Tick‐borne encephalitis virus in cows and unpasteurized cow milk from Norway

Paulsen, Katrine Mørk; Stuen, Snorre; Neves, Carlos G. das; Suhel, Faisal; Gurung, Deepa; Soleng, Arnulf; Stiasny, Karin; Vikse, Rose; Andreassen, Åshild Kristine; Granquist, Erik Georg

doi:10.1111/zph.12554

Cited by 50 publications

(47 citation statements)

References 38 publications

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“…TBE positive samples were furthermore detected in the counties of Østfold, Rogaland and Trøndelag, which is located outside the area of reported human cases. This supports previous findings of TBE antibodies in blood donors, and in TBEV in ticks and unpasteurized cow milk (Larsen et al, ; Paulsen et al, , ; Soleng et al, ).…”

Section: Discussionsupporting

confidence: 92%

“…Moreover, Steinkjer is located too far away from TBEV endemic areas to attribute migration of mammals from endemic areas (Norwegian Surveillance System for Communicable Diseases (MSIS), ). This, in accordance with previous findings in ticks and cow's milk in non‐endemic areas (Paulsen et al, , ; Soleng et al, ), seems to indicate that TBEV is spreading northwards, which may be of relevance for public health considerations.. One must also take into consideration the role of migrating birds in the distribution TBEV in Norway (Hasle, ; Hasle et al, ; Waldenstrom et al, ). Moose preference for foraging in wet/lake areas may also contribute to the higher prevalence observed, as several studies (including in Scandinavia) have clearly identified waterbodies and well‐connected forests of oak, birch or pine, as relevant factors for tick abundance (Zeimes, Olsson, Hjertqvist, & Vanwambeke, ).…”

Section: Discussionsupporting

confidence: 89%

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Cervids as sentinel‐species for tick‐borne encephalitis virus in Norway ‐ A serological study

Paulsen

Neves

Granquist

et al. 2019

Zoonoses and Public Health

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Tick-borne encephalitis virus (TBEV) is the causative agent of tick-borne encephalitis (TBE). TBEV is one of the most important neurological pathogens transmitted by tick bites in Europe. The objectives of this study were to investigate the seroprevalence of TBE antibodies in cervids in Norway and the possible emergence of new foci, and furthermore to evaluate if cervids can function as sentinel animals for the distribution of TBEV in the country. Serum samples from 286 moose, 148 roe deer, 140 red deer and 83 reindeer from all over Norway were collected and screened for TBE immunoglobulin G (IgG) antibodies with a modified commercial enzyme-linked immunosorbent assay (ELISA) and confirmed by TBEV serum neutralisation test (SNT).The overall seroprevalence against the TBEV complex in the cervid specimens from Norway was 4.6%. The highest number of seropositive cervids was found in southeastern Norway, but seropositive cervids were also detected in southern-and central Norway. Antibodies against TBEV detected by SNT were present in 9.4% of the moose samples, 1.4% in red deer, 0.7% in roe deer, and nil in reindeer. The majority of the positive samples in our study originated from areas where human cases of TBE have been reported in Norway. The study is the first comprehensive screening of cervid species in Norway for antibodies to TBEV, and shows that cervids are useful sentinel animals to indicate TBEV occurrence, as supplement to studies in ticks. Furthermore, the results indicate that TBEV might be spreading northwards in Norway. This information may be of relevance for public health considerations and supports previous findings of TBEV in ticks in Norway. K E Y W O R D Scervids, sentinel animals, seroprevalence, tick-borne encephalitis virus | 343 PAULSEN Et AL.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 89%

Cervids as sentinel‐species for tick‐borne encephalitis virus in Norway ‐ A serological study

Paulsen

Neves

Granquist

et al. 2019

Zoonoses and Public Health

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“…Humans are mainly infected with TBEV via tick bites from infected nymphs, more rarely from infected adults, and only occasionally via consumption of unpasteurized sheep, goat or cow's milk, or other dairy products (Caini et al, 2012; Hudopisk et al, 2013; Paulsen et al, 2015; Pettersson, Golovljova, Vene, & Jaenson, 2014; Soleng et al, 2018; Suss, Schrader, Abel, Voigt, & Schosser, 1999). The presence of TBEV in unpasteurized cow milk is also recently reported from Norway (Paulsen et al, 2018). In Norway, confirmed TBE cases are reported from physicians through the Norwegian Surveillance System for Communicable Diseases (Norwegian Institute of Public Health, 2018).…”

