Asiantuntijatarkastetut artikkelit - Original articles and reviews


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  • Pasonen, P.; Ranta, J.; Tapanainen, H.; Valsta, L.; Tuominen, P. (2019)
    International Journal of Food Microbiology 2019: Vol. 304, pp. 97 - 105
    Listeria monocytogenes causes severe consequences especially for persons belonging to risk groups. Finland is among the countries with highest number of listeriosis cases in the European Union. Although most reported cases appear to be sporadic and the maximum bacterial concentration of 100 cfu/g is not usually exceeded at retail, cold smoked and salt-cured fish products have been noted as those products with great risk especially for the elderly. In order to investigate the listeriosis risk more carefully, an exposure assessment was developed, and laboratory results for cold smoked and salt-cured salmon products were exploited. L. monocytogenes exposure was modeled for consumers in two age groups, the elderly population as a risk group and the working-age population as a reference. Incidence was assessed by estimating bacterial growth in the food products at three temperatures. Bayesian estimation of the risk was based on bacterial occurrence and product consumption data and epidemiological population data. The model builds on a two-state Markov chain describing repeated consumption on consecutive days. The cumulative exposure is probabilistically governed by the daily decreasing likelihood of continued consumption and the increasing bacterial concentrations due to growth. The population risk was then predicted with a Poisson distribution accounting for the daily probabilities of purchasing a contaminated product and the cumulative total probability of infection from its use. According to the model presented in this article, elderly Finns are at a greater risk of acquiring listeriosis than healthy adults. The risk for the elderly does not fully diminish even if the products have been stored at the recommended temperature (between 0 and 3 °C). It can be concluded that the stage after retail, i.e. food handling and storage by consumer or professional kitchens, is essential to protection against listeriosis. The estimation model provides means for assessing the joint impacts of these effects.
  • Kaila, M.; Marjoniemi, I.; Nokireki, T. (2019)
    Acta Veterinaria Scandinavica 2019: Vol. 61, No. 15
    Seventy-two canine serum samples were analyzed for post-vaccination serum titers of rabies antibodies. The samples were divided into two groups: Group 1 dogs (n = 36) were imported dogs from the Russian Federation (n = 31) or Romania (n = 5), with a mean serum antibody titer value of 1.54 IU/mL. Group 2 dogs (n = 36) were Finnish dogs vaccinated in Finland, with a mean titer of 4.19 IU/mL. Altogether, 14 (39%) dogs (CI 95% 23–56) were without detectable antibodies (≤ 0.1 IU/mL) in Group 1, whereas in Group 2, all dogs had an antibody titer greater than 0.1 IU/mL. A statistically significant difference was observed between these groups when comparing the proportions of dogs with antibody levels less than or exceeding 0.5 IU/mL. In Group 1, 19 out of the 36 dogs (CI 95% 36–70) had serum titer values < 0.5 IU/mL, while in Group 2, only 2 dogs had serum titer values < 0.5 IU/mL. Despite the small sample size, this raises concern over the imported dogs having insufficient antibody levels required for international travel and implies that these dogs had perhaps not been vaccinated, even though they had documentation of vaccination upon arrival.
