uploads/2017/07/Norway.jpg1180250TBE in Norway Katrine M. Paulsen, Rose Vikse, Arnulf Soleng, Kristin S. Edgar, Heidi H. Lindstedt, Dagny H. Dorenberg, Berit Sofie Wiklund and Åshild K. Andreassen E-CDC risk status: endemic (data as of end 2022) History and current situation In Norway, tick-borne encephalitis (TBE) has been a mandatory notifiable disease since 1975 (Norwegian Surveillance system for communicable diseases, MSIS).1 According to ECDCs classification, coastal areas in southern Norway (counties of Agder, and Vestfold and Telemark) are endemic for TBE. Further, Viken County (former Østfold, Akershus and Buskerud), and western and northern Norway to Brønnøy municipality is imperiled.2-9 The first reported case of TBE occurred in 1997 at Tromøy in Agder County.10 This is a region with holiday cabins and outdoor recreation areas for both local inhabitants and tourists, and it is known for high temperatures during spring and summer. In addition, TBE antibodies in dogs and tick-borne encephalitis virus (TBEV) in ticks have been detected in this area.8,10-13 A total number of 245 TBE cases have been reported to MSIS per February 2021 (Fig. 1). Of these, 201 cases are autochthonous infections, while 44 cases were infected abroad or have an unknown infection history. The number of cases varies annually between 1 and 41 (Table 1 and Fig. 1). Data for 2018, 2019 and 2020 shows an increase in the number of cases, especially in the county of Vestfold and Telemark (MSIS, February 2021). The TBE patients’ age distribution is in accordance with other European studies, with a higher infection rate for those older than 30 years (Table 2 and Fig. 2).14-15 According to MSIS, the reported cases in Norway are represented by the counties of Agder, Vestfold and Telemark, and Viken, all located in the southern part of the country (Fig. 3). No cases are reported from the western or northern coastal areas, nor from the area east of the Oslofjord, even though outdoor recreation activities are common in the whole country. Ticks and TBEV in Norway The castor bean tick (Ixodes ricinus) is the most common tick species in Europe,16 and considered as the major vector of the European TBE-virus.17-18 The geographical distribution of I. ricinus in Norway has been examined in several studies.2,19-23 Both Tambs-Lyche (1943) and Mehl (1983) found I. ricinus to be mainly distributed in the coastal areas of Norway, from the southeastern border to Sweden, along the southern and western coastline, up to Nordland County at ~66°N.19-20 The density of ticks varies between locations, even when separated by short distances. This is probably caused by differences in microclimatic conditions, vegetation, and density of vertebrate hosts. However, locations with a high density of ticks are found all over the major distributional range. The density of ticks declines rapidly with both increasing distance from the coast and increasing altitude. In a multi-source study, Jore et al. (2011) suggested that tick populations in Norway had undergone recent shifts in latitudinal and altitudinal range.24 This result is, however, disputed in recent studies.2,21 Although ticks are reported far outside (i.e., northeast) of the hitherto established distribution limit of I. ricinus in Norway, the vast majority of these are engorged females.22-23 Migratory birds may deposit engorged larvae or nymphs in areas where temperatures permit development to the next stage but not completion of the life cycle. Thus, such records do not constitute evidence for established and sustainable tick populations as this requires the presence of all the active stages (larvae, nymphs, and adults) in a locality for at least two consecutive seasons.25-26 Using flagging and dragging, Soleng et al. (2018) found tick larvae, nymphs and adults to be abundant at 64.5 and 65.1°N. Only a few tick nymphs and adults, and no larvae, were found at locations close to 66°N. At several locations from 66.3°N up to 67.5°N no ticks were found.2 In a recent study by Hvidsten et al (2020), the occurrence of ticks in northern Norway was examined by dragging in 109 separate locations between the latitudes of 64°N and 70°N. The northernmost location with a permanent I. ricinus population was at 66.2°N on the Island of Dønna (Fig. 4).21 It is noteworthy that the taiga tick (Ixodes persulcatus) and the meadow tick (Dermacentor reticulatus) were not detected in a large screening of ticks collected in the southern part of Norway in 2016.27 Studies in I. ricinus in Norway have detected TBEV in nymphs with prevalence ranging from 0% to 1.1%. In adult ticks collected from the same areas, the prevalence ranges from 0% to 20.6%. TBEV positive ticks have been found in sampling areas along the Norwegian coastline from the east of Viken county to Brønnøy in Nordland county.6 The highest estimated TBEV prevalence in adult ticks has been found in the counties of Rogaland and Vestfold and Telemark. In nymphs, the highest prevalence has been found in Vestfold and Telemark, Agder and Rogaland.6 Historically, the first suggested TBEV isolate from Norway was collected in I. ricinus from Vestland County (former Sogn and Fjordane) in June 1976 as described by Traavik and coworkers. Five virus strains with close serological relationship to the TBEV complex were detected in this study.28 One pool of ten nymphs collected from southern Norway has been whole genome sequenced and phylogenetically characterized. The strain, “Mandal 2009”, was found to belong to the Scandinavian group of the European TBEV subtype. Interestingly, “Mandal 2009” revealed a shorter form of the TBEV genome within the 3’ non-coding region, similar to the highly virulent “Hypr” strain.29 Seroprevalence in animals In addition to tick studies, a seroprevalence study has detected TBE antibodies in specimens from cervids (deer) collected in Farsund (Agder County) and Molde (Møre and Romsdal County). In Farsund, located on the southern coast of Norway, 41% (22 of 54 animals) were TBE-positive. This is in contrast to Molde, situated midwest, where the prevalence was 1.6% (1 of 64 animals). The same study detected antibodies to Louping ill virus (LIV), a closely related flavivirus, in 14.8% (8 of 54) of the analyzed cervid sera from Farsund.30 A