Section: Introductionsupporting

confidence: 58%

Geographical distribution and prevalence of tick‐borne encephalitis virus in questing Ixodes ricinus ticks and phylogeographic structure of the Ixodes ricinus vector in Norway

Vikse

Paulsen

Edgar

et al. 2020

Zoonoses and Public Health

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The tick-borne encephalitis virus (TBEV), a zoonotic flaviviral infection, is endemic in large parts of Norway and Eurasia. Humans are mainly infected with TBEV via bites from infected ticks. In Norway, the main geographical distribution of ticks is along the Norwegian coastline from southeast (~59°N) and up to the southern parts of Nordland County (~65°N). In this study, we collected ticks by flagging along the coast from Østfold County to Nordland County. By whole-genome sequencing of the mitochondrial genome of Ixodes ricinus, the phylogenetic tree suggests that there is limited phylogeographic structure both in Norway and in Europe. The overall TBEV prevalence is 0.3% for nymphs and 4.3% for adults. The highest estimated TBEV prevalence in adult ticks was detected in Rogaland and Vestfold County, while for nymphs it is highest in Vestfold, Vest-Agder and Rogaland. The present work is one of the largest studies on distribution and prevalence of TBEV in ticks in Scandinavia, showing that the virus is wider distributed in Norway than previously anticipated. K E Y W O R D Sgeographical distribution, Ixodes ricinus, phylogeography, prevalence, TBEV, WGS | 371 VIKSE Et al.

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“…Additionally, a TBE outbreak was reported in Hungary in 2012, where the infection was transmitted by unpasteurised cow's milk [22]. More recently, TBEV RNA was found in unpasteurised cow milk in Norway [23]. The alimentary route is rare but should be considered as a potential risk factor as TBEV infections have expanded to multiple European sites in recent years.…”

Section: Introductionmentioning

confidence: 99%

Revealing new tick-borne encephalitis virus foci by screening antibodies in sheep milk

et al. 2020

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Background: Tick distribution in Sweden has increased in recent years, with the prevalence of ticks predicted to spread towards the northern parts of the country, thus increasing the risk of tick-borne zoonoses in new regions. Tickborne encephalitis (TBE) is the most significant viral tick-borne zoonotic disease in Europe. The disease is caused by TBE virus (TBEV) infection which often leads to severe encephalitis and myelitis in humans. TBEV is usually transmitted to humans via tick bites; however, the virus can also be excreted in the milk of goats, sheep and cattle and infection may then occur via consumption of unpasteurised dairy products. Virus prevalence in questing ticks is an unreliable indicator of TBE infection risk as viral RNA is rarely detected even in large sample sizes collected at TBE-endemic areas. Hence, there is a need for robust surveillance techniques to identify emerging TBEV risk areas at early stages.Methods: Milk and colostrum samples were collected from sheep and goats in Örebro County, Sweden. The milk samples were analysed for the presence of TBEV antibodies by ELISA and validated by western blot in which milk samples were used to detect over-expressed TBEV E-protein in crude cell extracts. Neutralising titers were determined by focus reduction neutralisation test (FRNT). The stability of TBEV in milk and colostrum was studied at different temperatures. Results:In this study we have developed a novel strategy to identify new TBEV foci. By monitoring TBEV antibodies in milk, we have identified three previously unknown foci in Örebro County which also overlap with areas of TBE infection reported during 2009-2018. In addition, our data indicates that keeping unpasteurised milk at 4 °C will preserve the infectivity of TBEV for several days. Conclusions:Altogether, we report a non-invasive surveillance technique for revealing risk areas for TBE in Sweden, by detecting TBEV antibodies in sheep milk. This approach is robust and reliable and can accordingly be used to map TBEV "hotspots". TBEV infectivity in refrigerated milk was preserved, emphasising the importance of pasteurisation (i.e. 72 °C for 15 s) prior to consumption.

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Tick‐borne encephalitis virus in cows and unpasteurized cow milk from Norway

Cited by 50 publications

References 38 publications

Cervids as sentinel‐species for tick‐borne encephalitis virus in Norway ‐ A serological study

Cervids as sentinel‐species for tick‐borne encephalitis virus in Norway ‐ A serological study

Geographical distribution and prevalence of tick‐borne encephalitis virus in questing Ixodes ricinus ticks and phylogeographic structure of the Ixodes ricinus vector in Norway

Revealing new tick-borne encephalitis virus foci by screening antibodies in sheep milk

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