  • Jaakkonen, A.; Castro, H.; Hallanvuo, S.; Ranta, J.; Rossi, M.; Isidro, J.; Lindström, M.; Hakkinen, M. (2019)
    Applied and Environmental Microbiology 2019: Vol. 85, No. 7
    Shiga toxin-producing Escherichia coli (STEC) and Campylobacter jejuni are notable health hazards associated with the consumption of raw milk. These bacteria may colonize the intestines of asymptomatic cattle and enter bulk tank milk via fecal contamination during milking. We studied the frequency of STEC O157:H7 and C. jejuni contamination in tank milk (n = 785) and the in-line milk filters of milking machines (n = 631) versus the frequency of isolation from cattle feces (n = 257) on three Finnish dairy farms for 1 year. Despite simultaneous isolation of STEC O157:H7 (17%) or C. jejuni (53%) from cattle, these bacteria were rarely isolated from milk filters (2% or <1%, respectively) and milk (0%). As revealed by phylogenomics, one STEC O157:H7 strain at a time was detected on each farm and persisted for ≤12 months despite rigorous hygienic measures. C. jejuni strains of a generalist sequence type (ST-883 and ST-1080) persisted in the herds for ≥11 months, and several other C. jejuni types were detected sporadically. The stx gene carried by STEC was detected more frequently from milk filters (37%) than from milk (7%), suggesting that milk filters are more suitable sampling targets for monitoring than milk. A questionnaire of on-farm practices suggested lower stx contamination of milk when major cleansing in the barn, culling, or pasturing of dairy cows was applied, while a higher average outdoor temperature was associated with higher stx contamination. Because pathogen contamination occurred despite good hygiene and because pathogen detection from milk and milk filters proved challenging, we recommend heat treatment for raw milk before consumption.
  • Alisauskaite, N.; Cizinauskas, S.; Jeserevics, J.; Rakauskas, M.; Cherubini, G.; Anttila, M.; Steffen, F. (2019)
    Journal of Veterinary Internal Medicine Vol. 33, No. 3
    Background There is a successful outcome after surgical management of spinal arachnoid diverticula (SAD) in up to 82% of cases. Hypothesis/Objectives We hypothesized that Pugs have favorable short‐term and poor long‐term prognosis after surgical treatment of thoracolumbar SAD. The aim of the present investigation was to describe clinical findings, short‐ and long‐term outcomes, and follow‐up magnetic resonance imaging (MRI) findings in Pugs with thoracolumbar SAD. Animals Twenty‐five client owned Pugs with 12‐month follow‐up information after surgical treatment of thoracolumbar SAD. Methods Multicenter retrospective case series. All medical records were searched for Pugs diagnosed with SAD. Data regarding signalment, history, surgical procedure, outcome, histopathology, and follow‐up MRI results were extracted. Results Mean age at presentation was 7.32 (range 2‐11) years, 80% were males. Short‐term outcome was available in 25 dogs, and improvement was confirmed in 80% of dogs. Long‐term outcome was available in 21 dogs, and deterioration was confirmed in 86% of cases, with late‐onset recurrence of clinical signs after initial postsurgical improvement affecting 85% of Pugs. A moderate correlation (r = 0.50) was found between duration of clinical signs and outcome. In 8 dogs with deteriorating clinical signs, follow‐up MRI revealed regrowth of the SAD in 2 cases, new SAD formation in 2 cases, and intramedullary T2W hyperintensity/syringomyelia in 6 cases. Conclusions and Clinical Importance This study suggests that Pugs with thoracolumbar SAD do not have a favorable long‐term prognosis after surgical treatment for reasons yet to be determined.
  • Wisselink, H.; Wisselink, H.; Smid, B.; Plater, J.; Ridley, A.; Andersson, A.-M.; Aspán, M.; Pohjanvirta, T.; Vähänikkilä, N.; Larsen, H.; Høgberg, J.; Colin, A.; Tardy, F. (2019)
    BMC Veterinary Research 2019: Vol. 15, No. 86.
    Background Several species-specific PCR assays, based on a variety of target genes are currently used in the diagnosis of Mycoplasma bovis infections in cattle herds with respiratory diseases and/or mastitis. With this diversity of methods, and the development of new methods and formats, regular performance comparisons are required to ascertain diagnostic quality. The present study compares PCR methods that are currently used in six national veterinary institutes across Europe. Three different sample panels were compiled and analysed to assess the analytical specificity, analytical sensitivity and comparability of the different PCR methods. The results were also compared, when appropriate, to those obtained through isolation by culture. The sensitivity and comparability panels were composed of samples from bronchoalveolar fluids of veal calves, artificially contaminated or naturally infected, and hence the comparison of the different methods included the whole workflow from DNA extraction to PCR analysis. Results The participating laboratories used i) five different DNA extraction methods, ii) seven different real-time and/or end-point PCRs targeting four different genes and iii) six different real-time PCR platforms. Only one commercial kit was assessed; all other PCR assays were in-house tests adapted from published methods. The analytical specificity of the different PCR methods was comparable except for one laboratory where Mycoplasma agalactiae was tested positive. Frequently, weak-positive results with Ct values between 37 and 40 were obtained for non-target Mycoplasma strains. The limit of detection (LOD) varied from 10 to 103 CFU/ml to 103 and 106 CFU/ml for the real-time and end-point assays, respectively. Cultures were also shown to detect concentrations down to 102 CFU/ml. Although Ct values showed considerable variation with naturally infected samples, both between laboratories and tests, the final result interpretation of the samples (positive versus negative) was essentially the same between the different laboratories. Conclusion With a few exceptions, all methods used routinely in the participating laboratories showed comparable performance, which assures the quality of diagnosis, despite the multiplicity of the methods.
  • Mikkelä, A.; Ranta, J.; Tuominen, P. (2019)
    Risk Analysis 2019
    Several statistical models for salmonella source attribution have been presented in the literature. However, these models have often been found to be sensitive to the model parameterization, as well as the specifics of the data set used. The Bayesian salmonella source attribution model presented here was developed to be generally applicable with small and sparse annual data sets obtained over several years. The full Bayesian model was modularized into three parts (an exposure model, a subtype distribution model, and an epidemiological model) in order to separately estimate unknown parameters in each module. The proposed model takes advantage of the consumption and overall salmonella prevalence of the studied sources, as well as bacteria typing results from adjacent years. The latter were used for a smoothed estimation of the annual relative proportions of different salmonella subtypes in each of the sources. The source‐specific effects and the salmonella subtype‐specific effects were included in the epidemiological model to describe the differences between sources and between subtypes in their ability to infect humans. The estimation of these parameters was based on data from multiple years. Finally, the model combines the total evidence from different modules to proportion human salmonellosis cases according to their sources. The model was applied to allocate reported human salmonellosis cases from the years 2008 to 2015 to eight food sources.
  • Kontturi, M.; Junn, R.; Simojoki, H.; Malinen, E.; Seuna, E.; Klitgaard, K.; Kujala-Wirth, M.; Soveri, T.; Pelkonen, S. (2019)
    BMC Veterinary Research 2019: Vol. 15, No. 44
    Background: Severe outbreaks of bovine interdigital phlegmon (IP) have occurred recently in several free stall dairy herds in Finland. We studied the aetiology of IP in such herds, and the association of bacterial species with the various stages of IP and herds of various morbidity of IP. Nineteen free stall dairy herds with IP outbreaks and three control herds were visited and bacteriological samples collected from cows suffering from IP (n = 106), other hoof diseases (n = 58), and control cows (n = 64). The herds were divided into high morbidity (morbidity ≥50%) and moderate morbidity groups (9–33%) based on morbidity during the first two months of the outbreak. Results: F. necrophorum subspecies necrophorum was clearly associated with IP in general, and T. pyogenes was associated with the healing stage of IP. Six other major hoof pathogens were detected; Dichelobacter nodosus, Porphyromonas levii, Prevotella melaninogenica, Treponema spp. and Trueperella pyogenes. Most of the samples of acute IP (66.7%) harboured both F. necrophorum and D. nodosus. We found differences between moderate morbidity and high morbidity herds. D. nodosus was more common in IP lesion in high than in moderate morbidity herds. Conclusions: Our result confirms that F. necrophorum subspecies necrophorum is the main pathogen in IP, but also T. pyogenes is associated with the healing stage of IP. Our results suggest that D. nodosus may play a role in the severity of the outbreak of IP, but further research is needed to establish other bacteriological factors behind these severe outbreaks.
  • Isomursu, M.; Koivusaari, J.; Stjernberg, T.; Venäläinen, E.-R.; Hirvelä-Koski, V. (Springer, 2018)
    The white-tailed eagle (Haliaeetus albicilla) suffered a severe population decline due to environmental pollutants in the Baltic Sea area ca. 50 years ago but has since been recovering. The main threats for the white-tailed eagle in Finland are now often related to human activities. We examined the human impact on the white-tailed eagle by determining mortality factors of 123 carcasses collected during 2000-2014. Routine necropsy with chemical analyses for lead and mercury were done on all carcasses. We found human-related factors accounting for 60% of the causes of death. The most important of these was lead poisoning (31% of all cases) followed by human-related accidents (e.g. electric power lines and traffic) (24%). The temporal and regional patterns of occurrence of lead poisonings suggested spent lead ammunition as the source. Lead shot was found in the gizzards of some lead-poisoned birds. Scavenging behaviour exposes the white-tailed eagle to lead from spent ammunition.
  • Hallanvuo, S.; Herranen, M.; Jaakkonen, A.; Nummela, M.; Ranta, J.; Botteldoorn, N.; De Zutter, L.; Fredriksson-Ahomaa, M.; Hertwig, S.; ohannessen, G.S.; Ludewig, M.; Messelhäußer, U.; Sigvart-Mattila, P.; Thisted-Lambertz, S.; Thure, T.; Vatunen, E.; Interlaboratory study group (Elsevier, 2018)
    EN ISO 10273 method for the detection of pathogenic Yersinia enterocolitica in foods was validated in the project Mandate M/381 funded by European Commission. A total of 14 laboratories from five European countries participated in the interlaboratory study (ILS) organized during 2013 and 2014. Before the ILS, the method was revised by an international group of experts and the performance of the revised method was assessed in an ILS study. The results are published as a part of the standard EN ISO 10273 revision. The study included three rounds with different sample types; raw milk, iceberg lettuce and minced meat, inoculated with a low and high level of pathogenic Y. enterocolitica strains representing major pathogenic bioserotypes 4/O:3 and 2/O:9. The homogeneity and stability of the samples were verified before dispatching them to the laboratories. The results demonstrated the method sensitivity of 96% in raw milk, 97% in minced meat, and 98% in lettuce at high inoculation level of pathogenic Y. enterocolitica. The specificity was 100% in raw milk, 96% in minced meat, and 98% in lettuce. The level of detection, LOD50, varied between study rounds, being 9.4 CFU/25 ml in raw milk, 9.9 CFU/25 g in minced meat and 63 CFU/25 g in lettuce samples. During the study, confirmation by using real-time PCR method ISO/TS 18867 together with pyrazinamidase testing was also validated, as alternative to conventional biochemical confirmation. When comparing different isolation steps used in the revised method during the study rounds, PSB enrichment and plating on CIN after alkaline (KOH) treatment showed the highest sensitivity (52–92%) in raw milk and minced meat samples. In lettuce samples, however, ITC with KOH treatment before plating on CIN showed higher sensitivity (64% at low level; 82% at high level) than plating on CIN from PSB with KOH treatment (44% at low level; 74% at high level). Statistical analysis of different isolation steps supported the use of two enrichment media, PSB and ITC, in the revised method. Recovery of pathogenic Y. enterocolitica on CIN was most efficient after KOH treatment and, based on the analysis, plating on CIN agar without KOH treatment could be left as optional procedure in the method.
  • Dillard, Kati J.; Hytönen, Marjo K.; Fischer, Daniel; Tanhuanpää, Kimmo; Lehti, Mari S.; Vainio-Siukola, Katri; Sironen, Anu; Anttila, Marjukka (PlosOne, 2018)
    Ciliopathies presenting as inherited hepatorenal fibrocystic disorders are rare in humans and in dogs. We describe here a novel lethal ciliopathy in Norwich Terrier puppies that was diagnosed at necropsy and characterized as diffuse cystic renal disease and hepatic fibrosis. The histopathological findings were typical for cystic renal dysplasia in which the cysts were located in the straight portion of the proximal tubule, and thin descending and ascending limbs of Henle’s loop. The pedigree of the affected puppies was suggestive of an autosomal recessive inheritance and therefore, whole exome sequencing and homozygosity mapping were used for identification of the causative variant. The analyses revealed a case-specific homozygous splice donor site variant in a cilia related gene, INPP5E: c.1572+5G>A. Association of the variant with the defect was validated in a large cohort of Norwich Terriers with 3 cases and 480 controls, the carrier frequency being 6%. We observed that the identified variant introduces a novel splice site in INPP5E causing a frameshift and formation of a premature stop codon. In conclusion, our results suggest that the INPP5E: c.1572+5G>A variant is causal for the ciliopathy in Norwich Terriers. Therefore, genetic testing can be carried out in the future for the eradication of the disease from the breed.
  • Nokireki, Tiina; Tammiranta, Niina; Kokkonen, Ulla-Maija; Kantala, Tuija; Gadd, Tuija (Wiley, 2018)
    A tentative novel member of the genus Lyssavirus, designated as Kotalahti bat lyssavirus, was detected in a Brandt's bat (Myotis brandtii) in Finland. Based on phylogenetic analysis, the virus differs from other known lyssaviruses, being closely related to Khujand virus, Aravan virus, Bokeloh bat lyssavirus and European bat lyssavirus 2.
  • Lienemann, Taru; Beyer, Wolfgang; Pelkola, Kirsti; Rossow, Heidi; Rehn, Alexandra; Antwerpen, Markus; Grass, Gregor (BioMed Central, 2018)
    Anthrax, the zoonotic disease caused by the gram-positive bacterium Bacillus anthracis, is nowadays rare in northern parts of Europe including Finland and Scandinavia. Only two minor outbreaks of anthrax in 1988 and in 2004 and one sporadic infection in 2008 have been detected in animals in Finland since the 1970’s. Here, we report on two Finnish B. anthracis strains that were isolated from spleen and liver of a diseased calf related to the outbreak in 1988 (strain HKI4363/88) and from a local scrotum and testicle infection of a bull in 2008 (strain BA2968). These infections occurred in two rural Finnish regions, i.e., Ostrobothnia in western Finland and Päijänne Tavastia in southern Finland, respectively.
  • Tuomola, Juha; Yemshanov, Denys; Huitu, Hanna; Hannunen, Salla (2018)
    Surveying multiple invasive pest species at the same time can help reduce the cost of detecting new pest invasions. In this paper, we describe a new method for mapping the relative likelihood of pest invasion via plant propagation material in a geographic setting. The method simulates the invasion of a range of pest species, including arrival in an uninvaded area, spread, and survival in a novel landscape, using information on the spatial and temporal distribution of the suitable host crop species and tentative knowledge of the spread and survival capacities of the target pests. The methodology is applied to a gridded map in which each map cell represents a site in a landscape. The method uses stochastic simulations to depict plausible realizations of the invasion outcomes and estimate the distribution of pest invasion likelihood for each cell in the area of concern. The method then prioritizes the cells based on the stochastic invasion outcomes using a pairwise stochastic dominance rule and a hypervolume indicator. We demonstrate the approach by assessing the relative likelihood of pest invasion for strawberry production in Finland. Our method helps to differentiate sites in a landscape using both the estimates of pest invasion risk and their uncertainty. It can be applied to prioritize sites for plant health surveys and allocate survey resources among large geographic regions. The approach is generalizable and can be used in situations where knowledge of the harmful pest species is poor or nonexistent.
  • Nokireki, T.; Sironen, T.; Smure, T.; Karkamo, V.; Sihvonen, L.; Gadd, T. (2017)
    European bat lyssavirus type 2 (EBLV-2) was detected in Finland in a Daubenton’s bat (Myotis daubentonii) found in the municipality of Inkoo (60°02′45″N, 024°00′20″E). The bat showed neurological signs and was later found dead. The laboratory analysis revealed the presence of lyssavirus, and the virus was characterized as EBLV-2. This isolation of EBLV-2 was the second time that the virus has been detected in a Daubenton’s bat in Finland. This provides additional proof that EBLV-2 is endemic in the Finnish Daubenton’s bat population.
  • Nokkireki, T.; Jakava-Viljanen, M.; Virtala, A.-M.; Sihvonen, L. (2017)
    Background: Rabies is preventable by pre- and/or post-exposure prophylaxis consisting of series of rabies vaccinations and in some cases the use of immunoglobulins. The success of vaccination can be estimated either by measuring virus neutralising antibodies or by challenge experiment. Vaccines based on rabies virus offer cross-protection against other lyssaviruses closely related to rabies virus. The aim was to assess the success of rabies vaccination measured by the antibody response in dogs (n = 10,071) and cats (n = 722), as well as to investigate the factors influencing the response to vaccination when animals failed to reach a rabies antibody titre of ≥ 0.5 IU/ml. Another aim was to assess the level of protection afforded by a commercial veterinary rabies vaccine against intracerebral challenge in mice with European bat lyssavirus type 2 (EBLV-2) and classical rabies virus (RABV), and to compare this with the protection offered by a vaccine for humans. Results: A significantly higher proportion of dogs (10.7%, 95% confidence interval CI 10.1–11.3) than cats (3.5%; 95% CI 2.3–5.0) had a vaccination antibody titre of < 0.5 IU/ml. In dogs, vaccination with certain vaccines, vaccination over 6 months prior the time of antibody determination and vaccination of dogs with a size of > 60 cm or larger resulted in a higher risk of failing to reach an antibody level of at least 0.5 IU/ml. When challenged with EBLV-2 and RABV, 80 and 100% of mice vaccinated with the veterinary rabies vaccine survived, respectively. When mice were vaccinated with the human rabies vaccine and challenged with EBLV-2, 75–80% survived, depending on the booster. All vaccinated mice developed sufficient to high titres of virus-neutralising antibodies (VNA) against RABV 21–22 days post-vaccination, ranging from 0.5 to 128 IU/ml. However, there was significant difference between antibody titres after vaccinating once in comparison to vaccinating twice (P < 0.05). Conclusions: There was a significant difference between dogs and cats in their ability to reach a post vaccination antibody titre of ≥ 0.5 IU/ml. Mice vaccinated with RABV-based rabies vaccines were partly cross-protected against EBLV-2, but there was no clear correlation between VNA titres and cross-protection against EBLV-2. Measurement of the RABV VNA titre can only be seen as a partial tool to estimate the cross-protection against other lyssaviruses. Booster vaccination is recommended for dogs and cats if exposed to infected bats.
  • Jaakkonen, A.; Salmenlinna, S.; Rimhanen-Finne, R.; Lundström, H.; Heinikainen, S.; Hakkinen, M.; Hallanvuo, S. (2017)
    Shiga toxin-producing, sorbitol-fermenting Escherichia coli O157 (SF O157) has emerged as a cause of severe human illness. Despite frequent human findings, its transmission routes and reservoirs remain largely unknown. Foodborne transmission and reservoir in cattle have been suspected, but with limited supporting evidence. This study describes the outbreak of SF O157 that occurred in Finland in 2012. The outbreak originated from a recreational farm selling unpasteurized milk, as revealed by epidemiologic and microbiological investigations, and involved six hospitalized children and two asymptomatic adults with culture-confirmed infection. An identical strain of SF O157 was isolated from patients, cattle and the farm environment, and epidemiologic analysis suggested unpasteurized milk as the vehicle of transmission. This study reports the first milkborne outbreak of SF O157, provides supporting evidence of cattle as a reservoir and highlights the health risks related to the consumption of unpasteurized milk.
  • Kyyrö, J.; Sahlstrom, L.; Lyytikäinen, T. (2017)
    The NORA rapid risk assessment tool was developed for situations where there is a change in the disease status of easily transmissible animal diseases in neighbouring countries or in countries with significant interactions with Finland. The goal was to develop a tool that is quick to use and will provide consistent results to support risk management decisions. The model contains 63 questions that define the potential for entry and exposure by nine different pathways. The magnitude of the consequences is defined by 23 statements. The weight of different pathways is defined according to the properties of the assessed disease. The model was built as an Excel spreadsheet and is intended for use by animal health control administrators. As an outcome, the model gives the possible pathways of disease entry into the country, an overall approximation for the probability of entry and the subsequent exposure, an overall estimate for the consequences and a combined overall risk estimate (probability multiplied by magnitude of consequences). Model validity was assessed by expert panels. Outside Africa, African swine fever is currently established in Russia and Sardinia. In addition, there have been cases in both wild boar and domestic pigs in Latvia, Lithuania, Poland and Estonia. Finland has frequent contacts with Russia and Estonia, especially through passengers. The risk of African swine fever (ASF) introduction into Finland was tested with NORA for the situation in December 2015, when ASF was endemic in many parts of Russia, Africa and Sardinia and was present in Baltic countries and in Poland. African swine fever was assessed to have a high probability of entry into Finland, with high consequences and therefore a high overall risk.
  • Holopainen, R.; Eriksson-Kallio, A.M.; Gadd, T. (2017)
    Archives of Virology 2017: Vol. 162, No. 11, pp. 3459 - 3471
    Abstract Infectious pancreatic necrosis virus (IPNV) has been isolated annually since 1987 from salmonids without clinical signs at coastal fish farms in Finland. In the inland area, viral isolations were rare until 2012, when IPNV was detected at several freshwater fish farms. Between 2013 and 2015, the infection spread and IPNV was continuously isolated from several farms, both inland and on the coast. The aim of this study was to genetically characterise the IPNV isolates collected from Finnish coastal and inland fish farms over the last 15 years, and to detect genetic changes that may have occurred in the virus populations during the study period. The partial VP2 gene sequence from 88 isolates was analysed. In addition, a complete genomic coding sequence was obtained from 11 isolates. Based on the genetic analyses, Finnish IPNV isolates belong to three genogroups: 2, 5 and 6. The genetic properties of the isolates appear to vary between inland farms producing juveniles and food fish farms in the coastal region: the inland farms harboured genogroup 2 isolates, whereas at coastal farms, all three genogroups were detected. Little genetic variation was observed within the Finnish genogroup 2 and 5 isolates, whereas among the genogroup 6 isolates, two subgroups were detected. All isolates studied demonstrated amino acid patterns in the viral VP2 gene previously associated with avirulence. However, increased mortality was detected at some of the farms, indicating that more research is needed to clarify the relationship between the pathogenicity and genetic properties of IPNV isolates from different genogroups.
  • Vennerström, P.; Välimäki, E.; Lyytikäinen, T.; Hautaniemi, M.; Vidgren, G.; Koski, P. (2017)
    The eradication of viral haemorrhagic septicaemia virus (VHSV Id) from Finnish brackish-water rainbow trout Oncorhynchus mykiss farms located in the restriction zone in the Province of Åland, Baltic Sea, failed several times in the 2000s. The official surveillance programme was often unable to find VHSV-positive populations, leading to the misbelief in the fish farming industry that virus eradication could be achieved. The ability of 3 other surveillance programmes to detect infected fish populations was compared with the official programme. One programme involved syndromic surveillance based on the observation of clinical disease signs by fish farmers, while 2 programmes comprised active surveillance similar to the official programme, but included increased sampling frequencies and 2 additional tests. The syndromic surveillance concentrated on sending in samples for analysis when any sign of a possible infectious disease at water temperatures below 15°C was noticed. This programme clearly outperformed active surveillance. A realtime reverse transcriptase-polymerase chain reaction method proved to be at least as sensitive as virus isolation in cell culture in detecting acute VHSV infections. An ELISA method was used to test fish serum for antibodies against VHSV. The ELISA method may be a useful tool in VHSV eradication for screening populations during the follow-up period, before declaring an area free of infection.
  • Koski, P.; Anttila, P.; Kuusela, J. (2016)
    Killing of Gyrodactylus salaris By heat and chemical disinfection

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